Resolved 90 Running Rough

[Cheezit033094]

Hey guys, my 90 TSI AWD is running strange lately. She starts fine and when she warms up, she starts to idle surge between 1k and 600. When I start to go, she runs good then goes rich (12.8:1) and starts to sputter bad. Just to see, I built some boost and she boosts fine. Doesn't even sputter at WOT. I pulled over and when I put her in neutral, she idled at 500. I turned around to go back home and pushed the clutch at 3k rpms and she stalled. I checked and regapped my plugs to .030 and the same thing happened. Any ideas? Thanks in advance.

 

[nelliott500]

Probably a massive boost leak. Do a boost leak test and report back.

 

[1990TSIAWDTALON]

I'm having similar issues at higher rpms...around 6500 and am checking for boost leaks also.

 

[Cheezit033094]

I'll check for boost leaks tomorrow morning. I find it strange that it builds boost like a champ, though

 

[mitsubishikid]

Also check the ISC for proper operation.
check youtube theres a good video on how they are supposed to operate.
also inspect the TPS, and the two wire coolant sensor.

sometimes it also can be caused by carbon build up in the inside of the ISC port [on the throttle body] might want to check that too.

 

[Cheezit033094]

A bad isc would only affect my idle, though.

 

[GRAVEDIGGER]

Are you venting the bov to atmosphere, or recirculating it? You really need to create a dsm profile so we can see what kind of mods, (or not) you have.

 

[mitsubishikid]

My friends 1g did this [ it had a bad ISC]when it wormed up the idle was sometimes 500-1000 rpm and sometimes back and forth, and his car would also kill sometimes [even when wormed up], its worth looking into if you've never checked it anyway.

Otherwise it could also be a clogged injector or the ecu starting to go on the fritz.
but it seems by the way you posted it that the car is not idling after a lot of hard driving...

Also if you have the means, do the boost leak test, just like others have already mentioned.

 

[Cheezit033094]

I currently don't have the means to blt but a clogged injector would read lean, not rich. I need to find my multimeter to test my isc, injector resistor pack, and other things. If the minor stuff I've tried doesn't work, I'll unplug the o2 sensor and baby it in open loop until I can get it right. Also, I'm recirculating my bov. Crushed 1g.

 

[Cheezit033094]

I'll get a DSM profile going

 

[Seamus]

Aside from the idle stuff is it very repeatable or more random?

 

[thejollyrancher]

Check your MAF. Replace it with a known working MAF and see what happens.

 

[Cheezit033094]

It is fairly repeatable. I have to get my hands on another maf. Not a whole lot of dsm'ers in my area. I'll find something, though.

 

[Vestic]

I'll check for boost leaks tomorrow morning. I find it strange that it builds boost like a champ, though

Did you check this yet, any luck? I had a similar issue awhile back and it ended up being old vacuum lines needing to be replaced - worth checking out if still have some stock lines in various places.

 

[Cheezit033094]

I've been too busy moving and working lately. I'll go to autozone today and buy fresh lines and hose clamps. I've been dailying my bike that I just got up and running.

 

[Cheezit033094]

I fixed it. I put in new vacuum lines. I've only got the fuel pressure regulator, boost gauge, and bov that use them. While I was there, out of curiosity, I removed my oil cap and sniffed. Sure enough, it smelled a little like fuel. As it turns out, when the previous owner did the injectors, they did a pretty sketchy job. The wires rubbed through the insulation and connected on cylinder 1's injector causing it to stay open. I re-soldered that injector plug, checked resistance (3.0 ohms) and inspected the others. I then changed the oil, of course. She fired right up, idles great, has good AFRs and doesn't try to stall on me. I found my Palm pilot and checked over my stuff. My fuel trims are all 100%. Thank you guys for all your help and suggestions.

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[Vestic]

Nice man, congrats - thats a good feeling!

 

[Cheezit033094]

Yes it is!