Stalling. At wits end!

[dallas121469]

Started with a serious idle issue with vehicle dying after starting. Replaced IAC, TPS and FPR. Cleaned MAF, cleaned EGR. When MAF is connected the VX will start fine then start to idle down until it stalls. With MAF disconnected it will run albeit with a high idle around 1500. I can drive it and it does not stall with the MAF disconnected but will continue to idle high. Replaced the MAF with the one from my other VX and nothing changed. It would still die after idling for about 30 seconds. Really makes no sense that the stalling goes away just because I disconnect the MAF. I have a new fuel filter but doubt that will solve the problem. I also understand that the intake manifold gasket causes idle issues but is stalling one of them or just erratic idling. I did many searches and am getting a headache.

[89Vette]

The first thing I thought of is the intake manifold gasket. They have been know to be problematic on this engine. Yes, that can cause outright stalling if the leak is bad enough....and, especially, erratic idle.

As for the difference between the MAF being connected vs not, the obvious difference is how the computer handles (or doesn't handle) fault conditions. With it connected, the ECM "sees" more air at the O2 sensor when there's a manifold leak. Fuel would be added to compensate while it ALSO would shut down the IAC in attempts to lower the thing to idle. Eventually, it would shut the IAC so far it probably chokes it down. Without the ECM trying to compensate, it's just getting more air -- which is what you do to get an engine running faster.

Many people spray starter fluid or propane (unlit) around the manifold to see if the engine speeds up. With a "fuel-enriched" air leak, it will run even faster. But, this practice can be dangerous if you aren't careful about spraying fuel on hot surfaces!!! People also use inert gas/smoke to look for leaks -- which is more the practice nowadays.

I suspect you can find some education vids on YouTube regarding the diagnosis of an intake manifold leak. I'm guessing you'll find that's what it is...considering what you've tried already. And, based on the symptoms. Good luck!

[dallas121469]

I swear that O'reillys and Autozone think their products are made of gold. Both wanted $45 for the intake manifold gasket set. Summit wanted $35 and Rock Auto just under $31. Rock Auto also has it on "wholesaler closeout" for less than $20. It's the same Fel Pro gasket set in all cases. I have other things I can fix while waiting for the gasket set. Thanks for clarifying things.

[dallas121469]

What other things should I replace while I have the intake manifold off?

[Y33TREKker]

What other things should I replace while I have the intake manifold off?
Might not be a bad time to look over the Knock Sensor.

Speaking of OReillys though, have you tried taking it to a place like that and having them hook it up to one of their diagnostics/code readers?

I asked them to hook theirs up to my '01 not long ago because my idling VX had been feeling different than what I'd become used to. We were able to watch various real-time sensor readings to see if anything looked abnormal, although we didn't really see anything that looked out of the ordinary. I verified this by taking it to a local auto shop with a more advanced diagnostic machine and saw nothing on theirs either. (I'm thinking at this point that the "rough idle" sensation I'm "feeling" is possibly worn motor/trans mounts.

If you take your VX to Oreillys though and trying running it with the MAF hooked up and it stalls then and there, maybe one of the sensor readings will make the cause obvious? Worth a try anyway since they charge you nothing to do it.

[eternal21]

What other things should I replace while I have the intake manifold off?

I'd replace the 2 o-rings for the hard coolant pipes. They have a tendency to get brittle and fail, leading to a very, very slow coolant leak that's very hard to pin down.

[89Vette]

The EGR tube runs through the manifold. I'd clean it while apart! There's a YouTube vid on how to do it.

[dallas121469]

Speaking of the EGR tube......how the he** do I separate it from the manifold so I can lift the manifold off? There's a rusted nut on the bottom of the EGR mount that I highly doubt will come off without destroying something. Am in the middle of this right now so if someone could answer ASAP that would be most helpful. Thanks. If I destroy the EGR tube is it really that essential to the vehicle operation?

[dallas121469]

I'm used to working on vehicles in Michigan and when stuff looks as rusted as the EGR fitting looked I figured it was going to break but it didn't. I did have to buy a wrench but such is life. It's running great now with the new intake manifold gaskets, TPS, IAS, FPR etc. Thanks for all the help. Anyone want to buy a very low miles (73,000) 2001 Ebony VX with lots of new parts?