2001 Screw, 5.4, 182,000 miles. I have been fighting a ping and engine stumble scenario for almost 2 years. i will describe the symptoms, then describe everything i have changed... Help if you like...

Cold truck runs perfect. Just as the truck warms up (goes into closed loop mode?), the truck begins stumbling and pinging under load. This is much more prevalent on cold days. might be nonexistent in the summer (alabama). Also seems under powered. Can sometimes turn off key, turn back on and clear the ping/stumble. I have no codes.

Here is what i have fixed/changed:
EGR
All COPS and plugs
removed injectors cleaned and tested for flow, all good..
remove and cleaned Throttle Body (TB)
removed and replaced intake manifold (dont ask)
replaced all 4 O2 sensors
tested CATS, they are all good.

I do have the GOTS mod (more air flow to MAF and TB) wonder if its leaning the mix too much.??

ideas? Thanks.

 

If your going into a closed loop mode you would definitly have a check engine light and codes. Have you done a fuel pressure test?

 

Yes, sorry forgot to add to the list, i did fuel pressure check, it was good, but on the bottom end so i changed the fuel pump anyway... :/ codes do work. over the 2 years i had one O2 sensor die and got a code and replaced.

here is my updated list of things i have fixed:
Here is what i have fixed/changed:
EGR
All COPS and plugs
removed injectors cleaned and tested for flow, all good..
remove and cleaned Throttle Body (TB)
removed and replaced intake manifold (dont ask)
replaced all 4 O2 sensors
tested CATS, they are all good.
Fuel Pump (pressure on new is good)

repeat of my symptoms:
Cold truck runs perfect. Just as the truck warms up (goes into closed loop mode?), the truck begins stumbling and pinging under load. This is much more prevalent on cold days. might be nonexistent in the summer (alabama). Also seems under powered. Can sometimes turn off key, turn back on and clear the ping/stumble. I have no codes.

Thanks

 

I would take it to a shop that can do a BG or Motorvac job, it sounds like you may have excessive combustion chamber deposits. If you don't want to spend the money, start throwing Techron in the gas tank.

 

I wonder if one of the temp sensors is not responding well? or perhaps a weak T-stat?

presume that you have checked for vacuum leaks?

 

If there are not codes you need to focus on things that could cause these issues and not set codes. Fuel has been eliminated. glc points to carbon build up. Thats next.

 

What you did not do is look at the live data on a running with a Scanner to see what is out of limits.
It would have saved you all the expense and work.
My bet is the EVR is leaking vacuum and opening the EGR a small amount.
This won't set a code because it temporary.
Turn ignition off and it's cancelled.
Cold starts runs rich fuel injection.
As soon as closed loop is achieved the fuel leans out.
Add to it a leaking EGR, the mix goes leaner and ignition timing advances causing the ping.
Not really a big mystery.
Check/ clean the EVR solenoid.
Good luck.

 

Bluegrass, where is the EVR???
Thanks.

 

Follow the vacuum line from the EGR back to the EVR location.
Good luck.

 

Bluegrass i did...
Turns out they call that an EGR Vacuum Solenoid... it was cheap so i replaced it and then i traced back all the vacuum lines that feed to that, found dry rot at T's and replaced all that.... still no joy! I also have repaved the Pressure Feedback sensor.. here is an updated list of what i have changed and my symptoms. This is driving me crazy!

here is my updated list of things i have fixed:
Here is what i have fixed/changed:
EGR, EGR VAcuum Solenoid, Pressure Feedback Sensor
All COPS and plugs
removed injectors cleaned and tested for flow, all good..
remove and cleaned Throttle Body (TB)
removed and replaced intake manifold (dont ask)
replaced all 4 O2 sensors
tested CATS, they are all good.
Fuel Pump (pressure on new is good)
Also ran Berryman Chemtool combustion cleaner through...

repeat of my symptoms:
Cold truck runs perfect. Just as the truck warms up (goes into closed loop mode?), the truck begins stumbling and pinging under load. This is much more prevalent on cold days. might be nonexistent in the summer (alabama). Also seems under powered. Can sometimes turn off key, turn back on and clear the ping/stumble. if its very cold out the stumble and ping comes back until after a lot of driving... this is very outside-temp related...I have no codes.

Thanks Bluegrass and anyone else who can help.
Best.

 

Another sensor that may cause an issue is the intake air temp sensor out of calibration.
Another is the knock sensor.
The knock senor is supposed to retard timing when ping and the more severe knock is detected as block/piston/ crank ringing. This may be the lack of power due to retarded ignition when ping an knock is detected.
It can be as much as 8 degrees +/- of retard.
Looking at this from purely technical point is the ping is advanced timing for 'some' reason when it should not be.
The EGR system will do it, lack of sufficient fuel supply, excess air, incorrect intake air temps signal to the PCM, carbon accumulation in the cylinder causing pre ignition, excess engine operating temperature, blocked exhaust..
Note that advanced timing is not the same as pre ignition.
One is 'incorrect' timing control, the other is not but a random hot spot initiation of cylinder ignition..
I would be looking at live sensor readings at this point to try and determine the possible cause.
The system was not designed to run this way without detecting it in some manner.
Good luck.

 

bluegrass,
Thanks, that's even more smorgasbord of idea...if i wanted to do live data, what type of instrument would i need??? i don't have access to fancy computer instruments unless i just take it to a dealer... i did some work with a small shop and they cost me some of those other mods i did... no joy. we did do some driving with the computer in the guys hands when it was happening and he did not say much.. don't think he is qualified as well as i am not for this level of issue...

And yes i have thought of the knock senor and am kicking myself for not replacing when i had the intake off! so stupid!! i am considering going back in and doing that since they are not too costly and i know how... but it would be another guess, which is all i can do w/o data...

And one idea, another guess... a few years back, i cant remember how many, i did the "GOTS mod" where i enlarged the air intake so more air is getting in. i have been wondering if at cold temps the compressed "more air" being, is just too much oxygen. Could that be???

Thanks

 

No substitute for a qualified tech looking at the live data and mode 6 info. In the long this is much less expensive than the shotgun approach of changing parts. That said I would like to see data on IAT.CTS, and KS while problem is occurring.

 

The IAT was located in the original air tube.
What happened with it?
You may have upset the mass air metering with your pipe change.
The air meter is designed to sample a small percentage of the air passing through it and generate a signal in 'proportion'. If it is altered, the fuel metered by injection is changed and ignition timing could be changed as well.
You really didn't accomplish much with the Gotts mod.
Why: at normal driving levels the throttle body opening amount controls the air passing into the motor, not the air filter or it's piping.
The air is no cooler because it's coming in at the same point unless you changed it.
The only possible advantage is at wide open throttle their could be some small advantage 'if' some restriction were present in the factory system because we don't normally go around at wide open throttle besides you cannot feel less than about a 10 hp difference by the seat of the pants dyno feel.
Certainly not feel anything under less throttle than that.
Sorry if some disagree with the working description of that mod but that's the way it goes.
Wait till the dealer see the mod.
Good luck.

 

The Gotts mod is all before the air filter and doesn't affect a darn thing after the filter. Messing around with the intake tube AFTER the filter sure will affect things though.