Help with '88 3.2 Carrera throttle pulsing at constant speeds

[DossMan]

Need help diagnosing problem
I put in a Steve Wong chip in my otherwise stock '88 Carrera 3.2 about a month ago and am having the following performance issues post performance chip installation and wondered if anyone had any suggestions/similar experiences.

(1) car runs fine at wide open throttle (WOT) but pulses/lunges under about 3K rpm in all gears This is most noticeable when driving slow, e.g., through a parking lot, as the car lunges back and forth and shakes as a result. This pulsing/lunging is also noticeable at hwy speeds when under constant accelerator pedal pressure. Occurs and can feel it even when when cruise control engaged on hwy.

(2) seems to have lost some hp/throttle response under 4K rmp. With stock chip the hp seemed to kick in around 3K, now doesn't kick in until between 4K and 5K rpm, but even then, seems less than what it used to be.

(3) car starts and idles fine, the idle is the same as with stock chip, around 800 rpm.

Car has about 165K miles on it with stock exhaust.

Anyone have similar issues/recommendations.

Thanks in advance!

[slodave]

Cruise control still hooked up? Try disconnecting it...

That's my only guess.

[geoz]

did you try to contact steve already?

[mthomas58]

What is the condition/age of your clutch/pressure plate. I'm getting some slipping with mine - symptoms are similar to what you describe. I've got 180k with records showing clutch was replaced at 80k.

[IROC]

Mine does this exact same thing. '88 3.2 with a SteveW chip. Only did it after the chip was installed, so I'm sure it's the chip. It happens right at 3k rpms independent of the gear. I installed a new flywheel/clutch right before the chip, so that's not it. No cruise control on my car.

In my case, the surging is minor but it's there for sure.

[Tim L]

I think it's your air flow senser.

[Talewinds]

I'll assume there are plenty of people here w/ 87-89 Carreras who have SW chips installed and they operate just fine. But we continue to identify subtle differences in parts between the 84-86 and 87-89 cars...

[cgarr]

If its not your air flow needle tracks try and unplug the O2 sensor and run it, see if there is any difference, I was chasing a bucking feeling on mine for years and as soon as I unhooked the O2 it was fine.

[Tigerrat]

Email Steve if you haven't already. He provides excellent customer service and knows the Motronics. He helped me with a post chip problem same day I emailed him. Ken

[john walker's workshop]

just for test purposes, drive it with the oxy sensor unplugged and see if it smooths out.

[PatrickB]

Doss Man~

Welcome to the Board!
I went through this night mare several years back. After wasting MUCH time and money, it turned out to be bad injectors... Just do a search on this board for "rough running 3.2"
With that many miles, if they've never been replaced or rebuilt, JUST DO IT! Your car will run 100% better!. If you're a DIY guy, take them out and send them to WitchHunter.

How long have you had the car?
Reason I ask, have you noticed any significant change in fuel economy?
Any difference in MPG after the chip?

If you want, I'd be happy to drive it and give you my opinion. I'm in Brea.

[IROC]

I would call SteveW (I probably should myself). I am almost sure this issue is a result of the chip. As I mentioned, I have the same issue (although mine is very mild) and it is almost assuredly from the chip. Car ran fine - installed chip - slight surging at 3k rpms. Nothing else was changed.

If you call, please post what he says.

[PatrickB]

Originally Posted by cgarr

If its not your air flow needle tracks try and unplug the O2 sensor and run it, see if there is any difference, I was chasing a bucking feeling on mine for years and as soon as I unhooked the O2 it was fine.

Band aid solution. That either means a bad O2 sensor, or by fattening up the mixture, problem solved? Replace the O2 sensor, and if the problem still exists, obviously something else is going on. By removing the sensor, your fuel economy will tank. Fattening up the mixture may give the false impression that the car is running better. You actually may lose power, and also be using considerably more fuel.

[cgarr]

I had SW tune my custom chip without the O2 but then again we don't them in Michigan anyhow.

[DossMan]

Thanks all! This forum rocks because of the responsiveness of its members!!!

I contacted Steve W late last night and we are talking, may end up trying a new chip. Will try the O2 sensor disconnect test or replace. Will check on the fuel injectors and get 'em cleaned if necessary. Saw WitchHunter before and was thinking of using them. Thanks PatrickB (btw, have you used them in the past and were you completely satisfied?). Is there a way to inspect/check the injectors to know if they are clogged etc., without running them through testing/cleaning?

CGarr, not sure what you mean by "air flow sensor tracks." Can you explain please.

Thanks again to all for the 411 on all this! I will keep you posted when I find the problem and solution.

[Steve W]

Quite possibly it could be worn air flow sensor tracks - very common on cars after 80k miles. Surging sounds like a lack of fuel, and when the track is worn, the voltage out from the sensor will drop off, along with fuel and a miscalculation of load for ignition timing. Here's an example. When you see the white substrate coming though, your sensor is really shot:





The new chip is so much more fuel efficient at light throttle loads and cruise, that it needs less air to make power, so it's possible that the flapper angle is less than with the stock chip at cruise, and the wiper may be gliding over a worn area of the meter with the new chip. The wiper may be transitioning between a worn vs unworn spot causing the surge. See the following links for more info on AFM testing and renewal:

http://www.the944.com/afm.htm

or download a pdf from here:
http://www.clarks-garage.com/pdf-manual/elect-22.pdf

[Tigerrat]

I used Witchhunter after 60k miles and think it made an improvement. They test before and after cleaning and give you the results of both. Ken

[88911coupe]

I had this problem and per a suggestion here changed the O2 sensor which solved the issue.