New motor issues

[mykscholze]

We finally got the motor to turn over and had trouble getting the thing to idle. There was a little bad gas and we could get it up but no idle.

After a while we finally got it to idle and it seemed to still have a slight miss I assumed was the bad gas. The check engine light was on and the midpipe just past the converters got red hot and started glowing.

We eliminated the thermactor tube from the heads but I still have the smog tube and pump on it, however we did eliminate the diverter and bypass valve.

We think it is running lean, maybe vaccum leak.

Anybody here have any ideas?

 

[jrichker]

No clues as to your car's engine, mods EFI or carb. That will make troubleshooting your problems more difficult.

That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing.

The crystal ball says maybe EFI, so here goes the EFI route...

See "Help me create the Surging Idle Checklist" at http://forums.stangnet.com/showthread.php?t=534062
for help with your EFI idle problems. The first post contains all the updates to the fixes. I continue to update it as more people post fixes or ask questions.

One of the first steps in the surging idle sticky is to dump the codes.

 

[mykscholze]

Yea... I was planning on updating the sig just never got around to it.

Mods are listed now.

 

[SamSnyder]

I suffered a vacuum leak under the lower manifold on a new engine. I used Felpro race gaskets (I think they were pn 1250) and there was a mismatch with my iron GT40 heads and stock lower manifold. The gaskets were intended for larger ports and sucked air from under the manifold. Symptoms were idle hunting and a high soft idle that would not snap back to attention when you got off the gas. A guy spotted the leak by looking for vacuum at the oil filler neck. I switched to regular Felpro stockers and the problem was solved.