Diagnosing another no start condition..

Series8217 · Post by **Series8217** » Wed Mar 29, 2006 10:16 pm

I had just gotten back from a test drive to see fi my new trunk was going to heat up and burn.. everything looked okay so I backed out of the driveway to go for a longer drive and then my engine stalled. It won't restart. ARGH!

I just went through this same problem from a bad injector ground. I now have all new grounds, so that's certainly not it. The engine cranks normally, battery voltage is good, fuel pump turns on, there's fuel pressure, the tach works (getting ignition pulses; the CPS must be working), the ECM is picking up ignition pulses (I'm seeing RPM data on the scanner) and all sensor readings check out fine on the scanner.
The only thing peculiar I noticed was that Integrator stays at 0 while I'm cranking. Wouldn't that mean the ECM has decided to NOT fire the injectors for some reason? Any ideas?

Series8217 · Post by **Series8217** » Thu Mar 30, 2006 5:05 am

This POS decided to start without me doing anything. :mumum:
I'm going to go over ALL of the wiring tomorrow. These gremlins are pissing me off!!

Aaron · Post by **Aaron** » Thu Mar 30, 2006 5:42 am

Series8217 wrote:This POS decided to start without me doing anything. :mumum:
I'm going to go over ALL of the wiring tomorrow. These gremlins are pissing me off!!

Honestly dude, that sounds like a 3.4 DOHC to me.

What year injectors are you running?

My car used to do the same thing with the factory 91-93s. Even after the new chip, raised idle, and everything else (INCLUDING the new injectors), it'd still die once in a while. When it did, it would usually not restart immediatly. But 5 min later, while starting it, I held the throttle wide open, and after trying a couple times it started right up. I still don't know what it was, just thought it came with the territory kinda thing.

Series8217 · Post by **Series8217** » Thu Mar 30, 2006 8:51 pm

Aaron wrote:
Series8217 wrote:This POS decided to start without me doing anything. :mumum:
I'm going to go over ALL of the wiring tomorrow. These gremlins are pissing me off!!
Honestly dude, that sounds like a 3.4 DOHC to me.

What year injectors are you running?

My car used to do the same thing with the factory 91-93s. Even after the new chip, raised idle, and everything else (INCLUDING the new injectors), it'd still die once in a while. When it did, it would usually not restart immediatly. But 5 min later, while starting it, I held the throttle wide open, and after trying a couple times it started right up. I still don't know what it was, just thought it came with the territory kinda thing.

91-93 injectors. You did nothing but change to the later ones and it fixed the problem?

Aaron · Post by **Aaron** » Thu Mar 30, 2006 10:38 pm

I'd bet a lot of money that is your problem. The 91-93 injectors are known for being responsible for the "phantom stalling" problem. In the stickshift w-bodies, they would stall whenever you put the clutch in and slowed down, such as to come to a red light. This would happen nearly 1/3 of everytime you went to stop at a light. Even with my custom chip and raised idle it still stalled out. Usually when it stalled at a light, I was still moving and could just drop the clutch to get it to start again. But sometimes when I was just idling and it would stall, it wouldn't start again for a few minutes, and even then I had to hold it WOT.

All of these issues went away with the 96 intake swap, which included with it 96-97 injectors. If I were you, I'd swap to the newer injectors asap. And intakes, but we've already talked about that :thumbleft:

Series8217 · Post by **Series8217** » Thu Mar 30, 2006 11:42 pm

Aaron wrote:I'd bet a lot of money that is your problem. The 91-93 injectors are known for being responsible for the "phantom stalling" problem. In the stickshift w-bodies, they would stall whenever you put the clutch in and slowed down, such as to come to a red light. This would happen nearly 1/3 of everytime you went to stop at a light. Even with my custom chip and raised idle it still stalled out. Usually when it stalled at a light, I was still moving and could just drop the clutch to get it to start again. But sometimes when I was just idling and it would stall, it wouldn't start again for a few minutes, and even then I had to hold it WOT.

All of these issues went away with the 96 intake swap, which included with it 96-97 injectors. If I were you, I'd swap to the newer injectors asap. And intakes, but we've already talked about that :thumbleft:

How could you possibly start the car holding it at WOT? That puts it in clear flood mode.. i.e. it doesn't fire the injectors.

Will the later injectors fit in the early fuel rail? I'm not switching intakes..

whipped · Post by **whipped** » Thu Mar 30, 2006 11:45 pm

Series8217 wrote: How could you possibly start the car holding it at WOT? That puts it in clear flood mode.. i.e. it doesn't fire the injectors.

Will the later injectors fit in the early fuel rail? I'm not switching intakes..

Sounds to me like he had an intermittant sticking injector.

GM MPFI injectors are pretty universal. I've got LT1( or something) injectors in mine.

Oh, btw, I had a 93 dohc that stalled as well. It was pretty much random, and only seemed to happen when I was pulling into a parking lot. I forced it to run rich by changing the minimum BLM value, and richening up the VE table. Never stalled after that.

Aaron · Post by **Aaron** » Fri Mar 31, 2006 12:59 am

Series8217 wrote:How could you possibly start the car holding it at WOT? That puts it in clear flood mode.. i.e. it doesn't fire the injectors.

Will the later injectors fit in the early fuel rail? I'm not switching intakes..

Don't ask me. This wouldn't be the first time you were wrong about the ECU though....like the max rpm....hehe

Yah the injectors will fit and plug right in, their outside is the same.

Whipped, that is exactly waht most 91-93 3.4s do, with the 5-speeds being almost dangerous about it.

Series8217 · Post by **Series8217** » Fri Mar 31, 2006 1:48 am

Aaron wrote:
Series8217 wrote:How could you possibly start the car holding it at WOT? That puts it in clear flood mode.. i.e. it doesn't fire the injectors.

Will the later injectors fit in the early fuel rail? I'm not switching intakes..
Don't ask me. This wouldn't be the first time you were wrong about the ECU though....like the max rpm....hehe

Crank PW multiplier vs TPS:
1.00 for 0-24.9%
1.06 for 25.0-87.4%
0.00 for 87.5% and up

Pretty much every EFI GM car has the clear flood feature.

Your motor may have been getting flooded and would start up on the residual fuel in the intake?

Anyway, I went over my wiring today and didn't find anything bad. My plug wires are routed pretty badly and could be crossfiring; I'm going to pick up some seperators tomorrow and keep them apart. Might clear up some idle misfires too, though I think thats mostly from the cam timing.

Aaron · Post by **Aaron** » Fri Mar 31, 2006 9:06 am

Series8217 wrote:Pretty much every EFI GM car has the clear flood feature.

Your motor may have been getting flooded and would start up on the residual fuel in the intake?

Could be, I'm not sure. I just know it used to help it start after it died. In fact, I've found a lot of times flooring a car helps it start. Helps my Fiero too. Maybe like a choke action I don't know.

Anyway, I went over my wiring today and didn't find anything bad. My plug wires are routed pretty badly and could be crossfiring; I'm going to pick up some seperators tomorrow and keep them apart. Might clear up some idle misfires too, though I think thats mostly from the cam timing.

I'm telling you, pick up a set of 96 injectors. If nothing esle, your motor won't sound like a diesel from the old ones anymore..

whipped · Post by **whipped** » Fri Mar 31, 2006 9:49 am

So what's it doing? It just stalled and won't start now?

Can your scanner read injector PW?

Check the fuses.

Series8217 · Post by **Series8217** » Sat Apr 01, 2006 12:12 am

whipped wrote:So what's it doing? It just stalled and won't start now?

Can your scanner read injector PW?

Check the fuses.

Yeah, scanner shows injector PW to be like 5 or 6 ms (I don't remember off hand). I checked all the fuses with a fuse tester to make sure they don't only look good but are good.
I got it to start yesterday without touching anything.. but I'm still worried that its gonna stall and not start when I'm in the middle of nowhere on my drive back to LA on Sunday. I haven't tried to start it since... the battery is out because I'm rebuilding the front compartment and moving the battery as low and toward the rear as it will go in the front. I'll try it out tomorrow when the tray is done, to see if its being stubborn about starting again.

whipped · Post by **whipped** » Sat Apr 01, 2006 1:48 am

I think you need to rewire your injectors. Just start from scratch, buy a new injector harness from the junkyard and go from there. Where are you getting power for your injectors from?

Series8217 · Post by **Series8217** » Sat Apr 01, 2006 2:59 am

whipped wrote:I think you need to rewire your injectors. Just start from scratch, buy a new injector harness from the junkyard and go from there. Where are you getting power for your injectors from?

One of the injector fuses sends power through a C203 pin to the miniharness connector. Past the miniharness connector it splits into 6 power wires.. one to each injector.. they're parallel.. I really doubt the problem is past that point, since it wouldn't make sense that they all go bad. The miniharness connector was giving me trouble with the TPS a while back. Maybe the problem is in there; that has the injector grounds AND power going through it. I'll take a look..

Aaron · Post by **Aaron** » Sat Apr 01, 2006 5:25 am

whipped wrote:I think you need to rewire your injectors. Just start from scratch, buy a new injector harness from the junkyard and go from there. Where are you getting power for your injectors from?

I think he needs to buy newer injectors. Rather, I know.

whipped · Post by **whipped** » Sat Apr 01, 2006 11:34 am

Series8217 wrote: One of the injector fuses sends power through a C203 pin to the miniharness connector. Past the miniharness connector it splits into 6 power wires.. one to each injector.. they're parallel.. I really doubt the problem is past that point, since it wouldn't make sense that they all go bad. The miniharness connector was giving me trouble with the TPS a while back. Maybe the problem is in there; that has the injector grounds AND power going through it. I'll take a look..

One? The stock fiero use 2 fuses 5 amps each, one for each bank.

MNFatz · Post by **MNFatz** » Sat Apr 01, 2006 1:08 pm

Aaron wrote:Could be, I'm not sure. I just know it used to help it start after it died. In fact, I've found a lot of times flooring a car helps it start. Helps my Fiero too. Maybe like a choke action I don't know.

This is a <another> lie. Like someone else said, the fuel injectors are shut down when you floor the pedal and the motor isn't running.

Series8217 · Post by **Series8217** » Sat Apr 01, 2006 2:27 pm

whipped wrote:
Series8217 wrote: One of the injector fuses sends power through a C203 pin to the miniharness connector. Past the miniharness connector it splits into 6 power wires.. one to each injector.. they're parallel.. I really doubt the problem is past that point, since it wouldn't make sense that they all go bad. The miniharness connector was giving me trouble with the TPS a while back. Maybe the problem is in there; that has the injector grounds AND power going through it. I'll take a look..
One? The stock fiero use 2 fuses 5 amps each, one for each bank.

Not a stock Fiero

I followed the factory 3.4 DOHC wiring. It only uses one fuse. I put a 10A fuse in one of the injector fuse slots and use that for the power. The wire is the same gauge as everything else on the fuse box that uses 10A..

Aaron wrote:
whipped wrote:I think you need to rewire your injectors. Just start from scratch, buy a new injector harness from the junkyard and go from there. Where are you getting power for your injectors from?
I think he needs to buy newer injectors. Rather, I know.

Aaron, I drove for 7,000 miles without any stalling issues like this. The injectors were cleaned and tested 7,000 miles ago. They don't just randomly go bad all at once. I think your car had other problems.

Series8217 · Post by **Series8217** » Sat Apr 01, 2006 2:32 pm

The housing on my middle ignition coil is getting cracked (again... wtf?). I'm going to replace that and see if it helps any with starting or idle stability. I've started and ran on 4 cylinders before, but it sure can't hurt to have all 6 running right.

whipped · Post by **whipped** » Sat Apr 01, 2006 2:43 pm

Have you checked for spark? If your coil is exploding, maybe your ignition module is sending a billion amps through it (+/- a billion).

The good news is parts for them are cheap at a junkyard. Buy 2 of everything :p