Like it says my motor bogs down bad after 4-5 seconds of wot. Its getting really frustrated I got my *** handed to me by a old body style lighting the other day because of this. Also at the track today it did it everytime. I have a walbro 255lph fuel pump and 42lb injectors so I really dont think i am running out of fuel but thats what it feels like. It did this with the factory pump too, so i really really dont think its the fuel thing. Has anyone else had these problems or maybe a solution for this. It feels like im running at a 1/4 throttle when i am at 100 precent. If anyone has any ideas please chime in.

thanks
Jon

 

What is your fuel pressure gauge telling you?

 

I dont have a fuel pressure gauge unfortunately

 

Have you replaced the fuel filter?

 

does it throw any codes ?

 

Time to buy or borrow one then

 

You need to hook up a wideband and see what your AFR is at WOT. It's most likely fuel or timing. If it had a mechanical problem causing it I don't think it would run very long.

 

I would guess it's cat overtemp protection (COT)
kicking in, which jacks your AFR to about 10.25:1
(commanded, +/- whatever other errors / trims
may be up to).

 

^ wow i did not even know our cars had something like that. thanks for sharing

 

Pulled codes all i got was one for the evap system. Should have mentioned that the truck has a fuel cell in the back and an inline pump. It did this before the fuel cell and pump though. I changed the filter about a week ago and pulled it off to make sure it wasnt bad yesterday. I blew it out and it seemed to flow just fine. Tomorrow after work I am going to get a pressure gauge on it and see what is going on with that.

 

Fuel pressure is good, it maintains 60 psi the entire time??? I have no clue what to do now.

 

what other mods are done to the car?

 

Does it seem like the rev limiter is kicking in and cutting the fuel off?

Shot in the dark but i had the same problems years ago and had water in my knock sensor valley holes and it shorted out the knock sensor and eat up the wiring. What mine did is it felt like it was falling on it's face hard but if i lifted the gas some it would go. You need to do a loged run and check everything out.

 

Its a truck, Ls1 swap, truck intake though. MS3 camshaft, cold air, longtubes, e-fans, 160 thermo, 42lb injectors, walbro 255lph pump, t56 swap, tune. NO cats, NO egr

 

I took the truck out with my shitty data logging software and this is what i was seeing happen when I went full throttle and then it bogged after a few seconds.

The map and maf, in this log i didnt let off or anything, even though the map and maf values fall
17:43:50 > Mass Air Flow > 223.17 g/s> 29.5 lb/min
17:43:50 > Intake Manifold Pressure > 97 kPaA > 14.1 PsiA
17:43:50 > Mass Air Flow > 203.12 g/s> 26.9 lb/min
17:43:50 > Intake Manifold Pressure > 96 kPaA > 13.9 PsiA
17:43:50 > Mass Air Flow > 34.19 g/s> 4.5 lb/min
17:43:50 > Intake Manifold Pressure > 19 kPaA > 2.8 PsiA
17:43:50 > Mass Air Flow > 18.95 g/s> 2.5 lb/min
17:43:50 > Intake Manifold Pressure > 17 kPaA > 2.5 PsiA
17:43:51 > Mass Air Flow > 18.95 g/s> 2.5 lb/min
17:43:51 > Intake Manifold Pressure > 22 kPaA > 3.2 PsiA
17:43:51 > Mass Air Flow > 18.47 g/s> 2.4 lb/min
17:43:51 > Intake Manifold Pressure > 27 kPaA > 3.9 PsiA


This too, the mph is off by alot, like im doin over twice what it says.
17:35:21 > Absolute Throttle Position > 49.4 %
17:35:22 > Engine Speed > 2694.25 Rpm
17:35:22 > Vehicle Speed > 24 Kmh > 15 Mph
17:35:22 > Calculated Load > 55.7 %
17:35:22 > Absolute Throttle Position > 100.0 %
17:35:23 > Engine Speed > 3411.25 Rpm
17:35:23 > Vehicle Speed > 31 Kmh > 19 Mph
17:35:23 > Calculated Load > 73.7 %
17:35:23 > Absolute Throttle Position > 100.0 %
17:35:23 > Engine Speed > 4215.00 Rpm
17:35:24 > Vehicle Speed > 37 Kmh > 23 Mph
17:35:24 > Calculated Load > 95.7 %
17:35:24 > Absolute Throttle Position > 100.0 %
17:35:24 > Engine Speed > 4566.00 Rpm
17:35:24 > Vehicle Speed > 39 Kmh > 24 Mph
17:35:25 > Calculated Load > 5.9 %
17:35:25 > Ignition Timing Advance Cyl #1 > 54 Degrees > Advance (+)
17:35:25 > Absolute Throttle Position > 0.0 %
17:35:25 > Engine Speed > 3115.00 Rpm
17:35:25 > Vehicle Speed > 38 Kmh > 24 Mph
17:35:26 > Calculated Load > 5.1 %

This again is a cheap logger and software, it only logs what window I have open I found out but if I dont have any open it will log all so i will go back out and get a better log with everything. But please if anyone can tell anything by this dumb **** up I logged It would be great.

THanks
Jon

 

Clueless and frustrated I took the intake off and looked at the knock sensors, and hopefully streetstalker led me in the right direction. I found a piece of one of the connectors laying up against the knock sensor. Unsure if this was making it do it or not but I sure hope so. I checked both knock sensors though and they both were withing the tolerance 99.4 on one and 99.9 on the other, they both also moved up when i tapped them. The harness was also good, so back together it goes now and hopefully it works now.

 

 

Good question since it all happened ten years ago...

 

No kidding, I have the EXACT same issue with my truck. I wonder what the cause/fix was?

Chad

 

i know, I have a 5.3 Sierra and it’s hooked up to a 50 dry shot, it makes less power on the same tune while spraying then running naturally aspirated