Guidance needed please.... engine stumbling

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Mar 7, 2006 | 01:21 PM

irokru

Thread Starter

Instructor

Joined: May 2005

Posts: 159

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From: Z16 Crystal River,FL.

Guidance needed please.... engine stumbling

Hi all, Trying to determin the cause of an engine stumbling (missing?).
I have a 1992 Lt1: LT, high flow cats, 3" exhaust, 3" in/out flowmasters
52mm T-body, AFR, MSD plug wires about 1 year old, ignition module replaced 1 yr. ago, 354 rear, 2600TC lock up, PCMforless chip. guess that taks care of the Mods. Now the history... About 6weeks ago a mech. friend said i had an opti going out. He replaced it and it didn't help the stumbling. ( he didn't charge me since it didn't help... good guy)
3 weeks ago u-joint on short shaft making noise, took it to another mech. friend (closer shop) to r&r u joint. He also noted stumble and replaced plugs to see if would help....Didn't help. The stumbling doesn't occur when cold, but begins when H20 temp reaches around 140. If throttle held at steady speed ( 60ish or slower) the stumble will intermittently come and go. Doesn't seem to happen when accelerating
fairly hard. I looked for arching in dark and didn't see any.
Any ideas as to what to check out would be very helpfull.

Mar 7, 2006 | 03:38 PM

Lichen

Melting Slicks

Joined: Nov 2002

Posts: 2,471

Likes: 2

From: 1993 Quasar Blue 'vert Scottsdale AZ

Since you are running longtube headers, have you replaced your stock O2 sensors with heated ones? That cleared up the stumbling in my '93.

Mar 7, 2006 | 03:52 PM

Morley

Drifting

Joined: Mar 2005

Posts: 1,923

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From: GA

Also look to the coolant temp sensor, since you said it happens once it is warmed up.

Mar 7, 2006 | 11:24 PM

irokru

Thread Starter

Instructor

Joined: May 2005

Posts: 159

Likes: 0

From: Z16 Crystal River,FL.

thanks guys , a couple places to look at this weekend. Downloaded the tech tip on 02 sensors and will gather parts & a new temp sensor should be fairly stright forward.

Mar 7, 2006 | 11:35 PM

Lichen

Melting Slicks

Joined: Nov 2002

Posts: 2,471

Likes: 2

From: 1993 Quasar Blue 'vert Scottsdale AZ

Check out Casperselectronics for O2 sensors.

Mar 8, 2006 | 01:59 AM

Demonic85

Team Owner

Joined: Feb 2006

Posts: 24,460

Likes: 7

From: sw Ohio

Another thing that could cause this is dirty fuel injectors, but maybe not since it only happens when the car is warm. Never hurts to clean them anyway though.

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