Delayed acceleration when warm.

[Fordtruckman80]

Alright, so my 03 Ranger is having a problem with accelerating from stops. When I start the truck up in the morning, it runs great, no problems at all. But after about 20-30 minutes of stop and go driving, I will come to a stop at a light or stop sign, and then when I accelerate from the stop, the truck will go forward a little bit, kind of hesitate/bog down and then go. It idles perfectly fine, even when it warms up, although it is at about 700, which may be a little low, i'm not too sure. I've hooked the truck up to a code scanner, and it is not showing any codes, not even pending codes. Whatever is going on isn't falling outside of the computer's allowable parameters.
This problem developed after a short trip off-road, through about 2 feet of mud. All the mud has since been cleaned off.

Things i've checked:

-Air filter/Air Intake tube= Clean, no sign of dirt/mud/water.
-IAC replaced a month or so prior, so sign of failure or carbon build up
-MAF is clean
-TPS has a strong reading across acceleration with no dead spots
-Throttle linkage is moving freely.
-Vacuum hoses appear to be okay upon first inspection.

Now, this is what i'm thinking of checking. Please add to this as these are just from the top of my head

-Re-check for Vacuum leaks
-Test MAF
-Check Plugs(Wouldn't bad plugs give me a problem throughout driving, and when the truck is cold as well?)
-Check O2 sensors, both upstream and downstream

And that's all I have. Has anybody ever had this problem before? Once I check that stuff above, i'm stumped. Any help/ideas are greatly appreciated.

 

[Irokranger93]

you can check the oil level may be by chance that would be rather low. a though ,your rpm increased a little bit ex:800-900 tr min I would make like to me another days.
yours fuel filter can be...
next :: water temps sensor :: is often the problem of hot day that thing

 

[TOPGLOCK]

My 98' ranger does the same thing....I hope someone gives some insight

 

[Fordtruckman80]

Thanks for the replies. I'm not sure it would be any kind of temp sensor, because wouldn't they have trouble even when the truck is cold? I may try cleaning the connector to this water pump sensor just in case. Whatever this is happened right after I got out of the mud. I didn't really push the truck hard, so I imagine something is just dirty.

Another thing I thought of today is when I replaced the IAC on the truck, I threw the included gasket on just for fun. My truck being an 03, it has the plastic upper intake plenum, unlike the older 3.0's with aluminum. My upper intake plenum has two little blue o-rings where the IAC mounts, so i'm thinking that maybe when I added the extra gasket, I created some kind of air gap, which could possibly explain why the problem only arises at temps.

Another thing I thought of is the possibility that I incorrectly installed the new TPS, since it seems this problem occurs from a stop all the way to about 3k, supposedly when the TPS sends it's info to the computer. May try pulling it off and checking to see if I had it right or not. Hopefully these two things will work for now.

 

[Irokranger93]

have you camera and made video the engine run near the iac......and post here

 

[Rearanger]

Another thing I thought of is the possibility that I incorrectly installed the new TPS, since it seems this problem occurs from a stop all the way to about 3k, supposedly when the TPS sends it's info to the computer. May try pulling it off and checking to see if I had it right or not.

If this truck had a carburetor instead of fuel injection I would suspect the accelerator pump was not functioning. When you press the throttle the air flows faster than the fuel unless you have a way to increase fuel flow when the throttle is pressed. You're first description said the TPS tested OK, now you say you replaced it. At this point I would suspect the TPS adjustment, seeing it's new and probably OK. I'm not sure the MAF could act fast enough to send the ECU a signal to increase fuel flow when the accelerator is pressed, but maybe someone else can contribute.

 

[Fordtruckman80]

If this truck had a carburetor instead of fuel injection I would suspect the accelerator pump was not functioning. When you press the throttle the air flows faster than the fuel unless you have a way to increase fuel flow when the throttle is pressed. You're first description said the TPS tested OK, now you say you replaced it. At this point I would suspect the TPS adjustment, seeing it's new and probably OK. I'm not sure the MAF could act fast enough to send the ECU a signal to increase fuel flow when the accelerator is pressed, but maybe someone else can contribute.

Thanks for the reply. In the first description when I mentioned the TPS was okay, it was because I just recently tested the new TPS to check and see if it was having any issues. I had previously replaced the TPS due to the old one having a dead spot around 800-1200 rpms. I figured the problem i'm having now was related, and that it would fix it since there was clearly a dead spot after three tests. I went back out and re-checked the TPS mounting, paid close attention to make sure the TPS engaged with the throttle shaft like it should, and it was.

One more bit of info, after I got done with the mud, I immediately took a trip to the car wash, and washed the mud off the outside. I then took a trip to the store, picked up some foil, and then returned to the car wash, covered the air box, PCM, IAC, TPS, MAF, and then Throttle Body, and then turned the nozzle to light pressure and gently sprayed off the engine from a far distance. Could there be a chance that I water fouled my plugs or the plug wires?

 

[fivespeed3.0]

My 2000 3.0 used to die on me only when cold. After warm up, it was fine. I posted here and Big Jim suggested I replace the coolant temperature sensor. It worked. Your problem could be at the opposite end of the spectrum from mine. As I understand it, the coolant temperature sensor sends information to the computer with regard to coolant temperature so the computer can adjust spark advance. If the engine is cold, but the cts is telling the computer it is warm, spark advance is wrong and runs like crap cold, but runs great when warm. (my problem) Yours could be telling the computer the engine is cold, when in reality it is warm, and so, the engine runs like crap when warm, but runs great when cold. Easy to replace and inexpensive.

 

[Fordtruckman80]

My 2000 3.0 used to die on me only when cold. After warm up, it was fine. I posted here and Big Jim suggested I replace the coolant temperature sensor. It worked. Your problem could be at the opposite end of the spectrum from mine. As I understand it, the coolant temperature sensor sends information to the computer with regard to coolant temperature so the computer can adjust spark advance. If the engine is cold, but the cts is telling the computer it is warm, spark advance is wrong and runs like crap cold, but runs great when warm. (my problem) Yours could be telling the computer the engine is cold, when in reality it is warm, and so, the engine runs like crap when warm, but runs great when cold. Easy to replace and inexpensive.

Interesting, thanks for the insight!!

Any chance you can give me an approximate price and location of this part on the engine?

 

[Big Jim M]

Bout maybe

Twenty bucks and it sits next to the thermostat.. There are two sendors there one for the temp gauge and the other for the computer... The computer one is the one he spoke of..
Although that might be the problem, I'm leaning toward the TPS! You may be having a failure from built up heat changing the output of the TPS. I'd be for unplugging it and checking the innerds of the plug anyways..
Big JIm

 

[Fordtruckman80]

Twenty bucks and it sits next to the thermostat.. There are two sendors there one for the temp gauge and the other for the computer... The computer one is the one he spoke of..
Although that might be the problem, I'm leaning toward the TPS! You may be having a failure from built up heat changing the output of the TPS. I'd be for unplugging it and checking the innerds of the plug anyways..
Big JIm

Thanks for the reply! You think the heat deal can happen even with a brand new TPS? It hasn't even been on for more than two weeks. But anyways, when you say check the innerds, do you mean check the voltage readings again?

 

[Fordtruckman80]

Well, as an update, I took the truck to Auto Zone to see if any codes popped up. I picked up two, one being for the IAC, and the other being for the Intake Air Temp sensor. The IAC and IAT codes are most likely because I unplugged the IAC and the MAF while the truck was running. I replaced the Coolant temp sensor since it looked like it was leaking, with no change in performance. It's still bogging down, and idling poorly. Now it's started dying on me too.

 

[Fordtruckman80]

Since I absolutely hate it when I see a thread with a similar problem to mine that nobody updated on, i'll give an update. I'm still currently fighting this problem. I tried testing the TPS, and I couldn't pull steady numbers from it, so I decided to just swap it out with a new one. Now the truck has stopped dying, but it still hesitates. I hooked up the vacuum gauge to the truck, and it's pulling about 18" of vacuum at idle in park, so it doesn't look to have any vacuum leaks that I can tell. The one thing I have yet to check is the fuel pressure, and the transmission controls. One thing I did remember is that since about two weeks after I bought the truck, it's had a strange shutter whenever I accelerate in reverse. It shutters enough to almost make the truck die if I accelerate fast enough. The truck always coasts under it's own power whenever I put it in reverse, so this original issue never bothered me much. But now I think it and my bog at acceleration may be somehow related to each other. I still have absolutely no codes, so i'm just taking things step by step trying to figure out where exactly the trouble is coming from. At this moment, i'm suspecting some kind of fault within the transmission, possibly a solenoid issue. But i'm not getting any codes in the Transmission Control Unit, so i'm not sure. I'll update further when I find out something new.