1990 tsi FWD... car is dead... no spark..

[defrag010]

OK. I have a 1990 tsi FWD that i'm building. I put my car together this weekend, and It's not getting any spark and the injectors aren't firing. I measured the coil pack connector, and the coil is getting power, but no pulse. I took the CAS off and spun it, but the injectors did not fire. The fuel rail is getting fuel, but it's not getting past the injectors.
I hooked my datalogger up, but it acts as if there is no ECU.
All of the fuses in the vehicle (under the hood and inside) are fine. The only thing I haven't checked is the ECU power wire because I don't have an ECU pinout. It could be possible that my ecu isn't getting power. I even went so far as to check the voltage on the wires After the fuseblock on the battery terminal. All three wires had power.
Could it have something to do with the MPI relay being messed up? The car has a new CAS, coil, and transistor. If it helps, The only dash lights that come on when I turn the car on are the Battery, Seatbelt, and Parthenon (coolant). I opened up the ECU, and it looks clean with no burnmarks or exploded caps. It smells pretty too. I was thinking about running a hot wire from a separate source to the ECU to see how the car would react if the ecu was getting 100% power, but I didn't have a pinout and I didnt' want to risk frying anything.
I don't have a spare 90 ecu to test out, and I have to get my car running by november or I will have to tow it to another garage.

Oh, it's also 100% stock electronics and engine.

Hope you can help.

 

[BISHILVR]

yeah, your thinking in the right direction, check the ecu for b+ AND good ground for sure....then the mpi relay should be checked while your in the area..........

 

[i1nk83]

where exactly is the mpi relay and waht does it look like?

 

[defrag010]

it's behind the center console, next to the ECU on the passenger side. It's a small gold box about 3"x2" that has one 5(i think) prong connector. I've switched three of them in there and none of them make a difference.

 

[91talontsiturbo]

i have the ECU pinout printed out ,but i just got to find the website where i got it from so i can send it to ya, i'll get back to ya as soon as i do thow

 

[91talontsiturbo]

aright here it is, for 1G in everything enjoy

http://www.vfaq.com/mods/ecu-harness-1G.html

 

[defrag010]

thanks for the help. I got a new ecu out of a running car today to try and get to work. My problem is that the ECU isn't getting any turnon power. I ran fused hot wires to pin 102 and 107, and now the ECU turns on. My problem is that it STILL isn't sparking!!! I took my MPI relay cover off, and observed that both of the relays are working. My CAS will fire the injectors now, and everything is working like it Should, except the spark.
The ECU still brings in code 25 (mass airflow meter, barometric).
I don't know what to do.

 

[defrag010]

hmm

 

[steve]

The same side of the MPI relay that powers 102 and 107 powers the MAF, CAS, ISC, Solenoids, o2 Heater and injectors. the Coil and PTM get power from the ignition switch.

There isn't much to the MPI side of the MPI relay. Power from the fuse on the battery winds up on pin 10. The ECU pulls pin 8 low to turn on the relay causing powe to be switched to pins 4 and 5. The ECU has to be getting backup power from the footwell fuse 19 on pin 103 and see the ignition switch on pin 110 to power up the MPI relay.

Steve

 

[defrag010]

Thank you steve!

I went out and tinkered with it some more. My CAS gets power, and when its turned, the injectors fire. I measured voltage at the coil, and it gets power, but I don't know where to measure power to the transistor. It's 5 wires... a ground, two that go to the ECU output (i think pin 53 and 54), and two that go to the coil. Whenever I crank the car, the power transistor does not get any pulse from the ECU to fire the coil. I didn't check pin 110 because I didn't know what it does.
When I measured, pin 103 was getting constant power even with the car off. Does pin 110 need to give power to the ECU for spark to happen? I'd be concerned with hooking it up to an accessory, because then the ECU would lose power when the car is cranking.
The MPI relay powers up, and both relays inside will click whenever the car is cranked. By looking at the wiring diagram, It looks like one side controls ignition, and the other side controls fuel. Even though both sides of the relay are working, the car is still only getting fuel.

 

[steve]

110 goes to 12v when the ignition switch is in the RUN position.
This causes the ECU to pull 63 low, turning on the MPI relay and powering up the ECU.
If the ECU boots it will turn on the CEL light for about 4 seconds, and set the boost gauge to 0.
108 goes to 12v when the ignition switch is in the START position.

This wiring diagram isn't 100% correct for a '90 because of the differences in the coil pack and PTM but it will help. http://www.taboospeedshop.com/wiring.htm

54 and 55 are the ECU to PTM spark signals.
The PTM has 6 pins. 1- C1, 2- ECU 55, 3- GND, 4- NC 5- ECU 54, 6- C2

Pins 1 and 2 on the coil to the the outputs of the PTM
Pin 4 on the coil is power.
Pin 3 is the tach pulse back to ECU pin 109.

I would expect 110 would have to be at 12v for spark but I wouldn't expect the injectors to fire without it either.

Steve

 

[defrag010]

see that's whats so frustrating... The diagram is almost the same as the one I have, and It just doesn't make sense to me. When i turn the car on, the ECU boots up like you mentioned, and the boost gauge goes to zero. The only power sources that I can find are 102, 103, and 107.. and all three of them have power on mine. I see that 102 and 107 T off and end up at the MAS. One thing that keeps on happening is that the logger is giving me code 25 for the barometric sensor in the MAF. Could my bad barometric sensor tie in with the ECU having power issues? The maf is getting the needed 5 volts. The only way I can get the ECU to work is by jumping power from 102 to 103 and 107. Otherwise, it just won't get any turnon power. I can remember checking 63 and 66 for power (i think they were small blue wires), but I could never get any power from the ECU on those pins.
On the PT, mine has 6 spaces, but only 5 wires going to it. The actual transistor unit itself only has 5 prongs, also. I'm assuming "NC" means no connector?

This is why it's pissing me off, because everything Should be working just fine. The only reason I'm stumped is from the lack of ECU turnon power. I can't find where the ECU turnon power is sourced from. Every wiring diagram I find puts the ECU turnon power as the same circuit as the MAF, ISC actuator, solenoids, injector resistor, and CAS. I don't know if it is in conjunction with the fact that I'm getting code 25, but on the original ECU, my ISC motor will just go CRAZY whenever the computer is on. My CAS, ISC, and MAF are all getting power, so it doesn't make sense why the ECU isnt getting turnon power. Does the ISC have a separate actuator? or is it just referred to as the whole ISC motor in the throttle body? I checked impedance on my ISC coils, and they were all at 32-33.

In all honesty, it almost sounds like my ECU is the culprit for the no spark situation, eh? I'm more worried about solving the turnon power problem right now, as that will make me belive that the actual ECU is what is preventing spark. Once I can figure out the hardwiring part of my problem, I can figure out the computer related part.

So Where should I source the power that goes to pin 102 and 107 from? Is it the MPI fuse on the battery terminal? All three wires coming off of the terminal carry power and the fuses are ok.

 

[defrag010]

where did you go steve?

 

[steve]

where did you go steve?

I had a bunch of work come in today and then a panic call from my Mom because the ice maker hose burst. Too bad she forgot about the valve, it would have shortened her cleanup time. Lots of water can spray in the half hour it took me to get there.

I'm confused when you say.
"The only power sources that I can find are 102, 103, and 107.. and all three of them have power on mine." and "The only way I can get the ECU to work is by jumping power from 102 to 103 and 107." and "My CAS, ISC, and MAF are all getting power" The MAF, CAS, and ISC all get power from the MPI relay, the same place where the ECU pins 102 and 107 go.

I've told you to check:
"Power from the fuse on the battery winds up on MPI pin 10. The ECU pulls MPI pin 8 low to turn on the relay causing power to be switched to MPI pins 4 and 5." If you don't have battery voltage at MPI pin 10 then you can't get power to 102 and 107. If you do have power to 10 then jumper pin 8 to ground and see if the relay switched it to 102 and 107 as well as the MAF, CAS, ISC. You can't check this while you have a jumper from 102.

I'm just trying to eliminate problems other than the ECU. It's already suspect.

Steve

 

[defrag010]

ooooohhh. sorry, this is the first time i've ever had to mess with any car's electrical/computer system. sorry for being unclear.

"The only power sources that I can find are 102, 103, and 107.. and all three of them have power on mine." - By looking at the wiring diagrams, It seems that the ECU only recieves power from those three pins. After I jumped power, those are the only three pins on the ecu that are getting power.

"The only way I can get the ECU to work is by jumping power from 102 to 103 and 107." - Wire 102 and 107 to the ecu are dead. I took the connector prong out of the pin 103 connection and connected two wires to it, with which I connected to pin 102 and 107 so that all three wires are hot.

I'm going to try what you suggested on the MPI relay and get back with you. again, sorry for being incomprehensive.

 

[steve]

Cool,
I figured that you still had the power hotwired and you need to go back at this point and disable your hotwiring to debug why the MPI relay isn't working correctly.

We are going to start makeing sure that battery voltage reaches pin 10 in the MPI relay and that when pin 8 is connected to ground battery voltage gets switched to the pins that feed the ECU, MAF, CAS, etc.

If that works you'll need to check that the ECU can turn the power on. For that you need to watch pin 110 and make sure that it goes to battery voltage when you turn the ignition switch on to the run position. If the ECU is working it will pull it's pin 68 that is connected to MPI relay pin 8 low and the power should turn on. If it doesn't then there is a problem with the ECU. That's what I'm expecting.

Steve

 

[defrag010]

Steve... thanks again. I wrote down cliff notes the pins on the MPI relay and ECU to watch so I could have them out there with me when I was working on the car. However, I had dsm guru friend who had a spotless '90 ecu that he let me borrow. I left it hotwired, and the car fired right up. I haven't tried re-wiring it back the way it should be yet, but I still gotta debug a few things on the car first.
The idiots that I had rebuild my head forgot to put the cam seals in, and I used bolts with crush washers to tighten down the Tbelt tensioner. There was oil leaking down into the cam gears which slung it all around the engine bay, and the Tbelt tensioner bolts were leaking and dripping oil right onto the timing belt. I got all of that fixed, though, so I gotta put my pulleys and belts back on and mess with the ECU some more to see what I can discover as far as the stock wiring goes.

One thing I did observe is that the new ECU throws a CEL 44 (ignition coil). The coil measures out fine on impedance, and it obviously sparks fine. The thing that is messed up is my Tachometer. It reads half of what the real RPM is. The whole time the car is running, it gives the CEL, but once it's off, it goes to stored memory and does not remain active. Could having a different year transistor cause this? The guy I got the transistor off is the same guy that let me borrow his ECU tonite, and he said that it's off of a '90.

 

[Royalty]

i hate to bring this back from the dead, but was this ever resolved? this is whats happenig to me.

 

[defrag010]

Yeah. It turned out that the two wires that went from the ECU to the PTU were shorting out. I just cut the wires off from the harness plug and ran two new wires straight to the PTU. Works fine now... It took me enough as to replace my PTU and have my ecu rebuilt, though..

 

[steve]

So the wires to the PTM were the final problem? Cool.
Replacing the PTM might have been unnecessary but the ECU needed the work, it was seriously fubar'ed.

Steve

 

[dsmracer_1991]

OK. I have a 1990 tsi FWD that i'm building. I put my car together this weekend, and It's not getting any spark and the injectors aren't firing. I measured the coil pack connector, and the coil is getting power, but no pulse. I took the CAS off and spun it, but the injectors did not fire. The fuel rail is getting fuel, but it's not getting past the injectors.
I hooked my datalogger up, but it acts as if there is no ECU.
All of the fuses in the vehicle (under the hood and inside) are fine. The only thing I haven't checked is the ECU power wire because I don't have an ECU pinout. It could be possible that my ecu isn't getting power. I even went so far as to check the voltage on the wires After the fuseblock on the battery terminal. All three wires had power.
Could it have something to do with the MPI relay being messed up? The car has a new CAS, coil, and transistor. If it helps, The only dash lights that come on when I turn the car on are the Battery, Seatbelt, and Parthenon (coolant). I opened up the ECU, and it looks clean with no burnmarks or exploded caps. It smells pretty too. I was thinking about running a hot wire from a separate source to the ECU to see how the car would react if the ecu was getting 100% power, but I didn't have a pinout and I didnt' want to risk frying anything.
I don't have a spare 90 ecu to test out, and I have to get my car running by november or I will have to tow it to another garage.

Oh, it's also 100% stock electronics and engine.

Hope you can help.

hope this helps bro i had the same problem not too long ago. check the temperature sensor for the ecu.it is on the bottom of the thermostat housing on the left if you are standin in front of the car. thats what my prob was. one of the wires was broken. hope thats what it is.

 

[defrag010]

steve,

the underhood weatherstripping was gone when I got the car, and upon inspection it looked like water drained down into the engine bay and sat stagnant inside the loom of the wiring harness. When I tore the loom off the underhood harness, the wires were so fragile I could have broken them without effort. I did alot of patching on the corroded wires, but I got everything working.

did you read on nabr what happened to the car on christmas night? :laugh: