Starts then dies - HELP!

[r70chevy]

Hi - I'm new to HP tuners and have a problem I hope you can help me with.

I have a 1970 Camaro that I have rebuilt from the ground up. I put an LS1 motor out of a 2004 Corvette into the car with an American Powertrain 6 speed manual transmission. The engine is stock except cold air intake, headers and a mild Crower cam. The issue I have is the car will start and then die.

If I disconnect the battery and let the car sit for several hours, I can get it to start and run. When it runs it runs great, no issues. If I then turn the car off, I can get 1 or 2 more starts and it runs fine. After that, it will run for 5-10 seconds, then die. After that, it fires and immediately dies. After that, it turns over but will not start.

Here is what I have tried:
When its in the mode of start and dies. The injector flashes 1 or 2 times then stops flashing.
Fuel pressure is always between 58 & 62 lbs normal pressure - pump runs exactly how it should.
Confirmed all grounds are good and all connections are clean.
PCM has the battery connections and ignition connection correct. It has voltage when it should have voltage.
Confirmed VAT system is turned off.
There are no pending or stored codes.
I have put in 3 different computers, no change
I have moved the tune from computer to computer, making sure its all the same.
I have been reading all the forums I can and have tried everything I can find, no change

I know I am new but if there is any help or thought that would be greatly appreciated.

Thank you !!!!!
R70chevy

[5FDP]

Post the current tune you are using and any logs you have.

More details on parts used too. Still using stock injectors? What type of fuel system, return or returnless?

Is it drive by wire or drive by cable now? Is the calibration matched to the DBC or DBW?

[r70chevy]

Hi 5FDP

I have stock injectors, stock heads and stock intake, the fuel system is a returnless, set up. Fuel tank and pump are from Holley. The system is the stock DBW, all calibrated. When the car runs, it never skips a beat. Hope that helps....

[5FDP]

Good info.

Still need the tune and if you have logs.

[r70chevy]

I do
sorry for the delay.1-8-2024 Read Braxton's.hpt... thank for the help

[r70chevy]

here is what I have

[r70chevy]

sorry it took so long, I thought I uploaded it but I guess I did not

[r70chevy]

I bought a new battery for the Camaro. I was thinking that it might be a low voltage problem. I put the new battery in the car, started 6 times in a row. I then let the car sit for about 20 min. Went out and tried to start the car again. It will not start, same symptoms as listed above. I am at my wits end...... Any one got any ideas? Please !!!! Thank you

[Fuse]

I am new to hp tuners so not going to help you on the tune part. It most differently could be a tune problem not opening the injectors enough during cranking or not having the correct timing. I'm an ok mechanic so dose it run on an external fuel source? Like brake clean or starter fluid? This could be an indication the engine is not getting enough fuel. Possibly stuck closed injectors, lose power wires or high resistance on power wires running to injectors, lose or high resistance on the wires running from the injectors to the pcm. Does it have spark when its doing this? How about rpm in the vcm scanner? No rpm input to the pcm = no start.

Is the pcm you are using for that exact motor? I dont know anything really but general stuff so............ dose your engine use a maf sensor? Is it possible your cold air intake is throwing off your maf readings? If you have a maf sensor, will it start with it unplugged? Are you getting any maf data? No maf data can cause problems.

Im new just trying to help. I assume you are using noid lights because you mention 2 blinks. Usually, the injectors open a little more the first couple of pulses during starting but if you can’t see anything after that the injectors aren’t opening or so little you’re going lean. What are you afrs when it runs? Lean?

[r70chevy]

thanks for the feed back I will go thru these items. I have done some of them but I will go thru it again, make sure I have not missed anything.
Will let ya know

[gtstorey]

Post in the appropriate GM section, depending on what the ecm is out of. The people that can help probably won't see it here.

[r70chevy]

I will try to figure out how to post it on the GM section, Thanks

I did go thru what Fuse suggested, here is what I found:
Timing is on looking at the tune
It will start and run with Starting Fluid, keep giving it squirts it keeps going
As I was cranking the motor the tac was moving showing the RPM's while cranking
I did put a test bulb in the #1 injector wire, when I crank the motor over it flashes 1 to 3 times then stops even if I keep cranking.
thanks

[2xLS1]

If it stays running on starting fluid then the problem is fueling, not ignition. Fuel delivery can be a problem on swaps because you are typically not using the robust OEM fuel system. Put a FP tester on the rail. Check the +12V going to all the injectors. The PCM pulses them with a ground signal.

[Fuse]

Explain in more detail how your using the test light. Connector plugged in or unplugged? Are you testing power or ground side? Your on the write track its fuel related.

[r70chevy]

its a little diode lite tester that plugs into the power and ground wire on the harness, its fits right into the harness where the harness would plug into the injector. Its strange that it only flashes about 2X then never flashes again as you are cranking. If you stop cranking wait a sec or 2 then do it again it will again flash 2 my be 3 times and stop flashing. If you then go back and disconnect the battery wait 20 minutes or so, the car will start right up and run perfect, no codes. The fuel pressure is always at 58 to 66 psi. The fuel pump and tank are new, they are from Holley, its a sniper conversion set up, fuel line is the same size as the stock Corvette I took the motor out of.

[r70chevy]

Also I have a mechanical pressure tester right on the rail, the voltage at the injector is 12 volts.... and the lite tester blinks nice and bright

[Fuse]

Ok so your using a noid light. Can you Hook up your mpvi and run vcm scanner? To me it sould like one of your sensors is not reading correctly. Ect,map,iat. After letting the car sit for several hours iat and ect should match. With key on engine off baro and map should match. Get on YouTube hp tuners did some video about putting the system into speed density. If it runs in sd it could be maf scaling. How do your ltft and stft look when it is running?

[Fuse]

Where is your maf sensor located? Is the pipe the same size as the stock pipe? Is the pipe before the maf straight? Maf sensors are very touchy about changes and won't read correctly.

[Waterboy109]

Ok I?ll ask this here to keep from making a new thread. I?m new to tuning, and slowly learning. I have a 97 K1500 with a swapped LQ9 running a mild cam nothing hard core. I?m having a couple issues. 1st at WOT I?m hitting the rev limiter before it shifts, I have seen multiple ways to change this through different settings, what?s the correct way? Also my truck appears to be running rich, at start it puffs a little smoke and once it?s running and idling I can rev it up and let it settle down but most of the time when the rpms drop it kills itself. I have smoke tested this and there are no vaccum leaks. This motor is fully rebuilt, and I?m running a standalone harness from PSI conversion. They installed a basic tune, but I believe they set it up for the LQ4 instead or it may not make a difference. Thanks for any help. I?ll continue to research before I adjust anything.

[r70chevy]

MAF is off to the left side of the motor, all the same size pipe straight in and out curves just before the TB. the pipe is 3.5 inch
I did run thru your other post with the mpvi all seemed in line, I had to disconnect the battery for a while to get it to start, but when it did all was good.