This problem is driving me crazy! Help/ideas/suggestions needed!

LAzevedo · May 7, 2016

So I've been having a bogging, power loss, hesitation, stumble.. Taking off from a dead stop I need to rev up to 3.5k just to accelerate normally. I can be doing 60, in 6th, and floor it, it doesn't accelerate. And then, the problem dissappears. It'll run perfect for 2-3 months and bam.. Problem is back for a while. It's been a year and a half of this and I still haven't been able resolve it. Different shops, some tuning shops, and some 6 mechanics. Details below.

Mods:

AFE Stage 2 Intake
JBA Short Tube Headers
3" Y back
76mm throttle body
Intake manifold spacer
Urd thermostat
Walbro 255lph fuel pump
Unichip (tuned)

I've tried disconnecting the Unichip and reconnecting stock harness. New plugs, new injectors, new coil packs.. Nothing has resolved the problem. It bogs when I use race fuel or fuel system cleaners. And to top it off, cruise control doesn't turn on. I don't know what to do :/

Redlantern · May 7, 2016

U check your fuel filter?

kwigs160966 · May 7, 2016

Take a closer look at the throttle bodie clean it and the maf sensor. Replace either or both of you find a thing

Gadget · May 7, 2016

When this happens, do gauges in the instrument cluster do anything weird, like the tach drop all the way to ZERO and not reflect actual engine speed?

You may want to switch back to the stock throttle valve and see if that has any affect on it.

G

LAzevedo · May 7, 2016

I've checked the fuel filter and have tried reverting back to stock throttle body. The gauges stay put.. They don't go to zero.

LAzevedo · May 7, 2016

https://youtu.be/-nDNm6fXMQA

armyoffoo · May 7, 2016

Does it only do it when the tank is low? I had this problem with my truck, turned out that the fuel hose clamp on my URD fuel pump upgrade ate through the hose...my fault, over-tightened it. When the tank was full, no issues, once it dropped under 1/4 it would have issues. Do you have a fuel pressure gauge?

LAzevedo · May 7, 2016

I haven't even thought/noticed about the tank level. Truck is running awesome today btw.. Been about two weeks since I've felt zee powa!

autobodyX · May 7, 2016

armyoffoo said:
Does it only do it when the tank is low? I had this problem with my truck, turned out that the fuel hose clamp on my URD fuel pump upgrade ate through the hose...my fault, over-tightened it. When the tank was full, no issues, once it dropped under 1/4 it would have issues. Do you have a fuel pressure gauge?

Fuel problem line is my Guess too.
I Had a problem with the submersible line in the my tank. I had too sharp a bend in the line and it cracked and leaked pressure. Took me quite a while to figure it out.

SgtBadA · May 9, 2016

Happened to my friend but it would shutter at lower speeds. It was his fuel line bleeding off pressure

LAzevedo · May 23, 2016

Bleeding off pressure how? Only way to check the fuel pressure would be in-line right?

Mallcrawl · May 24, 2016

I just noticed now, but maybe you know......unichip?

LAzevedo · May 24, 2016

What about the Unichip? I've removed it and the problem was still there. Starting to think it's the ECM. My A/C has been acting weird (randomly turns off when on, but higher idle as if A/C was on) and my cruise control works every so often. Can't be a coincidence right?? Anyone know how to test the ECM?

BSP06XRU · May 24, 2016

Cruise control may be affected my brake fluid level.
The rest I have no idea. Good luck!

autobodyX · May 24, 2016

A/C kicks out if it senses belt slip. Needs a belt or something Is leaking and getting on the belt making belt slip.

Pull sending unit you will find a leak in the fuel line is cause of your other problems.

volcomstone_1223 · Jun 9, 2016

I'd definitely clean the maf sensor even if it looks clean I had a similar problem cause by that, A/C also turns off when at WOT so maybe an issue with the throttle body?

LAzevedo · Jun 9, 2016

I have a 2uzfe throttle body.. 76mm. I'm just getting misfire codes from pretty much every cylinder.. No other codes other than misfires.

LAzevedo · Jun 20, 2016

I replaced both fuel filters and I replaced a spark plug from cylinder 2 (had a PO302). Truck ran perfect for about 5 days then boom, problem is back! If I go less than half throttle truck will accelerate Okay. When more than half, it'll start to bog a bit and if I floor it while it bogging, it'll misfire every time.. PO300 is the only code I'm getting. Help?!!

Coupe · Jun 20, 2016

I will assume you checked all plugs.

You could have a weak fuel pump.

This is out there a bit, but you could have a battery with a weak cell or a bad ground.

I would vote for a bad ground.

Torspd · Jun 22, 2016

Do you have any aftermarket components wired into your truck? Radio, gauges, other?

Do you live in an area that has a lot of mice or rodents? Have you checked your electrical harness for broken shielding?

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