I’ve just got my ‘84 back together after swapping in a 3800sc, I’ve come down to starting it now. The car will start for a second or two then dies. A bit of background: I have gone through and checked the the injectors all all have power and are working, my crank and cam sensors are sending signals, I have fuel pressure, pump primes and runs, I have swapped out ICMs, I’ve checked for any vacuum leaks (found none), inspected and cleaned IAC (it’s working as it should) I’ve tried starting with the MAP unplugged, nothing changes. Tried starting with MAF unplugged, nothing changes. I’ve jumped the fuel pump relay so it constantly ran while starting, nothing changed. This engine/ harness/ trans all came out of another Fiero running and driving. So I’m at a loss as to why this is happening!! Any input would be greatly appreciated!
First question; Has the VATS code been disabled in the PCM?
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Regarding the VATS, the ecu has been unlocked as it has an aftermarket tune. And it was in a running driving Fiero 4 months ago. So I wouldn’t imagine that would be the issue, but it’s a slim chance it could be I guess.
Once the VATS has been disabled in the code it is very unlikely that it needs to be reset. I would scan the PCM for any codes as a defective crankshaft or cam sensor would cause a no start condition. Have you measured to see if there is 40-43 psi of fuel pressure at the rail? Point is that you need to use a systematical approach to the tests to find what is wrong. The first step is a PCM scan. The DTC (code) should indicate a defective sensor.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
So I just scanned for codes, only one came up for the MAP sensor just because I unplugged it. That’s the only code I’ve seen this thing throw. I’ll be getting a pressure sensor this afternoon.
Do you have a spare ignition module to try or test the one you have on a known running 3800?
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
Spoon. Yes, I actually have 6 ICM’s I have swapped out a few but the problem doesn’t change. I’ve just put back the one that it was using to run before.
I am just totally stumped at this point. It must be the VATS, but it shouldn’t be. I will have someone with HP Tuners look at it soon.
When an engine will not continue running it has to be either spark or fuel as a reason for the problem. If it is the VATS then the injectors will shut off a few seconds into the start. If its the spark then an intermittent crankshaft or camshaft sensor signal is being supplied or it could be another sensor. Has this engine ever started before?
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
This engine was pulled out of another Fiero this past summer, it was running and driving. Since it was pull it just sat in my garage untouched until I put it I put it in my car in December.
OntarioKev, I’m from Sarnia. If I give it some throttle when starting it wants to rev up for that brief second it fires. And off the throttle it just fires for a second. And the blower spins nice and smooth.
