will not start unless MPI fuse is removed then installed

[billgsxr]

recently when I try to start my Talon it will turn over but not start. If I remove the MPI fuse and then plug it back in, then I here a rapid clicking noise that sounds like it is coming from the intake. After the clicking noise stops the car will fire. I also noticed that before I remove and replace the fuse the stock boost gauge is bottomed. After I pull and replace the fuse the boost gauge rests at zero. The fuse itself is fine.

 

[toybreaker]

The clicking and boost gauge anomolies are two classic signs of an impending ecu failure.

You're going to have to pull your ecu and inspect your caps. Please search for the vfac. A black spooge on the board around the caps is what you're looking for.

You didn't mention whether you had any idle issues.

In this particular case, you might also have some issues with the iac, (this could be the source of the clicking at the intake manifold)

So, please check the coils of your iac before installing another ecu. Damaged iac coils can and will frag the drivers in the ecu, which will ruin your replacement ecu.

On a side note, please try and keep the fuse pulling on a live circuit to a minimum. There's all kinds of sensitive components in the electronic circuits in these cars, and many of them don't take kindly to arcs, sparks, and powerus interuptus....

(It angers the automotive gods sleeping in the caps, diodes and transistors, and they have a way of knowing when you have a date, and it's raining... and they will smote you... )



Good luck, and let us know what you find.

 

[steve]

Yep, I'm sure your ECU has bad caps.
Everytime your pull the fuse your resetting the power to the ECU. One of these times when the power comes back on one of the bad caps is going to short out releasing the magic smoke and you'll be looking for a new ECU.

Steve

 

[billgsxr]

Yes I do have idle problems as well. Were are the coils located?

 

[toybreaker]

Steve is way more qualified to answer your questions, as he understands the inner workings of the ecu better than anyone else here.

I only know that a shorted iac coil can place an unreasonable current demand on the ecu, and cause internal trauma to the ecu.

The iac is located on the throttle body housing, under the throttle plate. There's a couple of pretty good how to's on idle issues that give excellent advice on how to check/troubleshoot idle issues.

Please check them out, and let us know what you find.

 

[steve]

I like the VFAQ in the 3000GT/Stealth site better because it explains what the ISC is and how it's used as well as showing the how it comes apart. What Jeff doesn't do as well a job of is cover how to measure a the coil resistance.

These will help you check the ISC itself but that's only half the system. The harness can be checked by measuring the end to end resistance. Testing the ECU operation of the ISC is more difficult. I have a "dummy load" I use along with a custom version of the ECU software that checks each of the four drivers to make sure they are all good.

http://www.stealth316.com/2-isc-iac.htm
http://dmtalon.v8eaters.com/ISC.html

These guys are DSMTuners members and have reasonable prices for new OEM ISCs.
http://www.dsmisc.com/dsmweb-dw/index.html

Steve

 

[billgsxr]

Thanks for the info I will let you know what happens.

 

[nickclay9395]

I like the VFAQ in the 3000GT/Stealth site better because it explains what the ISC is and how it's used as well as showing the how it comes apart. What Jeff doesn't do as well a job of is cover how to measure a the coil resistance.

These will help you check the ISC itself but that's only half the system. The harness can be checked by measuring the end to end resistance. Testing the ECU operation of the ISC is more difficult. I have a "dummy load" I use along with a custom version of the ECU software that checks each of the four drivers to make sure they are all good.

Stealth 316 - ISC Servo Motro
DmTaLoN's Idle Speed Control Test/Fix Page!

These guys are DSMTuners members and have reasonable prices for new OEM ISCs.
DSMISC Automotive (New ISC Supplier)

Steve

if the ISC is going bad will it get hot???