major bucking problem

[boosted92laser]

I am having a major issue with my car. It bucks like crazy once it is warm. It doesn't do it when it is cold. Once it warms up, if I press the gas more than like 5%, it bucks like mad. If I shut it off for a minute, it will drive normal for a minute, then start bucking again.

Here is a bit of history on the car. It has NGK plugs and wires (about 100 miles ago). I thought part of the problem was the MAS, so I bought one from a member on here. I put it in and it acted the same. So I bought a Reman. MAS from work and put it on, and it actually got a little worse. I did a compression test and came up with 149, 153, 157, 154. The motor only has about 800 miles on it, and for the first 700 miles, the oil pressure was low because the engine builder forgot to mention that he didn't put the oil squirters back in.

The car is really pi**ing me off. I am just dropping money into it. Any input would be great.

 

[diablos991]

Did you make sure and gap those spark plugs to the correct gap before installing them? (00.028-0.031)
I would start by taking them out and inspecting the plugs and the gap on the plugs.

 

[boosted92laser]

Did you make sure and gap those spark plugs to the correct gap before installing them?
I would start by taking them out and inspecting the plugs and the gap on the plugs.

Yes I did make sure the plugs were gapped correctly, both when I first installed them and when I did the compression check. The plugs look great.

 

[diablos991]

Have you performed a boost leak test?

 

[boosted92laser]

The only boost leak that I had was from two of my vac. lines, which I fixed. It held 20psi for almost a minute.

 

[boosted92laser]

A couple of guys at work recommended to change the coolant temp sensor since it only happens once it warms up.

I ordered a new one from work and put it in today. It seemed to help a bit, but i have only driven it home. It still bucks and jerks, but it is more bearable now.

Does anybody have any input? If so that would be great.

 

[spyderturbo007]

Pull the ECU and check it out.

 

[Maglin]

It's one of 2 things. The cause I'm almost certain is it's running to lean. The 2 causes are either the O2 is bad and once it turns out it is saying it rich and it leans it out. You should have a datalogger or something to see what your trims are looking like. If all is good their then you might have a issue with your ECU. Could have a cap that leaked and eaten a trace on your PCB. It happens a lot on 1G's. If so take it to an electronic's shop for repair. Shouldn't cost you more than $60 to have it fixed. It's a fast and easy repair for someone that knows how to do trace repair.

 

[boosted92laser]

It's one of 2 things. The cause I'm almost certain is it's running to lean. The 2 causes are either the O2 is bad and once it turns out it is saying it rich and it leans it out. You should have a datalogger or something to see what your trims are looking like. If all is good their then you might have a issue with your ECU. Could have a cap that leaked and eaten a trace on your PCB. It happens a lot on 1G's. If so take it to an electronic's shop for repair. Shouldn't cost you more than $60 to have it fixed. It's a fast and easy repair for someone that knows how to do trace repair.

The guy I bought the car from already replaced the caps in the ECU. He did it so he wouldn't have to do it later.

I have another O2 sensor. I will throw that on and see if it helps. I will also pull the ECU and check it out too.

 

[boosted92laser]

I got under the car to look at a leak and noticed that when the exhaust shop did my exhaust, they didn't put the ground strap onto the exhaust. It is just hanging there. Wouldn't that mean that the oxygen sensor isn't grounded right and that could cause it to run rich/lean, right? I also noticed that the muffler is right upp against the gas tank heat shield. My next day off, I am taking the car back to them and making them redo the muffler and tack the ground strap back on.

 

[Maglin]

The ground strap is definitly good for your O2. Glad you found something.