97 c/k 1500 5.7 Missing

[stormo03]

It has a 350 in it. In the last year i have put all 8 new injectors, plugs, wires, distributor. It has a new fuel pump and filter. It misses on cylinder 7. But not all the time it misses when its cold and it misses if i'm driving down the road and let off and get back on it, it will miss for a little bit and then come back out of it. I'm at a loss as to what can be wrong with it because it doesn't miss all of the time. If anyone has some info or something else to try please let me know. The pickup has dropped four miles per gallon since i have owned it. Thanks.

[tblake]

Welcome to AF!!!

Have you ever changed the LIM gaskets and how many miles are on your truck?

While its idling, take the oil cap off and see if it misses or tries to stall out. Your Lower intake gasket could be sucked in in port #7 causing a lean mixture. What does #7's plug look like as in compared to the rest?

Have you done a compression test to rule out a mechanical issue?

[stormo03]

No i havent ever replaced the Intake gaskets on it. And i haven't had the time lately to do a compression test. The thing that really confuses me is that it only misses when i first start it in the morning or if i rev it up when it comes back to an idle it will miss for a little bit and then run good

[tony1113]

there is also the possibility of a sticky lifter/valve. I would try running some "seafoam" in your oil for a full 3000 miles. If there is any carbon build up this will help decrease it, possibly fixing your problem. hope this is a help to ya!

[j cAT]

the reason your not knowing whats going on with this engine is because you did not do any testing !

these forums are here to help vehicle owners troubleshoot the problem then make the correct repair.

this is not a shotgun troubleshooting forum .

many come here to find the answer to the problem ,and expect all vehicle symptoms to require the same corrective actions .

testing may take some time ..but it is alot cheaper , and then provides a more reliable repair !

plug wire resistance , wire condition, routing, distributor cap,rotor,distributor bearing , intake manifold leak test, compression test,spark plug replace compare to other plugs, injector leak down test , even a fuel pressure test.

when you do this the answer will in most cases be very obvious.

[tblake]

As stated, I'd run a compression test to make sure the motor is mechanically in good shape first.