andrewmacc

Just bought the truck for a daily, just an '88 ext cab pickup, 3.slow, R150/VF1A, rough shape body-wise. Trying to keep the street miles to a minimum on the Jeep (don't shoot me guys), more because I find driving one tons and 40"s a pain in the ass daily. The pickup has 279,000 kilometers on it.

Anyway, it came from Vancouver Island, where they don't require Air Care (which is the British Columbia emissions testing program), so it was running no cat, and no upstream or downstream O2 sensor, which may be important in my question..

So it was running fine for the multiple hours I drove it home etc, idled well, ran well, but now it idles very roughly. Chugs like a V8 with a big bumpstick. Aftermarket cheapo tachometer is fluctuating in the 500RPM range.

Been doing lots of reading on here as it is (real gauges, bucket seat swapping etc), so I've accomplished the paperclip code reading and all it gave me was a Code 22 (two flash, pause, two flash), open/short on the temp sensor.

So the truck is bucking, lurching, sputtering, and hesitating anywhere in the low to high throttle range. But mash your foot on the throttle and go WOT, and it rips along (as much as a 3.0L can) just fine.

What gives? I'm not sure if that rules out vacuum, but it's close, to me. I feel like it rules out ECU, or typical plugs/wire/cap/rotor stuff (which will get done regardless). Would it still be an O2 sensor, because at WOT it goes open loop? Or maybe Throttle Position Sensor?

Thanks in advance. Tried to read lots of threads, but the WOT business seems to demarcate it from the others I've read so far..

andrewmacc

Little bit of an update.

Not sure if it's because it was still warm, but it was definitely a harder start than before. I'm letting it cool down to see if it goes away once cold.

Tried unplugging the TPS to see what happened. Idle went up to about 1,000-1,200RPM, but even at that RPM it was still stumbling.

I've removed the throttle body (stupid TPS housing screws are stripped), so I'll clean it up and bench-adjust the TPS with feelers and an ohmmeter. I hate to say I feel like it's not going to fix it.

Also, I'm thinking a bad O2 sensor would still only just make it run rich, not have this drastic effect.

May as well replace the temp sensor too, see if that helps anything. I'll look around in the manual but does anyone know off hand where the sensor is? I couldn't spot it just by looking.

Any other suggestions? I just don't get why it's strong at WOT.

edit: and as much as I don't like doing it, I tried spraying some starter fluid to look for vacuum leaks.. I definitely found a few seemingly random lines plugged with a screw or sitting with nothing attached, but the starter fluid had no effect. Also wouldn't explain why it ran fine beforehand IMO.

Gamefreakgc

Sounds like the previous owner was just letting it go and didn't care much for it. With a little TLC you can get it running like a champ. Mine has 279k miles (446k km) so you can make them last a long time.

Honestly, you just described the symptoms of a bad coolant temp sensor since it runs ok cold but gets worse when warm. Codes are the best indicators of issues. It may not say exactly what to replace every time but will give you a good place to start. Let us know how things go after you replace it (TPS would be next place to check but it looks like you're already on that one).

Co_94_PU

iTrader: (-1)

Maybe whatever they hacked in to replace the o2 sensor fell off?

If the temp sensor is in spec, you can probably get away with just cleaning the gunk off it. I've seen some posts that said it made a big difference.

If you unplug the TPS and the engine speed goes up it's probably properly adjusted. Try jumping the Idle connection to it's ground on the harness, this will simulate the "at idle" but leave the wierd throttle opening reading. Should drop back to normal idle speed.

andrewmacc

I tested the TPS, and I have to say in hindsight the old one might still be good (so I'll keep it around), but the multimeter I tested it with, I failed to get adequate readings. After having tested a new one, and noticing that I only had 2000 ohms and 200k ohm settings on this cheap meter, that I probably wasn't capable of getting the required readings within those two ranges. 20k ohms I assume would have done it.

Nonetheless, I put in a new TPS and tried in as many ways to get it in spec using the techniques provided on 4crawler's site, about CCW/CW turning to get infinite, then >2.3k ohms. Seems to have worked, although I believe it's worth tuning it even moreso, I feel like there's a flat spot between 1.5k-3k and then it takes off much better. Could just be the nature of the beast for these motors, I'm not sure. Never had one before.

Also I did replace the coolant temp sensor. What a PITA. The engine code hasn't gone away, however. I will reset the codes (remove neg.) then check. If not, what else? Temp sender for the gauge? Will that trigger a CEL? Or is it wiring between ECU from there?

Anyway! It runs way better. I may have a slightly weak fuel pump, too, because if I just insert the key and immediately crank, it cranks a couple more times. If I turn the key and let the fuel pump pressurize (only a slight pause, maybe 1 second), it cranks to life within 2 cranks.

As well, cold idle is really high for the first 5 minutes or so (1.5k to 2k). Could just be part of dialing in the TPS though. Thoughts?

Thanks guys! This forum has been a wealth of knowledge thus far.

andrewmacc

Well, back again.

CEL is back, seems like it's spitting out a Code 21 now. So I guess it's time to change that O2 sensor. Which means waiting.. local Canadian parts stores want from $120 to $180 for an any old off brand upstream O2 sensor. No thanks.

Idle problem came back last night, but not as bad. Power was hesitant too but nowhere near as stuttering as before.

And of course, I can't shift gears very well anymore. Such a low clutch pedal that I have to push it into the floor hard and I can still feel the drag of the gear slowing down the idle... Been looking around to see if the clutch bracket is cracked. Can't tell. Looks like the brand new clevis rod bushing at the pedal is already worn out (wow), my Yota friend says he has a solid one laying around he'll give me.

Just picked up a slave and master, I know it sounds like that's just throwing money at the problem but I just want to eliminate old parts if I'm gonna have problems.. I noticed the old slave doesn't have a boot on it.. probable failure point? And the end play of the master rod at the pedal end was very loose.

ROCKLAND TOYOTA

look for a DENSO sensor and you should be good....

andrewmacc

Ordered one on Sunday, along with the gasket.

Truck left me stranded last night. 15km down a logging road in the pitch black and rain with no cell reception, the girlfriend and I had to walk all 15km to get cell service to make a call and get a ride.. I had been behind my group and they didn't notice that I dropped off the radar.. Took almost 5 hours. Been a long day..

Got to the truck this morning, got it going, but the whole time it idled and ran like absolute crap. Rough, low idle, smelled very rich, and absolutely no power. The power picked up slightly above 3,000RPM but it was still horrible. But as per my previous post, if you put the pedal to the metal, and I mean 100% throttle, not 95%, and it suddenly picks up and goes with no hesitations, like, spinning tires in 2nd gear from a roll.

Obviously gonna read more, but what's a good procedure for checking the timing? I'm used to more modern vehicles, hah. Is it like checking the diagnostics? You put a "jumper" between two terminals, crack the dist. bolt and rotate to what, 10 degrees advanced with a timing light?

stuartvff333

Mine is doing the same thing. I unplugged the TPS and it ran worse but I did not check ohms. I was told by another person that the fuel pump was going out. He changed his in his 4runner and he said that it took all the problems away. Have you tried that yet?

Gamefreakgc

7 month old thread bump ftw!

whiskchef

Kolton5543

Since the dead thread had been revived I'll chime in on to try to make it a little more useful. Whiskerchef, some of this information may pertain to you but it may not. You need to be sure to do some diagnostic work to confirm the similar characteristics. Im going to give advice based on what the original poster had provided.

The op said there was a code set for a circuit fault in the coolant temp sensor circuit. A shorted circuit will trick the ecu into thinking the engine is hot and will starve it of fuel. This will likely cause it to run worse on WOT. A open circuit will trick the ecu into thinking the engine is cold. This will cause it to run extremely rich, especially when hot. Rich enough to make an engine run rough and many times even stall. However at WOT the engine can intake enough air to allow it to actually use the amount of fuel being dumped into the engine. The OP said that he replaced the Coolant temp sensor and it didn't help. What wasn't said was if the wiring checked good back to the ecu. It could have been the wrong sensor also which we are unsure of. There are two. One for the ecu and one for the gauge. The gauge sensor is a one wire sensor and surely wont affect the runability of the engine. Also, the O2 sensor needs to be functional. Without it the engine won't know its running to rich or lean and will run on base fuel maps. If it does work correctly it will see that it is too rich and correct some but it cant correct completely.

Start by confirming if your truck seems rich, lean or right on the money. Check for codes even if the light isn't on. Codes rarely pinpoint the problem but they will set you on the right path to solving it. Look for vacuum leaks. These symptoms seem like vacuum leak symptoms too. The difference is they will cause lean.

Plus, give us some more details. Tell us what you drive what engine it has, transmission type, miles, and any mods that could be related. Tells us what you have already checked and what your actual findings are. Don't just tell us it checked fine. If you check fuel pressure tell us the fuel pressure it made and if it built pressure quickly and if it holds for a while. Don't leave out any details.