Need help with 90 talon tsi

[JKL]

The car is able to start but once warmed the idle fluctuates between 550-750. I have tried to adjust the idle w/ the bliss clipin the two wires to ground but doesn't help. When the idle dips around 700 or lower, there is a ticking noise that bcomes very loud. The prob is when i step on the gas in or out of gear the car revs up then as it comes down it begins to sputter around the idle rpm then stalls out. The car stalls almost everytime after i gas while the rpm drops down. Any thoughts? Thanks
-Joon

 

[bushy]

I'm having the same problem, any help would be appreciated. I'm guessing either ISC or TPS

 

[billys90tsi]

sorry to say i had the same problem and i fixed it i replaces the isc and then the tps and runs like a dream but its about $400 to do all that the stealership will rob you for the isc

 

[majik2k5]

Do a boost leak check first. The O-Ring around the BISS screw can go bad causing idle surge like that, but more often than not it turns out to be the ISC. I replaced both the o-ring and the ISC. I have a spare one that came off a good running 1g around here somewhere.

 

[19Eclipse90]

sorry to say i had the same problem and i fixed it i replaces the isc and then the tps and runs like a dream but its about $400 to do all that the stealership will rob you for the isc

Agreed. Try unplugging the sensor on the rear of the throttle body. It should be a little black slip on plug to a metal tab. That is the TPS. My 91 Talon runs wonderfully without it plugged in and fluctuates at idle between 1000-1500. I don't find any ill effects from running it this way either, though I cannot say for a fact that there is absolutely no problems with running it like that. Plus it's free
Brian

 

[majik2k5]

Agreed. Try unplugging the sensor on the rear of the throttle body. It should be a little black slip on plug to a metal tab. That is the TPS. My 91 Talon runs wonderfully without it plugged in and fluctuates at idle between 1000-1500. I don't find any ill effects from running it this way either, though I cannot say for a fact that there is absolutely no problems with running it like that. Plus it's free
Brian

Bad bad bad idea. Running with that unplugged can be detrimental. It is not the TPS either. The TPS is located on the front of the throttle body. The sensor you have indicated tells the ECU when the throttle is completely closed or open. When it's closed, it grounds out. Running with that unplugged is extremely bad. I would plug it in immediately.

Bad advice

 

[TimG]

Bad bad bad idea. Running with that unplugged can be detrimental. It is not the TPS either. The TPS is located on the front of the throttle body. The sensor you have indicated tells the ECU when the throttle is completely closed or open. When it's closed, it grounds out. Running with that unplugged is extremely bad. I would plug it in immediately.

Bad advice

It's the idle switch, which activates a seperate map for idling the car.

But, I'm not so sure it's bad for the ECU. It may not activate the idle properly but what detrimental harm could this possibly cause?

 

[andymoraitis]

I had this conversation with an ASE Master Mitsu tech on Friday and it was his recommendation for curing idle surge in the absence of a new ISC. If surge gets bad enough, it can harm the ECU. Unplugging it has no effect other than the requirement that idle needs to be set with the BISS and cold idle can be low and require throttle input to keep the motor running.

Andy

 

[19Eclipse90]

First - My apologies for not knowing the name of the sensor.
Also I reread my last post and got a little confused at one part.
What I meant to say is that it runs beautifully now that it is unplugged. The idle would fluctuate between 1000-1500 with it plugged in. Sorry for that confusion.

andymoraitis and TimG - Thanks for clearing that up for me.

 

[JKL]

Thanks for the inputs. I tried running the car w/it unpluged and the car behavies the same. Idles erratically between 600-850 rpm almost close to stalling and dies coming down from a rev as it approches the idle range. I be attempting to test the isc and tps as per vfaq. Has anyone tried the test? Pretty straight foward? Could this be from a bad maf (if it was, then the cel would've came on)?

Also, as stated on my first post, during the erratic idling the ticking/knocking noise gets very loud. I can hear it w/ the hood closed inside the car but the noise level lower when the idle stays steady. I'm limited with car experiences so I never heard a knocking before.