Before jumping on plugs, coils, fuel filter and fuel pump ; read how this shows it'self.
Off idle pull from a stop feels a miss and at low throttle application during cruise. This is intermittant and of varying severity as though the ignition had been cut off.
There are no codes as a result so no specific clue.
The plugs are recent, the filter is recent, the fuel pressure is at 36 psi and holds.
Starting and idle is ok as is general run-up..
EGR has been disabled for testing, removed and found no carbon fouling with no better results.
TPS has been tested for smoothness of output
Water inhibiter has been added to the fuel, different fuels have been used.
Fuses have been seated in both locations.
Mass Air plug has been checked for seating. Air meter has been spray cleaned, IAT is plugged up and in place.

EDGE monitioing detects no interuppts in any PIDS, Tach does not vary with the miss.
The crank sensor and cam sensor plugs have been reseated.
My feeling is the crank sensor or cam position sensor may be the fault because the fault has no chance of being detected being intermittant and not lasting long enough to be detected later in the ignition process.
Towing is not affected under hard pulling, only very light throttle openings and lower loads.
Is there any experience on this type fault and what did you find as the cause..

 

My truck was doing the same thing..new plug wires fixed it...that's the one thing I don't see you list as being done.

Good luck!

 

Hi Thunder, The truck is an 02 with coils on plugs.

 

Pull the coils and check for corrosion.

 

Sorry, Bluegrass..my bad- mine is a '98.

 

could be faulty injectors....sounds like thats all that is left

 

Check the rubber boots on the coils.

 

Did you ever find a solution? What you are describing is exactly what I'm experiencing. I've done plugs, wires, fuel filter, pcv.....nothing changes.

 

I am still tracking the problem.
I use an EDGE tuner data stream and making a large number of recordings and analyze, print the results of them on a computer.
I constantly see the IAT abruptly jump in output value and some other minor PIDS that have fast movement that would normally move slowly in response to temp changes.
Maf, spark and other paramteres don't seem to follow in any pattern as of yet.
I can't tell yet if this is a secondary response to the source of the problem.
Done a longer trip and had a chance to record under other conditions.
I tried the AM radio on a frequency not used in my area and can hear the pops when the missing ocurrs. I have concluded it is ignition but a fault that happens at a very early stage like the crank or cam position sensor and may be the reason why no codes are set.
Ignition code, if not at full fault, are sampled at the later stages after PCM calculation.
On the way I stopped at a fast food. Restarted and never missed a detectable beat for the next 50 miles.
Surely I can't attribute this kind of action to plugs, coils or boots.
The fuel has been treated and changed to different brands weeks ago.

Thank you for coming in with your attempts and work on solving the problem.
Keep reporting if you get any resolution and I will do the same.
As I use the EDGE more I get better at interpeting the various actions seen on the readout. For example I can now see the point that the EGR routine is called up just by watching the spark and one of the any MAF flow, load %, instant mpg or output shaft speed. By doing this it keeps the engine in the best range for fuel milesage. Got a high of 18.2 using this method.

 

This is driving me nuts. No codes being thrown. My mechanic has no clue as to what the problem is. I dont want to keep throwing $$ at it hoping to hit on the solution. If you ever find whats causing this please post...

BTW - mines a 97 4.6 Windsor, auto.

I was sure the plugs, wires, fuel filter and pcv would fix it as I've experienced similar symptoms in my 4.3 S-10 which were cleared up with those replacements. Didnt make a lick of difference. I've tried the simple stuff too.....different gas, water eliminator, fuel injector cleaner, cleaned the maf.

I'm suspecting a vacuum leak somewhere, but would expect a code on my obd2 reader. Do you think this is a crossfire situation? May play with plug wire routing this weekend.

Other than this weird stuttering between 40-50 mph/1500-2000 rpm the truck has been solid.

The "missing" doesnt seem to impact mpg or accelleration which intrigues/confuses me.

Oh well, pre-season hockey game about to start.....see ya

 

Welcome to the forum swlabr

How long does the problem occur for when it happens?
Is it just a momentary thing or does it feel like it's stuttering for any length of time?

 

Racerguy, thanks.

The problem happens all the time, its not like a once a week/month thing. Anytime in the 40-50mph/1500-2000rpm range. The engine will stutter for 1-3 seconds, then go back to normal, then go back to the stutter. As long as you keep the throttle in position it will do that, giving more gas makes it dissapear. The time period between stutters varies, sometimes every 10 seconds, sometimes every couple minutes.

Took the truck onto a country road on the weekend, freshly paved and straight. WOT - no bogging down, everything felt right.

It idles smooth.

It's only in the very specific speed/rpm range at low throttle that the engine is doing this. Been driving me out of my mind for three months now

 

Any chance this is torque coverter shutter?

 

I think so Joe.
swlabr have you ever changed the transmission fluid?
Torque converter clutch chattering is quite common. The clutch can chatter as it locks and unlocks, usually under light throttle in about the mph ranger you're having the problem at. Usually having the transmission fluid flushed or changed will cure it. Your truck should have a drain plug on the converter so make sure that it gets drained too.

 

Joe: no idea what that feels like, so I cant answer that.

Racerguy: I bought the truck used, dont know when/if the tranny has been serviced. I havent changed it in the time I've owned it (one year). Oil change on this weekends schedule. Will get the transmission fluid/filter done at the same time. I'm too lazy to change the oil myself and usually go to the Jiffy Lube down the street, you think they do a decent job with tranny service? Or should I take it to a real service center.

Thanks for the advice guys. If this solves it, I owe you a beer