Engine/Transmission (1998.5 - 2002) uphill stutter with cold engine?

[NWest]

When I start my truck in the morning, I notice a little "stutter"-- I lose power, then its back, then its gone, then back again. It feels like my old ford ranger did when I was running out of gas. I'm hoping that it's my transmission, so I will be able to justify a performance upgrade to the wife, but my gut tells me its a fuel delivery problem.



This only happens when the truck isn't warm. Anybody have any thoughts?

 

[ThrottleJockey]

NWest,



Do a search on the infamous 'APPS'.



The Accellerator Pedal Position Sensor.



You can replace the sensor, or use a CaTCHER to overpower it. The CaTCHER is more fun.



Brian

 

[NWest]

Thanks for the APPS tip- I'll disconnect the battery tonight and reset in the morning.



After searching APPS threads, I'm noticing that most of these problems have manifested themselves more severely (engine dies when put in gear), or at highway speeds. I'm only seeing this problem under 15mph, under very light throttle.



The other difference I noted was that the power/no power/power/no power cycle all takes place in about 2 seconds total. I'm noticing substantially longer intervals in the APPS threads (e. g. https://www.turbodieselregister.com/forums/showthread.php?t=137155)



Hopefully I'll be trouble-free in the morning and my observations will be for naught.

 

[ThrottleJockey]

Are you losing prime?



After you check the APPS, check your fuel pressure.

 

[NWest]

Well, looks like fuel pressure is next. Reset the APPS this morning, and same thing. (However, throttle response seems a lot better overall!)



Is it possible that this is just normal behavior going out of first and into second? When I'm headed uphill slow, I almost always have to put it in first or endure endless shifting.

 

[NWest]

Are you losing prime?



After you check the APPS, check your fuel pressure.

Is there a way to check fuel pressure that doesn't involve permanent gauge installation?



I *do* want to install gauges, but I haven't figured out how i want to mount four of 'em yet (slowly working my way through Readers' Rigs looking for ideas) and I also need some time to butter up the wife. So in the interim, is there something that will do the trick?

 

[jetenginedoctor]

You need to make sure your TPS isn't bad, not just reset it. Do so by figuring out which wire is +, which is -, and which one is + but at a value les than the other one. This is the wire you need to observe the voltage on. Using an analog voltmeter or digital with an analog display, look for the voltage to be roughly 1 volt with foot off throttle pedal, and 5 volts (roughly) at WOT. With the key on, engine off, have somebody SLOWLY work the throttle pedal back and forth. If the TPS is good, the needle on your voltmeter (or little set of bars on an analog/digital meter) should move from one side to the other smoothly. If it's jerky, you need at TPS. Odds are, you probably need a TPS anyway. I've dyno tested a few trucks that act like this, and it's mighty scary when they get bad enough that the engine doesn't respond till the pedal is half-way or more to the floor. YIKES!!!!

 

[NWest]

Should I test at the ecm or at the sensor? Which is easier to access with a meter?

 

[jetenginedoctor]

Since it's the sensor you are concerned about being bad, I'd check it right there at the sensor itself. If you check it on those same wires near the ECM, you're testing both the sensor and the associated wiring. Odds are, the wiring is fine, and the sensor is worn out. That said, you could probably do it at either point and accomplish acceptable results.

 

[NWest]

Okay-



still working on testing fuel pressure. I am going to get permanent gauges set up, but i can't decide on the mount. In the meantime, I purchased a fuel pressure tester at autozone, but I read on the packaging that it is "not for diesel engines".



Any idea why they would make that statement? (The part is Autozone #CP7818)