As you may know I have chronicled my 91 Z28 thats stalled- restarted- stalled and never has restarted.

The car has a new 383 TPI motor in it... broke the engine in with 300 miles. Still running the 190,XXX mile 305 prom and orginal 350 injectors. ( I have new 350 injectors on my workbench)

The car acted like it ran out of fuel... very low power, stubles, misses then finally died after multiple short starts without being able to restart.

The car cranks strong (new gear reduction starter, cables, optima)

Vehicle has 39 pounds of fuel pressure at the rail with new fuel pump relay, maintains the fuel pressure while cranking.

The spark patteren out of cap was weak and irratic... so i dropped in a new remanufacturered distributor with new pick up.

I also replaced the coil with a new coil. This improved the spark pattern and strength but still no start.

With a noid lamp there was found to be NO INJECTOR PULSE

INJ1 and INJ2 ECM 10 amp and battery fuseable link are OK

The ground wire from the computer to the injector blue and pink wires both Bank 1 and Bank2 have continuity from the computer to the injector (0.8 ohms to 1 ohm). With finding this I figured that with new inputs from the ignition module and dist.- and that the wiring from INJ1 and INJ2 and wiring from the PCM were ok that the PCM was bad.

I replaced the PCM (engine computer) with a remanufacturered NAPA unit and swapped the 305 prom over with a new hypertech 350 TPI module. With some help in the DIY PROM threads I deteremined that the 305 chip and Hypertech would act like a 350---Still no injector pulse.

I reverified Ignition timming- pulled #1 plug out... spun the engine over to TDC and had the distributor pointing to the #1 cap terminal.

As I understand the ESC module is intergrated into the MEMCAL chip is it possible the orginal 305 PROM/MEMCAL is deffecitve?

I need some help bad... I figured I have checked just about everything... I haven't ohmed the injectors... I figure even if I have one shorted injector I should still be running right?

Is the ESC actually intergrated into the MEMCAL?

VATS disables igition not fuel pulse right?

I am only working with a haynes manual so my engine control diagram is generic from 1988 to 1992 so I am limited to that. I am a very experenced technician but I am scratching my head on this one.

Anyone else have ANY other ideas? or similar problems?

help!

by the way if your help leads me to fix it.. I will buy you dinner at outback! Seriously!

Ok so I ran out and checked the injectors from what I understand that 16-16.8 at 68 degrees is about normal for new injectors they all ohm out at 16.3-16.5 (too bad they are not installed yet!)

Bank #1

Cyl #1 16.4 ohms
#3 14.9 ohms
#5 1.1 ohms
#7 12.3 ohms

Bank 2

#2 14.8 ohms
#4 12.3 ohms
#6 14.4 ohms
#8 16.6 ohms

So deffently # 5 is FUBAR, #7 and #4 are very "if-y" do you think this enough to make the driver go crazy and not send an injector pulse?

Yes. With number #5 virtually a dead short it is having an affect on the other injectors working properly. 1, 3, 5 and 7 may not be working at all on that bank and maybe some firing on bank 2, 4, 6 and 8. You need to put the new injectors in there. Hopefully that is the only problem you have. I would think you will also need a custom tune.

By GM specs, the only fubar injector is #5, spec calls for ohms greater than 10. Only 1 fubar injector will still allow the car to run...just went through the same problem with my car.The bad injector will eventually burn out the injector circuit in the ECM...my problem...bad #4 jector fried the ECM.If the security comes on and then goes out than thats not the problem, and I think VATS prevents the car from cranking.If you are getting no pulse in the noid light it might be a bad ignition module in the dizzy, that is the signal the ECM uses to fire the 'jectors and very common for failure.Also, I think the dizzy grounds through the engine...not sure if that would be a problem though.

Thanks... I got the specification from Alldata (16-16.8) I have als heard must be greater than 10 ohms on here.

I don't think that a few cranks on the FUBAR injector would have fried the new PCM but its got a 1 year warranty on it anyhow...

I will try and swap injectors in between my honey do list tomorrow and before the Penguins vs. Captials hockey game comes on...

The new dizzy also has a new ignition mod. in it too.
Thanks for the prompt feedback guys- I will keep you posted as soon as I figure swap in the injectors.

did you replace the ignition module by chance? the PCM on these cars gets it's signal from the Distributor, look for any broken or corroded wires between the distributor and the PCM, no fule on these cars in 90% of the time due to no reference signal to the PCM that the motor is cranking.

yep it has a new distributor and a new ignition module and I do have spark out of the cap too.

I think you are on the right track. Replace the injector(s) and see what happens. Then we can go from there if there is still a problem.

Yep I hope to find some time to do it tomorrow... its super nice here in VA we had 12" of snow last sunday and Friday, today and tomorrow it was/going to be 78 degrees plus! Love it... perfect for wrenching in the garage

Too bad I have a ton of stuff to do (honey do) and then the Penguins hockey game is on at 330. I might be able to squeeze injectors in there... but I will keep you al posted! Thanks

[QUOTE=lucky14;4071373]Yep I hope to find some time to do it tomorrow... its super nice here in VA we had 12" of snow last sunday and Friday, today and tomorrow it was/going to be 78 degrees plus! Love it... perfect for wrenching in the garage

Where in VA are ya? I live in Spotsy, Fredericksburg area, might be able to help you out if you're close to the Fred area.

Hey neighbor! I am in Mechanicsville- Hanover County- just south of Ashland.

I got the injectors in today... car starts and runs... runs like hammered you know what though... idles ok but no timming advance. My buddy was helping dignosis the car and we were using the Haynes manual...

he was convienced the knock sensor lead and my yet installed fan switch lead were crossed. The haynes manual shows two knock sensors for 1988- up mine only has one...

The haynes manual showed one knock sensor with a white wire so my buddy was convienced it was hooked up incorrectly. Even though it never had a problem wired up that way for 300+ miles... I think it was the beer talking!

Anyhow The blue wire was hooked to the knock sensor never was an issue the white or gray-ish wire was loose waitng for my hypertech switch to be installed.

After I got it running I noticed I had an SES lamp and felt like no timming advance- booged down with load and my fans were on all the time.... then saw the knock sensor lead was switched by my buddy (white wire on the knock with the blue loose) He must have switch them when I went into get more beer last night!

I checked out the cooling system forum and found the wiring digram calling for the secondary fan switch to be sorta grayish... so I figure my SES lamp is an ESC or Knock code due to an over eager helping buddy...

Is the knock sensor suppose to be the blue wire and the fan switch white/gray/tan right?

I will mess with it Monday or Tuesday when I get some more time.

However, the injectors fixed the no start. Thanks for all the help and confirming my diagnositics. For the help I won't back out of my offer for dinner.... when I get this thing permantly up and running hopefully this week I am going to the local outback and anyone thats local is invited. Bgood71 is your the winner... perhaps we can meet up in spotsy-tucky when I worked the bugs out for beer/dinner.

Are you getting any codes?

Yea... got an ESC code.... confirmed the knock sensor was miss wired by my buddy.... going to fix that and put the right lead on tomorrow.

Looks like you are making progress. After you get that fixed then we can go from there if need be.

Hey Lucky, did you get that wire fixed? I was gonna consult Alldata on the wire colors, but work changed the password and said that we couldn't use it at home anymore...they were gonna fine the dealership $10k for unathorized pc's using it When you get it going let me know and we can meet up somewhere, I'm willing to drive south too... Richmond has some killer saltwater fish stores... and the cruise is cool to That offer for help still stands if you ever need a hand.

Thanks... yea I got her up and running fairly reliably.

Here was a list of what had gone wrong since the new engnine was dropped in

The ignition pick-up and coil both went out (so she got a new HO coil and dist.)

3 of 8 Fuel injectors went out shortly there after (got new 350 FI)

When #3 Injector shorted it toasted the PCM- (got reman PCM and Hypertech)

Then finally got her up and running went for a spin... lost #6 and 8 plug wires to a smolder/fire on the headers! Uggh... so then she got Accel SS jackets double walled custom plug wires and plug socks...

She runs REAL good now...

But she has an oil leak somewhere thats getting on the collector pipe and smoldering.. took her up to the shop to have her run on the lift so I can see where its coming from.

Also I think the drychem from the small fire took out my AIR pump its noisy as hell now too..

So 3 steps forward 5 back!
Uggh..

Glad to hear that you got it running good. I've been having issues like yours with my car also. #4 injector crapped out taking the ECM with it. Fixed those problems, ran good for a week and then the mass went out, now put on headers and it runs like the heat is toasting my wires...this sucks. Well more parts on the way, lol.

Ditto on more problems-Yea I think I might also have a breather issue. When I pulled the car out of my extra bay at the shop I had a puddle under the center of the car. I had R+R the rear main once after I first had the car on the road.. it was leaking.. but it looks as though its leaking again
(didn't put it up on a hoist since its a pain in being so low!)

The reason I think I have a breather system issue is that the RM didn't leak when the car was sitting at all. But leaked like a civ when i drove it the shop and parked it.

Didn't take in acount that I should improve the breather system. After all it is only N/A without any power adders. Might run a manometer test once I get her 100% running.

Ps I am so down for the cruze once we get them running better