Lexus SC430 :: 2002 - Intermittent Hesitation Or Stumble / Momentary Power Loss
Nov 4, 2015
When I take off from a start it will intermittently stumble or hesitate, seems to be around 1500 rpm. have also noted it at higher speed while cruising. its more like a momentary power cut than a miss fire.
So far I have done the following
new fuel filters
clean MAF
new PCV valve
new spark plugs
check all hoses and plugs etc
injector clean
checked techstream for codes. there is one for a heated O2 sensor but dont think thats it.
2002. SC430
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I just bought a 2004 F350 6.0 cclb 6 speed with 260k on it. The previous owner seemed to have taken good care of the truck. It is basically stock with the exception of the blue spring mod, and a sinister diesel coolant filter. Anyways, I brought the truck home and it ran great. Now I have an issue that needs to be addressed.
The issue: I am experiencing a intermittent loss of power, stall, or stumble when engine is cold. After sitting all night the truck will start fine and idle fine. But when I try to accelerate and bring engine RPM up the engine will stumble and lose all throttle response, when this happens the WTS and WIF light flash. Sometimes it just stumbles, sometimes the truck will actually die and then restart. The issue seems to go away after the engine has reached operating temp.
I did some research on the issue and it seems there is actually a TSB out from ford for this issue. It explains that some 2003-2004 6.0's might have wiring harness chaffing issues. This is what the issue I am having seems like to me (shorting harness). I looked up codes on the truck and there is an active code (#8 glow plug circuit fault). I did a short visual inspection of harness and didn't see anything out of the ordinary. But i wonder if it would be worth changing both sides of the glow plug harness?
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I've mentioned in earlier posts that my speedometer has been swinging around wildly off and on, and that on two occasions this has been coupled with a momentary engine stumble. This morning on the way to work it was doing it again but this time the engine stumble happened several times as well. I plan to check the speed sensor, but I wonder how this is also causing the engine stumble?
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Alright, my '06 SV6 AWD has a major problem...I'm about to blow it up! But seriously, I've had an issue for a few weeks now with intermittent acceleration/hesitation problems. Basically it started as a rare occurrence and is happening more often now. Yesterday, it did it consistently for 20 minutes on one trip around town. 1 hour later, it didn't happen noticeably at all on the way home. It happens while accelerating, usually from a stop, but also sometimes when cruising at highway speeds.
The car does not stall or stumble. Everything sounds fine and smooth, but when accelerating from a stop, the car will stop accelerating and the speed slowly drops off. Pushing the accelerator down further to the floor does nothing for several seconds, then the power returns and the car responds to whatever position the pedal is in. If you haven't pushed further it continues accelerating where you left off. If you've got it to the floor, it takes off quickly. When cruising at speed, you don't notice anything until you start slowing down, and the pedal reacts the same way. NOTE: The engine does not rev up when this is happening. It's not like the tranny is slipping.
It really seems like a fuel delivery problem and not transmission. It has all the normal symptoms of a failing pump. And about 2 months ago, I had the fuse for the fuel pump melt (not blow). These problems didn't happen immediately after, but they did happen a few weeks after that.
That said, I have noticed that when cruising I occasionally hear a light clunking noise that sounds like the rear diff engaging. I assume this is just due to play in the drive train. I also had to recently do the expensive versatrack fluid flush and fill to get rid of the diff groan. But I still feel like it's probably fuel related because the engine doesn't rev up.
Here's what I've done so far:
1. Checked the wires at the problematic C305 connector. I already had to completely redo that connector several years ago as the PO had removed the connector and directly twisted all wires together covered the with tape, and filled hole with silicon. BTW, GM does sell all of those harnesses with length of wire, connectors, and heat shrink covers for reasonable $$. Anyway, found 2 wires with insulation slightly shaved off. Neither was for the fuel pump, everything else still looked good.
2. Checked voltage at the gray fuel pump wire just after the new harness (about a foot before the fuel pump). And checked the ground at the same location. Haven't checked at pump connector because I don't want to drop tank just yet. Both were fine with almost no resistance on power between that location back to the fuse box. So, it doesn't look like a bad or shorted wire unless it is in that short length up to the fuel pump that I cannot access w/o dropping the tank.
3. Checked fuel pressure at the fuel rail. The pressure when primed and idling is a consistent 60-62 psi. I know the manual states 60psi as the max. Maybe this has something to do with it?? Perhaps my cheap actron pressure guage is a bit off or perhaps the pressure regulator is bad. Could this cause the issue.
4. Checked for DTC's with code reader. No active or pending codes.
The other things I think could be the cause based on internet research:
1. Accelerator Pedal Position (APP) sensor
2. Throttle Position Sensor (TPS)
3. PCM
4. O2 sensor
The problem is that all of those things tend to set a DTC from what I've read. I still think the fuel pump us going bad and the pressure was fine because the problem is intermittent. I just don't want to spend the $$ on a new pump to find out it was something else.
Tomorrow, I will have access to a scanner that can log 10 seconds of data from the computers while driving. I think that might shed some light if I can get the problem to happen when recording. I'm not familiar with fuel trims and the lot.
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2001.5 V6 Tiptronic ... A few times in the last couple of months I've felt what I think is a quick lapse in power, like 1 sec. or less. I say "think" because sometimes a bump in the road, traction related, or some other perceived issue can feel strange, especially when cruising along on a smooth cruise-controlled drive.
Each time this has occurred I've been in cruise control, freeway driving, relatively low speeds (65 MPH) . No other signs of anything wrong, chimes, flickering lights, vibration, nothing.
I can't be sure this time around but it seems in the past it's been on the same stretch of freeway, perhaps the same spot. In other words perhaps just a subtle anomaly in the road ...
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Twice now I've been driving and there was a few second lull where pressing the gas did nothing. The first time I was passing a car on the right, and the other I was pulling out between two cars to make a left on a busy road. Is there some kind of collision detection system that's causing the loss of acceleration? It's odd that the 2 times it happened I was so close to other vehicles. It's concerning since I needed to pull out quickly the second time and I was stuck for a few seconds without acceleration.
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I have had the car sense it was brand new and sense I have had it I have had this problem. I mostly notice a problem soon after starting the engine up and come to a stop, but is not limited to that all the times. When I come to a stop the car will feel like it is struggling to maintain an idle as I sit at the light or stop sign and it will actually shake the car a bit. I have noticed when it does do this the fan is on and it might be related to having the alternator trying to keep up with power draw.
I have noticed a loss of power when I am driving down the road it will cut out for maybe a half a second and come back. Usually doesn't happen more than once in one trip. I have brought it to the dealership multiple times to try and see if the can hunt down a problem but it keeps coming back with a clean bill of health. So my question is it something that is normal with diesel engines or is it something that I should take a further look at.
And while on the topic of diesel engines, my uncle a mechanic for diesel engines suggested that I spray a small amount of propane into the air intake to burn up sludge to keep the engine relatively clean. Need to get second opinion of that idea before I try it?
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I bought a 2002 santa fe last week. it was a non runner. the previous owner said he took it to the garage for a crank oil seal leak. when he went to collect the car they had removed the head saying oil was leaking from the gasket. he towed it away and i bought it. i have refitted the head. the engine runs smooth at idle. when i first start up in the morning there is a loud rattle for a second or so. it sounds like a diesel starting up. when i am driving it hesitates and seems to lose power. also at a certain position on the accelerator pedal this rattle is there. it goes away when i accelerate more.
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The car started rough idling and a few weeks ago while driving "lost power" momentarily. I went to take a look at it and even just idling it will randomly drop 1000 rpm, or when the gas is one in P it does the same thing. also the dash lights dim at the same time.
I pulled these codes (below). I cleared the codes and tried to replicate with no luck. The car had been sitting in a parking lot outside for a few days and it has been -15C. I asked if it seemed to only happen when it was warm (the week before it was +10C) and they said yes. It has been another week (still cold) and the codes have not returned.
Quick google of these codes suggests maybe a throttle position sensor and/or loose battery connection.
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It did this funny thing about 4-5 times over a span of about 24 hrs before dying and then won't start. It was like hitting the limit on a speed governed car.....sudden momentary loss of power..and it seemed to be when accelerating if that matters. The thing I'm sure of at this point is that the fuel pump is not coming on when the key is turned, I know that sound well, but also checked it at the external connector with a test light for thoroughness. I also found a blown fuse under the hood which coincided with a little smokey smell inside the car when the fuse was replaced and blew again.
There is no spark as well. My Haynes book says that the PCM is behind the passenger kick panel but I only see the eecv and it doesn't smell burnt. The IFS is good. There is power at the coil packs. Fuel pump relay fuse is good. Is it more likely the ccrm since it contains the fuel pump relay and PCM relay or could it still be the eecv? It feels like one part failed but is causing more than one "problem", no power to fuel pump and no spark.
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Having problems where sometimes the car won't go into gear, other times it's fine? The problem started after some hard acceleration in 3rd, there was what felt like a momentary loss in power. I dipped the clutch as I thought a boost pipe had popped off, all was fine (still seeing boost when revved). After this it got progressively harder to get gears, finally resulting in not being able to get into gear at all.
I found I could get it into 1st with the engine off and could go up gears normally, but couldn't change down without stopping and turning the engine off. The clutch is working fine, the biting point is normal. The problem seams to come and go randomly, it will work fine for a while and then start playing up again. When working the gearbox feels normal, there is no grinding or wining noises. I can move between gears normally and do clutch less gear changes.
There is now a vibration which can be felt at 1000rpm when stationary. It feels like it coming from the engine/gearbox and seems like something is out of balance as it shakes the whole car. The car is on 91k, supercharged running 470hp & 370lb/ft (at flywheel) and is fitted with a Spec stage 3+ clutch and solid flywheel.
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I have a problem with my 2004 Santa Fe, 2l diesel. Will try to keep this short!
When driving it suddenly 'heaves' (not sure how else to describe it), then it cuts out. I wait about a minute and then it restarts.
At first there was no 'heave' but there would be a momentary loss of power (I thought it was the clutch). Then it progressed to the 'heave' and then cut out, this happened now and then. Very quickly it started to do it every time I drove it. My neighbor mechanic blew down the fuel line, said the fuel pump in tank sounded ok, seemed to do it more when below quarter of tank.
So I kept tank topped up, it seemed ok, then on one 11 mile journey it did it 3 times, the last time the engine management light came on, crawled it home, after which it would not start at all. The computer said it was either fuel rail or coolant sensor. Neighbor replaced coolant sensor, it started ok. Tried it next day - 6 miles and it heaved and cut out again. This time no light coming on.
I've read about cam sensor, crank shaft sensor, fuel pump at back of engine...
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Just curious about power loss issue that occurred yesterday.
I have a lengthy commute and in the afternoon drive home I get into a great deal of stop and go rush hour traffic. Yesterday about a fourth of the way in as I was slowing down the red battery light came on, the radio stopped, and interior lights dimmed, ie a general loss of power. As soon as I hit the accelerator all the power was restored. This occurred frequently the rest of the commute, but the loss of power became worse. There was never a hint that the engine was going to stall.
I assumed it was likely my battery going bad and that the car would likely not start this morning and I would jump it and get the battery checked. However, I had a full power crank. The drive to work does not have the stop and go, thus I only had to stop at a few red lights, and there was no power loss, until just as I arrived at work, the radio went off and came back on, but no battery light or anything like that.
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The primary electric fuel pump in the fuel tank of my 2004 W12 failed last month, shortly after I had set out on a cross-Canada trip from Vancouver Island to Toronto. The whole process of diagnosing and identifying the cause of the problem, mitigating it so that I could continue the trip, and finally replacing the fuel pump was kind of complex, so, here's the write-up.
The problem presented itself as a surging of the engine - a momentary loss of power - at normal highway operating speeds. The onset was progressive, but it didn't take very long - only about 60 miles of driving - from the first little cough of the engine until total failure of the pump. The first indication was failure of the car to maintain speed (while on cruise control) when climbing hills. That progressed to failure to maintain speed on flat surfaces, and finally led to the car coasting to a stop, engine stalled, at the side of the road.
I soon learned that if I floored the accelerator pedal and held it against the floor, the car would cough and burp for a few seconds, then take off like a rocket. So, for the next 40 miles, I coaxed the car into the next city by flooring it, accelerating to about 80 MPH, then coasting until the speed dropped to 20 MPH, and flooring it once again and accelerating to 80 MPH. Fortunately, I was on a remote road with few other cars, and no police.
I checked the fuses for the two fuel pumps - fuses 34 and 35 in panel C (above the left battery), and they were both OK.
The next day, I visited a VW dealer in the Canadian Rocky Mountains, and together with the parts manager and one of the technicians, we looked at the Self-Study Guides (SSGs) for the Phaeton, and looked at wiring diagrams. Eventually, we came to a tentative conclusion that the primary electric fuel pump in the fuel tank had failed. The SSGs stated that the primary electric fuel pump (the pump on the right side of the car) operates all the time, and the secondary electric fuel pump (the pump on the left side of the car) only operates during starting and during 'periods of high demand'. That made sense to us - the car started fine, and worked OK when the accelerator pedal was held to the floor (high demand). It just didn't work worth a darn at any other time... the engine would stall, or, the car would not accelerate at all.
Here are two illustrations taken from the SSGs that describe how the fuel delivery system works. The first image is taken from the 'Phaeton Overview' SSG, which applies to all vehicles. The second image is taken from the W12 engine SSG. I kind of suspect that all the Phaetons operate in the same way, regardless of engine, because the fuel tank in all the Phaetons has the same shape - two lower lobes, which means two pumps are required.
Descriptions from the SSGs
I think that there may be an error in the description above. My experience suggests that the right hand pump (identified as G6, above) is the primary pump, and the left hand pump (identified as G23) is the one that switches on during starting and periods of high demand. Note also how the identification of G6 and G23 in the illustration above is reversed from what is shown in the illustration below. I believe that the text and illustration below is correct, and the text and illustration above is incorrect.
The 'effects of failure' in the description above would, I believe, make sense if it was the left-hand pump that failed. In my case, the right hand pump failed, and the effects of failure that I experienced were as I set them out in the beginning paragraphs of this post - quite different from the 'effects of failure' of the left hand pump that are described in the SSG above.
After coming to the tentative diagnosis that the primary electric fuel pump (the right hand pump) had failed, we checked the parts stock status in North America. There was one pump in stock, but it was in the United States, and being that it was a Thursday, the pump could not be delivered before the following Tuesday. I didn't want to spend that much time waiting for it, so, we started thinking about other possible solutions.
If we could somehow get the secondary electric fuel pump - the pump on the left side of the car that only operated during starting and heavy demand - to operate, that just might put me back on the road again. So, I removed the plastic cover from the small relay that operates the secondary pump, and wrapped a rubber band around the relay, thus keeping the relay in the closed position. A short test drive proved that this solution worked just fine, the car once again operated normally. The only "problem" was that the last 25% of the fuel in the tank would be unusable, because that fuel would be left behind in the right-hand lobe of the tank - the lobe with the defective primary fuel pump.
Electric Fuel Pump Relays
Here is an illustration from the Phaeton wiring diagrams identifying the various relays above the left battery.
Here you can see the two relays for the electric fuel pumps. They are identical part numbers.
Here you can see the relay for the secondary electric fuel pump, with a rubber band wrapped around it to keep it continually closed.
Aside from the loss of use of the last 25% of the fuel in the fuel tank, the car worked just fine with the secondary electric fuel pump running all the time. There were no problems noted even under heavy acceleration. It was, however, necessary to physically remove the rubber-banded relay from its position in the relay panel whenever the car was shut down for more than half a hour. The power to this relay comes from Terminal 30 (battery direct) - it is not switched on and off with the ignition as Terminal 15 power is. This meant that if the rubber-banded relay was left in position overnight, the left hand battery would totally discharge, because the fuel pump would operate continuously all night. I discovered this the morning after the first night...
So, for the next 8 days, I drove across Canada, removing the relay each night and replacing it each morning. I didn't bother to remove it when I stopped for meals or fuel. The rest of the 3,000 mile trip was uneventful - except once, when I let the fuel tank run down a bit too close to the 1/4 full mark, and the car began surging again because the left hand lobe of the fuel tank (with the functional secondary pump) had emptied out. That was a close call, but I managed to get to a gas station and refuel.
After arriving in Toronto, I called the parts staff at my home VW dealer and ordered a new primary electric fuel pump. I discovered that the left and right hand pumps are slightly different (the various hoses coming out of the pumps are different), and I also discovered that a pump costs about $400. The parts staff suggested I order two seals (one for each side of the tank), because I would have to remove both the right and left fuel tank covers to change the right pump. The seals were not expensive.
Here are two pictures that illustrate where the pumps sit in each lobe of the fuel tank. Note the fuel filler port on the left side of the pictures (as we know, it is on the right side of the car) for orientation.
Phaeton Fuel Tank, showing pumps
Fuel Pump Access Panels
Below is a picture that shows where the access panels to the two fuel pumps are. It's easy to get to these access panels, just remove the carpeted panel from the floor of the trunk.
Here's a close-up of the right side (primary) electric fuel pump access panel.
The instructions (from the VW Repair Manual, or the ELSA / ErWin system) for replacing the fuel pump are quite well written. The repair manual suggests that the fuel tank be drained before replacing a pump. I didn't want to drain the tank, so, I ran the fuel level down as low as I dared (remembering that 1/4 full is effectively 'empty' with a failed primary pump). That proved to be adequate.
There are a heck of a lot of steps involved in disconnecting all the hoses and loosening the various components before the pump can be removed. I strongly suggest that anyone attempting this task have a printed set of instructions before starting disassembly.
The fuel pump has quite a few hoses and connections on it, but fortunately, each connector is unique in design, thus it is not possible to hook things up the wrong way when installing the new pump. It is possible to 'lose' a hose inside the tank... for this reason, I attached a small piece of string to each hose I disconnected from the pump.
The process goes more or less like this:
1) Remove the two 404 relays, to ensure no power is sent to either fuel pump.
2) Lift the rubber cover, and remove the electrical connections from both pumps (left and right).
3) Using a special tool, lift up the three fasteners that hold the cap over top of the access panel (these are NOT threaded fasteners!)
Here is a side view of the three fasteners that hold the plastic cap in place - they are friction fit, not threaded.
4) Now you have a clear view of the access panel. It will probably be dusty and rusty, and should be vacuumed clean before proceeding, to prevent crap from falling into the fuel tank when the cap is removed. The rust is due to condensation forming on the cold metal part whenever the car is filled with cold fuel from an underground storage tank.
5) A special VW tool is used to remove the locking ring from the access panel.
6) After removing the locking ring, I buffed it up with a wire brush to remove surface corrosion.
7) The plastic access cap can now be lifted. There are two electrical connectors on each fuel pump, but three possible fittings on the plastic cap. Fortunately, the three fittings are keyed differently.
8) This is what you see inside the tank after removing the plastic cap.
9) After following all the detailed instructions for disconnecting and stowing hoses, disconnecting the fuel measurement probe from the pump housing, etc., it is possible to lift the pump out. It will be full of fuel.
10) The old and new pumps, side by side. I was very surprised at the amount of crap that was trapped in the filter screen at the bottom of the pump. The car only has 60,000 miles on it, and I have always used premium fuel in it.
11) I was also a bit surprised at the discolouration of the pump components. Below you can see the old and new pumps side by side.
12) It is necessary to get access to the opposite side (in this case, the left side) fuel pump, because hoses from each pump travel horizontally across the tank and connect to the other pump.
13) Here you can see a new hose from the right side pump connecting into a T fitting above the left side pump. It is easy to thread this hose across the top of the inside of the tank.
14) As mentioned earlier, there are three possible fittings on the base of each plastic cap, but only two connectors within the fuel tank. Everything is keyed, thus improper assembly is not possible.
Once the new pump has been installed, the hoses connected, and the fuel measuring probe reset into the side of the new pump, re-assembly of everything is quite straightforward. I replaced the rubber ring around the access panel opening on each side of the tank, and I also buffed up the locking rings using a wire brush (to remove corrosion) on each side.
It was not a pleasant job - your hands get covered in fuel, and there are some hazards associated with working on an open fuel tank with vapour escaping, but it is not a particularly difficult job. It is time-consuming, though.
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I have owned this car for six months. The car now has 39K. The problem is getting worse.
Re: Lexus 2011 LS460 AWD
Subject: Hesitation / momentary loss of power when accelerating after turn.
When accelerating after a sharp turn with light to moderate acceleration, the car will have a momentary loss of power for about 1, 2, or even 3 seconds. This does not happen often, but perhaps once every two weeks and I cannot replicate the problem despite attempting to do so.
In all cases, I am talking about DRY pavement. It always happens after a sharp turn usually to the right. (Probably because most sharp turns are to the right actually it only happened once on a left turn that I will describe below.) Acceleration is light to moderate NOT hard acceleration.
In one case it caused a serious situation. I had just purchased gas and was entering a busy freeway. When accelerating, the engine had a total loss of power for a couple seconds as a large semi truck bore down on me with its air horns blaring.
I have a strong clue that may debug this problem. Once, when turning left, the car suffered a total loss of power. There was no traffic and I kept my foot lightly on the throttle. The car remained unresponsive. The engine did not stop, but it did not respond and remained this way for at least 5 seconds until I took my foot off the accelerator and then back on to the accelerator. During this period of suspended throttle, I noticed that on the right side of the dash an orange alert symbol was flashing I think it was a swerving car? I assume this indicated that the car was losing traction and the computer decided to cut power until traction was regained. But the pavement was dry, and the acceleration was normal. In no case did I ever sense that one of the wheels was slipping.
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I have a 1999 F350 200,000 miles. Now getting an intermittent engine light. Still runs well, although once or twice I felt a momentary surge at highway speeds. The light is on intermittently about 1/2 time. I read the codes and the following codes, as in the thread title, came up:
P0280 - ICP circuit out of range - low
P0113 - intake air temp sensor circuit - high input
P0470 - Exhaust back pressure sensor circuit malfunction
P0478 - Exhaust pressure control valve - high input
What would make these all code at the same time? Would these not make a noticeable problem driving? And how do I resolve these?
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2002 ... I've been getting a soft engine fault all three lights on and reduced power. This usually occurs if I accelerate hard but also happens if I take a small pot hole in the front, a little bump seems to trigger it as well. Also engine resets to normal after removing key.
It's not logging the fault as had dealer read ECU and said was not logged.
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I have a 2007 LS460 L. It has recently started losing electrical power in fraction of a second intervals. The map data sometimes works or displays an error on the screen. The radio has been functioning but now is also starting to flash off intermittently. Now when this happens it feels like the engine dies and ALL electrical is off and then power resumes. This affects steering, engine power and brakes. My wife drives this car and loved it until now.
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2001 V10 160000 miles.
1st happened Wednesday on way back. Temps all fine but had been in stop and go traffic earlier. Truck was on cruise and felt like fuel cut. I disengaged cruise. Throttle would keep it running and within 5-10 seconds it caught and ran fine.
Connected and reconnected all injectors, coil connections, tb and MAF connections. Nothing noted loose. No codes on OBD reader.
Drove around town last couple days no issues. Today towing three dirt-bikes about 45 miles. towards the end of the 45 miles. she stumbled as we crossed an intersection. Then caught and ran fine. Did it twice on way back home towards the end of the trip.
Had OBD reader in gauge mode with ignition advance, tp sensor, voltage and gallons per hour showing. None seemed to change when it stumbled.
Fuel pump is about 2 years old. Coils maybe 4 or 5 years old. Aftermarket. No codes on OBDII reader.
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Where the license plate lights get thir power from? I have a 2002 SC430 and the plug is just dangling. It goes behind the plate and then if I look under the car, it is just there by the bumper and I cannot find a connector that it can reach.
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So I have had my 02' Camry for a little over a year. Love the car, it is a 2.4L SE with a 5-speed manual. Recently it has developed this mystery misfire/hesitation under a load and at idle with the AC on. I replaced the plugs with OEM Toyota Iridium and it seemed to clear it up for about a month, but now has come back. If I start the car and turn on the AC it will intermittently start to miss but not only when the compressor is engaged and it does it every now and then under a load specifically in 4th or 5th gear under a load with lower RPM's (under 2000).
The check engine light is not on and hasn't as much as even flashed on at any time so there must not be any hard misfire codes. I want to stop by Autozone and see if they will scan it to find any stored codes but haven't had time. I would think that if it was a coil pack that it would be a hard misfire. I'm stumped. This car is in great condition...no oil leaks, interior is near perfect (replaced a worn shift knob, and door panel pieces around the window switch). Also car has 160k miles.
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