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I spent last night rechecking all of my wiring, I even opened up the VEMS unit to confirm all of the pinouts following a suspicion. I noticed something weird in that one injector would make a buzzing noise whenever I disconnected the flyback and energized the ignition. Baffled, I went checking voltages of the injector pins, flyback, etc. Apparently, when the ignition is turned on there seems to be a voltage potential between the two pins of the injector harness. If that's true then my assumption is that one of the FET drivers may have failed and fuel is being dumped (I only checked Inj #5 for this). I don't know why they might have failed, so far I have not found any mistakes with any of my wiring. Some people online refer to a poor ECU ground causing FET drivers to blow. I have a thick ground wire going all the way from the ECU to the bottom post of the coil pack bracket bolt (where the distributor used to be). I will confirm all of this again over the weekend, it was pretty late last night so I need to look at it fresh.
Also, I found something else pretty dumb, the injector mapping on the config files provided were incorrect. I should have re-read the first three posts of this thread to find this mixup earlier.
Corrected:
Again, any sample VEMS configurations would be much appreciated just for comparison. Thanks!
I never installed the coil packs so did not have validation that it had no errors. I was able to drive with the distributor config with 24lb injectors and TPC supercharger. The ECU had been checked and tested by Raceboy recently, but it ended up that I needed an engine rebuild though.
Good news! My buddy and I spent the long weekend getting the car up and running on VEMS. A little story on our discoveries, hopefully it will help others out in the future:
In order to remove any doubt about my spark plugs, we replaced the old units with brand new ones (I figure they could use replacement anyways, as some were fouled up pretty badly). After doing so, we still noticed no spark on cylinders 2 and 5. Also, while testing spark, we confirmed that cylinder 6 was in fact fully open when ignition was energized, all other injectors were fine. Heeding some advice from Alex and being fed up with messing around with assumptions for pinouts, settings, etc, I decided to open up the VEMS unit once again to verify all of the ignition/injector outputs, flyback/iacv diodes, install the IAT ground wire, etc. In doing so, I discovered that my ECU was in fact different from others. It was wired to use ignition drivers 04,05 for cylinders 2 & 5 instead of 06,07 like other ECUs Peep have configured. After confirming this, I wired in the proper IAT ground to pin 26 on the Motronic 55-pin connector, fixed some other poorly soldered points, and closed up the unit. Miraculously, injector 6 started behaving as normal and did not open up when the ignition was turned on. I reset the configuration back to the maps Peep supplied and after making the appropriate modifications for different ignition setup, req_fuel, and injector output fixes, the car fired up right away and was running beautifully!
We installed the EGT on the stock headers near the drivers side heat exchanger, as close as possible to the head. It took several drill bits, some griding, but we got the tap in there and installed the bung.
Unfortunaly the good news was short lived. The next time I opened up the VEMS unit to sort out the heatsink, my injector 6 started staying open on ignition. My theory is that something inside the ECU box is causing the transistor to short, as it seems to change behavior everytime I open/close the unit. I will open it up tomorrow to test the transistor and/or replace if need be from the rescue kit
Once I get the car running again and start to tune it, I will post my logs and config. Thanks for everyones help!
Great news that you got the car running nicely, albeit for a short while.
Maybe check the injector fets if they are irf640N they must be insulated from the case and the heat sink bars, vems call for mica sheet, mine had parcel tape.
Wow, thanks for the heads up. I was under the assumption that it was some thermal transfer tape in lieu of thermal paste. Now I'll make sure to insulate the transistors from the case. In retrospect, mine looked like parcel tape as well.
Insulating the FETs with some Kapton tape worked wonders. Apparently, the parcel looking tape was in fact, mica tape, but it had started pealing off on the edges from the screw holes. I cleaned up everything, insulated the FETs from each other and the case using Kapton tape and added some thermal paste.
This datasheet explained everything: http://www.irf.com/product-info/data...ta/irf640n.pdf The pin 2 and the package are both connected to the Gate, as a result, if they would ground out or touch another active FET, the transistor would basically be bypassed. This was causing my injectors to be stuck open.
Have the car running well on Peep's maps with my req_fuel adjusted for my injector sizes. The WBO2 still shows a somewhat rich mixture, so hopefully this weekend I will get some proper tuning done.
Next steps are to fix all of the output signals for the gauges. Right now, my Oil Pressure gauge is my Tachometer.
I think the tach issue was a setting issue on the outputs (on the distributor config). Might be same for coil pack config. Will try to see if I have anything on it.
You are correct. I took a look at the output configurations and it looks pretty straight forward. I just need to spend some time to confirm the pinouts.
09-03-2015, 02:06 PM
