03renntechamg

So, the other day my check engine light came on!! I read the codes (P0171, P0300, P0303). Meaning im running lean, random misfire detected, random misfire cylinder 3.

Knowing that this could be a number of things, I decided to do the "smoke test" to eliminate a vaccum leak. Upon testing I noticed a leak coming from the intake manifold or injector seal right above cylinder three!!!! Im guessing this is my problem considering my rough Idle and deteced misfire in that cylinder but I want to be sure.

Any suggestions? It was hard to tell which it was coming from. Im thinking intake manifold gasket. Should I do the injector seals as well anyways? Does this sound like a common issue?

Any help will be greatly appreciated!!!

Thanks

number_one_c55

Very good diagnosis! Take it step by step. Do the obvious first. Before you rip the motor apart, try swapping injectors along with new seals to another cylinder and see if the problem switches to another cylinder. If that doesn't help and the misfire is still on #3 swap spark plugs - wires - coil packs. Do these steps on at a time start with spark plugs then wires the coil packs. Do the simple stuff first!

400HP55

Look at your coil pack clips. Sometimes they break/slip and and come off the coil packs causing the same codes to pop.

number_one_c55

The clips won't cause a check engine light, the harness going to the coil pack could be loose causing a misfire. Defiantly worth checking. Be-careful when removing the coil pack wiring harness the clips are fragile and break easily...I've broken my fare share of clips

03renntechamg

Sorry for the late response but I figured out my problem.

It was indeed the intake manifold. Not the gasket but the actual intake manifold. Apprently there is no gasket between the upper and lower portions of our intake manifolds, so instead of doing a ghetto create a gasket ,I decided to just replace the entire manifold.

I sourced a fairly cheap one from a local yard with 35k on it. It came with injectors which I used. I also replaced the intake manifold gaskets, injector seals, and replaced all 16 plugs.

Upon further inspection I concluded that the old plugs looked fine, it appears they had been done before, which i didnt know. I also inspected the old injectors they looked fine as well, I just choose to go with the lower mileage ones. I also smoke tested the old manifold off the car and there was a definat leak, coming from between the upper and lower portions of the manifold.

No more check engine, no more rough idle. Problem solved.