Car wont idle

[twizted_3kgt]

Ok I just finished an intake manifold gasket install, and now the car won't idle...it stalls immediately after starting unless you hit the gas, in which case it gives gas and then cuts gas repeatedly with some backfiring. I broke a t-connector for one of the vacuum hoses that connects to the back of the intake manifold so one of the hoses isn't on there too good and i can hear it leaking, and also a plastic vacuum line that connects to the underside of the front of the intake manifold which i used duct tape to reconnect...I don't know if I have some hoses switched around or some plug wires got switched around or if it's just too much unmetered air or what, any suggestions?

[Injuneer]

I'm going to take a wild a$$ guess that your talking about a 4th Gen LT1, since you fixed an intake manifold leak - always a good idea to include a "signature" with year of the car, model, tranny, major mods, etc.

Will it idle if you hold the throttle blades open slightly? Might be a problem of not enough air to idle. Did you reconnect the idle air motor on the plate on the bottom of the throttle body? Is the MAF reconnected? Is the rubber inlet elbow on tight with no tears?

What vaccuum hose on the back of the intake did you break? There are some on the sides, but in the back, other than the line to the EGR valve. Did you try to stop the leak you can hear?

You've got to correct all the damage you did to the vacuum lines, and insure you have all the electronics reconnected correctly..... really sounds like a sloppy job.

[twizted_3kgt]

oh sorry, it's a '88 L98...sloppy b/c 2 18 year old plastic vacuum lines broke? hmm. The maf and iac are connected, the vacuum line that broke on the rear was on the back pass side of the manifold, it goes in right next to the line for the fuel pressure regulator

[Injuneer]

oh sorry, it's a '88 L98...sloppy b/c 2 18 year old plastic vacuum lines broke? hmm. The maf and iac are connected, the vacuum line that broke on the rear was on the back pass side of the manifold, it goes in right next to the line for the fuel pressure regulator

OK.... ignore everything I said. My stupidity to ASSume it was an LT1.

My apologies.

[fastTa]

Ok I just finished an intake manifold gasket install, and now the car won't idle...it stalls immediately after starting unless you hit the gas, in which case it gives gas and then cuts gas repeatedly with some backfiring. I broke a t-connector for one of the vacuum hoses that connects to the back of the intake manifold so one of the hoses isn't on there too good and i can hear it leaking, and also a plastic vacuum line that connects to the underside of the front of the intake manifold which i used duct tape to reconnect...I don't know if I have some hoses switched around or some plug wires got switched around or if it's just too much unmetered air or what, any suggestions?

I think you have already answered your own questions. You need to repair all the vaccum leaks that you created and you need to make sure you re-installed your EGR and your throttle body correctly. I really don't mean any offense, but maybe if you cannot determine whether or not you switched around some of the plug wires, maybe you should get a mechanic to do the work on your car.

Additionally the fact that you mentioned the car was backfiring would suggest that the timing is retarded way too much.

How did you set the timing and what did you set it to? At what RPM does the timing fully advance? You realize you have to unplug the timing lead and then set a zero base timing point correct?

[twizted_3kgt]

Ok I was just searching for some quick suggestions last night before I went to bed and this morning before work...considering I am a mechanic i'm definitely not taking it to one of my co-workers so they get paid off me lol.

Anyways I found the vacuum leak tonight after I got out of work, one of the intake runner gaskets got bent somehow right where the cold start injector plugs in...sprayed some soapy water there and it sucked it right up. Just have to fix that and it should run fine.

Thanks for the help guys.

[fastTa]

How about the timing?

How did you set the timing and what did you set it to? At what RPM does the timing fully advance? You realize you have to unplug the timing lead and then set a zero base timing point correct?