I have this issue posted in another thread but I thought I would try another approach.

OK here is the problem very quickly 2005 F150 5.4L;
I have a hesitation / hicupp at very low RPM during acceleration under moderate load, such as going up a hill. It only happens between 1000-2000 RPM until the tranny down shifts. Usually happens at about 40-45 mph while in with increasing pedal application.

DTC's are not stored but I was able to get the following codes during a live scan.

P0443 Evap purge
P0505 Idle air control
P0123 TPS switch circuit high
P0118 Engine temp high
P0113 Intake air high
P1249 APSOL Solenoid control (Air polution valve)


I can monitor the TPS with the scan tool and see blip type peaks maxing out during the hesitation. However, the blips do not replicate during a KOEO throttle sweep. The TPS also does not to read 100% with the pedal fully depressed KOEO. No other sensors seem to have any abnormal graphs during the hesitation. The blip / hesitation usually happens while moving the pedal down or opening the throttle.

I'm leaning towards replacing the TPS but it does not completely fit, I don't understand why it only happens under the very specific conditions or what all the other codes mean.

Any help would be greatly appreaciated.
Thanks!

 

It would seem to me that you are having more than just TPS issues. It is almost as if you are having an issue with the VREF for these sensors. I wish I had an electrical diagram for your truck. The misfire under load seems like it would be more ignition related.

I would not throw a TPS at it right away. Maybe someone else will have some other thoughts on it.

 

Yeah it seems like a voltage thing, I actually just went to the library to see if they had an electrical service manual but no luck.

Both the TPS Absolute and TPS Reference live data graphs will peak with the studder. This to me indicates its not the Vref.

 

OK so I brought the thing to Ford to have the tranny service done and rule it out. I also got them to through in a free PCM update. I was able to talk to the tech who did a pretty good diagnosis. Note that before I brought it in I noticed that although I am not getting misfire codes on my scan tool I am getting misfire counts on the 5-8 cylinders or left bank.

He tells me he is geting a VCT error above limits. Now I think this makes sense as the cam phaser make that noise.

The thing that kills me is that I almost walked away from this truck becasue of the noise, but they had their mechanic check it out and he told me it was fine.

 

If you clear your codes, do they all come back instantaneously? Or does it take a few drive cycles.

If it comes back right away, take a multimeter, hook the black lead to the battery negative, turn your ignition on, disconnect the air temp sensor and measure the voltage. It should have 5 volts going to it. If neither wire does not have 5 volts then we need to start tracing wires. I would not worry about your cam phaser at the moment. If you cannot trust your readings from your TPS, CTS, and IAT sensors, what makes your mechanic think he can trust any other measurement the scan tool takes?

 

The codes do not come back and in fact I have not been able to replicate them. I think I must have unknowingly activated a drive cycle to get the codes the first time. The only thing that is consistent is the TPS spike before the stumble. I don't even know if I believe the kid, I can't monitor the same PID's with my scanner. I'll try what you are suggesting, thanks!

I can't even begin to describe how frustrating this is. I can't even look at the plugs because they will break if I try to pull them.

 

Ok,

Since the codes do not come back right away It seems that they may have been activated in error, like if you had the ignition on while unplugging a sensor. Now may be the time to consider the cam phaser or possible mechanical issues with the engine.

What do your fuel trims look like?

 

OK thanks, I was suspicious of those codes because I haven't been able to replicate. Although the TPS spike bothers me.

So here is my plan, as soon as I get some time.
Check wiring harness and plug connections on left back. Check voltage on IAT and both TPS voltage signals.

What should I look for in the fuel trims? I've watched the live data but didn't see anything that looked abnormal.

My latest theory is that the problem is related to the #2 TPS which is monitored by the PCM for slight throttle movement. This would sort of explain the way the problem only happens on gradual accels. I can't monitor each TPS with my scanner so I don't know which signal the PCM is looking at when it shows me a spike.

Honestly if its the phasers I'm gonna cut my losses and trade it in. I don't have time to do the job and that issue along with the plugs is just too much.

 

You dont live in MN do you? I'd be more than happy to help you if you are around here (mankato area).

For fuel trims, look for anything that is +/- 10%. A positive fuel trim reading indicates the engine is running lean, and anything negative indicates the enigne is running rich. Once you find your fuel trim readings on the scan tool, observe them at an idle, and at 2500 RPM.

You will likely have multiple TPS circuits (proably 2 or 3 of them because this is an electronic throttle). I would not worry about the glitch that you see on your scan tool because the PCM's on these trucks will usually pick up most issues with the TPS. Also since there are multiple TPS circuits, your PCM can determine when one is not right, and will set a code for it. However in case i'm wrong, test the voltage at the TPS and do a couple of sweeps on each wire. You are looking for a smooth transition.

 

No man I live in the great state of New Jersey, which I am embarresed to say these days with all the news about that MTV show. I appreciate the offer, and I wish I had friends like you here.

Part of the problem is the weather has been too cold to really monkey around with the thing at all. Hopefully I'll get chance this weekend.

 

OK I tested the voltages from the TPS nothing strange. Did sweeps on both wires and smooth transitions Vref looked fine.

Short fuel trims bank 1
idle
-3.1% - 1.6%
2500
-1.6% - 4.0%

Short Trim Bank 2
Idle
-2.3% - 2.3%
2500 RPM
-4% - 4.1%

When driving bank two seems more erratic, I saw peaks up to 20%.

Too cold to do much more today.

 

What did the long term look like? Anything unusual there?

 

OK so after I did that I pulled each coil on the left bank, inspected them and shot liquid wrench onto the plugs thinking I might try to change them next weekend. I then took it for a ride about a hour later. I went on the same route I always go on I come to the spot where I always get the hesitation and guess what...nothing.

I'll try it again tomorrow, I highly doubt that what I did could have made a difference but who knows.

 

What you are describing does sound like an ignition issue, however since you had a misfire count on all cyl's 5-8 I figured it was unlikely that all coils would go bad at once.

 

Three of the four coils on the left bank had different markings. There was paint markings on 6-8 and but 5 was not marked. Looked like the same PN but there was some different numbers on 5.

Somebody had definitely been in there since it left the factory. Is there any way to check the coils these days?