Car cranks but no start. Help! Trying to make SIV.

[teedoff00]

Hey Guys,

Cliff Notes: Cranks but no start. Checked CPS, Igniter, Coil Packs, Spark Plugs, Fuses, Has fuel pressure. No codes are stored. Details below.

So I've had a bad run the last few weeks with my new turbo not arriving on time and then my AEM tune not going well. I could use some help figuring out my issue.

So, I installed an AEM V2 with Driftmotion PnP harness a few weeks ago. All stock ECU wires remained the same, I just added a MAP sensor and IAT to the AEM harness and tapped the IGF for the TACH input. I started the car and drove it down my hill to put it on the trailer to take it to the tuner. It drove like it had a huge MAF leak but ran and started fairly easily.

I took it to get tuned at KaizenSpeed and after 6 hours of "attempting to tune and setup the AEM" they told me I have hardware issues and the car doesn't start and shows in the AEM software that it isn't getting spark. They get it running and then it would take 20-30 mins to get it started again...

I pushed the car back on the trailer and then I pulled all the AEM stuff out and put the car back to the stock piping, MAF and ECU in an attempt to figured out the issue, as I'm for familiar with the stock TCCS and TSRM.

So car cranks great, very similar to the EFI fuse being pulled. I have checked and tested a spare Igniter, Coil packs, Wires, New Spark Plugs, Fuses under the hood and drivers kick panel. Checked the CPS wires inside and the connectors. All seem good and test good.

I can't get the car to start. Fuel pressure is there according to my Aeromotive AFR guage.

What could it be? Any ideas, advice, help would be so appreciated!

Thanks!

 

[Piratetip]

Have you actually verified the spark plugs are firing?

Fuel / Spark / Compression

You are missing one.

Did they pull a log on the CPS when the AEM was still installed?
Was it a clean signal?

 

[teedoff00]

It did spark from 2/5 from the plug while cranking. It did not from 1/6. After a few more iterations, it did spark briefly from 1/6. The oddity is that the car doesn't even stumble or try to start. It just cranks.

As to the AEM, uunfortunately I have no idea. I tried to get a play-by-play from them but wasn't getting much. I decided to abandon the AEM and go with something more familiar...

So far, that doesn't seem to be working.

What would cause the injectors not to fire if there is fuel pressure? I know I have fuel pressure
Not 100% that the injectors are firing. But it does smell like it.

 

[Billybob9187]

It honestly sounds like bad CPS wiring from what you are describing. Especially after the heat soak 30 min problem you were having with the AEM.

 

[teedoff00]

Yah, it really does seem like CPS. I did look over the wiring and it looks pretty good... hmm...

 

[Piratetip]

These CPS are very old. Just because it "looks ok" or has close resistance readings does not mean it is fully functional.

You actually have to take a scope to it and view the signal to see if its ok.

1st thing to try is to re-gap the coil pickups as close to the wheel as you can.
Might be able to get it working at least for a little while.

 

[teedoff00]

Worth a shot.

Thanks for the tips Nick.

 

[teedoff00]

So in reading and searching online. It seems that if the TACH bounces(mine does) while cranking the CPS is reading properly? Anyone confirm this? I am at SIV right now and am going to check the CPS per TSRM when I return. Just wanted to confirm the TACH bounce.

 

[plaaya69]

So in reading and searching online. It seems that if the TACH bounces(mine does) while cranking the CPS is reading properly? Anyone confirm this? I am at SIV right now and am going to check the CPS per TSRM when I return. Just wanted to confirm the TACH bounce.

Yes it does bounce while cranking. Also if you turn the key to the on position (not started) and look at the RPM gauge fast enough, you will see it jump a very small bit also.

 

[Zazzn]

Sucks that the car didn't make it I had the stock 60k mile mk3 because my 2jz mk3 couldn't make it. Figure out the problem last minute but no time to finish the car!

 

[teedoff00]

So today I rewired the CPS and wired in a new Weatherpak connector. Unfortunately, it didn't change my symptoms. Verified the car is getting fuel. Just must not be getting spark, at least consistently. I've tried a different Ignitor and different coil packs and those didn't change symptoms. Car cranks great, TACH bounces steadily. (Similar to what the EFI fuse is pulled). There are no codes stored. Light blinks rapidly.

How often to CPSs go? I'm at a loss right now as to what to try next. It doesn't even try to start or stumble just cranks. Has to be spark, what what's keeping it from sparking?

 

[f00g00]

Did you do this page from the TSRM?
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=IG&P=12

 

[teedoff00]

Yah thanks for the help. I had ran it before. But just went and checked again. 13V across all connectors and 4ohm of resistance. All coils are specing out. I previously tested the igniter and it appeared to be within spec as well.

So that's why I'm assuming it has to be CPS, but the wires are good now... So failure of the unit itself???

 

[teedoff00]

So I just went out and spec'ed the CPS again. Resistance looked good. Air gaps were good on G1 and G2. But NE was at about .46mm. So .06mm over max. Would this cause a no start condition? It's outta spec, but should it still run?

Thanks for the help.

 

[f00g00]

Is it possible that it is installed wrong after re-wiring it?
You could also ohm it out from G1 to N and G2 to N and you should see a change in the reading when the lobe passes the coil when you spin it by hand.

 

[teedoff00]

I didn't remove the CPS when I did the rewire just cut off the connectors, removed the bad section of wire from the harness. Put on the new connectors. I've checked a few times to make sure everything is lined up from harness to CPS.

When I line up TDC the CPS wheel appears to be in position according to TSRM installation instructions. Timing hasn't been messed with since it last ran.

I just regapped Ne to .250mm. Still no change... So as far as I can tell the CPS is good... man. What could it be?

 

[plaaya69]

I had a bad CPS where one of the wires inside the unit shorted out through the heatshrink on that wire and touched the CPS housing which caused a no start condition. How are the condition of the wires inside your CPS unit?

 

[teedoff00]

I have yet to pull them all the way out, but the inside does look very clean and no areas appear worn. I guess it's worth pulling them out.

 

[f00g00]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=IG&P=16
Check that but also read them to ground. If anything reads to ground it is like plaaya69 says and won't start.

 

[teedoff00]

Ok, so I pulled the harness out of the CPS and all the wires appear to be in fantastic shape. No cracking, all the stock shrouding is in place. The inside of my CPS is clean. I do believe my unit is newer (got it with my 7mgte motor back in 2006) it has a grey plug (89-92 I believe) and the harness side was green.

I also did a continuity to ground test and all wires passed.

Man, why can't I find a smoking gun. I dont know what else it could be... if CPS, Igniter, Coils, Wires, and Plugs are all good, and there is still no spark, what could be the culprit? I believe the ECU to be good because it ran find before removal and installation of AEM and then I took the AEM out (same symptoms with AEM, crank and no start) and put the stock ecu back in to no avail.