As you may know I have chronicled my 91 Z28 thats stalled- restarted- stalled and never has restarted. I have posted this to TPI, DIY PROM, and DIGI EFI to expose it to the full brain trust of thirdgen.org- sorry I am loosing my mind!

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

 

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?

 

Sometimes it's the simplest things................
I once encountered something very similiar to your situation. Spent days and days chasing the problem, good spark, no fuel.
To summarize......I had hooked up one of the connectors to my distributor without the Weatherpack rubber insulator in place. That caused the distributor to not send a reference pulse to the ECM to fire the injectors, which led to a no fuel situation. I found an old connector and pirated the insulator from it, put it on the loose connector and the engine fired right up and ran great from that point on.
Way off topic, I know, but like I said, sometimes it's the simplest things we overlook..........

 

I'll just toss out some generic thoughts.

You can verify that your getting no fuel with a can of starter fluid or equivalent. If the motor fires up then stalls its a fuel problem. If it doesnt even hiccup then its a spark/compression problem.

-- If you can pull an injector you might inspect the inlet for junk. Its possible that after your rebuild you broke loose some old junk in the tank or line that plugged the injectors. Was your fuel filter really old?

Is there a sensor wire that tells the ECM your cranking and to start? You might check that if it exists on your car.

Make sure this is the compression stroke. If you can see the rocker arms they should both be up. Or you can put your finger over the spark plug hole as you manually crank to the TDC and feel the compression.

If you get it running dont forget to disconnect the wire that lets you set the timing to whatever the car calls for.

You might re-verify the plug order on the wiring.

1 8 4 3 6 5 7 2 the intake has it embossed on the manifold (or should)

Ohm out your spark plug wires.

Do you have a good ground strap between your battery -> Block -> Frame?

Do you have an EGR valve on the car? If that is stuck open or is open at idle the car will bog and stall.

Have you replaced the ignition module?

If you can connect to the computer you can verify that the other sensors are ok..

Just some random ideas.

Eric

 

That injector with 1.1 ohms of resistance is bad and will keep the car from starting. It was very common on 2.8, 3.1 motors. And VATS disables fuel and starter on most vehicles and some just the starter and some just the fuel.

 

Thanks ... I might try to squeeze swapping in the new injectors tomorrow... although the wife has a ton of stuff planned.... plus the Penguins vs. the Captials game is on at 3 all that cuts into Camaro time...

 

Eric thanks for the ideas:

New AC Delco wires 8MM- firing order is ok

I have EGR and likewise it is new AC Delco unit... along with the Intake and runners were cleaned and ported when building the engine

The ignition module is new along with the distributor

New ground wire (2 gauge) from the battery to the block and chassis grounds to the harness are intact

Verified TDC on crompression (forgot the boroscope at work) but with a feeler tool and verify the piston is roughly at TDC and it blew my finger off the hole too

 

Here is the result:

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... albeit as were were hitting up the Yiengling and Molson's pretty hard

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... and I knew it wasn't the issue seeing as prior to my stall I had advance and no SES or predetionation.

The haynes manual showed two knock sensors even though I only have one knock sensor with a white wire so my buddy was convienced it was hooked up incorrectly. As mine was wired with a blue lead. 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 (TPI forum).. perhaps we can meet up in spotsy-tucky when I worked the bugs out for beer/dinner.

 

83z28camaro stated injectors were a problem in the 2.8 & 3.1's. I dont know if the same applied to the v8's but I had a z24 with 1 bad injector. They all ran in series, so if one is bad they all shut down.
Good its running.