ECU Compatibility?

[jordan_jensen]

Hello, Im in the process of finishing up a father son project and am running into some issues and hoping for some insight. Its a 69 Fastback / Auto with Fuel injection. All FI components were looked over or rebuilt by Jim Adney. Original Engine with fresh rebuild. Just installed new FI Harness that was built by Jeffs 914 Harness (Very nice Harness). The car starts up and runs good but after about 5 minutes it shuts off. I have narrowed it down to a faulty ECU as I swapped a replacement unit in when this happed and solved problem but runs with a slower idle and smells rich.
The original ECU has a Sticker over part number that says unit has been revised 311 906 021 BV 280 000 004 REV.
I wasn't able to find exact replacement in my searches but seller said it should work so I bought it. Replacement reads 311 906 021A 280 000 001. When Jeff was making my new harness he mentioned the original harness was unique and has not come across one like it before which Im assuming relates to the revision?
So my question is is it ok to run replacement ECU which seems to work but maybe I just need to increase idle / Reset Timing? Or do I need to find exact replacement Revised Edition ECU? Or maybe original ECU can be fixed? Let me know what you guys think. Thanks, Jordan

[Tram]

[Bobnotch]

[raygreenwood]

Yes, need and answer...because teh slow winding down (with or without submarining idle)...and then hard restart ...is usually a fuel mixture issue. Usually rich.
Many times just a small vacuum leak that is enough to keep an overly rich idle or it can be leaking injectors or cold start injector. The gist beeing that at idle it cannot use all of the fuel....and at idle, all D-jet runs to wet ports. At higher rpms its not an issue.

The two out of time injections when idling for a while...when running rich...slowly flood those two cylinders. Restarting one like this is a mess. Its usually not the ECU.

Ray

[jordan_jensen]

Thank you guys for the responses. Im not sure what seemed unusual about harness but he said he was glad I sent my original as it had a slight difference from what he normally sees. I Can Email Jeff to see If I can get that info from him. Shut off is electronic like it was turned off with Key. Fuel Pressure is exactly at 28PSI With reading from MCMaster Carr Gauge Ray recommends. Up until this 5 minute mark it runs very smooth and doesn't smell rich even when running in my garage. Again, I bought a spare ECU, not an exact match of my original so when it shut down I tried a restart and wouldn't start, immediately plugged spare ECU in and started with no problem but with a much slower idle and smelled rich. So this different running condition with spare ECU is what's keeping me from using it. Maybe spare ECU is ok to use and just adjust timing / Idle? Wondering If after these adjustments would that change the rich smell Im noticing with the spare ECU? Thanks in advance for your guys help!

[Tram]

[Bobnotch]

[jordan_jensen]

Ok so I Just got home from work and tried the Spare ECU from a cold start and planned to increase Idle as Tram recommended. It Started right up with slow idle and blowing smoke and smelling rich. So I Increased Idle, Idle screw was responsive but smoke is excessive and smells rich still after increase of idle.

Bob, the unit I bought is Marked with a sharpie A. I put the actual part numbers of ECU's I'm working with if that means anything to you in my first post of this thread.

[Tram]

Email me if you want another B to test. I am thinking you possibly have a fault in each of yours. At least a known good one to test will tell us for certain.
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[raygreenwood]

[Bobnotch]

I agree with Ray, check the voltage at the 5 minute mark, and see if it's dropping. I only mention this as my own car had that happen as the VR started going bad (the voltage dropped from 14.5 to 12.8 and was still dropping). In my case I set up a road test circuit, and watched the voltage drop as I drove it. It was good for the first 2 miles, then started dropping off the further I went. By 8 miles it was having a hard time running and the voltage was down to less than 12.3 volts.
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Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120

[KTPhil]

And just for benefit to others who might check this thread titled "ECU Compatibility" here is a list of the proper part number sets over the three FI generations:

[jordan_jensen]

Tram, That sounds great. I emailed you so we can work out the details.

Ray and Bob, So with Original ECU it actually Runs perfectly but at 5 Min Mark it just shuts off like the key was turned to off position, not running rich though. I did go out to check voltage this evening and it would not start with Original ECU (which is a first this has happened) I plugged in Spare Version A and started right up but smokey and rich. Definitely starting to think we have an ECU Issue.

Thanks for posting that Chart Phil. Good info to refer back to.

[rosevillain]

My experience with d-jet makes it necessary for me to first check component compatibility, then look at general tuning (valves adjusted, timing/dwell set, compression), then check for loose or broken wires, connectors, and vacuum leaks (remembering that vacuum leaks usually cause a rich condition in these systems), adjust/ check the AAR, then check fuel pressure and temp sensor resistances.

There may be more than one issue causing you to think that the ECU is bad. A bad AAR and a bad temp sensor, or a plugged injector or two, a loose wire on the trigger points, weak ignition... These engines run very different warm vs cold, and there are a few components, not just the ECU, that keep them running during the warm up period and beyond.

[Bobnotch]

[Tram]

[t-royR]

Hey all.

Just curious on something. I have a spare ecu and it has the number of 311906021A

I am not finding much reference to this part ending in "A", and what year and other parts it is compatible/intended for. Anyone know?

The Bosch # is 280 000 001
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T-roy
75 Super
71 Super
71 Ghia coupe auto-stick
71 Ghia conv
69 Fasty
74 Ghia conv

[jordan_jensen]

So here's an update on this subject. So Tram is working on sending a know good version B ECU. In the mean time I found another Version B from a samba member which I bought and had shipped. It Arrived yesterday and plugged it in. Started right up but ran rough and super smokey, Same exact running condition as the spare version A I Bought. So decided to plug in O.E ECU (which last time decided it didn't even want to work even when spare would start but didn't run good) Well it decided to start up perfectly and run great for the whole time I was testing. 13.8-14V at Idle and it never stalled out like the original 5 minute cut out issue that started this thread. Even turned it off a few times after engine was a full operating temp and started right up with no issue. Pretty much ran perfect but before updating this thread yesterday and celebrating I wanted to retest today and make sure all was well. So I went out after work today and NO Start, Just Cranking over, nothing else. Plugged in one of my spares with and had an instant start but rough running and smokey. Re-Plug in OE ECU still nothing. So to sum it up. The 2 spare ECU both run Real rough and Rich. OE ECU runs perfectly only when it wants too? Starting to wonder if someone test / rebuilds these and can find and fix a Glitch in my OE ECU. As these spares ECUs Ive been getting just aren't running correctly with my system.

[Tram]

Jordan- when you get the no start issue, can you hear the initial "whirrr- click" of the pump when you turn the key?
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[jordan_jensen]

Hey Tram, Yes Fuel pump activates with turn of the key every time and with all 3 ECUs I've tried.