Guys, I desperately need some help….

Two years ago, I did put a S5 T2 in my 87 GXL.
For this to succeed, I had to redo the emission harness connectors (FEM-01, FEM 02 and the last plug on the ECU, the little small one from the front harness). It did work very well, I did not had any problems, car was running great, did a 14.02@98 mph ¼ mile run.

Unfortunately, I had an accident and had to the scrap the car. I kept the engine, tranny, differential, all my wiring and S5 electronics I used for my conversion. So far so good. I then bought another seven, an 86 Automatic (hey, it was cheap) with no engine or tranny.

Here is the problem I’m facing now and is getting me stomped:
I re-did ALL the wiring the exact same way I had on my old car (which wasn’t an ATX)
Now, I didn’t get spark, so verified the coils: +12v, resistance is ok. Grounds at the ECU are fine. So I went and removed the CAS and with the key at ON position, turned the CAS. SPARK and INJECTORS CLIQUING !!!
However, when my friend cranks the car, spark is gone and injectors remain silent!
Put the key back at the ON position, all systems function properly.

I looked thru the FSM wiring diagrams but couldn’t find anything. Another thing had my puzzled to, even with the jumper wire grounded the pump wasn’t getting +12v. I had to jump the circuit opening relay to get the fuel pump energized. I’m thinking these two things are related to each other but after 3 hours of troubleshooting finally gave up.

Anyone having any ideas ?

 

did you try jumping the battery to see if it was just low?

 

Hmm - you turn the CAS by hand & you get spark & fuel..

1) Recheck the for a loose connection at the strut tower fuse block.
2) Pull the CAS cover & see if it turns when cranking.

 

Karack :
Battery is good no question about it

SureShot :
1) Will verify
2) It does, I even tried turning the CAS by hand while my friend was cranking and no spark untill he let's go and put the key back at the "ON" position.

 

Doing what you did with the cas out should have proven everything is working right. I suggest doing what you did to other people who say they get no spark.

What happens is that when your cranking with a so, so battery/starter, the batt/starter drag the voltage down, plus the cas does not turn as rapidly and puts out a lower voltage to the ECU, all of which causes problems.

One thing you might want to give a try, is to pull the four socket plug off the Main Relay. Jumper the Black/Green to the Black/yellow and also jumper the White/Blue to the Black/White. That should simulate the Main Relay being pulled it. Then try to start the engine. Might help. Might not.

By the way, the Black/Green and the White/Blue should have batt voltage on them since they come directly from the engine bay fuse box.

Before you do that, try this: disable the fuel pump by pulling the pumps connector off. Get some starter fluid and spray no more than two seconds into the airfilter and then try to start the engine. IF it starts for a moment and then dies..............the engine was just flooded. Really, try that first.

And while here, I'm a little obsessed by pin 3B of the ECU of a series four car. Make sure that when you hold the key to START, that while holding the key to start you have batt voltage at that pin. If not, then the START sequence is not right and the ECu is actually sending not enough fuel to the injectors during the cold starting . The engine will start without 12v at 3B but will be difficult to start if the engine is cold. Once heated up the engine will start normal..............til it cools off and then back to square one.

 

Thanks for the reply Hailers.

I'm almost 100% sure that the battery is godd and all the systems get enough voltage during cranking because I verified the voltage at the ECU while cranking and got around 10v, which I think should be ok right ?

The engine is not flooded, in fact, the pump is not getting energized while cranking :S This is really strange.

I will try the main relay this week when I get back there (car is apx 30 min from home)

I would like to emphasis the fact that the ECU is an S5 N326, so the pin #3b you mentionned is the pin #1C on the S5? I did verify this and did get around 10v when cranking. Rulling this option out I guess...

I'll go back at my books and verify if I did not miss anything between the engine harness and the front harness, but I don't think so cause the I kept the 86 engine harness, changed only the emission harness. Do you think it could have something to do with the fact that the car was an ATX ? Maybe I missed something there.... I removed the EC/AT control unit. I don't think this should change anything cause the S5 ecu seems to get ALL the required inputs and, correct me if I'm wrong, but it seems that there is no such thing as an S5 turbo II automatic. If so, I did not find any inputs to the ECU that had anything to do with the transmission.


One very last thing, if this is it I feel really stupid : should the pin #1Q, clutch switch, should get 12v when I press on the pedal with my foot ?? Cause it does.
(I've always been a bit confused with the released & depressed thing)


Thanks
One very lost guy...

 

1Q should have approx 12vdc until you push the pedal in. Then the voltage drops to less than 2vdc. You put a gnd on that circuit when the pedal is pushed in. It's just a signal to the ECU that you've put the clutch in, and I assume it anticipates your about to drive the car. 1Q is NOT a big player in much of anything that I've ever noticed.

I really don't understand your car. You did the spin the CAS with your fingers deal and you had spark and the injectors clicked. You should have the same results when the cas is installed and using the starter. It's puzzling.

The fuel pump should only run when you have the key to ON, and the engine is actually running, OR if the key is to ON and the yellow fuel pump check connector near the right front strut tower is jumpered. About the yellow connector: What your doing when you jumper that plug, is put a gnd on the Circuit Opening Relay. One wire in the yellow connector is a gnd wire. The other wire leads to the negative side of the Circuit Opening Relay. So you just supplying a gnd to that relay. If you read voltage on either of those wires, you were just reading thru the Circuit Opening Relay coil to the positive side of that relay. Just FYI.

I thought if you jumpered those wires of the Main Relay, that you'd eliminate any chance that the ignition key being put to start was SOMEHOW robbing the Main Relay from power to pull in. IF you jumper those wires, turning the key to start shouldn't effect them in any way.

Nope. your car is a puzzler from here.

 

check the inputs/outputs at the ignition switch, i'm thinking the switch is cutting voltage to the ACC2(run) circuit while cranking.

i would have to double check the wiring diagrams but i believe that is the circuit that feeds the ECU power right?

 

Hmm, possible, will check !
I Did not think of this.

I'll update you when I get a change to get back at the car.

Thank you guys for your inputs

 

I like Karack's idea.

 

Ok !
First of all, thank you everyone for the ideas.
I got it running yesterday

I feel So stupid..... I re-verified my power circuits to the ECU and it was on the IGN2 power circuit !!!!! DUH !!

Re-wired it to the IGN1 and it fired right away.

Tks all