Momentary Engine Cut-out Problem

My 1995 3.8 has a long-term engine cut-out problem that I can't fix. Have replaced the crank sensor, coil pack, and ignition switch. The TPS checks out fine, but the cut-out even occurs when idling. Some days are worse than others, but it ALWAYS cuts-out every day. These cut-outs only last a second or two, and the engine keeps running unless it's idling.

Have checked and removed/replaced all the fuses, and the SES light stays off. Scanner shows no problems. I ran a separate ground from the instrument panel to ground, no help. I know there is a "major" ground point behind the left kick panel, but haven't removed the panel yet.

What I'd like to try is to run a separate wire, thru a switch, directly from the battery to the ignition module. Before I attempt to dig thru the wiring diagrams, does anyone know which wire directly feeds the ign. mod. from the computer/whatever?

An interesting observation. This cut-out problem is not affected by bumps in the road, vibration, etc. The only thing is seems to be related to is other vehicles. When I'm running along on a deserted road, it doesn't seem to cut-out. But whenever I'm in a pack of other vehicles, it does.

I'm thinking it's related to either CB radios or more likely cell phones. However, my own CB and cell phone do not cause it to cut-out.

Any ideas?

If it was a radio wave, would not one think cars would be miss-firing all over the place? Can you imagine a traffic jam and I've never heard of that situation is yours would be the first.

I am not knocking the thought process one bit. I just present an observation like yours and present it in return is lettuce sit down and toss that idea around.

Say at idle, that sorta has the most middle of the road hard pulsing action on the return is the action for every reaction, (is not high speed running, meaning). Like pow out of the intake throttle body gasket is a slight air leak? Say it wants to almost stall, but you drive fine in the sustained throttle. Say that lean catches more air in a cylinder than the correct proportioned gas if that leak was closed. Like it acts exactly like a spark leak to ground and not to the spark plugs side electrode.

So, I agree is pull one out of the hat (is a theory that makes sense), is swapping all those electrical parts chasing basically the same thing miss.

On the other hand, you observe that you are with a wolf pack of cars and cannot move, so your throttle is on and off basically, rolling up and slowing down with traffic. Sorta a low idle effect to that miss again.

Might that slowing down the air leak be a slight hist to a miss? Maybe a cold engine with say contact cleaner, brake clean, or way too oily and flammable is WD-40 is be careful about this leak test and what you use as a chemical and spraying the house in flames down is roll the car outside.

So more or less, you have something that evaporates clean but can both burn for an idle rise, or blow the idle down is spray a 360 degree circle around the gasket is it might be slight bit tiny hole to find?

I mean, you threw a lot of parts at it, mentioned nothing about an intake gasket between throttle body and engine, so that is more or less my counter to your AM/FM waving in the window next to you is mine is running fine.

I had a longterm random cutout loss of power scenario in a Dodge minivan & definitely had some things come up but had nothing to do with the problem.

Used to be on my way to work, right at about the 10 minute mark, as I was passing by an international airport, van would start to miss.. & wondered if there was a connection.

My mechanic had fun with that one & started talking about aliens.. & outer space lol..

Turned out to be an O2 sensor.

Only thing I can think of to try to narrow it down whether it's fuel or spark is when it cuts out at idle, pull the front plugs. Might give a clue if spark or fuel is the prob, but I suspect spark or electrical.

Thanks, 96tsport,

The problem has got to be electrical. Every time it happens, the gauges go crazy--the needles fly upwards, then return. I'm about to the point of replacing the computer--can't think of anything else. I took the plastic cover off, and I can reach my foot over while driving and give the computer a little kick--no effect at all.

This has got to be a weird grounding or 12V supply problem, but it is proving very hard to find.

This has the makings of a Failed 94-95 3800 PCM... All of the 94-95 U, C and H Bodies used this very PCM and also suffered from these issues..

Had My 95 Do this to me the other day as I was accelerating through a traffic light... Died out for a split second and started going again..

If you were to start the van and let it idle on its own will it stall out as if you reached in and shut the key off?

Also if you can scan it for codes do you have a P1361 Stored?

Yes, it has stalled like that on occasion. That code has never been stored, but I'm not sure that Checker Auto has the correct scanner. A few weeks ago the SES light came on--no changes in the cut-out problem. Checker scanned it, said NO codes were set. They used some kind of adapter cord because my OBD1 van has some kind of 1995 transition plug.

Am I correct in assuming a new computer should solve this problem? Is there a "better" or newer computer available that will work?

I don't even know how to explain about the PCM you have... LOL

You do have a Transition PCM of sorts... You have the old 12 PIN ALDL connector as opposed to the 16 Pin OBD2 style the 3800 C and H body cars used.. But your PCM uses OBD2 codes.. Problem is that it was still OBD1 Compliant... A lot of places can't read the 3800 powertrain for 94-95 in the U, C and H bodies for this reason... If the SES light came on then there should have been a code stored..

I can't promist that replacing the PCM will solve the problem, But I do feel its a road worth taking from what has been described..

94-95 are very funky years for this PCM..

I am on the 3rd on in my Bonneville, and am Having issues with the one in my van and can't get it to run right... I always have a Trunk PCM with me on trips just in case...lol... If you were closer we'd drop one of mine in just to test with...lol

I finally broke down and had a dealer install a new ECM (or is it a PCM?) Total cost was ~$480, which included a $100 rebate for the old ECM. Problem seems fixed at last-2 days of no problem.

The problem was slowly getting worse, such that instead of a simple 1 second engine cutout and the trans. going into neutral for a few more seconds, it would actually stop running even at 75 MPH.

My neutral-start switch also went bad, which meant I'd have to coast to a complete stop and shift to Park in order to restart it. This was the straw that broke the camel's back.

I found a "reman" ECM on eBone, P/N 16193247--supposed to fit a 1995 Chev. Lumina with the 3.8 engine--same year and engine I have. Ad said it would require "reprogramming". Called the local Pontiac dealer, whose service dept. I don't like, and the parts man told me the orig. ECM P/N is 16183247. When I told him the number of the eBone ECM, he said "no problem, that's the right one".

Took the van to a Chev. dealer who I think does better work, and they said it wasn't the correct one. Went ahead and had the install a new one--probably a reman., but if it works that's OK.

Can there really be a difference between the Trans Sport and Lumina ECM's?

Anyone want to buy the Lumina one?

Depends on the year and which engine you have..

the 94-95 3800 Lumina APV, Transport and Olds are all the same as long as its a 3800... Should even have the same program on the Eprom as all of these with the 3800 used the 3.06 gear ratio..

I have a 1994 pontiac trasnsport w/ the same cutout prob. I retrieved codes from an auto mech. and the P1361 was one along with P0341,P0342
on initial start up it will run normal for about 7 seconds and die ..I then must turn the key back to off position and restart and it does same thing untill engine warms up a little. If i dont return to the off position after it dies it will not restart. they sold me a hot temp. sensor but i cant seem to locate it . Is it behind the alternator?? Any other ideas??
Thanks