As you can see I've just had enough of this stuttering crap. Its pissing me off big time. My car stutters on the freeway at constant throttle position. It happens only when I go over uneven road surfaces. It will last for the next 5 to 10 seconds after that and will go away if I floor it. Can a faulty clutch type LSD cause this? I'm also getting a loud tranny roaring sound when I release throttle at rpms greater than 4000rpm. Is it a symptom of a dying LSD? Can I remove the LSD from my tranny and still use the tranny without the LSD?

The stuttering problem was solved when I changed out my trany fluid about 1 month ago, but now this problem is back. Did the new tranny fluid increase the threshold of the LSD before acting up? And now that the tranny fluid is old, the problem is back.

I did some TPS adjustments between 0.45V and 0.5V to see if it solved the problem. Apparently, the problem would go away maybe for a day or 2, but it returns after that. Could it be my TPS then? I was suspecting a dirty fuel filter, but it wouldn't make sense for the filter to get clogged only when I go over uneven road surfaces. I really hope someone here can give me a lead. I'm so pissed that I am close to selling my ride.

 

Do you have an aftermarket fuel rail?

Ur lsd shouldnt be causing a stuttering, especially while going straight.

 

I dont understand how uneven road surfaces would cause "stuttering". I dont see how this would be related to LSD. And my tranny is loud on decel also, but its been like that for years so I dont know if its "normal".

From your description, my first thought was TPS or maybe MAP. Dirty fuel filter wont really cause stuttering, more like sluggishness. When I think of stuttering, I picture a quick on/off type of effect, sort of like if you were to tap the gas and let go repeatedly. Is that what you are describing but its occuring at a constant throttle position? Any CEL's recently?

 

walker111, I do not have an aftermarket fuel rail. Maybe the clutch plates on the LSD are badly worn down?

RTW DC2R, the stuttering is almost identical to how you described which can be immitated with throttle on and off. But the stuttering is much more harsh than throttle on and off. Its more like misfiring. But it only happens going over uneven road surfaces. I have no CELs. But yes it happens on constant throttle input. If I floor it during the stuttering, it goes away totally. And somehow my engine feels rough during that entire journey with this problem.

Dudes, it's most likely an electrical problem. It seems when the entire car vibrates over the even road, it causes the electrical connection to be disconnected momentarily. But I have recently sanded down most of the grounding points. Even got a new earth wire for the battery. I even checked my ECU harness.

 

Do you have a VAFC controller or anything? When mine came loose (connection), I got roughly the same problem. The car goes into some weird form of limp mode.

 

If it only happens mostly on rough road, sounds like a loose ground or something. Are you using a stock ECU?

 

Nope, I'm running on Apexi PowerFC.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RTW DC2R &raquo;</TD></TR><TR><TD CLASS="quote">If it only happens mostly on rough road, sounds like a loose ground or something. Are you using a stock ECU?</TD></TR></TABLE>

Also, it went away when changing tranny fluid--- maybe triple-check grounds at-or-near the top of the tranny. Or, any other wires you might have been able to bump while changing it near the dizzy, throttle, etc.

Also try wiggling wires while the car is idling to see if anything bad happens. You might not notice it, but worth a shot. Maybe you can have a friend hold it at 4K RPMs.

-Chris

 

Okay, just spoke to a very experienced mech at my area. He swears its the TPS but since my problem is going over uneven road surfaces as well, he advises me to check my throttle cable and loosen it if its too tight.
I just swapped out my TPS. TPS calibrated to 0.45V on closed throttle. I have not adjusted my throttle cable. I want to really nail down this problem once and for all. If the problem surfaces again, I will adjust the throttle cable. Only by making changes one at a time will I be able to nail this freaking problem.

Will update you guys on the outcome. I will monitor the problem for a whole month with updates every week. Many thanks to all who contributed.

 

I actually have a very similar problem. I can't find it. I've checked all sensors with a multi-meter. I swapped out an ignitor, coil, fuel filter,and plugs. The fuel press. don't drop off. I have no dtcs. The next step I guess is draining the fuel tank, to see whats in there.

 

Keep us updated. I can't say for sure TPS would solve it since I've been on it for only 2 days. I won't be suprised it's just an overtightened throttle cable or a fuel filter. Anyway that will be the sequence of rectification for me.

 

Okay, the problem surfaced again just now. Damn TPS and loosened throttle cable did not help. Will be getting my fuel filter replaced in 2 days time.

 

Where is the car idling at? If it isn't within the OEM specifications then this will cause jerking at partial throttle. Also pull the IACV off the back of the intake manifold and give it a thorough cleaning with carb cleaner. Take the intake hose off of the throttle body. Open the butterfly valve and check inside the throttle body. If there are any ridges from carbon/gunk build up, clean thoroughly.

Has anyone adjusted anything on the throttle body? Idle screw, throtle cable, throttle stop screw?

Like Chris said check the grouds, but I would take it a step further and clean the contact areas of the ground to ensure a proper contact.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by garyc17 &raquo;</TD></TR><TR><TD CLASS="quote">As you can see I've just had enough of this stuttering crap. Its pissing me off big time. My car stutters on the freeway at constant throttle position. It happens only when I go over uneven road surfaces. It will last for the next 5 to 10 seconds after that and will go away if I floor it. </TD></TR></TABLE>

I had the same exact problem and turns out it was the primary O2 sensor. It goes away when you floor it bc the ECU goes into closed loop (or open loop I cant remember)ignoring the O2 readings. Maybe you could have hit it or something? I replaced mine and problem solved.

 

You Big Dummy, I only have one O2 sensor. My car is OBD2a. The sensor is on top of the cat directly under my intake manifold. I have checked the wiring going to it but there's no breaks. And I'm not getting a CEL for O2 sensor. At times when I VTEC hard and shift to the next gear, the CEL comes on and stays on for maybe 1 to 2 seconds. But the car still goes fine.

Haleiwa-Brando, I'm not running on a stock ECU. I am on PowerFC. I would idle usually around 930rpm with A/C. My idle hunts occasionally at the lights. I have sanded down most of the grounds in the engine bay. Unless I missed one out. Can you tell me where most of them are? I have removed my IACV before and it was not clogged or very dirty and the screen. Will try some carb cleaner tomorrow.

 

I have already swapped out my o2. I have a chipped p28 with 310 injectors, no CEL. Thats why I think I may have something in my fuel. We have had several newer cars at work come in with water in their gas tanks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by garyc17 &raquo;</TD></TR><TR><TD CLASS="quote">You Big Dummy, I only have one O2 sensor. My car is OBD2a. The sensor is on top of the cat directly under my intake manifold. I have checked the wiring going to it but there's no breaks. And I'm not getting a CEL for O2 sensor. At times when I VTEC hard and shift to the next gear, the CEL comes on and stays on for maybe 1 to 2 seconds. But the car still goes fine.

Haleiwa-Brando, I'm not running on a stock ECU. I am on PowerFC. I would idle usually around 930rpm with A/C. My idle hunts occasionally at the lights. I have sanded down most of the grounds in the engine bay. Unless I missed one out. Can you tell me where most of them are? I have removed my IACV before and it was not clogged or very dirty and the screen. Will try some carb cleaner tomorrow.</TD></TR></TABLE>


I was working on a friends car that had the same problem as "dummys", no CEL at all. Would sputter/bog around 4k at partial throttle (cruising), turned out to be a bad primary o2 sensor.

Another situation I had a bad wire to the map sensor and it would cause the same symptoms as you are describing. Sputtering and intermittent CEL.

OBD2a - Here in the states runs 2 o2 sensors, I'm assuming you're overseas?

"CEL when shifting hard" Sounds like a frayed/broken wire to me. Is your ecu mounted in the factory location?

As a start, I would let the car idle and start "wiggling" the harness at the plug connections on both the sensors and the shock tower side. That way we can narrow it down.

 

good info in here

 

My ECU is at the correct location. It's not mounted but just placed there. Its help there by the kick panel at the passenger's leg. I have pulled on the wires and also checked them. They seem good. Would a fuel filter be responsible for this sort of problem? I surge/stutter on around 3.5krpm. The cars just surges forward and backward terribly. From what I know, there is also no CEL code for a constant CEL light for 1~2seconds. Or is there? My tuner tells me that PowerFC has this problem of throwing CELs irratically occasionally.

You mentioned wriggling the wires. You refer to the O2 sensor and MAP sensor? The problem is that this problem occurs infrequently. But when it does, its crazy bad.

 

Have you checked TPS voltage at that RPM?

Try to pull CEL codes and see if anything comes up. Im running a chipped P28 and dont show any codes. But when I actually went to adjust my base timing and jumped the jumper, sure enough there were like 3 codes there. I dont know if thats just because the P28 was looking for something that wasnt there (since I have a lot of **** removed) or if it was in fact a problem. Im not sure if checking codes means much if you arent using a stock ECU, let alone using something else like the PowerFC as well.

I would definitely mount that ECU securely. If the ECU is flopping around under there who knows what could be happening.

And I believe that person is correct in stating that OBD2 cars SHOULD have to primary O2 sensors. I assume one of them could be ignored if using a PowerFC. But it might not hurt getting another O2 sensor. Might not be a bad time to get a wideband sensor with a gauge.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by garyc17 &raquo;</TD></TR><TR><TD CLASS="quote">At times when I VTEC hard and shift to the next gear, the CEL comes on and stays on for maybe 1 to 2 seconds. But the car still goes fine.
</TD></TR></TABLE>

Might be an idea to see what code is stored for that CEL before doing anything else

 

The CEL is probably a sign of my TPS out of the max allowable voltage. But I have checked my TPS at closed throttle and its 0.5V. If I were to adjust the TPS to be 0.8V. It would definitely come on during hard VTEC. Its a code showing that the TPS is out of spec. It will blink 7 times when its out of spec as well during full throttle. I know all this because my TPS was out of spec before and all these happened. I just checked my Haynes manual and it seems there is no CEL code for a continous CEL light for any duration. It should blink. As for the O2 sensor, I am using a EK9 exhaust which only has one O2 sensor attached directly to the cat. I'll change my fuel filter tomorrow and see how it goes.

The most irritating part is that the problem occurs so infrequently that its almost impossible to trace the problem. When it happens, I'll be on the freeway. There is one thing I notice when the problem occurs. My idle drops alot during the hunting rev. It usually hunts between 500rpm and 1300rpm. If I were to encounter the stuttering during the journey, it will hunt between 500rpm and 1000rpm at the next stop at the lights.

A friend of mine says that my fusebox has to be replaced because my ELD voltage is out of spec. This will affect engine loads during travelling. I'm getting 3.5V compared to the norm of 4.5V . Is the ELD critical to normal car operation? My Haynes manual says that if the ELD is out of spec, the symptom would be a driveability problem. They were not specific in the driveability problem. But even a ELD fault should appear as a CEL. I got none for that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by garyc17 &raquo;</TD></TR><TR><TD CLASS="quote">
You mentioned wriggling the wires. You refer to the O2 sensor and MAP sensor? The problem is that this problem occurs infrequently. But when it does, its crazy bad.</TD></TR></TABLE>

While the car is running, wiggle wires around the connection of each sensor (tps/map/o2..etc). Also wiggle the harness plugs mounted on the shock tower.

 

Just replaced my fuel filter. Will be going for a test drive soon. But this problem does not occur all the time. It will be impossible to say if my problem is gone until maybe at least a month of driving or until the problem occurs again.

What about the ELD problem I mentioned? Anyone?

 

the ECU tune is based on load so I would assume if your ELD is having a problem then the symptoms would be similar to having a bad TPS. I dont know much about the ELD though.