Thread: 91 GST jerky after 3k

Okay, so I put my GST back together and it runs nice. Idles at 650 smooth, no idle surge, starts without complaining every time. Runs smoothly until about 3000 rpm, and if I open it up to WOT it gets jerky from 3k to redline. However, if I back off on the throttle after 3k so that it's only open about 1/2 then it smooths out. I get better pull at 1/2 throttle than at WOT.

It's like it's leaning it out at WOT and something in the fuel system can't keep up. Any ideas guys?[/list]

What mods ? :roll:

100% stock

What had you done to it to have to put it back together ? Any problems before ?

I had to replace the head. The old one was too warped to start the car. Replaced intake, exhaust and head gaskets.

Replaced fuel filter last night - not much difference, if any. Old fuel filter was a *little* clogged, only slightly harder to blow through than the new one.

Problems before were overheating primarily. Water in the cylinders made it run poor anyway. If it was doing this then I didn't notice.

I got this problem on a few of my dsms when the spark plug wires fouled out....or my spark plug gap was too wide. I don't know how, but I've seen my gap increase over time. Wouldn't hurt to check your coil or power transistor as well (quick voltemeter check).

increasing gap syndrome...interesting. I'll check the gap. Thanks.

The plug wires are probably due for a change also anyway. Lord knows they haven't been changed recently.

I'll check the coil and power transistor.

Now it's leaking oil from *somewhere* too...argh. I wish I had time during the week to work on it.

Check your plugs, and if you have a DMM, check your wires' resistance. inspect the wires thoroughly. Check the power transistor module and the coil, and check your MAF.

So I changed the plugs yesterday. Put some BPR6ES's in there, made sure they were gapped at .030 and it got rid of all my problems. Thanks fellas. The old plugs were all .040 or bigger.