Gen 3 start up issue

[stangman105]

Hello I am new to tuning. I have the MPVI2
I did an LS swap into a 99 ZR2 blazer. The motor is from a 2002 tahoe. I think the PCM is a 2000 but its essentially the same.
The motor is completely rebuilt. The pertinent changes are a cam, extensive head porting, and a return style fuel system with regulator on the return line.
So I just tried to start the vehicle a couple days ago. Ive turned off the VATS and all that.
The motor cranks and starts to fire but then goes back to cranking again and may or may not try to fire again but never runs. I cant get a data log since it wont start so I cant supply that info. Ive checked all the injector plugs with a noid light to make sure they are firing. Ive checked all the coils for the same. Ive dbl checked pinouts to verify the right plugs go to the right injectors and coils respectively.
Im wondering if since I changed to a return style set up this is causing an issue. It seems to be something between crank and run that changes
Any help would be appreciated
Craig

[5FDP]

What's your fuel pressure?

The 2000 computers already use a return fuel system, so that is not a problem.

Are you running the stock 5.3 MAF sensor still?

A data log still helps, it will at least tell you if some of the sensors are reporting good values when it's KOEO and while cranking.

[stangman105]

What's your fuel pressure?

The 2000 computers already use a return fuel system, so that is not a problem.

Are you running the stock 5.3 MAF sensor still?

A data log still helps, it will at least tell you if some of the sensors are reporting good values when it's KOEO and while cranking.

Ive tried fuel pressure from 42 to 62 the higher the pressure the more it tries to start, stock mass air
I have a short log of cranking the motor but I cant see how to attach it here

[stangman105]

What's your fuel pressure?

The 2000 computers already use a return fuel system, so that is not a problem.

Are you running the stock 5.3 MAF sensor still?

A data log still helps, it will at least tell you if some of the sensors are reporting good values when it's KOEO and while cranking.

Until I figure out how to load the video here are the numbers
RPM 885
MAF .67 lbs per min
MAP 41.5 kpa
spark 20.6
TPS 0.1
O2 B1S1 581 mv
O2 B2S1 771 mv

Bank 2 is getting more fuel? IS that right?

[stangman105]

What's your fuel pressure?

The 2000 computers already use a return fuel system, so that is not a problem.

Are you running the stock 5.3 MAF sensor still?

A data log still helps, it will at least tell you if some of the sensors are reporting good values when it's KOEO and while cranking.

Until I figure out how to load the video here are the numbers
RPM 885
MAF .67 lbs per min
MAP 41.5 kpa
spark 20.6
TPS 0.1
O2 B1S1 581 mv
O2 B2S1 771 mv

[5FDP]

Set the fuel pressure to 58psi, that is how the stock injector flow rate is set for.

Use the advanced reply box to add the log file and tune file using the attachment icon.

[stangman105]

Set the fuel pressure to 58psi, that is how the stock injector flow rate is set for.

Use the advanced reply box to add the log file and tune file using the attachment icon.

Im sorry I still don't see how to attach it. Im new to windows ten and this forum

[stangman105]

attempting to start.csv

[stangman105]

maybe lol

[stangman105]

Yay I did it lol

[5FDP]

Things look to be working. Seems you live up pretty high in elevation based on the MAP sensor key on engine off readings.

So now it's down to why it's shutting off after starting. Being it a VATS issue or that fuel pressure is dropping after the prime. Can you hot wire the pump?

[stangman105]

Things look to be working. Seems you live up pretty high in elevation based on the MAP sensor key on engine off readings.

So now it's down to why it's shutting off after starting. Being it a VATS issue or that fuel pressure is dropping after the prime. Can you hot wire the pump?

yes I live in the denver area
Yes I can hot wire the pump.
The vats is shut off in the tune

I will do that tomorrow either before work or after
If it runs with the pump wired like that should I take it off the PCM and just run it on a relay or is there another option

[stangman105]

Things look to be working. Seems you live up pretty high in elevation based on the MAP sensor key on engine off readings.

So now it's down to why it's shutting off after starting. Being it a VATS issue or that fuel pressure is dropping after the prime. Can you hot wire the pump?

OMG I went back into the program again just to dbl check the vats and somehow it was on. I turned it off and wrote that to the PCM and we have lift off. DAMN THAT FEELS GOOD LOL
I did a one minute log so now I will probably need some guidance as to the tune if youre willing

[guhman2002]

Gotta love VATS... glad that worked out for ya man

[stangman105]

Gotta love VATS... glad that worked out for ya man

Thanks for responding. You got me pointed in the right direction. The weird thing is I checked that the other day and it was off lol

[stangman105]

OMG I went back into the program again just to dbl check the vats and somehow it was on. I turned it off and wrote that to the PCM and we have lift off. DAMN THAT FEELS GOOD LOL
I did a one minute log so now I will probably need some guidance as to the tune if youre willing

Now Im really confused
So I go out tonight and try and start the blazer and back to no start. So Im watching the fuel pressure gauge while Im cranking and its right at 58
So I stop cranking and for whatever reason I decide to pull the fuel pump relay and crank it and it starts right up. Runs until the pressure bleeds off and the pressure only starts at 20 lbs or so then dies of course. Plug the relay back in and no start.
So then I think, I wonder what would happen if I do that again and then plug the relay back in while its running. Sure enough it keeps on running
SO Im data logging and I get like 4 minutes of log time, stop the log, save it then let the motor come up to temp and shut it off.
Then I go back in the house to watch the log and the file is there but theres nothing on it.
So I go back out and start it again, have to pull the relay again, data log 1 minute and when I watch the log it says theres an error on the fuel. The spark seems to be jumping all over the place and there are 2 spots around 9 seconds and 13 seconds where the o2 readings spike
WTF So why is the spark bouncing around so much and why are there no fuel logs?

[5FDP]

What do you mean by fuel logs?

The fuel system status shows OL fault and the o2 sensors are moving because of that. There is also a current P0200 code in the details on that log and a current cam sensor code.

You can add in the injector pulse width avg to the main channels list if you want to see the injectors working and the duty cycle.

The timing movement is normal if the computer is trying to figure itself out. It can't control fueling or go into closed loop fuel control, so it's running on the raw MAF/VE data that is in there right now. Then if the cylinder airmass is jumping around a little with fueling changes, it will bounce the timing around some. Also the under/overspeed spark correction tables will cause the timing to jump back and forth a little bit too. If there has been headwork and a camshaft change the settings there should be cut in half so the timing can swing as much too.

[stangman105]

What do you mean by fuel logs?

The fuel system status shows OL fault and the o2 sensors are moving because of that. There is also a current P0200 code in the details on that log and a current cam sensor code.

You can add in the injector pulse width avg to the main channels list if you want to see the injectors working and the duty cycle.

The timing movement is normal if the computer is trying to figure itself out. It can't control fueling or go into closed loop fuel control, so it's running on the raw MAF/VE data that is in there right now. Then if the cylinder airmass is jumping around a little with fueling changes, it will bounce the timing around some. Also the under/overspeed spark correction tables will cause the timing to jump back and forth a little bit too. If there has been headwork and a camshaft change the settings there should be cut in half so the timing can swing as much too.

that code is for injector circuit malfunction? Is that a wiring issue or a tune issue.
Does OPen Loop fault mean that its stuck in open loop or it wont go into open loop?
Are you saying the MAF settings should be cut iin half? If so is that across the board or....
All the sensors are new and I know that doesnt mean they cant malfunction but could that be something in the wiring?

[5FDP]

A circuit issue.

It's stuck in open loop and won't use the o2 sensors.

Not the MAF, the under/overspeed idle spark correction tables can be cut back so it can't move the timing around as much.

[stangman105]

what do you think is the fuel issue?
WHy would it only start with 20psi but then continue to run at 58? And what would cause it to stick in open loop?

So I read that the vehicle will stay in open loop until its at a certain operating temp so I guess thats not an issue

the sensors are all new so Im wondering what could be the issue there
And where do you see the faults on the log?