NOT A TOYOTA, BUT it is a chevy, please help

[SilentYoda3]

Chevy Impala

Saw this format before and i liked it, so i copied it! And added to it.



Vehicle: 2005 chevy impala with 82,xxx miles



Story:

Roommates girlfriends car broke down. So of course being the one mechanically inclined friend they know, they call me. So of course being the good buddy i go and help. Worked on it for 2 hours after hauling it out of the road with my 4runner :bluejump: haha, but didn't make much headway. They said they were sitting at the stop light, she took her foot from the brake and was about to hit the gas when it died. she turned it over 'till it started then she drove it about another 50ft when it died again. She also said that there was a funky smell coming from the car, like a hot plastic smell. I couldn't seem to replicate it when i was working on it. (Smells like wiring :crybaby::crybaby::crybaby::crybaby: i hate wiring)




Problem:

Car won't stay running, it was, when i first started, trying to run but would run for a split second then die.

EDIT: Carcomplaints.com states that other's have had issues with the ECM computer and Air Idle valve

EDIT #2: Recent Repairs: Tune-up (spark plugs, plug wires, etc), New universal cat, new ign, all done in march of 2012

My process of elimination:

I checked each plug, each is getting sufficient fire (just because it felt like an easy place to start). Then i proceeded to find the fuel rail purge valve to check pressure, indeed it had pressure. Checked it a few times just to be sure. I then checked the fuses, pulled the ign relay to be checked tomorrow. Also as i was working on it, the car was turning over, AFTER ABOUT AN HOUR OF WORKING ON IT, it decided to not turn over. It's not the battery or alternator as it was 'plugged' into my truck. I feel like im forgetting stuff that i checked but that's all i can think of at the moment.

Thank you for any help guys!

 

[4runnerBrett]

I would say since it obviously has spark and is getting fuel to start to check the timing belt and check timing.

 

[SilentYoda3]

I would say since it obviously has spark and is getting fuel to start to check the timing belt and check timing.

my thoughts too, but then there should have been either a ping sound or clatter sound prior to the incident. Which there wasn't because i rode in the car the day previous. which would exclude the timing as an issue

 

[4runnerBrett]

That is not true. Timing belt can jump a couple teeth. Sounds just like what happened to Foot of god.

Atleast check the timing belt and make sure its all good.

 

[ChaosStarter]

There is no timing belt on that vehicle. You had 3 motor options (from what I remember): 3.4L, 3.8L, and the 3.8L supercharged SS model. Any CEL codes? That could point you in a direction first. An intermittant cam/crank sensor issue can cause a no-start or cause an engine to cut-off.

Remember the special 3: Fuel, spark, and compression.

You really need to hook up a fuel-pressure gauge to the rail to make sure fuel pressure isn't dropping off after crank. It may be enough during the initial priming, but it may not stay high enough to keep it running. Spec on that is around 52-60psi.

If spark is strong on all cylinders, check other things. Make sure your grounds are good and non-corroded. Make sure the battery terminals (since they're side posts) aren't stripped or loose inside the battery itself (I've seen that before. Loose terminal made the vehicle act funny and cause no starts because someone over-tightened it and stripped out the threads).

If fuel and spark check out, move onto compression. A compression test is fairly simple, and can detect somethings, but not all. A cylinder leak down test may be necessary.

 

[futureclaypool]

dont know if it will help at all but in the shop i worked at we had a ton of intake gaskets go on them. even to point of oil mixing with antifreeze.