After chasing a fuel leak for two weeks and finally getting it fixed properly, my 7 won't maintain a proper idle. After it starts, it does the normal rev to 3k.. but it doesn't hold whether the engine is cold or not. It just dies. If I give it gas, it will keep running. Throttling it, I can get it to about 1250 rpm before it is unrecoverable. From about the 2500 mark on down, the engine sputters like crazy.

Things i've checked: Injectors, atmo press sensor, CAS, TPS, Throttle Cable, AFM, Spark

I've checked all the vacuum lines that I can see for cracks, slices, anything to result in a leak and i've got no leads . I'm going to try spraying carb cleaner and see if I can find one that way, but wanted to get the post out there and get opinions in case I don't find anything. Hope you guys can help out.

Thanks a heap

 

any codes?

 

Even if you've checked the vacuum lines for cracks, they still may be broken. Some cracks are nearly impossible to see. On a car this old, it's almost required that all the vacuum lines be replaced if all the mechanical things meet specs (like what you checked; TPS AFM etc...)

Besides vacuum problems, you could have a fuel injector going bad, rotting wires, and an ECU that is falling apart.

One thing that may sound odd, but can make a big difference... make sure your AFM is laying flat, it can't be slanted, sideways, or upside down. Gravity sucks.

Don't forget your intake ductwork, it cracks too!

 

@speculum - Haven't checked codes yet, but planned on it. Gotta put together the LED checker thingy I saw on a website first. In fact I probably should have done that first, but after searching a lot of the posts said vacuum leak, decided i'd go after that first.

@RotaryRepair - I ran out of carb cleaner before I found any leaks, only about 25% of the engine is done. Also, I lost my helper, so I can't hold the idle long enough to check for any more. I actually just flipped the AFM over about a week ago, after I saw a post about it. As for the other stuff, I tried injector spares I had and the problem persisted... and the wires are virtually brand new. ECU I could see though.

Thanks to both of you for the advice. I'll keep working on it till I find something useful.

 

after re-reading ... cracked to hell intake duct sounds pretty good also ... altho I assumed when you said you checked afm that would ne the next logical place to check as well )

 

haha..i just got done fixin my car did the same thing..haha..umm check your brake pedal..is it stiff?..if so its you brake booster vac. line..mine reved to 3k..held for like 2 sec and clug clug die..so check that..the line where it blew off for me was behind to tmic and under the throttle body..check that..its hard to get in there though..

 

OK, heres the latest... Found a big vac leak, the hose from the block to the brake booster hardline, and discovered that another line that comes off the manifold and goes to the spider had stretched itself off. In addition, I remembered that my smog pump wasn't connected to the emissions system because the mounting bolt had been twisted off in it. Anyways, we put it back on and now it can run down to about 1750... still drops off dead like before though. Also, I can definetly hear a huge vac leak coming from somewhere I have yet to discover. Not any lines, proally a gasket somewhere.

Also pulled the ECU codes as advised - no codes were stored. Lucky Me.



Any other ideas?