98 Isuzu hombre 2.2l 2wd automatic 140000 miles. Bought knowing It had gremlins. Had a p0122 code idle at 2000 rpms and shifted hard. Turned out tps was unplugged but previous owner drove it that way for a long time. Plugged tps in, replaced fuel filter plugs and wires. A few days later the fuel pressure sensor went. Replaced untire pump/housing. Trans fluid was filthy because of the old owners driving, had it flushed and the shop that did it completely soaked my engine bay with fluid. Within a day the truck was disabled. P0300 code and no power. Diagnostic process resulted in new iac valve, tps, fuel injectors, coil packs, ecu, and finally the problem turned out to be the icm. All was good for a few days but then on a longer drive then usual a slight wiggle in the rpms when cruising started and over the next few days turned into a hesitation when accelerating. While trying to find the problem I noticed that moving the wires near the tps caused a change in the rpms at idle. I replaced the connector but no change. I cleaned the throttle body with throttle body cleaner and it seemed to do the trick but after about 3 days the problem started coming back,gradually getting worse over the next few days. Cleaned the throttle body again and it again seemed good but after a few miles the hesitation has started to return again.
Sorry for the delay, cold weather kept me from getting to it but I was able to do the smog test yesterday, results showed I visible leaks. Hopefully going to swap the tps out today with one that is known to be good and see what happens. It was suggested to me that I should replace the throttle body but it seems to me that would only be necessary if it was physically damaged.
It sounds like the electrical connector to the TPS got contaminated by the fluid that got all over the engine. I would get a spray can of electrical contact cleaner (CRC), clean the plug itself and the TPS connection, let it dry (or use a hair dryer) and apply dielectric grease to the male and female connectors and make sure it is properly plugged back in.
Check for vacuum leaks.
https://www.youtube.com/watch?v=zMok2y05jNE
https://www.youtube.com/watch?v=PnU-SY6egr4
I have tried findind leaks but this is something that I honestly hate myself for not thinking of. I do feel like the issue is a leak so I will be in the driveway with a cigar tomorrow!
If I simply used my air compressor and followed the sound what would be a safe psi level?
Nope don't do that.
Spraying starting fluid or misting water while the engine is running works too.
Forgot to say I tested and confirmed good compression and fuel pressure
I replaced the connector, cleaned the sensor contacts as part of the process. I have also searched for vacuum/air leaks but haven't found any. And also realize that I should have mentioned that hesitation goes away if I unplug the tps.
Tried the starter fluid/carb cleaner thing and I'm getting nothing. I've tried everything my (limited) knowledge base and everything I can find online. I am leaning towards an air leak but It would be somewhere I can't or don't k ow to access with the spray can. The smoke thing would have never occurred to me. It is way too cold to be out in the driveway today but I did find that those smoke machines only pump out about 8-10 psi. Nothing I would be able to hear even if I tried. (20+years of punk rock and power tools). I will give the cigar thing a try and just ordered a smoke machine. If I don't get this figured out before Christmas I will take it to a shop after the new year. Problem is I am stubborn as heck and don't know who to trust as I haven't lived here very long.
New Data. Today I realized that if apply "spirited acceleration" the hesitation is mostly unnoticeable. Also noticed that when I release the pedal and coast the rpms "wiggle", slightly up and/or down. Also talked to the previous owner and found out that the current engine (jasper rebuilt) has about 50k on it and the cat has been replace twice in that 50k. Not surprised since they were driving with the tps unplugged. Starting to think that my problem my be egr or cat related
Cleaned egr valve and ports today. Initial result is it was the problem but visual inspection points to it not being the likely cause. Seems Everytime I try something at this point it helps for a few hours to a few days but then the issue returns
All was good driving to and from work today however I just went to pick my son up from work and after idling on the parking lot for a few minutes I shifted into reverse and the rpms dropped substantially then came right back. I noticed signs of the hesitation returning. At home I then decided to shift through the gears and the rps jump up 1 to 200 from idle in each gear. That might be normal but I've not noticed it before. Seems odd that throttle body cleaner and carb cleaner seem to be temporary remedies
Just a thought but put a meter on your battery and check output with the car running. Alternator might be a little wonky.
Alternator was running a bit low, swapped it with a known good but no change. Sorry, I've done so much I'm the last 2 months I forgot to mention it. It's really starting to make me crazy. Everything I seems to fix it but only for a short time. I have big plans for this truck but I need to get the it stable first.
Only thing left is to get a new TPS. Rock Auto WVE 5S5049 - $20.79.
That is the exact TPS I put in when I first bought the truck. Swapped it with the TPS from my 99 S10 and so far that seems to have done it.when I pulled the TPS out it seemed worn out. Rotating well beyond the quarter turn and