Small stumble on acceleration

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Dec 6, 2001 | 12:03 AM

AS84

Thread Starter

Melting Slicks

Joined: Aug 2000

Posts: 2,009

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From: Springfield MO

Small stumble on acceleration

I don't believe its in the ignition. Would a bad IAC count cause a stumble at low rpms? Doesn't the idle screw on the throttle body control IAC counts? Or how about a slightly plugged main cat? I just gutted the precats and one was busted up, I wonder if pieces got into the main cat and ruined it too? Any help will be apreciated

Dec 6, 2001 | 03:16 PM

TIMSPEED

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Joined: Mar 2001

Posts: 9,464

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From: Modesto CA

Re: Small stumble on acceleration (AS84)

I would try putting on new plugs and wires maybe. It did the trick for me :D

Dec 6, 2001 | 07:58 PM

AS84

Thread Starter

Melting Slicks

Joined: Aug 2000

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From: Springfield MO

Re: Small stumble on acceleration (TIMSPEED)

I wish it was that easy. I've already tried that. Thanks anyway

Dec 6, 2001 | 09:40 PM

nobodyunknown

Drifting

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Re: Small stumble on acceleration (AS84)

Could be that cat material moved to the rear cat.
Could be low fuel pressure.
Did it happen before cleaning the precat?
I think turning the IAC will allow more air to pass but not change the pulse rate.

Dec 6, 2001 | 11:20 PM

AS84

Thread Starter

Melting Slicks

Joined: Aug 2000

Posts: 2,009

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From: Springfield MO

Re: Small stumble on acceleration (nobodyunknown)

yeah it was there before the precat. Actually its been there since I bought my car (way before the mods)

Dec 7, 2001 | 02:58 PM

Camvette

Instructor

Joined: Oct 2000

Posts: 206

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From: Nashville, Tn. 37211 TN.

Re: Small stumble on acceleration (AS84)

Check timing (long shot). Have you ever cleaned you throttle body? Replaced your IAC? Mine had so much crud built up in it that the throttle response was bad. Also, once you get it apart replace the IAC if you haven't. And be sure to clean out its opening into the throttle body really well. I've had my '85 for a little over a year now and have just about replace all the sensors and the ECM.
Just fell more comfortable knowing everything is new!
:cool: :cheers:

Dec 7, 2001 | 03:13 PM

dtorc4

Le Mans Master

Joined: Oct 2001

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From: Atlanta GA

Re: Small stumble on acceleration (AS84)

Try cleaning out your throttle body. Mine sometimes acts up and this usually cures it. It could possibly be a bad injector. Is your car hard to start if it is warm and has sat for awhile?

Dec 7, 2001 | 04:08 PM

PeteL

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Joined: Dec 1999

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From: And on the fifth day, subpoenas were served to Obama senior staff

Re: Small stumble on acceleration (AS84)

Does the stumble occur as you first start to accelerate or later during acceleration?

Former is probably TPS or Vacuum leak.

Latter could be a bunch of things.

Not sure about the cats, but I can tell you that my pre-cats clogged the main. Didn't cause a tip in stumble though.

You can check the TPS with an ohm meter (connector disconnected of course). Resistance shoud change evenly - not jump around - as you vary the throttle. If it jumps suddenly or drops out the TPS is bad. You can also check with with a volt meter with the ign. on and the TPS connected, like setting TPS (except I don't think you need to adjust the TPS on a 90).

Also you can't just mess with the minimum air adjustment on the TB. There is a proceedure that has to be followed (see Tech Tips section of forum). If min air is messed up that also might cause a tip in problem.

Good Luck,

Pete