1994 GM bucking on acceleration

[TechSys]

The car idles great. During acceleration it starts to buck quite a bit. If I let off the gas a little bit, for a couple seconds, then give it gas again, the bucking is (sometimes) not there. If, during the time it's bucking, I give it more gas, it usually smooths out. It does this with or without the AC on. Also, just to clarify, it does not do it all the time.

I'm thinking (hoping) it's something as simple as a clogged fuel filter. I'm just not sure at this moment.

This is pretty much going to be a loaded question, but, what could all the possibilities be for such a problem?

Fuel filter, catalytic converter, MAF sensor, full tune-up. What? It's driving me crazy. Car hasn't had a tune-up since I got it Christmas 2008, maybe it's due.

Any help is appreciated.

[SVT98t]

I'd try plugs and wires. My 93 had similar symptoms and a news set of plugs and wires cured that. Pull the plugs and see how bad they look. And roughly how many miles have you put on it since dec 2008?

-ryan s.

[jayh]

first dart- fuel filter
second dart- wires

[TechSys]

how many miles? I can't tell you. Wife drives the car everyday. Odometer quit at 143224 miles. That was before I got the car. Problem started coming back from spring break nationals, March 13th.

[79lincolnlover]

As the others have said, your GM is probably overdue for a tune-up.

[91waggin]

Rule of thumb: Whenever you have a running problem, do a tune-up before even asking a question about what is wrong. You'll save yourself a lot of time.

[jayh]

you can spray the wires with water, then try to do a brake torque(load the engine) but not to the point where the tires spin, and see if it misses

[Lincolnmania]

do a full tune up
also clean out the egr channels

[TechSys]

This is the stupidest design I have ever seen with the wire set.

Started changing the spark plugs today. The first wire broke about 1/2" from the end that goes over the plug. I figured that since the connector is still covered it'd be all right.
Got to the second one. The wire broke right where the connector is. Also looks like there might have been a hole in the boot, right where the connector is. Now I have to try to get a new wire set cause I think ALL of the wires are going to break when removed.

I would like to slap the hell out of the person that thought up the way the plugs go into the engine. I had one hell of a time trying to get the broken boots out of the cylinder/hole. My needle nose pliers wouldn't even grab them. I was finally able to get a socket forced over the top of the broken boot and pull it out while twisting.

Cheapest plugs I have seen so far, that resemble the ones I have now are $53.99.

[SVT98t]

These kick ass. My car was stuttering, i put these in with new plugs and..... SHIZZAM!!! Problem solved.

http://www.grandmarq.net/vb/showthread.php?t=34255

-ryan s.

[TechSys]

Problem seems fixed, at least for now.

Broke 2 wires. Thought I broke the intake whatchamacallit, but found out I didn't. Bought new wires, but haven't changed them all (shame on me). I will get to that when I feel like it and probably after we move to the new place.

I literally hate the way the plugs are on the 4.6L. Thought I was going to have to remove the fuel rail to get to the front 2 on the driver side. I did have to take the intake off though.

Took me, what, 4 hours total. Had to drive 20+ miles to get some money for the wires. Then found out I had $20 on my account at the parts store. Bought the $53 set of wires, which are the same as what was in the car. Only take me a half hour to an hour to change the plugs and wires in my Astro van and that thing is a pain to get to the plugs.

Oh... I came REAL close to going ahead and putting the car in the for sale section. I hate working on any ford/mercury product newer than '90

[ogre]

if it's fixed, great! If not check egr next. I just deleted mine runs great LOL.

[TechSys]

Problem came back beginning of this week. My van has also seemed to follow up with the same symptoms. I'm trying to figure out the common link between both vehicles now. We don't get gas at the same place, so that may be out of the question.

I did run a can of seafoam through the van intake and put a can in the gas tank. It seems to have helped a bit. Haven't put any treatment in the GM though. I'm going to see if cleaning the EGR and IAC will help out any. I "may" end up taking it to a shop to see if they can tell me what the problem is. I hate shops though, but, if I can't figure out the problem, that's the way I'll have to go.

Will give an update as soon as I can.

[jayh]

you were already told to replace the wires and the fuel filter?

your astro van most likely needs a cap rotor and coil wire. very very common on 4.3's

[TechSys]

Wow, where have I been. Oh.. fixing things.

The GM is running fine now. Just have an air bag light blinking code 15 (or maybe it's 51, I don't know right now)

The van is another story. Fuel pump, fuel regulator, fuel filter, spark plugs, spark plug wires, air filter, rotor, cap, cleaned EGR valve, and checked for any vacuum leak. It's running better but still has a little problem.