Sy dies after 30 seconds

[VermontTy]

Re: Sy dies after 30 seconds

Double check the grounds attached to the intake manifold stud. One is the 02 sensor system ground (the one with 2 wires on the ring terminal; a tan wire, and a white / blk wire). The other wire, a standalone tan one, is the ECM ground. Check that.

 

[bg_bls]

Re: Sy dies after 30 seconds

Thanks VermontTy!

I will double check the grounds tomorrow. I might have messed up the ground by the intake manifold when I took out the metal intercooler pipes. Hopefully this problem will be as simple as a loose or bad ground.

Thanks for the replies,
Brian

 

[VermontTy]

Re: Sy dies after 30 seconds

I double checked stuff when I got home yesterday and got this pic. The two grounds on the stud; one is a standalone tan/white wire, and the other is a standalone black one; I thought it was something different. Sorry. The tan/white is the ECM ground. Wouldn't hurt to just cut it and put a new ring terminal on.

 

[myclone]

Re: Sy dies after 30 seconds

Simple test to narrow down where you should concentrate your efforts (you could spend days trying to find an ignition problem and all along its been a fueling problem).

1. Remove turbo to IC hose.
2. Procure a can of ether (starting fluid).
3. Start truck and let it idle for about 20 seconds.
4. Grab ether and have the nozzle pointed towards/into the inlet of the IC and be ready for the engine to die.
5. When engine starts to die give the IC inlet a shot of ether (1 second burst should do it).
6. If truck keeps running then give it another shot of ether and see if you can keep it running (if this works dont do it more than 3 or 4 times...just let it die since prolonged ether exposure isnt good on rings, oil, plugs, 02 sensors, etc).

Question: Does engine die exactly like it has been before feeding it ether?
Answer: Yes.
Conclusion: Problem is electrical, ECM, or ignition side.
Answer: No.
Conclusion: Problem is probably in the fuel side.

So the above test splits the possible list of culprits in half (roughly) since youve taken out the electrical system side of the truck that provides fuel and you obviously have ignition since it ran on ether. You can now concentrate on a relatively smaller list of possible causes.

BTW, unless the engine is close to operating temp to begin with or the closed loop enable temp in the chip has been lowered 30 seconds is way to little time for it to go into closed loop. That narrows things down even more since in open loop the ECM ignores everything but the CTS, TPS, MAP, dist ref pulse read back, and VSS (generally speaking). What Im saying is dont waste time/money on say the O2 sensor since the problem occurs before closed loop when the ECM isnt even paying any attention to it to begin with.

BTW II, going by the above pic of the grounds they look fine to me. Not show quality but as far as electrons are concerned its a good ground and they could care less what a connection looks like to human eye balls as long as its a good electrical connection.

:2cents:

 

[TYGUY]

Re: Sy dies after 30 seconds

do you have an MSD box? i had this happen on my mustang on a road trip once....had to bypass the MSD on the side of the freeway with nothing but a pair of Scissors and a couple bandaids..... no joke.

Dustin

edit:
i had the exact same symptoms....just died while driving .....if i let it sit it starts back up...then dies shortly after again

 

[bg_bls]

Re: Sy dies after 30 seconds

Simple test to narrow down where you should concentrate your efforts (you could spend days trying to find an ignition problem and all along its been a fueling problem).

1. Remove turbo to IC hose.
2. Procure a can of ether (starting fluid).
3. Start truck and let it idle for about 20 seconds.
4. Grab ether and have the nozzle pointed towards/into the inlet of the IC and be ready for the engine to die.
5. When engine starts to die give the IC inlet a shot of ether (1 second burst should do it).
6. If truck keeps running then give it another shot of ether and see if you can keep it running (if this works dont do it more than 3 or 4 times...just let it die since prolonged ether exposure isnt good on rings, oil, plugs, 02 sensors, etc).

Question: Does engine die exactly like it has been before feeding it ether?
Answer: Yes.
Conclusion: Problem is electrical, ECM, or ignition side.
Answer: No.
Conclusion: Problem is probably in the fuel side.

So the above test splits the possible list of culprits in half (roughly) since youve taken out the electrical system side of the truck that provides fuel and you obviously have ignition since it ran on ether. You can now concentrate on a relatively smaller list of possible causes.

BTW, unless the engine is close to operating temp to begin with or the closed loop enable temp in the chip has been lowered 30 seconds is way to little time for it to go into closed loop. That narrows things down even more since in open loop the ECM ignores everything but the CTS, TPS, MAP, dist ref pulse read back, and VSS (generally speaking). What Im saying is dont waste time/money on say the O2 sensor since the problem occurs before closed loop when the ECM isnt even paying any attention to it to begin with.

BTW II, going by the above pic of the grounds they look fine to me. Not show quality but as far as electrons are concerned its a good ground and they could care less what a connection looks like to human eye balls as long as its a good electrical connection.

:2cents:

Well I tried to spray the ether in the IC, but it dies all of a sudden and I can't seem to get the ether in the engine in time. I tried guessing when it was going to die and a few times I think I got it close enough to rule out a fuel problem. Now I am on to look at ignition again and/or an electrical problem. Damn truck is driving me crazy.

Thanks for your help,
Brian

 

[bg_bls]

Re: Sy dies after 30 seconds

do you have an MSD box? i had this happen on my mustang on a road trip once....had to bypass the MSD on the side of the freeway with nothing but a pair of Scissors and a couple bandaids..... no joke.

Dustin

edit:
i had the exact same symptoms....just died while driving .....if i let it sit it starts back up...then dies shortly after again

I have an MSD box, but I already bypassed it and the problem stayed.

I have also went thru and cleaned off the grounds and they all look fine.


Brian

 

[leadfoot]

Re: Sy dies after 30 seconds

I had this happen to me on a 70's Chevy. Engine would start run for a little , then die.

Turned out to be the coil. As the coil heated up it expanded and allowed it self to arc and collapsing the fields. It had a hairline crack. Then it would cool enough to start again and repeat the pattern.

Do you have any extra ignition parts to swap by trial and error?

 

[bg_bls]

Re: Sy dies after 30 seconds

I had this happen to me on a 70's Chevy. Engine would start run for a little , then die.

Turned out to be the coil. As the coil heated up it expanded and allowed it self to arc and collapsing the fields. It had a hairline crack. Then it would cool enough to start again and repeat the pattern.

Do you have any extra ignition parts to swap by trial and error?

Yep tried that too. I had another coil to swap and I have already swapped out a complete distributor.

Brian

 

[VermontTy]

Re: Sy dies after 30 seconds

althouth it isn't the easiest, quickest removal, you might want to pull the ignition module and take it to be tested. I've seen it before where it works fine on the tester, but if you run it 2 or 3 times and get it good and hot, it'll start crapping out. I understand its a new dist., but being able to eliminate one piece at a time is a good idea.