LBZ Fuel throttle.

[Max1957]

Hi guys, have a twin Turbo LBZ with Race tune. , It ussually runs great. All of a sudden it will only give half throttle at times. I can give 100% throttle and it barely smokes and does not go, if I let off and try again she rips. If I hold throttle down it does its half fuel thing then all of a sudden it usually will take off. Then next time it runs great. I can tell it is giving a lot less fuel when its doing it. Looked for loose connectors, anything else?

 

[gmduramax]

Is the lift pump working? Can you log fuel rail pressure

 

[Max1957]

Is the lift pump working? Can you log fuel rail pressure

yes I data logged and have good fuel pressure,100% throttle position when it happens, seem for some reason ecu not telling it to give full fuel. MAP and MAF are registering. .trying to figure out how to post a data log. Do I need to convert it to a file??

 

[gmduramax]

yes I data logged and have good fuel pressure,100% throttle position when it happens, seem for some reason ecu not telling it to give full fuel. MAP and MAF are registering. .trying to figure out how to post a data log. Do I need to convert it to a file??

that I don’t know email it to me

 

[Max1957]

I see in Logs my MAF is reading Zero at idle and all the way up til MAP is at 30lbs boost. I cleaned it and still reading Zero at idle. I beleive it should read more than that . Older logs 2 years ago use to be at 49 at idle. Thought?

 

[Yngdmax92]

Why would it not be throwing a code at 0 when idling. Doesn't make sense.

 

[Max1957]

IDK?? No codes. Check Volts , Have 4.96 Volts . It did this a month ago with a new tune in it. I thoiught it was the tune because i put another in and it has been good till today. I guess I will try a new MAF. Thanks For helping.

 

[gmduramax]

Replace the maf with one from gm. Also if you want that motor to live you’ll need bigger injectors

 

[Max1957]

Replace the maf with one from gm. Also if you want that motor to live you’ll need bigger injectors

Have a GM MAF coming. I have 100% S&S in it now. Running a 60% locked Rob race tune though. It runs crazy great but need to get it retuned before it breakssomething. And it smoky. Tryed at two other big guy but they are just not getting it right. In Upstate Ny so no one near by to get it to.

 

[gmduramax]

Have a GM MAF coming. I have 100% S&S in it now. Running a 60% locked Rob race tune though. It runs crazy great but need to get it retuned before it breakssomething. And it smoky. Tryed at two other big guy but they are just not getting it right. In Upstate Ny so no one near by to get it to.

what size turbos do you have 100% overs at 2950 pulse is a lot of fuel

 

[Max1957]

what size turbos do you have 100% overs at 2950 pulse is a lot of fuel

S480/S366

 

[LBZ]

I feel you could probably dial back the pw quite a bit in those tunes with that setup.

 

[Max1957]

I feel you could probably dial back the pw quite a bit in those tunes with that setup.

Agree , thats for help and I will let you know when MAF Does

 

[Max1957]

I feel you could probably dial back the pw quite a bit in those tunes with that setup.

PW adjust and thats it??How much should I subtract on PW ?? Subtract same amount in hole table? I do have to back fuel down a touch idle- 1500 RPMs So not so smoky. It runs great, just sounds like it is free and wants to rip. Thanks

 

[Max1957]

what size turbos do you have 100% overs at 2950 pulse is a lot of fuel

So heres my findings. Put a new MAF on and samething. Data logged it and MAf was all over the place. So I tested wires and volts after searching all over the internet to find out how. Here it is. . Tested ohms for each MAF wire to ecu. Tested Map sensor wire to Low reference wire got 4.96 Volt. Have 12 volts at ignition wire so put a test light on it and check volts, No drop in volts. Hooked the 12 volts wire to MAF sensor wire and Efi Live MAF reads 634gs as it should. With no Volts Reads 0 with key on, engine no running. All good after wiggling the wire loom all the way up through to ECU.
I bent the pins in connector on the MAF Sensor connector so made better contact and time will tell but all seems to be good again. Thanks for the Help.

 

[LBZ]

PW adjust and thats it??How much should I subtract on PW ?? Subtract same amount in hole table? I do have to back fuel down a touch idle- 1500 RPMs So not so smoky. It runs great, just sounds like it is free and wants to rip. Thanks

You will likely need to pull a bit of fuel pressure and timing too but it depends on how it runs and egt’s. You want it to haze not smoke. Pull some off the top and see how it takes it. Smooth the rest out to match. But I wouldn’t go crazy until you sort out your maf issue.

 

[Max1957]

You will likely need to pull a bit of fuel pressure and timing too but it depends on how it runs and egt’s. You want it to haze not smoke. Pull some off the top and see how it takes it. Smooth the rest out to match. But I wouldn’t go crazy until you sort out your maf issue.

Thanks LBZ. OK, the weather is not cooperating here in upstate ny. Have to give it a try in couple weeks in FL.