ZX6ROCKET

Hi All,

Im still trying to fix a bad hesitation issue ive been having with my 04 5.4. Truck has 87k miles and for the most part runs great. For the past year I have been having a bad hesitation issue in 1st gear at full throttle. This started happening after i had my cam phasers serviced and my trans flushed. No clue if that had anything to do with it.

From a dead stop at a red light if i floor the pedal the truck will takeoff fine until about 3-4k rpms and then it will completely cut out. my foot will remain floored and it will all of a sudden come back in and punch it and eventually upshift. Sometimes it will come back in and cut out repeadetly until i let off and give less throttle. On the freeway or any other gear but 1st the truck is fine at full throttle, 0 issues. even if the truck downshifts from 2nd to 1st i dont have an issue. just 1st from a dead stop upshifting to 2nd.

Changed all of my plugs and coils less then 10k miles ago, didnt help
bought an intake, made problem much worse! took off
bought an edge, made problem much worse! took off
regeared truck for the 35's didnt help


has anyone had this issue?? please help.....

luckythirteen13

When was the last time the fuel filter was changed, tb cleaned, or fuel module checked?

Ian_T_S

Hey man, remember bogging down problem...still haven't solved it.

We are headed in the Fuel Pump Module direction though...it's being changed yesterday/today, ill let you know if this worked; it may be of good use to you

HardcoreFx4

If not take it to a auto parts store and have them put it on a machine and if its says a cylinder miss fire than get a ignition coil for it. it will run so much better if thats what it is.

diamonbird

Mine has done the same thing only I have never floored mine from a stand still but I have gone 3/4 throttle from a stand still and it has done exactly the same as yours.
Mine acts like the motor is cutting off and back on very rapidly, it feels like the trans is skipping.....I have asked this question before here and never got an answer about it.
I don't think anybody knows what's wrong.

wiseacre

My 06 is doing something similar but I've not had time to dig into the problem.

Mine will accelerate from a dead stop and pull hard to 3800-4000, then it seems to start shutting cylinders off like a car with traction control and the wheels are spinning. If I keep my foot floored it will rev but has no power.

It doesn't do it every time, about 50%. Other times it runs right up to 5500 and shifts.

It will also decide to act up when floored to pass at highway speeds, again about 50-50.

The things I'm going to check when I get time are:
-Does it still act this way with the stock intake (I have a K&N cai installed)
-are the vct solenoids partially plugged, maybe the cams don't always advance properly.
-fuel pump module.
-throttle opening to 100%, could be relaying bad information.
-every vacuum line, vacuum will read very low at wot and a cracked line could cause a sensor to read incorrectly.
-o2 sensors, you will run rich at wot.
-and not to be forgotten, plugs, coils and fuel filter.

JimWills

I've been looking at this post and felt I had experienced similar symptoms but the last post triggered my memory. I believe the issue is the MAF sensor. I installed a K&n filter (actually after I cleaned and re oiled it a couple of times) I began experiencing this issue when passing, The trans would downshift to second and around 35-38k rmp start missing and cutting out. if I let off even slightly it would even out. Ended up the MAF had gotten coated with oil and would not respond to the increased air flow resulting in a lean condition and severe missing. A thorough cleaning of the Mass Airflow Sensor cleared it up.

wiseacre

Thanks Jim.

That's a quick and easy thing to try.

ZX6ROCKET

I have never run an oiled air filter on there and the maf looks clean but I will try a can and see what happens.

Ian - sorry to hear the cats and exhaust did not fix the issue. Looks like we are back at square one.

wiseacre

This is interesting, doing some research on Tuners and found this list of features from the Diablo tuner literature:

Global Spark Advance
Idle Speed in Neutral
Idle Speed in Drive
WOT Fuel Table 2000-4000 RPM
WOT Fuel Table 4000-7000 RPM
WOT Spark Advance 2000-4000 RPM
WOT Spark Advance 4000-7000 RPM
Re-Calibrate Speedometer for Gear and Tire Size Changes
1-2 Upshift MPH
1-2 Upshift RPM
2-3 Upshift MPH
2-3 Upshift RPM
3-4 Upshift MPH
3-4 Upshift RPM
Rev Limits
Speed Limits
MAF Curve Adjustment
Internet Updateable

Looks like there are Fuel tables and spark advance tables for the 2000-4000 rpm range, then another set of values above 4000 rpm.

As out engines seem to lay down right at 4000 rpm, the issue might be right there.

Any one know exactly what sensor the computer uses to track RPM, cam sensors, crank sensor, other????