3FE hesitates and stumbles when trying to accelerate- TPS?

[Aggiesdm]

Yesterday, I got into my '91 with 279K on a 3FE motor and when I tried to accelerate, it hesitated and bogged down. She didn't die, but I thought she might. Did it for a couple of minutes while I tested it around the neighborhood, the it was fine and drove like normal. About 2 hours later, I started it again and same scenario...hesitate, almost die, then after a minute it seemed to right itself and all was fine. During the boughts of hesitation, there is absolutely no response from the accelerator pedal, from feathering to flooring it, it acts like it's not connected at all.

Without doing anything yet, my research on symptoms leads me to believe it might be the TPS. I've never touched it and it has performed well until yesterday.

Questions:

1. Is there any way to test it without pulling the throttle body?
2. If not, will I need a new TB gasket to reinstall?
3. Lastly, if it is the TPS can it just be cleaned and rehabbed with contact cleaner or does it need to be replaced?
4. Am I totally off base and looking at the wrong item?

 

[Aggiesdm]

Btw, I searched MUD quite a bit, but didn't really find any diagnostics that could be done without putting it on a bench with a voltmeter.

 

[Aggiesdm]

BUMP! Anyone??? I need the truck tomorrow to go hunting, so hopefully can get it taken care of today or tomorrow morn. Any help or advice would be appreciated

 

[M32H32is]

Have you pulled any codes?

Sounds like it's not getting spark or fuel - how new is the fuel filter? In-tank screen ever been replaced?

 

[Aggiesdm]

Fuel filter and sock are all replace new within the last six months. It's getting fuel and spark, it never dies and it never seems to be without combustion. Just unresponsive to the drop

 

[Aggiesdm]

Also, at idle the RPMs are jumping up-and-down probably 100 to 200 RPMs and it's really sporadic.

 

[tlin]

Pull codes paper clip method.....then marry up with FSM and we can help.

 

[Aggiesdm]

Pull codes paper clip method.....then marry up with FSM and we can help.

Ok! I was under the impression that I would get a CEL when there was a code present and I don't have a CEL, so I didn't check codes. Just went out and checked codes and as suspected I got #41 which is "TPS short/open circuit". I guess I will be replacing the TPS and report back later.

Thanks and sorry for my ignorance regarding the codes. Makes since and glad we tracked it down together.

 

[Alleycats]

Intermittent = pain in the ass

 

[tlin]

As antiquated as code pulling is with the 3fe, it does reveal useful information. Sounds like you're on target.

NOTHING to apologize for, glad you're moving forward

 

[M32H32is]

Report back if you can, let us know if that was the fix.

I'll be hunting in Kingsville this weekend best of luck to you man

 

[Aggiesdm]

Report back if you can, let us know if that was the fix.

I'll be hunting in Kingsville this weekend best of luck to you man

Hey Cullen, I'll be headed over towards Hondo to hunt. I ended up having to borrow a friend of mine's truck, because I can't get a throttle position sensor before Monday. No big deal, but I like taking the LC if I can. Good luck on your hunt. I hope you get the big one!

 

[SUMMIT CRUISERS]

Yesterday, I got into my '91 with 279K on a 3FE motor and when I tried to accelerate, it hesitated and bogged down. She didn't die, but I thought she might. Did it for a couple of minutes while I tested it around the neighborhood, the it was fine and drove like normal. About 2 hours later, I started it again and same scenario...hesitate, almost die, then after a minute it seemed to right itself and all was fine. During the boughts of hesitation, there is absolutely no response from the accelerator pedal, from feathering to flooring it, it acts like it's not connected at all.

Without doing anything yet, my research on symptoms leads me to believe it might be the TPS. I've never touched it and it has performed well until yesterday.

Questions:

1. Is there any way to test it without pulling the throttle body?
2. If not, will I need a new TB gasket to reinstall?
3. Lastly, if it is the TPS can it just be cleaned and rehabbed with contact cleaner or does it need to be replaced?
4. Am I totally off base and looking at the wrong item?

1. You really need to pull the throttle body to do an accurate TPS test.
2. I used the existing throttle body gasket.
3. Not aware of cleaning it with contact cleaner. As I recall it is a sealed unit.
4. Could be. Sounds to me like a vacuum leak between the AFM and the intake.

Here's a thread on what I learned about the TPS on my son's 92:
https://forum.ih8mud.com/threads/ne...tions-and-what-i-learned.723759/#post-8437914

 

[Aggiesdm]

1. You really need to pull the throttle body to do an accurate TPS test.
2. I used the existing throttle body gasket.
3. Not aware of cleaning it with contact cleaner. As I recall it is a sealed unit.
4. Could be. Sounds to me like a vacuum leak between the AFM and the intake.

Here's a thread on what I learned about the TPS on my son's 92:
https://forum.ih8mud.com/threads/ne...tions-and-what-i-learned.723759/#post-8437914

Thanks man. Turns out that it was throwing code #41, which indicates bad TPS. I have one on order thru my local dealership and should be here Monday.

I will definitely use your experience for setting up the new unit. Thanks for the write up.

 

[Aggiesdm]

Hoping for better performance and MPG. The MPG had been really sporadic lately (8-12mpg in town) and I read that the TPS can contribute to that. We'll see?

 

[jrmudder92]

Any updates on this? Having the same code!

 

[Aggiesdm]

Any updates on this? Having the same code!

It was the TPS. I replaced with OEM part and did the calibration per the FSM. No more issues like that, but my milage has never really recovered. I get basically 9-12mpg now and average about 10mpg. Still want to get injectors cleaned and clean up the intake as well. That project is on the list, but it's a LONG list, so might take a while.

 

[jrmudder92]

It was the TPS. I replaced with OEM part and did the calibration per the FSM. No more issues like that, but my milage has never really recovered. I get basically 9-12mpg now and average about 10mpg. Still want to get injectors cleaned and clean up the intake as well. That project is on the list, but it's a LONG list, so might take a while.

Thanks buddy! And its always a lit ever one has one xD