sprttrk

I know this is a car site. But I'm in dire need of some help. I have a new 350 5.7 installed in my truck about 6 months ago. Since then I have been chasing a wierd idle problem. My engine will stumble at idle whether is cold or warm at idle. It's a random problem, so it doesn't do it all the time. It seems that my injectors ( mainly the left one) are losing power and making a popping noise (not the normal clicking noise but a "POP") and then my idle will stumble. I have checked the wiring with a noid light and it seems to be fine. I have changed the injectors twice and the distributor twice. I still have the problem. Plugs and wires have been changed twice. I have checked for vacuum leaks, and have found nothing. I have checked the manifold grounds three times. Almost everything (except for the knock sensor and temp. guage) has been checked, cleaned or replaced. My next thing to replace is the ECM. But I don't want to if I don't have to. Anybody have any ideas what this could be. Remember it's a random problem. It doesn't always do it???? BTW if the Mods feel the need to delete this post, I understand. I read the rules. I have posted on every board I can find but have got nothing yet. I thought since this board was basicly the same engine somebody might have an idea. Thanks guys.

ShiftyCapone

iTrader: (7)

Hey welcome aboard. We will just pretend that your 350 TBI is in a camaro or firebird and not in a truck Since this can help anyone with a 350 TBI in an f-bod it really doesn't matter what platform your TBI motor is in, so we will overlook that for now. Have you checked the coil or the feed line fuel pressure? You have already covered the basics which is good. Also, check your TPS voltage and IAC as well. If you have fooled with the IAC lately it may be the culprit.

sprttrk

The coil , TPS, and IAC have all been changed out with new ACdelco ones. The IAC has been set. And the fuel pressure was checked and reading 12psi. The only thing I have let to do is change out the ECM. I have or have access to most the tools I need. I'm going to do a compression test and see if I have a bad head gasket this weekend. I don't think this is my problem since I'm losing no coolant. I did a vacuum test but it read everything was good to go. Plus I hope I'm not have gasket issues already with this new crate motor... I do have one concern, the copper braided ground lines on the back of the motor. If one of those were not grounded good could that cause a problem. BTW thanks for overlooking the body style issue.

ShiftyCapone

iTrader: (7)

So this is a crate motor? Is it a stock replacement or is it a performance crate? If it is a performance crate than your problem lies in the chip most likely. The stock chip will not suffice if you have a healthy motor now. I would look into datalogging and go from there.

sprttrk

Yea it's a stock GM crate motor 350 5.7. I do have a chip on the ECM from my old motor. I going to pull it tonight to see if that changes the way the motor runs.