bad ecu, or isc???????

[tbird]

I thought I was having an ignition problem, but I ended up getting the car started.... here is what its doin.. 91 tsi awd..

key on crank nothing...
if i key off a few times, and key on till I hear the isc click itll start..,, but if I dont hear the isc click no start..... and when it does start it runs real rough till it warms up.... any ideas????

 

[pj91gsx]

I thought I was having an ignition problem, but I ended up getting the car started.... here is what its doin.. 91 tsi awd..

key on crank nothing...
if i key off a few times, and key on till I hear the isc click itll start..,, but if I dont hear the isc click no start..... and when it does start it runs real rough till it warms up.... any ideas????

sounds like an ecu to me. My car did the same thing when i bought a bad ecu from a guy on here. luckily i do i have one in good working condition no leaking caps, just not sure if its a 91-94 or 90. i put it in my 91 and it ran great. if you want it i hate to see it go since i spend 150 dollar in trying to get one good turbo ecu this year. but ill give you a good deal if it turns out to be your problem. its noneprom.

 

[DSM1G90]

sounds more like the contacts in the starter solenoid are frazzled .. Does the stock Boost gauge go to "zero" when you pop on the key?

 

[fatness_42]

The boost gauge isn't always a clear indicator. I had a bad ECU and the boost gauge still went to 0. Turn the key on and see if the check engine light goes out after 5 seconds or stays on. Also check the codes with an ohm meter if you get one solid pulse (spikes and stays high) than the ECU is bad. I also have 2 good working rebuilt 91 AWD ECU's. 1 Eprom and 1 non Eprom 200 and 150. They are for sale in the classifieds. The non Eprom was just rebuilt by ECMlink within the last month and I have the receipt.

 

[pj91gsx]

1 Eprom and 1 non Eprom 200 and 150. They are for sale in the classifieds. The non Eprom was just rebuilt by ECMlink within the last month and I have the receipt.

its crazy what ecmlink charges, but they do fine work!! Its turning over everytime right? any when its running it running rich and blowing black smoke?

 

[steve]

Sure sounds like a bad ECU to me but it could be the MPI relay too.

The clicking from the ISC you hear is another indication that the ECU powered up along with watching the CEL and boost gauge. When the ECU resets it will initialize the ISC by driving it in and out so that it's in a known position each time.

 

[TurkF26]

Sure sounds like a bad ECU to me but it could be the MPI relay too.

The clicking from the ISC you hear is another indication that the ECU powered up along with watching the CEL and boost gauge. When the ECU resets it will initialize the ISC by driving it in and out so that it's in a known position each time.

Beat me to the punch!

Before dumping money into a new ECU, check all other variables, Relays, grounds, check engine light, etc... I had a 90 TSI AWD that did the same thing and when i pulled the ECU, it smelled like burnt plastic so i knew it was the ECU.

 

[tbird]

Im pretty sure the ecu has had the caps replaced in its life... doesnt mean its good but who knows.... I dont get a check engine light... or do you mean I should look at it with the key on?!?!?

im going to ohm test the isc today...

 

[TurkF26]

Im pretty sure the ecu has had the caps replaced in its life... doesnt mean its good but who knows.... I dont get a check engine light... or do you mean I should look at it with the key on?!?!?

im going to ohm test the isc today...

Turn the key to the "ON" position and watch the check engine light but dont start the car. The light should go out after a couple seconds. If it stays on, then it is most likely the ECU.

 

[pj91gsx]

Im pretty sure the ecu has had the caps replaced in its life... doesnt mean its good but who knows.... I dont get a check engine light... or do you mean I should look at it with the key on?!?!?

im going to ohm test the isc today...

the isc being bad wouldnt cause the car not to start. It will cause it to run rich. But it wont hurt to test the isc. I would rather see you try to read the CELs. You need a buzzer its white and about as big as your thumb.

Visual Frequently Answered Questions - Home Page
go to electrical then retrieving diagnostic error codes.

 

[tbird]

did a key on test the boost gauge doesnt move unles I key off then on like 10 times... the ce light stays solid also and doesnt turn off...... guess I have solved my problem.

 

[steve]

ECU Time.

 

[tbird]

thanks for the help Ill keep you guys posted!