lucky14

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

Ca[maro]88

iTrader: (2)

uhhh go carb?? how bout dinner

just kididng but i have no idea.. thats insane stuff. i went carb after my computer started messing with my engine. runs good now of course i lost a good 3 mpg butoh well at least it runs lol

lucky14

Nice try! lol

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?

1989GTATransAm

iTrader: (3)

Put in the new injectors.

RBob

iTrader: (1)

Yes, what 1989GTATransAm says, time for new injectors. Common failure for Multec's.

RBob.

lucky14

Thanks guys seems to be the consenus in both TPI and Digi fuel injection forums too. Thanks for your patience with the posting in DIY

Just a question does anyone know how the logic circuit is wired within the PCM/MEMCAL

I know B+ is supplied via ignition start/run through INJ1 and INJ2 and PCM supplies ground to the injectors based on input from ESC (MEMCAL) and Ignition module. Passed that is it sort of like a logic gate circuit where it is only looking for a specific closure of the injector?

Therefore if there is a shorted INJ it goes stupid and shuts the injector driver down? Do you think with only a few (5-6 cranks) on the engine with the PCM that the driver circuit is ok in the new PCM? I know early fuel injector drivers across the Euro/Asian/Domestic market in the 80's and 90's were sensitive to being burned out. Is this protected in any manner from an injector burning it up?

JP86SS

iTrader: (1)

Connect a datalogger/scan tool and see what the TPS reads.
If you are greater than 80% you will get no fuel.
VATS also kills fuel. Do you have VATS disabled or handled for function?
MMmmmm, Steak

Another thought,
Have you tried a noid light to confirm they are not grounding through the ECM?
Confirm that you are actually getting DRPs from the new distributor as well.

lucky14

Hey thats a good idea... if the TPS is way out of wack it thinks it going into "Clear Flood" mode and killing the injectors- good idea.. I will bring home my MODIS tool on Monday from the Shop.

VATS is still enabled as far as the MEMCAL/Hypertech unit. I Didn't have any problems with VATS before... and see as the car initally stalled after being driven for 15-20 minutes then exhibited these problems- furthermore, it has spark and fuel pressure (no pulse width at the injectors) can I assume VATS is working i.e. enabling starting?

Pinout-ing the ign mod. out of the dist. good idea. Do you know what the signal specification is? (i.e voltage specification, voltage range, I only have a crummy DVOM at the house the good 500V autoranger is at the shop)

lucky14

Noid lighting the injector harness already done... no pulse...

I forgot to mention (previous posts) that every once in a while I mean rare with the orginal computer and new dist./ign. module/coil I got one or two flashes out of #1 injector with a noid lamp but nothing else.

86White_T/A305

Are you getting oil pressure,the oil pressure switch is also a backup for the fuel pump.Do you hear the fuel pump prime when you turn the ignition on for 2 seconds.If not then something else is telling the ecm not to fire the injectors.Tps should be checked as stated above,all grounds to the motor..battery and ecm,check all fuses.Also having a 305 prom isnt the best way to break in a 383,are you getting a check engine light code with the key on?

lucky14

I am getting oil pressure, fuel pressure, and prime with key on. I am also getting the SES lamp key on test too. I had also checked the ECM fuse, grounds, etc... Thanks for the help from the great white north.. I loved Canada when I was there last year! Yukon was awesome so was Vancouver- I know BC is little west but hey it still beautiful.

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.

JP86SS

iTrader: (1)

Blue wire for the KS for sure.

lucky14

Knew it thanks JP... I will fix that tomorrow! I love this board.

RiV

1988 formula turned into a knight rider replica with a rebuilt 350 swap, with some warmed up parts. Drove 250+ miles on the engine until the first cam went down. Over tightned lifters and/or not changing the oil after the first 20-30 min break in.
I installed a new cam and 24# injectors... With my new prom installed after getting programed again for the 24#'s I got the car to start for the cam break in running at 2200 rpm for about 7 mins into the 20 min break in until I had problems. Seem to run ok with thoughts on having the timing light out later to get up to spec so to speak. 5-6 min mark started to sound a little clunky as it got hotter. Had some loose radiator hoses causing some fluid loss initially... ran through it because I didn't want to ruin my cam break in procedure...until finally had two spark plug wires blow up against my exhaust headers on the passenger side. #8 & #6. When I saw the smoke ect I got out of the car while it was running..glanced and shut her down. Got some new MSD 8mm wires and new cap/rotor, heat shield to protect the new wires. Car will not start. Got spark still out of the wires I checked... just can't get the damn thing to start. Going through a large range of t distributer postions almost gets it to stutter into cranking up. To no avail I keep trying over and over til the battery is dead. Fuel pump hums. Without checking all the obvious things, could the spark plugs that exploded on the exhaust headers weakend my coil, ignition module or destroyed my brain box ect? The above posts makes me ponder on all the possibles.. I got a MSD spark plug wire set that you have to crimp the connectors on ect so I will ohm those out in the morning. I'll also check and see if I get a code 12 on my engine light along with what ever else. I really need some help guys as I'm tossing money away atm. $2600 in on this new engine build and I got a drive way dustbunny. I'll addd that when we first got the engine running last time, that turning the distributer cut my fuel pump on and off somtimes. Guess it was the oil sending unit wire after reading above.

JP86SS

iTrader: (1)

Is this the same engine?
I was waiting to see what was found with this problem.

Turning the distributor can give you a pulse to make the fuel pump run. that would indicate the p/u coil is good etc and you have spark so you shouldn't need to look there.
Get the motor at TDC and take the cap off the dizzy. Turn it until the points line up. That should get you close enough to start it.

Put an ohm meter on each injector to confirm they are not less than 12 each. Just cuz they are new doesn't mean one isn't bad (hopefully)

Could be the plugs are just fouled and won't fire too.
Give them a good cleaning and try again.
Is there dinner involved with this one too?

RiV

Well... I'm down to buying a new distributer. My pick up coil has been rusty as hell, and I have had trouble restarting the car before after I drove unless I let it sit for 30 mins.

Initally had the car running during cam break in. Two spark plugs blown on exhaust headers during this process and resulted in getting new msd wire set, spark plugs, and cap and rotor. Returning to the ignition key for one more try I get no where but a engine turning over with seemingly no chance to crank up. I have redish arch when I try to short a plug wire to ground. This indicates weak spark? Pickup coil to blame? coil? TOo high resistance in the new wires? My new prom is fried or memcal malfunction?
My knock sensor is also not hooked up atm. Any help apprechiated at this time since I'm about to buy a Dizzy.