LS1 starts, runs for 5 seconds, stops

[bobpelikan]

I have a 2001 LS1 from a TransAM going into an old Plymouth. The ECU has been reprogrammed the usual way for stand alone applications. The VATS is off, rear O2 sensors disabled, etc. The log shows it going dead lean after 3 or 4 seconds. The fuel pressure is steady at 58 lbs. We tried unplugging the MAF - no change. We increased the fuel by 15% - no change.
We tested the injectors and they are all spraying normally. The spark stays strong as it dies. Can anyone tell what's going on from this log? Thanks.

Log 4.hpl
2.hpt

[5FDP]

Post the tune.

The log file says that the computer is from a 1999 Silverado so I'd want to see how it's setup.

[bobpelikan]

Sorry I forgot to post the tune.

2.hpt

[5FDP]

The fuel pressure is staying steady the whole time it's running right?

Did you remove fuel from the MAF curve for some reason? I compared it to a stock LS1 tune and it has less fuel in it. I would return that to stock.

I also notice that you have a ton of DTC's that are disabled for no reason and this could be a problem. You'd never know if you have an issue with a sensor if it can't report the problem.


You have MAF dtc's set to no error reported, you have MAP and TPS and intake and coolant temp DTC's set to no error reported. That is not going to help you here if you have a problem. If the sensor is there, the DTC's must be setup to function like stock.

[bobpelikan]

Thanks for the response. Yes the fuel pressure stays steady at 58 the whole time.

I didn't do the tune so I don't know why fuel was removed from the MAF curve. Frankly I am not familiar enough with tuning to try to change a fuel curve.

I think I can turn the DTC's back on. I'll give it a try and run another scan.

Would you consider tweaking my file to the stock LS1 tune and emailing it back to me?

Thanks again.

[bobpelikan]

Per 5FDP's suggesion I turned on as many of the DTC's that I think have anything to do with my setup. This tune and scan reflect the changes. I didn't modify the fuel/MAF curve because I don't know how to do that.
Any idea where to go from here to get this thing running?
Thanks.
2-2.hpt
Log 5.hpl

[5FDP]

There is a sample file of a 2002 Camaro with the 5.7 that you should have in the HP Tuners folder. You can copy the stock MAF curve from there to put back into yours. Or download a stock tune from the tune repository on your customer page to find a stock MAF curve.


Add commnaded AFR, cylinder airmass, knock retard, injector pulse width avg for both banks to your log. A wideband o2 sensor would be really helpful too, so that you could see what the fueling is really doing. Per the o2 sensors it's leaning way out and I'm not sure why yet.

[bobpelikan]

5FDP - Is the folder containing the sample file you mentioned on the CD I received when I bought the program? That was a few years ago but I think I can find it.
Also, where on the editor is the MAF curve?
I will add the perameters you suggested to the log and post a new scan. That I do know how to do.
I no longer have a wideband o2 sensor but I'm willing to get another one if that's what it takes to get this thing figured out.
I've closed up the shop for today but will be back at it in the morning.

[5FDP]

It's called the MAF airflow frequency table, it's in the main airflow tab in the editor.

[bobpelikan]

Here is the tune with fuel added to the MAF curve.
2-2.1.hpt.

Here's a log with the added scan parameters suggested above.
Log 6.hpl

[5FDP]

At this point I'm not sure anymore. The tune is basically stock but it seems to just lean itself out and die.

Short of trying a new computer I'm out of idea's right now.

[bobpelikan]

I have a new computer coming from the guy who modified my harness and did the original computer mods. I'll let you know what happens.

[bobpelikan]

I received the new computer to try and it did exactly the same thing - started right up, ran for 5 seconds, and slowly died. I'm open to trying anything at this point.

[5FDP]

Is the fuel pump on a switch to constant power?

Does the intake have any couplers that could be getting sucked shut?

Can you hold the throttle open and keep it running?

If a new computer does the same thing you figure it's a parts/sensor issue now.

[bobpelikan]

Thanks for hanging in there with me on this 5FDP. I've been busy with family matters for a few days and just getting back to this.
To answer your questions, no the fuel pump is not on a switch. It is on a relay through the ECU. I have two pressure gauges in the system, one on the regulator and one at the test port on the fuel rail and they both hold constant pressure at around 60 PSI throughout the start to stall sequence.
Regarding the intake, there is one coupler and it is quite rigid and holds it's shape while running. I also tried mounting the MAF directly onto the throttle body and it didn't make any difference.
Regarding holding the throttle open, I tried that and it still stalls.
I agree with your 4th point.
I'm attaching another scan (Log 8) done yesterday with the new computer. A couple of things seem strange.
1. The channel list on the left shows Closed loop active - no
2. The channel list shows Fuel system status - OL Not ready
3. I'm getting all zeros on the long and short term fuel trims for both banks.
4. The injector output signal stays somewhat constant as the O2 sensors show the motor going lean.
I've swapped out the MAF with a spare with no change.
My harness is a truck harness modified by a guy that does these mods for a living. He's done 5 or 6 for me and I've had no issues before. If it's a parts or sensor issue the harness could be suspect. Which sensors could possibly play a roll?
Log 8.hpl

[ZeroBoostBuick]

Engine has to reach a certain temp before it goes into closed loop. Even when starting a fully warmed up engine, it still takes a handful of seconds before it goes into closed loop.

Is the Money light ON (engine light) ?? if so,.. can you scan for codes ?