1987 Iroc-Z 305tpi MT all stock

Here is what is known:
When cranking, there is 40psi at the rail.
The car fires but immediately dies.
Once the car fires and I let go of the key the fuel pressure drops off sharply.
The car has been sitting for 2 months but i just gave it 9 gallons of fresh gas because at one point I kept turning the key even after it fired (i realize this is bad) and it actually started. I was able to pull it into my driveway but after turning it off there it would not keep running if I tried to start it again. I let it charge for 30 minutes on the charger, turned right on. I drove to get gas, turned it off and it turned right back on. Drove for about 20 minutes and stalled 3 times while parallel parking on a hill (been driving auto for 2 months), turned back on immediately each time, no problem. I let it sit for 2 days since this happened, and went out and it would not keep running again. I let it charge for 1 hour, still will not continue to run. Fires and dies not even 1/4 second after. My keeping the key all the way on trick did not work this time.

There is a brand new fuel filter on it as well.
Brand new connectors and relays at firewall. I have tried swapping fuel pump relay with maf burnoff relay... no effect.

What is going on here?

 

Fuel pump relay needs to see oil pressure to keep running after initial fire. Is your OP sender bad?

 

I'm fairly positive that I replaced the Oil pressure sending unit with a brand new one within the last 2 years. The gauge indicated '30' for oil pressure when the car was running a few days ago.

I will check the switch for it tomorrow... where is it and can I access it from up top?

 

some cars have 2 one on the left side of the dizzy and one above the oil filter

 

As a diagnostic test, temporarily unplug the connector on the side of the Mass Airflow Sensor. If it starts and continues to run, you've found the problem- a bad MAF sensor.

The ECM doesn't look at MAF sensor readings until the RPMs get up around 200 or so. It'll fire right up cranking on the starter but will die the instant the idle comes up over that threshold if the MAF is sending bad readings to the computer.

 

Sorry, I should have said in my original post that I already tried this to no effect.

 

Okay here is what I did today:

12v to G terminal at the ALDL so the pump is always on. Continues to fire only, and dies immediately.

I adjusted the ignition switch but I think I adjusted it wrong. Since turning the key to "on" pulls the line, i pushed the switch as far away as me as I could. If this is not the correct way to adjust it someone tell me what is.

Checked the cap and rotor... it is dirty but it shouldn't keep the car from running if it fires... especially since it ran perfectly the other day...

Anyone else have any ideas for things to test? Im willing to test almost anything you ask me to test if you have a procedure. I'm at my whits end.

I also did the procedure for setting the IAC valve base idle speed, and it would not run doing that either. Is there some way to check to see if the IAC valve itself is stuck in a particular position or not working properly?

What chance is it that the ignition switch itself has bad connections?

 

Update:

I hooked up the fuel pressure gauge again: 40psi when key "on" and when "cranking". Dips approximately 5psi upon "firing" and returns to 40psi as the car dies.

Ohm tested each injector: 16.5 exactly on each. Test light to an injector shows that when cranking, the test light does NOT blink... it simply dims.

I replaced the cap, rotor, ignition module, and ignition switch today.

Spark checked the coil and one wire: both show spark when the car briefly fires before it dies. I checked #1 plug and it is somewhat dirty but not fouled or excessively wet.

Applying vacuum to the pressure regulator (which holds vacuum), results in lower fuel pressure but has no effect on the car running or not.

I have fuel, I have spark, I have air... guys why the hell won't my car keep running?

A few signs, to me, point towards a faulty ECM... but I bought a brand spankin new one about 3 years ago so I have my doubts as far as that goes. I grounded the injector thus bypassing the ECM grounding it, no effect.

There is oil in the car and the gauge reads nearly 30 before it dies.

For a completely unexplained reason the car decided to fire and CONTINUED to run for approximately 5 seconds... as I was about to open the throttle it died infront of me again. After that I had a continuous and unexplained 60psi fuel pressure, no matter how many times I cranked and it fired and died.

wtf. I want to shoot it with my dad's .45

 

Fuel Pressure
A mechanically sound engine will produce 3-6 inches of vacuum while cranking so you would expect the fuel psi to drop while cranking.

Injectors
Correct injector resistance doesn't mean that the injector is actual flowing.
If you know the injector test light should be brighter find out why it isn't. If the cranking rpm is 20 then you will see the test light actually blink very fast, at 30 rpm and higher the light seems to dim.

Plugs
Fuel an heat is required to foul plugs, plugs can't get wet if the injector isn't flowing.
You should disable the injectors (pull fuses) when testing for spark, fuel shouldn't be allowed to sit in the cylinders for to long.

Combustion Requirements
Yes, you have fuel, air, and spark. Don't forget compression, and correct timing, and the quantity, and quality of each.

Partsl
I believe the manufacturer of your ECM would say you've gotten more than 3 times the warranty (usually 90 days.)

 

Why would the compression or timing change in the 45 minute time frame between me turning my car off and turning it back on, when it drove flawlessly before turning it off.

And btw, just because a warranty is only for 90 days that doesn't mean I can't expect a hell of a lot more life out of a 200$ part.

So in conclusion do you have any specific tests for me to try at this point in time? I have a full set of cleaned and flow tested injectors with brand new seals and such, stock injectors, sitting all nice and new in sealed plastic ready to go in. I forgot I had them from my old car. So, Im planning on changing those out and maybe fixing some lose ends if I find any while doing the job.

Unless anyone else has any other suggestions?

 

So,

I removed the injectors and fuel rail assembly. I am going to replace them with brand new stock ones but is there any way to visually check the old ones to see if they are ruined (what do I check for)?

I also found that my egr valve has a busted diaphram. Removed it from the car and tested it with a hand pump vacuum gauge and it won't hold. And the temperature diagnostic switch that screws into the side of it was broken off and intermittedly making contact (looks like someone broke it off and tried to JB weld it back together and it fell apart). This would explain why I had no codes when the egr failed. I doubt that this was my issue though, entirely at least.

I'll put in the new injectors in a few days and put everything back together with a new egr valve and egr temp switch and see what happens I guess.

 

Forgive me if you mentioned it but did you check for codes? Will the car run at all if you hold the gas down? How dirty is your mass air sensor? Have you checked your TPS voltage?

 

I did indeed check for codes, there are none present.

I tried to keep the car running after firing by giving it some gas but no combination of such an effort works. I even tried pressing the gas pedal all the way to the floor while cranking in an attempt to use the "clear flood mode" but apparantly that wasn't my problem because when I returned to normal cranking it did the same thing.

The MAF shouldn't be too dirty, it is the third new one from my last car (2-1/2 years ago) before I realized the ECM was frying them because it was faulty (resulted in a new ECM).

TPS voltage is 0.56 vdc... not perfect but within range for sure.

I'm leaning on either ECM (which is bullshit considering how new it is), injectors, or crapped out EGR valve + its broken in half temp sensor, or more likely a combo of all 3.

 

I installed the injectors and the new egr valve.

When I put it all back together, guess what? The sumabich turned on instantly.

Unfortunately it was running with a major engine vibration, at idle and any rpm.

I double checked to see if I had everything reconnected properly: I did.

I triple checked to see that the firing order was correct: It is.

Oddly enough, I was able to turn it on and off a few times in a row, then it went back to firing but not continuing to run. I threw a battery charger on it, same thing. I left that for a while and came back and it still wouldn't fire. I put everything away and gave it one last time: turned right on but ran with the engine vibration again.

I kept it at 2,000rpm and let it warm up. After about 4-5 minutes it just flatlines on me and DIES. No sputtering no choking just flat out dies.

No codes thrown. And now, it just cranks and doesn't even fire.

I also noticed that the "brake" light on the dash wasn't on for a while, then it came on for like 2 seconds, then it turned off... and never came back on again... in that 4-5 minute period of my car running. Dunno wtf that is all about but thought it worth noting.

Question: If you remove the hose from the egr valve while it is running, should you be able to to put your finger over the hole on the line side and be able to feel suction? Cuz I can't.... or for any other vacuum line I disconnected for that matter.

 

Even the smallest things can slip our minds sometimes.

Conclusion:

The early problem I was describing must have been the result of me add one or all of the following:
new injectors, new egr valve, new egr valve temp sensor, new gaskets and seals on the parts I removed.

The problem today with it misfiring and stuff was the result of one small issue:
Blown INJ2 fuse.

Doh. Lol.

Anyhow, I noticed also that some of my plug wires are burnt... gonna install a wire guide for them soon and new wires but other than that it ran stronger than ever. Must've burned most of the rubber off of my tires going around the block.

Thanks to all.

EDIT::went back to doing the same **** after I made this post. Ended up being BAD ECM... as much as I hate to admit it. The other things I did drastically improved performance though so they must've been contributing to the overall problem.