Stumbling/Hesitation

[Fat Kid]

For almost a year I've had problems with stumbling and hesitation with my GN. The problem isn't perpetual, but it's a frequent issue.

Thus far I've replaced the plugs, plug wires, fuel filter, fuel pump, TPS and coil pack, but to no avail. TPS settings are normal, as are all the others on the car. I've done the tapping test with the MAF, coming up with nothing.

Any ideas? Thanks!

 

[cmokem]

Does it happen just from the start..or anytime..like a 45mph punch..also what injectors/chip combo??

Bob

 

[Fat Kid]

It occurs on most partial throttle conditions, especially before shift points. It's especially bad when the car hasn't been run in a few days or still hasn't totally warmed up.

Injectors and chip are both stock.

 

[humberto]

Swap the maf with another one and see what happens knocking the maf sensor wont always work.Have you tried the esc module?Also check all your ground connections and your two bat cables make sure the pos cable isnt damaged by rubbing on the header.Good luck.

 

[BUICKTR]

I had similar problems under load and I replace cam sensor, coil and module and problem was fixed.

 

[Fat Kid]

Thanks for the replies. I guess the only thing to do is just keep replacing parts and hope I find the right one? There is nothing diagnostic that I can do?

 

[FreeJack]

I've got a similar problem with my 87 GN. It happens mostly when the car has sit over night and hasn't warmed up. When I put it in gear and begin to accelerate the car sputters until your give it more gas then goes away. Then when it is warmed up and I turn it off and wait 5 minutes then restart, it really stumbles (sounds like it is caming) until you give it gas. I think it's the MAF. My stock one went bad and now using a cardone. Other then the stumbling when cold, the cardone works.

 

[FastGN007]

do you still have a catalytic converter and if so, is it clogged? I had a similar problem and that was the fix. Let us know what you find out!!

Scott

 

[FastGN007]

Freejack, the problem with the car running rough when it is cold and all that could be the coolant temperature sensor. does it go away once it warms up a little?

Scott

 

[FreeJack]

I've got a new Hooker Cat... Been on the car less than a year. Could it be clogged that fast?

Which temp coolant sensor? I'be got a VDO temp sensor on the bottom. Or are you refering to the one on the intake?

 

[soman22]

I've had the same problem for over a year. I just replaced the tps - still have the problem. A friend of mine told me it could be a bad timing chain. Is that possible? Would love to solve this problem as the stumbling appears to be getting worse.

 

[first turbo]

get a can of throttle bottle cleaner and clean the body, may be a cheap fix.

 

[Fat Kid]

FreeJack, that's exactly the problem I have! The MAF is a likely culprit as mine may have gone bad, however, the MAF readings through the Scanmaster are still good and it doesn't trip any malfunction codes.

soman, I replaced my TPS, it didn't help worth a lick.

This sounds bad, but I'm glad other people have this problem. Maybe we can figure out a solution. FreeJack and soman, what other things have you tried? Sensors, other parts? Maybe we can at least isolate the problem.

I think it is likely something electrical, as that's what my mechanic told me. He just can't seem to narrow it down further.

Thanks for the replies!

 

[FreeJack]

I'm going to warranty out the MAF and put another one on it to see what happens.

 

[mgmshar]

For what it's worth...

I had a Cardone MAF on my car - for about 2 days. When I put it on, the car ran pretty poorly. Definitely had a case of the stumbles.

If somebody around you has a MAF that you can borrow (preferably an AC MAF), try it. I've found that each one behaves a little differently. Once you find one that you like, stick with it.

Good Luck,

 

[dataangel]

EGR Valve.

Mine does the same thing exactly and I'm pretty sure that's what it is. I've had other cars act this way with a bad EGR. I'll swap it out and let everyone know.

dataangel

 

[dataangel]

That was it. Replaced the EGR valve and it's gone now.

The replacement EGR from NAPA kind of sucks, though. The gasket has no locator hole on it (the stock one locates on the clamp stud), and the valve itself has no locator pin (stock protrudes a bit), so you're essentially just guessing when you put it on and line it up with the ports. I just made sure it was centered and hoped it was right.

dataangel

 

[Fat Kid]

Thanks for the help everyone. I ended up taking it to a diagnostic center where they discovered the crank angle sensor was in poor shape. I certainly didn't expect that one.

 

[TurboBuickSix]

Have you since driven it yet to verify it is fixed?

 

[Fat Kid]

I drove the car today. It seems much better, but I'm still not certain it's totally fixed. We'll have to see.