# fuel filling cylinders, causing hydrolock 88 golf digifant



## bpederndern (Nov 26, 2002)

i just finished replacing the engine in my 88 golf due to a rod knock....was running fine before all of this. started on the first crank, stalled out 30 secs later, and became increasingly difficult to crank. found the cylinders filling with fuel. cleared it out and it will crank fine, but not start....and eventually fill with fuel again.

i was told by the people i bought the car from that a similar thing had happened to them. after them spending alot of $ they said that the shop that had it replaced the ecm and it fired right up. i had been driving it for several months with no problems until the rod knock developed. 

i am not too familiar with digifant as most of my previous cars were cis or cis-e, and am a little bit of a loss.

it appears that they also had the fuel pressure regulator replaced, and the injector rail....not sure if that was done just because the shop was throwing parts at it,....or they were worn out.

is there any other typical component failures with these ?


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## Fat Rabbit (Nov 18, 2001)

Make sure that you have the ground wires well connected at the transmission end of the cylinder head. A lot of people forget to reconnect those wires after doing engine work and the result is a blown ECU and engine flooding. There should be two or three wires (brown, black or brown and black) that connect there. The wires can also corrode off or corrosion at the connector can block the ground resulting in the same issue. FR


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## ziddey (Apr 16, 2006)

Indeed, hook up the missing ground(s).

As far as your ECU goes, it may be possible to repair it yourself. I haven't had to do this personally, but I believe I've read (a long time ago) that once you open up the box, you'll find a burned trace and diode. But nowadays, you should be able to find another Digifant ECU for ~$40 or so.


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## bpederndern (Nov 26, 2002)

*thank you*

all grounds are hooked up, and cleaned up.....not sure if the corrosion on some may have caused this situation or not. 

trying to locate a used ecm and double check before starting it up after install.


besides changing the oil which is now fuel contaminated, (and putting in a little oil down each cylinder, is there anything else reccomended before i start this up again after the ecm replacement?

also, i am getting good spark....is the spark generated by the little ignition control module, and not the ecm itself?


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## WaterWheels (Aug 14, 2005)

bpederndern said:


> all grounds are hooked up, and cleaned up.....not sure if the corrosion on some may have caused this situation or not.
> 
> also, i am getting good spark....is the spark generated by the little ignition control module, and not the ecm itself?


Not faulting you but just something like checking for spark can fry the ECU if the grounds are not good before doing it. I say this because it is often said that people fry the ECU because they try to start the engine with the ground wire not being secured. Really just switching the ignition switch on for any reason can do it if the grounds are not connected. Say your in the middle of doing the work and decide to check power to something, lights, ignition coil, dash, you name it, but the ECU grounds was still not connected. That's all it takes sometimes to fry the ECU. It is always best to leave the harness off the ECU untill all has been checked and ready so less mistakes are made.

Digifant II should not have an ignition control module, it is internal to the ECU. Or are you asking about the Hall sender in the distributor?


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## bpederndern (Nov 26, 2002)

i am asking about the little 2" square black ignition control module that all of my mk1 cis/cis-e cars had. the car is an 88, (which i thought would still be cis) but it is digifant....the ecm says digifant 2 on the case, so i am also confused. 

i understand what you ae talking about when you say this can happen easily just by powering up something innocent and sending an ungrounded signal.


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## Fat Rabbit (Nov 18, 2001)

Digifant II does indeed have an ICM -- a silver rectangle that mounts on the ECM holder.

It is pretty easy to check the ground (Pin 19) for continuity from the ECM connector if you have a wiring diagram. I'd probably do that before hooking up a different ECM just to be sure that a wire isn't broken or something strange like that. Pin 13 grounds back to the battery. Pins 1 to 13 are in the longer row while 14-25 are in the shorter row on the connector. The lower numbers start on the harness wire in side of the connector. FR


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## bpederndern (Nov 26, 2002)

*wiring paths/ thank you*

thank you for the wiring advice. i will definetely be double checking before installing a replacement ecm. it does make sense that there might be a wiring issue since this sounds exactly like what the previous owner described happening.....and they were doing nothing to the vehick=le when it happened to them


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## WaterWheels (Aug 14, 2005)

Fat Rabbit said:


> Digifant II does indeed have an ICM -- a silver rectangle that mounts on the ECM holder.


 Thanks, sorry it was a European vs. North American glitch. The Digifant ECUs that I deal with here on Polos are true Motronic systems with the ignition internal. I guess this is where someone hip is supposed to say something like ”my bad” if I remember correctly, right?


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## cj_134 (Sep 20, 2012)

*dumb question of the day*

is the ecu / ecm being toast the only cause of the fuel pump running on and filling the cylinders, or are there other things that may cause this?


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## Fat Rabbit (Nov 18, 2001)

Since few people have decided to post their location it is really difficult to know exactly what VWs we are talking about since different variations appeared in different places. 

To answer the most recent question: Digifant injectors are opened and closed by grounding through the ECM. If the ground goes bad a path is usually made to another ground internal to the ECM. When that happens the injectors are held open when the key is on and the engine is flooded with gasoline. FR


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## cj_134 (Sep 20, 2012)

thanks for the reply 
my car is a UK 91 8v gti, digifant 2. It does seem to fit all the replies so far so i guess i will be sourcing a new / used ecu.


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## bpederndern (Nov 26, 2002)

*it is running finally *

after removing the current ecm and old one that came along with the car it is clear to see where the ecms were shorted. i cleaned up every ground after verifying a good ground circuit. 

a nice fellow vw enthusiast was kind enough to bring me 2 used ecms today. installed, and the car now runs. now to get a fresh oil change tomorrow and get the fuel soaked oil out of the engine and let it run for a while 
. 

thanks to everyone who posted and got me on the right path and ultimately solving my issue. first time in a very long time i actually got some responses and quickly solved my problem here


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## ziddey (Apr 16, 2006)

This might be bad advice but assuming your crankcase is able to vent well, maybe take it for a flogging to get rid of the fuel in the oil.


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## bpederndern (Nov 26, 2002)

crankcase is able to vent....but trust me, there is way too much fuel in there now to do it safely and not worry about engine wear.....especially since i think that may have contributed to the demise of the last engine. 4.5 qts of oil and a new oil filter is cheap insurance for me


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