hosrom_951

Guys,
i was installing a new 3-pole connector for the ISV harness, i had a friend in the driver's seat, to turn on the ignition so i can test the new connector; However, he accidentally left the ignition ON and two wires for the ISV touched and a spark occurred, which i was crimping new on new pins.

thing is, now every time i crank the car to start, the tachometer jumps to 2k rpms (while cranking) and when it starts (cold) the engine idles at 1,600rpms. I thought it was a leak, but no vacuum leaks, i even swapped ISV's and it still happens. I also CLOSED the idle screw completely, it idles at 1,400rpms.......

Could have the DME shorted somewhere? can one "reset" the DMe (by disconnecting the battery and reconnecting it)?

Any ideas are welcome......

Keithr726

Might as well try disconnecting the battery. I wonder if the DME relay could have fried ?

hosrom_951

Disconnecting the battery made a very small difference, the tachometer stopped bouncing, but it still idles 1,600rpms.

I completely disconnected the ISV connector, and it idles at 1,400rpms now.......

I will swap DME relays (i have a used one), let us see what happens...........

fast951

The ISV has a +12V and 2 pins that get ground from the DME. If the +12V & ground touched, there is a good chance the ISV circuit in the DME shorted.
If you unplug the DME, does it make a difference? You might need to trace the ground leads in the DME, some of the ground pins are on the same line. The factory wiring diagram is a must for this task.

hosrom_951

Thanks for the input John, i have the wiring diagram and i will unplug the DME and see what happens.

hosrom_951

No difference when i unplugged the DME.

So, i need to remove the DME, open it up and look for what exactly?

TRP951

might just want to open it up since it takes all of like 2 mins, and check for burned places on the board or a shorted smell.

hosrom_951

Tim,
I did that, i looked closely for any burned/shorted diodes, resistors or anything odd........could not find anything.....

I will be taking it to the Bosch service center tomorrow, in the mean time, i would like to know if someone has a 24-PIN DME they are willing to let go of.......

Tom M'Guinn

Not sure what you mean? Did you pull the plug off the ISV itself to see if the idle comes down?

hosrom_951

Yes Tom, the ISV is plugged off and the throttle body idle screw is fully closed, it idles at 1,400+rpms.

Im going to check ALL the sensors and wiring, maybe the DME is fine (since i could not find any signs of burned/shorted connections) and maybe a sensor got shorted since many grounds are shared.....

hosrom_951

Two wires (the Red/Blue and the Black/White) were exposed, about 1" down (i stripped the brown factory wire sleeve to expose the colored wires), the copper was exposed on both wires and they were touching.

Maybe this happened from when the two pins touched earlier (and caused the spark), or maybe because i was pulling (a bit) to connect the pins they got stripped.......

A very special thanks to JJ @ VR, replied to all my emails and helped me out, when he had better things to do..........

125250

I had the same problem. The wires just behind the plug had shorted. The DME would not raise idle when cold.I swapped DME and not realizing the wire harness was shorting fried a second DME.Only the curcuit for the idle stabilizer gets shorted. The car runs normal just wont idle correctly.I opened both DME but couldn't find what shorted. If you find out what curcuit it is could you let me know. I have 2 DME that can no longer control idle. Thanks

brad-cam

Waking up this thread - did you guys ever find out what fried (if anything did in fact fry) in your DME ? I suspect this has just happened to me too. I'll test the harness on the weekend to see if there is a short in the ISV cable... but I suspect there is.

ramius665

Hussam,

I had an engine fire in my 951, and it happened directly under the ISV. The DME harness going to the ISV was completely fused together, and when I sent my DME off for testing, they confirmed that my ISV circuit was damaged inside the DME. Rather than fix it, I just purchased a new/used DME. I'd bet even money that your DME is now messed up. You might be able to send it out to be fixed, but it'll likely cost more than sourcing a good used one.

brad-cam

Thanks - see my other thread. I fixed the problem - the Darlington's in the ISV circuit were in fact fried. I replaced them and all is well.

Cheers