ranger 2.3l problems, need a little help

jbkelly0211

jbkelly0211

Well-Known Member
Joined
Jul 20, 2010
Location
Charlotte
bought the truck a month ago for a hunting beat a round. 87 ranger 5spd 2.3l. quarter million miles. PO said it sat for 6 years, recently replaced gas tank, fuel filter, timing belt, and some other odds and ends. When I got it a month ago it had every code in the book. Replaced Coolant temp sens and that cleared a lot up. Replaced egr and egr position sensor, and that cleared the rest up. It has been running great for 3 weeks until yesterday, while at 70 mph on the interstate it starting bucking and lacking power. if I let off throttle it smoothed out, or pressed throttle harder it smoothed out. first thought was TPS, removed and tested and seems ok. Fuel pressure it good, 45psi with vac line off regulator, and 35 psi with vac line on. Fuel volume is good. No codes showing up. What I have not replaced are MAP, TPS, and IAC. I can crank truck and it idles good, will drive good until engine warms up. still idles good when warm, but shudders and lacks power while accelerating. removed vac line to MAP and it starts idling rough. removed harness to IAC and idle does not change. no change in driving with iac unplugged. Where should I troubleshoot next, I am almost out of ideas. TPS is discontinued from every vendor I have searched. would faulty IAC cause drivability issues like this? Cant find any vac leaks. When driving, first gear is ok, shift to second and it just starts shaking, push throttle to floor and it takes off like a bat out of hell. Any ideas????????
 
IAC problems won't change anything but idle. Even if it's totally stuck, it can't bypass enough air across the throttle plate to do much of anything bad. Look elsewhere.

Sounds like a common MAP or TPS problem.

RockAuto looks like they may have a Tomco TPS for that engine, about $19 on closeout. It's in the fuel/air section.
 
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Changed plugs, wires, and dist cap a month ago. I'm leaning away from IAC. Still has issue with IAC disabled. Just picked up a new map. Will replace that today and replace all vac lines to it as well. If that doesn't clear it up, the last price of the puzzle that hasn't been replaced in the tps. Just seems odd to me that rough running is in the mid throttle range. Wot and idle are fine. Also it seems to rev fine with no load.
 
jbkelly0211 said:
Just seems odd to me that rough running is in the mid throttle range. Wot and idle are fine. Also it seems to rev fine with no load.
Click to expand...

If you've got a worn TPS (instead of a broken/failed TPS), it's not going to have problems over the entire throttle position range. If that's the problem, you'll usually see the issue over the areas of throttle position where it spends the most time dynamically. Idle isn't usually a wear problem because you're not constantly adjusting the throttle position at idle with your right foot. Same thing with WOT; you don't spend much time there so there aren't generally mechanical wear problems in that area of throttle position.
 
Ok. After probing the tps with key on. Steady increase from .95 v at idle until right at 3.6 v it makes the meter jump to 6.7 for a fraction of a second then right back to 4.1v and smooth up til about 4.8 at wot. How can it jump that high with an input of only 5v?? If my meter is reading true then that definitely seems like it could be an (or the) issue. Because that is just above the mid throttle area where problems occur. I just replaced map sensor and same thing. 1st gear fine, shift to second and apply throttle and blah. Put it to the floor and threw my head into the back glass.
 
Don't worry about the 6.7V reading, that's just something with the way your meter is reacting to a fast change in voltage at that spot. You are correct though, you can't get a voltage higher than 5V from a sensor with a 5V supply, but don't be fooled by the shortcomings of your meter. A different meter will likely handle that transient very differently, and I'm thinking you're probably using an analog voltmeter based on the behavior?

It sounds like you've found the problem with the TPS though.
 
No this is a digital meter. Actually a southwire that I use everyday. Tested with my back up meter and it didn't read quite as high but did have a noticeable blip at the same spot. Just ordered a tps from rock auto. Now the waiting game.
 
I'm surprised you're using anything other than full throttle. Sounds like driver error. :driver:

But yes TPS sounds like the problem. If that doesn't fix it, bring it over and I'll take a look at it.
 
Try a blow down test.. remove radiator cap and pressurize each cylinder at TDC with 130-150psi air through a compression tester hose with the valve removed. if the head gasket is leaking the radiator will start overflowing nearly instantly. perform test on a hot engine preferably.
 
Ok here's the update. New tps and IAC came in today. Tps is on and with some modifications, has base idle set correctly. IAC on. Idling better than ever. Smooth and no surges. Took it for test drive. First mile was fine then right back to it again. First gear takes off good until higher rpm (around 3500) kind of sputters. Shift to second and it just struggles until I put it to the floor and it takes off. I bought an exact twin parts truck last night. Good drive train minus some Afro engineering but body is crap. So swap parts are readily available. What would be the next attempt. Will do leak down test today.


Edit: checked compression, 160 across the board.
 
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Reset the ECU to clear out all of the long and short term fuel trims, then try again. Maybe start pointing to an O2 sensor problem but I'm not convinced the symptoms line up.
 
I just checked codes after installing new tps. Had a code for tps low voltage. That has shown up since installing new tps. Pulled cables and drove again. Code has not come back. I drove with Egr disabled. No improvement. I think I may try and swap fuel rail and injectors from donor truck.
 
Changed the fuel filter again? Never trust a PO :D
 
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