Evap valve plugged in, engine stalls when vacuum line attached?

[Jszy25]

I have an obdi M52 in my 91' 318is. Right now I have a large vacuum leak coming from the nipple off the throttle body where the evap purge valve connects to via vacuum line.

Engine idles normally (other than a hunting idle every so often and it also breaks up during light load acceleration), but when I go to attach the vacuum line to the nipple at the throttle, the engine stalls and dies. I can keep it running with throttle input, but it won't idle.

Does this sound like a bad evap purge valve? It is weird that the engine runs pretty well with such a huge vacuum leak after the maf.

[RobertK]

Use a vacuum cap on the evap nipple, disconnect the battery for a few mins to clear the ECU and then hook it back up. Once you start it up the ECU should adapt to run correctly.

[Jszy25]

Use a vacuum cap on the evap nipple, disconnect the battery for a few mins to clear the ECU and then hook it back up. Once you start it up the ECU should adapt to run correctly.

I'll give it a shot.

I did put a cap on the evap nipple, but it wouldn't hold idle obviously. I'll try resetting the ecu to see it'll run right with it capped.

[RobertK]

I'll give it a shot.

I did put a cap on the evap nipple, but it wouldn't hold idle obviously. I'll try resetting the ecu to see it'll run right with it capped.

If it still gives you trouble after that then check / clean the ICV to make sure its not sticking.

[Jszy25]

Yea that didnt work.

I'll look I to the ICV next. Thanks for the suggestions.

[Jszy25]

I ended up disconnecting the vacuum hose from the canister to the purge valve. Engine no longer breaks up under light loads. Very happy about that.

I still need to do something about the large vacuum leak at the throttle body nipple. Not sure where to tie it back in. Gotta figure that out.

[Blaine0002]

Tie it back in? Just cap it off.. I took a piece of fuel hose, bent it in half, zip tied it and stuck it on there.

[Jszy25]

Tie it back in? Just cap it off.. I took a piece of fuel hose, bent it in half, zip tied it and stuck it on there.

I'll give it a shot.

I did put a cap on the evap nipple, but it wouldn't hold idle obviously. I'll try resetting the ecu to see it'll run right with it capped.

Yea that didnt work.

[Blaine0002]

even with no cap on there, you would simply have a small vacuum leak and your car would still run. This isnt your problem.

[Jszy25]

even with no cap on there, you would simply have a small vacuum leak and your car would still run. This isnt your problem.

The car does run...I daily drive it. I never said it didn't.

This is not a small vacuum leak by any means. I smoke tested it and smoke pours out of that evap nipple. That is unmetered air entering the system. So I fully disagree, this large vacuum leak is definitely one of my problems.

[Blaine0002]

Well reading everything you have wrote this thread. It doesnt make sense.

Cap it off, your car will idle. if it doesnt then it isnt your problem!!! Evap and the plug will not affect your cars ability to idle!

I did put a cap on the evap nipple, but it wouldn't hold idle obviously.

your WORDS, they dont make sense!!

[Jszy25]

Well reading everything you have wrote this thread. It doesnt make sense.

Cap it off, your car will idle. if it doesnt then it isnt your problem!!! Evap and the plug will not affect your cars ability to idle!



your WORDS, they dont make sense!!

When capping off the nipple at the throttle, the engine will stall out. You can just plug it with your finger for a second and it will choke and stall. It doesn't make much sense to me either.

[NickL]

What injectors are you running? I can almost bet your car is running rich and because of the unmetered air entering, its leaning it out and causing the car to run better.

My OBD1 S52 would hunt for an idle and break up part throttle because I was running a red label 413 with the stock chip for 17lb injectors. I forgot M52/S52 injectors are 21.5 and once I was tuned for them the car ran great.

I could unplug the brake booster line at the intake mani and the car would idle, roughly, but it wouldn't hunt. The unmetered extra air actually leaned the car out and caused it to run better.

[Blaine0002]

So since your ecu knows your evap is plugged in, cap off the nip, unplug your battery or ecu for x minutes (to unlearn it) then try again. if no luck, then its probably your ICV