ok so I have a strange issue and it seems to be a fairly common one but Mine does not fit in to any of the other topics about this I have seen.

My blazer stalls every other day or so at idle but the conditions are pretty random.

it has happened in drive, park and nuetral.

it has happened coming to a stop from 70mph and just in traffic or just running in the driveway.

it does not show any signs of other performance issues and it starts right back up with out any sputtering or issues....

it did have a slight hesitation on the throttle every once in a while when I got it but I ran half a can of sea foam down its throat and the other half in the tank. that cleared up the hesitation.

when it does stall it sounds like it chokes, not really missing on a cyl but like its starved for gas. sometimes you can tap the throttle and bring it back from the stall.


the suggestions I have gotten from local mechanics are:

Mass air flow sensor might be going out
fuel pump might be going bad
Idle Air Control valve might be failing
EGR Valve needs to be cleaned
Idle sensor issues
throttle positioning sensor
o2 sensor issues
fuel pressure sensor
vacuum leak
carbon buildup

any ideas which of the above might be the most likely candidate for this issue?

I am not sure which injection setup I have its a 97 vortec 4.3
I have seen the terms tbi and cpi (I think) thrown around
mine looks like a big butterfly inside a carb with a tube going to to the front of the engine in to an air box.

the truck has 150,000 miles on it
I just did a full tune up thinking this might solve the issue
(plugs, wires, rotor, cap, fuel filter, pcv, oil change, air filter.)

same issue...

any help is greatly appriciated

thanks
Thomas

 

I had the same issue on my Dad's '00 Explorer. It was the IAC. I could control the stall by driving two footed and holding the RPMs up a little. With the low cost of the IAC, I'd check that out.

Also bad gas can do it. Try running a bottle of Iso-Heet and run Shell Premium V-Power if you can get it, if not run Exxon/BP premium. Hopefully it'll work!

 

Yeah I thought about Bad gas. I filled up with BP 93 and still have the issue.... I will look in to the IAC

thanks
keep em coming.

 

I noticed a weird sound this morning on my way to work. under load I can hear what sounds like a small exhaust leak. just a little puff sound every cyl hit.
I wonder if that might be causing the issue???
anyone know how to trace down an exhaust leak?

 

Where is the IAC? is it the connection behind the mass air flow sensor?
that is what the diagram I saw on another site looked like...

 

Being a '97, you have the SCFI injection system. It was used from '96 thru mid-'02.

The IAC valve is located on the back of the throttle body. It is bolted in with two torx socket headed screws and will have a metal housing between the mounting flange and the electrical connection.

An exhaust leak should not cause the vehicle to stall at idle, but would have more pronounced impact on power as a leak prior to the upstream O2 sensors (the ones closest to the exhaust manifolds) will increase the oxygen content of the exhaust, messing up the true O2 sensor reading, causing over fueling of the engine.

I would also like to recommend that you remove the EGR valve and give it a good cleaning. You will need a new gasket and there is a gasket available with an integrated screen. I think that someone posted the PN a long while ago. A search should get that info for you.

Also clean the MAF sensor as improper airflow readings can cause several driveability concerns. Again, run a search as I posted the requirements a long while ago.

On a side note, please use the edit feature to add additional information to your post if another member has yet to reply.