94Q45 Code 21

[burijon]

As a tag onto this post:zerothread?id=243216

Is the ignition coil relay the blue one on the very left behind the ECU?

I got my Q back together from the plenum job:zerothread?id=246108

All new spark plugs, 2 replaced fuel injectors. all ohm within spec, all connectors got dielectric grease. I have doublechecked all connectors and grounds to make sure I didn't miss anything. The car cranks just fine sounding but doesn't catch. Code 21 is on the ECU. Is there a relay I can swap from somewhere else on the car to test?

Not that I think it matters but will mention it, I did the fuel pump replacement BEFORE the plenum and drove it to get gas after I replaced the pump.

[qsiguy]

The blue one I believe is the audio amp relay. The Ignition relay is the center green one IIRC. It should have 4 wires on it. Black/White, White/Black, Gray/Red, and Brown/Yellow. The White/black should have constant 12V+ at all times, even if the key is off. The Brown/yellow should have 12V+ if the relay turns on which goes to your ignition system. The black/white should have 12V+ when the key is ON. The Gray/Red is ground from the ECU to turn on the relay.

If you verify you have power on the black/white when the key is on you can pull the relay and jump the black/white to the brown/yellow to bypass the relay. If the car starts then you have a problem with the relay or the ECU is not sending the signal to turn it on. Here is a diagram of the system.



If you don't have 12V+ on the black/white or the white/black then check the 30A fuse shown on the diagram that supplies power to the system. Also if you find that fuse and there is no power there you need to check the connections at the battery where the 100A fusible links are.

[burijon]

I love NICO! Thanks. I will post back when I finished testing.

[burijon]

OK. I have 12 volts. I jumped the relay and heard another relay click. Tried to start it and still doesn't start.That probably means the relay is okay and it's something else?

Update! I just triple checked and found I put the fuel pump fuse in the blank spot of the fuse box. After insertion into correct receptacle it still doesn't start. Let me run my diags again.

[burijon]

I have 12 volts at the 30 amp fuse and at the big 100/120 fuses. I'm gonna reset the ECU and try to start again with all fuses(fuel pump) in place and see if it still codes for me.

I did mark the coil packs and put them back in their original location. Not sure if that matters at all. I'm looking at both rocker covers and the connectors on them making sure they are tight and secure.

[burijon]

YYYYEEEEEEEEHAAAAAAA! She lives!!!!!!

I guess after putting the fuel pump fuse back in and resetting the ECU did the trick. Thank you all for your help and time wasted reading this post!

I need to drain the coolant fully and tie up loose ends to get her reliable. So far no check engine light but I will wait and see after it goes to closed loop to make sure for that.

Thanks!!!

[maxnix]

Nothing like being in LOVE!
Modified by maxnix at 7:52 AM 5/12/2007

[qsiguy]

Amazing how much better the fuel pump works when it's got power

Congrats, glad we could help and glad you got it working. That is a great feeling!

[burijon]

Yes thanks for everyones help! I put the fuse in in the dark with a flashlight. I'm glad I triple-checked everything in the daytime.

My only fear now is that Y coolant hose under the plenum may leak! I'm doing the coolant today with some distilled water and replacing the lower coolant hose. and cleaning out the overflow. Changing the oil and filter and fuel filter and she'll be good for a while.