Talon TSi suddenly won't idle. Ideas?

[OhmegaMike97awd]

My 97 talon suddenly just quit idling. let off the gas, and it dies. I tested the ISCM and it's OK, there are no DTCs, no check engine, no clue! I ended up cranking the BISS screw out about 3-4 turns, and disconnecting the ISCM (to prevent it from damaging itself) as a temporary fix. I'm lost. Any clues out there??? It seems like the car is running richer now too.

What have I checked? The fuel press reg, all hoses and vac lines, pressure tested from the turbo to intake manifold (no leaks), ISCM checked the coil resistance, and mechanically seems fine. No errors showing up on the pocketlogger. Checked intake air temp sensor, coolant temp sensor. I didn't try running it with the MAS unplugged cuz I have big injectors. I may have to go back to stock injectors and disconnect the SAFC to help find the problem? Donno...

This happened suddenly, was never intermittant. one stop light it's idling fine, the next it died as soon as I put in the clutch/let off the gas.

Any ideas would be appreciated!

Thanks,

Mike

 

[OhmegaMike97awd]

Anybody? Please? Help?

 

[44pirate]

Are you venting to atmosphere?

 

[OhmegaMike97awd]

Nope, I've got a 1G BOV venting back into the intake plenum tube.

What about the MAP sensor? Or is there even one? I thought the sensor on top of the intake manifold might be a MAP, but I don't get a map reading from my pocketlogger. I've searched for info on MAPs but all I find is info on using a GM map instead of the MAS w/ the super afc.

I think tonight I'm heading to a buddys auto shop to replace ALL the damn vacuum lines, and I'd like to eliminate the EGR.

I tried a block-off plate, and ended up w/ the check engine light (EGR trouble codes). Is there a way around this?

It seems that the car went rich when this problem started. I had to turn the BISS out about 2-3 turns to get it to idle. The BISS is out so far it's making a hissing sound from letting more air in. Which would mean the mixture somehow went rich suddenly. Correct?

Can anybody verify? If I'm cranking the BISS out I'm adding more air around (bypassing) the throttle plate? Yes?

Thanks for the help!

Mike

 

[OhmegaMike97awd]

Oh Yea...

I've seen other similar posts here where people are diagnosing this as the vehicle speed sensor. Doesn't this sensor also supply signal to the speedo, and also the vehicle speed shows up correct on my pocketlogger. Is there a serperate sensor for this VSS that has nothing to do with either the speedo or the speed coming from the ECU?

Damn, I'm running outta ideas!

 

[stickyweed]

have you messed with anything in the S-AFC, a buddy of mine had the same problem when he changed it from Karman, its original setting, to another setting.

 

[OhmegaMike97awd]

Nope didn't change a thing w/ the AFC. And I really don't want to change anything w/ the AFC to try to fix the problem, cause I wouldn't really be fixing it, just compensating...

The problem just happened instantly, one traffic light, it was idleing fine, I pull up to the next stop, push in the clutch, and it dies. It wouldn't start back up unless I gave it some throttle. Let off the throttle, and it dies.

I think another thing I need to check out is all the damn solenoids for the vac lines. One is for EGR, one goes to the FPR, and I forget what the third one on the firewall does?

Because the problem was so instananeous, makes me suspect a hose break (even though I haven't found one) or an electrical failure of some kind.

One more possible clue is it happened shortly after gassing up w/ BP ultimate. My DSMer buddy said: You got water in your gas and probably blew the intake gasket, and or throttle plate gasket. He's had that happen to his car, but it's much more tricked out than mine. I figured the pressure test would have made a leak like that show up. it didn't.

It's just my luck. I couldn't just have some big $$ part fail, gotta have some mystery failure that'll rack my brain for days/weeks/???

 

[thehyena]

how about the ecu?

 

[1990EclipseGSX]

I had a very similar problem when I filled up with a tank of race fuel... My car just quit idling, period, and every time I would press in the clutch my car would die. It took a little while after I filled up to start happening though, probably 2 miles or so, enough for the ECU to adjust itself a little bit anyway... I checked my BISS and all that good crap, and what actually fixed it in the end was adjusting my AFC settings a little bit. I don't think I compensated for it, I think I was just too lean for my car to idle properly. You should try adding (or subtracting) a little more fuel with your AFC on the low RPM settings in Low Throttle, it might fix your problem, since your problem arose when you filled up your tank with a different kind of gas.

 

[OhmegaMike97awd]

THanks for the input on the gas idea. But I was running the same type of gas I always run in the car. Never had a drop of anything else in it as long as I've owned it. I may try trimming my idle mixture w/ the afc, but, it's been tuned and not even touched for 6months or more. It also seems to be richer across the rpm band. I'm seeing more black smoke out the exhaust at WOT than it used to have, and O2 voltage is a bit higher, EGTs are lower. So, whatever the hell it is, it seems to be affecting everything, not just the idle problem.

Thanks again!

Mike