jeeptester

I have a 2008 4.8 in a tj jeep.

I didnt really build it for drag racing but I did get my first challenge the other night. And well you know LOL any way I had him but just as its getting in top gear and pulling out in front its like I lifted off the gas and then it goes again.

Ideas? And what should I test?
Thanks
Lowell

V8Rumble

iTrader: (9)

Well, the first step is obviously to pull codes, & see if that tells you anything. The other thing that comes to mind is to check fuel pressure. Is the problem consistent, or sporadic?

ls1nova71

iTrader: (4)

Do you have an intank pump, with a good baffle? Is the fuel running away from the pump under hard acceleration?

jeeptester

P0030
P0053
P0054
P0135

The ecu has been flashed and the rear O2 are supposed to be deleted so I dont know why I have a Sensor 2

I did the checks on the o2 that I know to do, 12v(+) on the correct wire, and (-) is good at the connector. I swapped the sensors and the codes stay the same.

Can the above codes cause the condition I having?

Oh and Im gona have to do something I just got beat by a rice burner , Please HELP LOL

Its funny every time I come to a light somebody wants to run lol. I guess they can hear that its not a 4banger in it.

jeeptester

Its a in tank the oem housing with walbro pump and corvette filter regulator

jeeptester

What are symtoms of it hiting the rev limiter? Does it kill fire or fuel or both?

ls1_chevelle

iTrader: (9)

depends how it is setup. My factory DBW would close the TB. Was a very slow to recover limiter.

Go smash the limiter in first gear and see if it is acting the same as you are experiencing in high gear.

I doubt you are running out of gear but it is possible? maybe a video?

jeeptester

Ok I will try that

It doesnt help that the tach is not working so idk the rpm its doing it at. (its a speedhut gauge that I cant get it to not bounce all over the place, i tried a filter but still no go)

I will try to do a video tonight, it will have the speedo at least and can hear enigine to tell.

I just ordered the Edge Evolution CS Gas Programmer it may help me diagnose the o2 stuff and see whats going on maybe. Anybody know anything about the edge Ev ?

badss_02

iTrader: (2)

No, 02 sensors will not cause this problem. The upstream 02 sensors will cause it to cut out if they are bad but that would only happen under normal driving conditions. As soon as you accelerate hard the pcm does not use them.

i r teh noobz

iTrader: (4)

Do you run a MAF? I had an ongoing issue with sporadic cutting out with no codes. My MAF ground had worked loose.

jeeptester

I think I found the cutting out issue. Fuel Pump

It died one day and had a very lean smell. I checked the pressure at the rail and it was almost 0. Shot a little carb cleaner in the intake and tried to start. Towed it home, dropped the tank and the short rubber transition hose to the 3/8 hard line was kinked badly. So it must have been starving for fuel this whole time. I have also stopped having the random miss fire code. The bad news was after fixing the hose two days later it died again. I thought to hit the bottom of the tank hard, and it started.Then I knew it was the pump for sure. My theory is the kinked line caused the pump to work way too hard and killed itself.

Im still having
P0030
P0053
P0054
P0135

Does anyone know the symptoms of the above codes? How bad are they killing gas millage? Hurting engine?

jeeptester

You were right on. I had checked fuel pressure before and had assumed it was ok. But I forgot about how I had wrapped the line to protect it from heat from the new exhaust. I guess I moved the line just enough to pinch it while doing that.

Now if could just clear up these 02 code

Thanks

dynodanmanda79

iTrader: (3)

I was driving my 5.3/t-56 swapped camaro about a year ago and lost fuel pressure out of nowhere as well. Dropped the tank to find that short piece of hose that connects the pump to the hard feed line had turned to jelly. Make sure to replace it with submersible grade fuel hose, it's expensive but well worth it.

http://www.jegs.com/i/Gates/465/27097/10002/-1?CT=999

jeeptester

I finally got around to checking this, and I put a pressure gauge on the rail and did a WOT test. The pressure drops to 30 psi stumbles and comes back. That tells me at least its not electronic ? Right ?

Im using the OEM 97 jeep pump and its rated at 51 psi but Im thinking its not enough volume so I have purchased a OEM CHevy 2008 pump that says its rated at 95 psi I have yet to install it yet.

Two questions

1. Agree this new pump will correct the WOT problem ?

2. Is the EVAP system required at all? If I just have it plugged whats its impact ?

Thanks
Lowell

ls1nova71

iTrader: (4)

30 PSI at WOT is about half of what you need, so I think the new pump should remedy your problem. You don't need any of the evap stuff for it to run properly.

jeeptester

Fuel pump questions:

On the 4.8 2008 OEM silverado setup I see it had a fuel management relay that was independent from the ECU and (I think) used the pressure sensor to pulse the pump. ?

So using the corvette wix filter/regulator with the in-tank pump is the pump running all the time? And is that Normal?


What fuel setup did you do?

Thanks
Lowell

bigchief52780

iTrader: (10)

did you get the fueling problem worked out? i am having the same problems with a 70 cutlass ls3 swap. i also thought about going with one of the trucks e85 high flow and high volume pumps.

ls1nova71

iTrader: (4)

Yes, the pump will run all the time and the vett filter/regulator will regulate it, that's normal. That's what I would do since its the easiest way to do it.

What kind of pump are you currently using?

jeeptester

Thanks

I have the new pump just waiting on time to drop tank.

Another question if you dont mind? The Auto Shut Down Relay in the Jeep, Im thinking of wiring it into the fuel pump relay to kill fuel if roll over or impact, Im guessing it works off the air bag mod, Have you installed any cir like this for ASD function?

jeeptester

I have purchased another pump just waiting on time to install. But the tests I did definitely indicated low fuel pressure at WOT. It will really accelerate like is , its going to be interesting to see what it CAN do lol.

as ls1nova71 said , what pump are you running now ?