Car starts intermittantly, only runs for 2 seconds, new 3 bar os

[Ranger6202]

Are either of those 2/3 bar OS's?

[mecanicman]

One was a 4.8 12212156 with 2 bar. The other was a 12592618(P59) with maf installed.

The 4.8 started almost like nothing was wrong with the changed settings. I did a 2 bar corvette 12212156 recently with the exact settings that required feathering of the throttle to stay running and set code even after the tune was done. Not sure what the difference is.

[Ranger6202]

Interesting.....One more question mecanicman.......have you been able to run your tunes strictly MAF on the 2/3 bar OS's?

[mecanicman]

This is a base tune for a 427 procharged 2002 Firebird running id1000's and a 3 bar. Some basic idle tuning done and that about it, Fires right up and sets code immediately like nothings wrong.

[mecanicman]

Interesting.....One more question mecanicman.......have you been able to run your tunes strictly MAF on the 2/3 bar OS's?

Don't know if I have ever tried? I tune the MAF using a standard o/s and then just copy it over to the COS later if I am using the maf with it.

[Ranger6202]

So it would seem that you're like me and Motown and assume the MAF still works all the same since you copy the maf values over to the SD OS and leave it enabled on selective setups?

[Ranger6202]

need to apologize to ryanbgb22 for the tangent i started. All the MAF talk is irrelevant if you have the MAF installed. I read back through the posts and i don't see where you stated to whether it was even installed and being used or not.
Reading back through to where you had it running and then NOT, seems to me you have a control issue with your fuel.....missing ground, fuel pump not turning on....whatever. Probably need to start with the basics. Verify fuel pressure at the rails, after a start attempt smell for fuel at the exhaust or pull a plug and smell there, or have someone crank it with a pulled plug and watch for the mist at the hole. Once you have fuel verified, we'll move on to ignition.

[ryanbgb22]

need to apologize to ryanbgb22 for the tangent i started. All the MAF talk is irrelevant if you have the MAF installed. I read back through the posts and i don't see where you stated to whether it was even installed and being used or not.
Reading back through to where you had it running and then NOT, seems to me you have a control issue with your fuel.....missing ground, fuel pump not turning on....whatever. Probably need to start with the basics. Verify fuel pressure at the rails, after a start attempt smell for fuel at the exhaust or pull a plug and smell there, or have someone crank it with a pulled plug and watch for the mist at the hole. Once you have fuel verified, we'll move on to ignition.

No problem at all, all good information that is valuable to me as a very amateur tuner.

For my situation, I do not have a MAF installed, the connector on the harness side is just sitting unplugged in the engine bay. I haven't had much time to mess with the car the past few days, but I still have not gotten the maf to fail.

Currently, the car will not even start for the 2 seconds, it hasn't done that since it was up and running. During cranking, it just kind of stumbles and acts like it kind of wants to start firing, but doesn't ever give any real indication of running.

I will mess with the MAF setting some more and see if I can get them to fail.

As far as adjusting the throttle, I've tried from slightly open to WOT throttle to pumping continuously while cranking, nothing will make it fire up.

I am pretty sure I'm getting fuel. I have pressure at the little plug on the fuel rail, I smell fuel out the exhaust while cranking, and the injector duty is at 2% while cranking.

Tonight I'll get a video of the spark on one of the plugs to make sure it looks healthy enough to you guys. It looks good to me in my experience working on 2 strokes.


Thanks for all the support guys, don't really have anywhere else to turn.

[mowton]

For my situation, I do not have a MAF installed, the connector on the harness side is just sitting unplugged in the engine bay. I haven't had much time to mess with the car the past few days, but I still have not gotten the maf to fail.

Where is the IAT?

Ed M

[ryanbgb22]

Where is the IAT?

Ed M

Took a break from this thing for a bit....now i NEED to get it running.

My IAT's are ambient temps, around 70-75 here. My water temp is reading about 65 while cranking. Still NOT getting my MAF to fail before, during, or after, extensive cranking. I'm currently set at 8,000 high rpm disable, 100 hyst. I've tried 0's, I've tried 12,000....still nothing.

[Ranger6202]

try changing p0101, p0102, p0103 to Mil on first error. With, of course, the maf freq fail set at 0 and the other three in the dynamic section set at 0 too.

[ryanbgb22]

STILL nothing.....I don't know what to do. I'm seriously considering selling the car as is. It's a heavy paper weight taking up more than half my garage right now.

I tried all the different combinations of MAF cells suggested in this thread, MAF still won't fail. The only code I'm getting is a P1637 because my alternator is not hooked up. I'm so frustrated, the car was RUNNING!!

Today I tried going back to the original OEM tune (even though it was a 5.7 tune, not a 5.3) and getting it to start with just changing over the injector data, still nothing.

If anyone is willing to help, I'd be willing to throw them a few bucks via paypal for their time. I'm desperate.

[Ranger6202]

It pains me to hear that you're ready to throw in the towel, and i wish i could fly to wherever you are amd help. I read back through this thread to see if anything stood out. It seems we've changed everything in the tune to try and get it to start running again. The fact that it ran for a little while on one of the tunes tells me that even a bad tune would be a close enough calibration that it would at least try and struggle to stay running. I honestly think the issue is somewhere else in the build and not in the tune. I'm curious to what MAP sensor you're using, and if you have verified that spark and fuel are working.

[mecanicman]

Switch back to the tune that's a copy of what I posted. Load default imperial config and add commanded afr to it. Turn key forward, start log, then try and start the car. Post the log. What fuel are you running? Your positive you have proper fuel pressure?

[smokestack]

Post fuel pressure with key on. Then while cranking.

Sorry to just chime in again. But with you guys helping so much it cant be tune related. You guys all know your stuff and its not working. I bet its fuel. What fuel pump do you have installed? And hows it installed?

[ryanbgb22]

Well, I just bought a fuel pressure test kit from NAPA. As long as the gauge is accurate, I think I may have found the problem. Key on, fuel pump prime - 48psi. Cranking - 48psi.

Would being ~10psi low cause the car not to start?? I hope so! I do think the injectors ARE firing though, because I can still smell fuel out the exhaust after I crank.

Thanks a lot for your continued support guys.

[Ranger6202]

Being low isn't ideal, but it would still fire, it would start adding fuel like crazy once up to temp. I would check spark. If you can smell fuel out of the exhaust, you have enough to get it to atleast stumble and fire. I'm betting its spark you're missing.

[mecanicman]

What fuel are you running? Is this e85?

lol, apparently yelling is not allowed on hpt site, I capped all that and when I press save it puts it lower case. I asked 3 times now and no answer.

[ryanbgb22]

What fuel are you running? Is this e85?

lol, apparently yelling is not allowed on hpt site, I capped all that and when I press save it puts it lower case. I asked 3 times now and no answer.

I am running 91/93 octane. Fuel in the tank is ~1 year old, put about 5 gallons of fresh stuff on top.

I did notice that the connector that goes to my crank sensor looks a bit questionable (exhaust exits near the starter). All wires are in tact, but is there a way I can setup the scanner to verify proper operation of the crank sensor? Or do I know I'm good since I'm getting RPM readings?

[Ranger6202]

is there a way I can setup the scanner to verify proper operation of the crank sensor? Or do I know I'm good since I'm getting RPM readings?

I personally haven't had to do this yet, but a quick look in the scanner tells me you have a few pids looking at something with the cam sensor:
Campic.JPG

worth a try, let me know what you see.
or you can just pull a spark plug and watch it spark??