Cranks for days will not start

[bustac]

I've been working on this on and off for a few years now. The swap is all 2002 C5 PCM, TAC, BCM, Drivetrain all factory harness and fuse blocks.

I've had it running but never driven on the street, only in the driveway. Recently after pulling in the garage under its own power it wouldn't start back up.

Cranks hard, has spark at all plugs, injection pulse(noid), 60PSI while cranking, no DTC's, Vats disabled, tried with MAF unplugged too

New fully charged battery
New Crank position Sensor (I replaced this at one point since I had no RPM and some backfires)
New Cam position Sensor
New Starter
New Ignition Switch

The Tune is basically stock with some stuff turned off for headers, no cats.

My log when I try starting and tune?attempting to start.hpl 2002_Vette_modded.hpt, see next log with MAF connected, still no start

Willing to try anything if anyone has any ideas?

[5FDP]

You will need the IAT plugged in to get it to want to start up without trying to flood with fuel.

Double check the MAP sensor too, even while cranking and sucking in air the MAP never changes from 101kpa.

[bustac]

You will need the IAT plugged in to get it to want to start up without trying to flood with fuel.

Double check the MAP sensor too, even while cranking and sucking in air the MAP never changes from 101kpa.

During that attempt I did have the MAF/IAT unplugged but the symptoms are the same with them plugged in. I'll look at the MAP sensor.

[bustac]

attempting to start2.hpl

Here's a new log with that MAF reconnected and brake booster.

[bustac]

Also tried new Starter Relay and swapping relays in the under hood fuse box.

[2xLS1]

After cranking pull a plug and see if it is wet. Or see if it will start while spraying starting fluid in the intake tract.

[bustac]

After cranking pull a plug and see if it is wet. Or see if it will start while spraying starting fluid in the intake tract.

Have tried with spray and plugs get fuel on them, half tank of gas, plenty of fuel pressure too.

[turdbow fteenthousand]

Few weird things I noticed:

You're only logging bank 1 injectors? Is that correct? Maybe you left the other bank unplugged. You're either not logging bank 2, or they're just not plugged in and there's no info for them.

Your Maf is acting funny. It starts at 0, then it sort of bounces around when you crank it but then when you're done cranking it, it still just reads ~40 lb/hr.

Your bank 1 injectors are doing the same thing as above. They start at 0, then bump around while you're cranking it, but even after you're done cranking it and going to stop recording, they're stuck at 12.7ms.

It makes me think your computer is bad, or I guess wiring. I'm not totally sure, and I'm not that experienced. I'm just trying to help.

Also I noticed you had the STFT off during openloop. Turn em on and see which way they wanna go since you don't have a wideband.

Oh and did you leave the corvette accs? If you're running a different accy setup you might have to mess with the alternator terminals in the system options.

[bustac]

Few weird things I noticed:

You're only logging bank 1 injectors? Is that correct? Maybe you left the other bank unplugged. You're either not logging bank 2, or they're just not plugged in and there's no info for them.

Your Maf is acting funny. It starts at 0, then it sort of bounces around when you crank it but then when you're done cranking it, it still just reads ~40 lb/hr.

Your bank 1 injectors are doing the same thing as above. They start at 0, then bump around while you're cranking it, but even after you're done cranking it and going to stop recording, they're stuck at 12.7ms.

It makes me think your computer is bad, or I guess wiring. I'm not totally sure, and I'm not that experienced. I'm just trying to help.

Also I noticed you had the STFT off during openloop. Turn em on and see which way they wanna go since you don't have a wideband.

Oh and did you leave the corvette accs? If you're running a different accy setup you might have to mess with the alternator terminals in the system options.

attempting to start3.hpl

Added bank 2 logging with a few other channels, another start attempt

All the Corvette wiring harness are all there and not modified. I'm actually leaning on thinking the PCM could be bad too?

[turdbow fteenthousand]

Wait... try enabling the MAF SES stuff and setting it to MIL on first error.

Also, for shits and gigs, I pulled my fuel pump fuse and cranked my truck to see how it acted. My injectors sort of hang out too, instead of dropping all the way off like I assumed they would.

On my tune, I leave the first few cells of the maf alone all the way up to idle because if you look back in my post history I was having trouble getting my truck to start, and it was because of the weird MAF code nonsense.

Apparently some years you can just uncheck the SES box. Some other years you have to leave it checked but set it to "Don't report." Some other years you have to leave it checked and set it to "No MIL error."

Basically the computer is failing the MAF, but not using the speed density table either, because you're telling it that it's ok to have a bad maf, and not to do anything about it. If you tell it that failing the maf is a bad thing, then it'll use the VE table. The only exception I know of is some oddball OSs that apparently don't care about the the maf failing and will just do its own thing regardless of what you say lol.

after idle adjustments slight stumble but ok.hpt- flex log

tahoe flex run to radleys shop.hpl- flex tune, look at MAF errors

after trans adjustments.hpl- gas log

park to drive enrichment, zeroed maf, stall saver, fans turned vats off.hpt- gas tune, look at MAF errors

Like I said, apparently different years have different requirements for the MAF errors. Idk why, as I said earlier, I'm pretty new to all this. I just recently found out about the MAF code stuff. Mine DEFINITELY had trouble starting until I got the MAF stuff worked out. I'd say re-enable the MAF codes and leave them like stock, SES checked, MIL on FIRST error will help it fail faster and start easier. MIL on second error was stock. Either way will work, just make sure that it either fails, and you go into SD, or enable them so the computer can use the readings.

[bustac]

Wait... try enabling the MAF SES stuff and setting it to MIL on first error.

Also, for shits and gigs, I pulled my fuel pump fuse and cranked my truck to see how it acted. My injectors sort of hang out too, instead of dropping all the way off like I assumed they would.

On my tune, I leave the first few cells of the maf alone all the way up to idle because if you look back in my post history I was having trouble getting my truck to start, and it was because of the weird MAF code nonsense.

Apparently some years you can just uncheck the SES box. Some other years you have to leave it checked but set it to "Don't report." Some other years you have to leave it checked and set it to "No MIL error."

Basically the computer is failing the MAF, but not using the speed density table either, because you're telling it that it's ok to have a bad maf, and not to do anything about it. If you tell it that failing the maf is a bad thing, then it'll use the VE table. The only exception I know of is some oddball OSs that apparently don't care about the the maf failing and will just do its own thing regardless of what you say lol.

after idle adjustments slight stumble but ok.hpt- flex log

tahoe flex run to radleys shop.hpl- flex tune, look at MAF errors

after trans adjustments.hpl- gas log

park to drive enrichment, zeroed maf, stall saver, fans turned vats off.hpt- gas tune, look at MAF errors

Like I said, apparently different years have different requirements for the MAF errors. Idk why, as I said earlier, I'm pretty new to all this. I just recently found out about the MAF code stuff. Mine DEFINITELY had trouble starting until I got the MAF stuff worked out. I'd say re-enable the MAF codes and leave them like stock, SES checked, MIL on FIRST error will help it fail faster and start easier. MIL on second error was stock. Either way will work, just make sure that it either fails, and you go into SD, or enable them so the computer can use the readings.

attempting to start4.hpl

I added a couple more channels and the recommendations you made, still a no go. I did notice that TPS reads 0.00V I'm assuming that needs a voltage while cranking?

tacmodule.jpg

I have 5 Volts at these TPS Pins and 0 volts at Pin F. I also have continuity from PIN F to C2 PIN 11 at the TAC module.

Maybe the TAC module is the culprit, does the PCM tell the TAC to provide that voltage?

[mowton]

I May be late to the party or repeating, but you must set P0101-103 to Mil on first error.....to fail over into SD. Is DTC P0103 set? If not you are not in SD. Leaving the MAF at their normal values will cover the startup until the pCM has officially failed ove and help starting.....

Ed M

[bustac]

I May be late to the party or repeating, but you must set P0101-103 to Mil on first error.....to fail over into SD. Is DTC P0103 set? If not you are not in SD. Leaving the MAF at their normal values will cover the startup until the pCM has officially failed ove and help starting.....

Ed M

P0101-103 was set to Mil on first error.

[mowton]

P0101-103 was set to Mil on first error.

Last file I looked at said No MIl....Load the MAF table with data and see what happens. Again the file I am looking at shows all zero's

Ed M

[mowton]

Try a flood clear. Hold Pedal to Floor while trying to start....injectors look very high on startup....

[bustac]

Last file I looked at said No MIl....Load the MAF table with data and see what happens. Again the file I am looking at shows all zero's

Ed M

Maf.JPG

You're talking about these right?

[mowton]

Maf.JPG

You're talking about these right?

Yes

Ed M

[2xLS1]

If it won't stare on starting fluid and it is not mechanically out of time then you are not getting spark or spark at the right time. I've run cars for as long as 30 seconds on continuous starting fluid with 0 fuel pressure.

[turdbow fteenthousand]

I'm unfamiliar with the TAC modules. I didn't tune my c5 or my V, this old truck is my first tuning experience. Can you try pumping the pedal while you crank it? Your tps is solid at 16%. even better would be to get a friend to watch it while you pump the pedal and see if it's moving. That oughta be a real quick check to see if your TAC is working properly, right?

[bustac]

I'm unfamiliar with the TAC modules. I didn't tune my c5 or my V, this old truck is my first tuning experience. Can you try pumping the pedal while you crank it? Your tps is solid at 16%. even better would be to get a friend to watch it while you pump the pedal and see if it's moving. That oughta be a real quick check to see if your TAC is working properly, right?

The TAC module does run the TAC motor and it moves consistent with the pedal. The TPS 5volts also comes from the TAC module, right now that's the only thing I can find missing is 5volts on PIN F.