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Hello all. I've recently acquired a 94 Ranger 3.0 v6 XLT with 140k miles. I'm sorting through some issues and I can't seem to figure out why this one just RUNS when I lift off the brake pedal. I don't even touch the gas pedal and it gradually gets to 20-25 mph and even SHIFTS to second gear, lol. Is this even normal? It doesn't feel so. I hate it that I don't have a Tach so I don't know if it's a high idle problem but it doesn't feel like it's idling high. I've cleaned out the throttle body with carb cleaner and IAC valve with carb cleaner as well. I verified TPS voltage at rest is 0.9v and 4.5v at WOT.
Hello all. I've recently acquired a 94 Ranger 3.0 v6 XLT with 140k miles. I'm sorting through some issues and I can't seem to figure out why this one just RUNS when I lift off the brake pedal. I don't even touch the gas pedal and it gradually gets to 20-25 mph and even SHIFTS to second gear, lol. Is this even normal? It doesn't feel so. I hate it that I don't have a Tach so I don't know if it's a high idle problem but it doesn't feel like it's idling high. I've cleaned out the throttle body with carb cleaner and IAC valve with carb cleaner as well. I verified TPS voltage at rest is 0.9v and 4.5v at WOT.
If your base Idle is ok then I can only assume the torque converter is the issue.
I do have some rough-a$$ shifting sometimes but haven't noticed anything with the torque converter such as stall-outs or vibrations. And I take that back previously. It DOES seem to be idling kind of high. Again, tough to know without a tachometer. These things are so old school, can't even connect an OBD II reader on it. I disconnected the IAC completely and the idle went down, maybe a little too down, but the truck still runs. I can even drive it and it doesn't do acceleration creep, I actually have to press the pedal to go. I just have a feeling the IAC blows (a little too much air). Resistance is 10.3 ohms on it. Not sure, I am just going to change it out and see. Easy enough to do although I try to avoid being parts changer.
I do have some rough-a$$ shifting sometimes but haven't noticed anything with the torque converter such as stall-outs or vibrations. And I take that back previously. It DOES seem to be idling kind of high. Again, tough to know without a tachometer. These things are so old school, can't even connect an OBD II reader on it. I disconnected the IAC completely and the idle went down, maybe a little too down, but the truck still runs. I can even drive it and it doesn't do acceleration creep, I actually have to press the pedal to go. I just have a feeling the IAC blows (a little too much air). Resistance is 10.3 ohms on it. Not sure, I am just going to change it out and see. Easy enough to do although I try to avoid being parts changer.
let me explain I have a 2001 3.0L with it in drive RPM drops to 650 RPM the torque converter is in stall as the RPM increases to 750-850 the torque converter is no longer in stall and will start to move the Truck so RPM is critical that it’s correct.
Update: Replacement IAC (not OEM btw, but standard motor products, part AC58) literally did not make any difference compared to the previous IAC. This leaves me with possible a vacuum leak somewhere (already smoke tested and saw no smoke anywhere) or perhaps an underreporting MAF sensor. I'll have to do some more examination and testing. Any further advice appreciated.
Back when I was in high school, OBD ports didn't exist. Tachometers did though. Perhaps you'd consider going old school on this and install one the old-fashioned way. You know you are going to want one anyway.
I know this won't solve your problem but perhaps it will help you narrow it down? This one is $80 on Amazon and should work for you:
Thank you. At some point I would want a permanent tach mounted (not sure how it works and where I would plug it in) but for the time being, I bought a cheap laser-powered tach meter that will do the trick so i can see where the base idle is with the IAC unplugged, then plugged in, so we'll see. I was reading service manual for IDLE adjustment and it says that there may be a small hole on the throttle plate that needs to be plugged so the idle can be reduced and to use a specific 'plug' for that from some service kit that has been discontinued for likely decades, lol. I think also my throttle stop screw has been messed with.
If you get bored, here's a video I found on how to install a tach in your Ranger. It's not a perfect video but it should give you an idea on how it could be done:
My digital laser tach device came through and I did some measurements on the steering pump pulley, which was easier to deal with than the crank pulley. I realize the steering pump pulley may spin at a higher rpm compared to the crank since it's smaller diameter, but I did some compensation with the numbers to scale them.
This definitely confirms my high idle issue. 1180 rpm on a warmed up engine is TOO high. Outside temps 80f+.
What I did:
-Taped the factory hole on the throttle plate, unplugged IAC again, and rpm yielded way too low, ~560 rpm. Truck was ready to almost stall. Screwed in the idle stop screw clockwise further in and got up to 630 rpm base idle. Plugged in the IAC and it was SCREAMING, 2300+ rpm for some reason. Did not want to go lower, so I scrapped the idea of plugging up the factory throttle plate hole.
Next, I did away with the tape on the hole, and just adjusted base idle to around 650 rpm with the stop screw. Plugged IAC back in, disconnected battery for about 15 minutes, reconnected, started up truck and let it idle for 10 minutes. With the IAC plugged in, it was now idling at around 1040rpm, better than previous 1180, but still too high.
I was at a loss, clearly something was telling the engine computer to keep the idle rpm high. I was thinking for a while, played around with the MAF disconnected, but idle rpm only went higher with MAF disconnected.
After more thinking, I figured let me check the ECT, engine coolant temp sensor. I unplugged it and saw some crusty green corrosion on the connector. I washed it up with some deoxit spray and sprayed the ECT sensor itself a bit. Plugged it back in and started the Ranger and let the rpm's settle down. TO MY SURPISE, the idle was now even lower!! I measured about 920rpm final idle with IAC plugged in. Best yet, although I'm feeling it needs to be lower than 900, maybe 850 target. Feels to be running better, the acceleration creep is much less now although still happens. It creeps up to about 15-18 mph gradually but still much better than before. I don't know if I should switch out the ECT and see if it gets even better or pursue something else, or just leave it be. But this seemed to certainly be a big culprit, corroded ECT connector!
Final update, I replaced the coolant temp sensor and wow folks, it's RIGHT on the money idling now. 850 rpm, also starts better with barely any cranking. So much better and better gas control, does not do acceleration creep any longer. Just normal rolling. Thanks for all that assisted.
Final update, I replaced the coolant temp sensor and wow folks, it's RIGHT on the money idling now. 850 rpm, also starts better with barely any cranking. So much better and better gas control, does not do acceleration creep any longer. Just normal rolling. Thanks for all that assisted.
screw the base idle screw out until it no longer makes contact. Check there is no air gap between throttle body and butterfly, now turn screw in until it just makes contact at that point go 1/4 turn more. You should be able to slide a .003-.004 .Now adjust the screw until voltage at red wire and battery ground. Don’t unplug sensor you’ll need to pierce the red wire. Now have some cycle on and off ( don’t start) voltage should be .9-1.0 VDC
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