Bosch Digifant ECU help

[bvo...@my-deja.com]

My son's 1988 Jetta 1.8L just quit. Seems the injectors all fire
continuously flooding the engine. It appears the output device to
the injector (pin 12) is shorted. Pulling off the injector rail connector
stops the flow of fuel so not a stuck injector. All plugs wet.

Has anyone any help/advice to give in repairing the output
transistor/Mosfet in these ECU's? Or links to other help sites. Or
other Newsgroups to post to?

Bill Vorbau
bvo...@hotmail.com

Sent via Deja.com http://www.deja.com/
Before you buy.

[bvo...@my-deja.com]

1988 Jetta 1.8 8v won't start. Car was at shop for a clutch change (I
didn't relish the job.) After a week they admitted they couldn't get it
to start. I went and towed it home. I think he was happy to see it go
- still have not paid for clutch.

Found all cylinders and crankcase FILLED with fuel. Clutch Guy
said it initally started but ran poorly so he put in new rotor, dist.
cap, plugs. Then it wouldn't turn over (hydro-locked - he didn't know
it) so he bought a new starter. You can see he was never going to
solve this.

I replaced original starter, gave new one to Clutch Guy to return.
Drained and refilled oil and replaced oil filter. Cranked engine with
plugs out to re-oil.

It floods all cylinders with gobs of fuel. Pulling injector connector at
the end of the fuel rail stops the fuel. Pulling fuse #5 (Fuel Pump)
has the same effect. Then I can get it to start and run a few
seconds on the accumulated fuel, so ignition etc. is OK.

Tomorrow I'll look at the ECU and injector wiring. Has any one tried
to repair the internals of the Digifant ECU?

Any suggestions would be appreciated.

[kc8adu]

if it ran good when you took it in maybe clutch guy left something unplugged
or worse pinched some wires in between trans/block?
<bvo...@my-deja.com> wrote in message news:8rtsl1$2k1$1...@nnrp1.deja.com...

[bvo...@my-deja.com]

UPDATE:

Checked all the wiring and sensors - all OK. Opened up Digifant II
and found a shorted 1N4004 protection diode in the injector output
circuit and replaced it. Didn't fix the problem. Checked all the
power devices and they test good.

Still get all injectors on as soon a key goes on. Can any one
confirm that injectors should NOT be on with ignition on and not
cranking?

Also, mine is CA car with OBD (OnBoard fault Diagnosis). Bentley
Pg85 says ign on then hold sw for 4 seconds to read codes. On
mine light not on with ign switch and no codes after holding the
switch. This a bad sign - probably means the CPU is fried.

In article <8rtsl1$2k1$1...@nnrp1.deja.com>,

[bvo...@my-deja.com]

First, Its not a Bosch ECU. After removing, I see it is marked
Thompson-Adler Digifant II ECU 037906022AK.

I pulled the EPROM from its socket (2764 marked FAGB04 00.102)
and its alright - I can read it in my programmer.
I had replaced a shorted protection diode (1N4007) in the injector
driver circuit with no success.

I set the ECU up on the bench, supplied 14v to the appropriate
pins and a trigger for the Hall sensor distributor signal and then
probed around the two CPUs (one controls fuel and the other is for
ignition) with my oscilloscope and found the fuel control CPU
(8039) was dead. Fortunately, my local electronic parts store had
one in stock ($2). An hour or so with the soldering iron and solder
sucker and I had a 40 pin socket in place of the CPU. Plugged in
the new part and it worked.

Bill Vorbau

[eivan...@gmail.com]

hola buen dia,, si mira por lo que entiendo tus inyectores estan umedos, y tienes temos de tener un insendio ,, si te voy a decir que los inyectores ya no sirven son sellados y soportan una precion de conbustible al no poder soportar la precion se fugan ,, remplazo total de cada inyector en ese estado o con esos sognos ,, no hay ningun problema con tu bomba ni con tu regulador de gas,, saludos y suerte

[jurb...@gmail.com]

Good that you fixed it, you hit the right combination of ingenuity and luck. Part of that luck I think is in the fact that it is an older vehicle. Newer ones probably have proprietary processors with embedded code which are likely made of unobtainium.

For future reference, most fuel injection systems are made specifically not to fire the injectors unless there are crank (or cam) pulses. The reason is to prevent what happened to you.

So you got a free clutch and a $3 engine flush, now would be a time to Slick* it and get another million miles out of it.

*Slick - a slanng term for using Slick 50 oil trwatment which is a PTFE resin. Used to be super expensive until the patent ran out. There are some similar to it - at varying prices.

[lsmartino]

Espero que hayas notado que el post original fue publicado en el año 2000, es decir, hace exactamente 13 años. Es capaz que el carro ya ni exista!

I hope you noticed that the original post was published in 2000, thirteen years ago. I bet that car doesn´t even exist today!