94 1uzfe has me really ready to give up on the car-details inside

[xspsi6]

Ok so I bought a 94 sc400 for cheap just as a work car to restore over time however I can not seem to get it running properly enough to drive yet here is the story.....

217k miles compression and leak down is within range fuel pump ecu works as it should did the bypass just to eliminate that as a problem.
I bought it from a redneck pick up truck "shop" that was far out of there element and gave up on the car I bought it home and threw a battery and fresh gas in and it started after sitting for 3 years but ran with a misfire so I did plugs,wires,and new coils as one on the drivers side was bad so I changed them in pairs.
now the car has an odd misfire and backfires through the intake and wont rev over 2k rpm unless you feather the gas at partial throttle to get it to 3500 ish rpm then it will rev clean to rev limit sometimes also the car runs very rich so I noticed this morning upon cold start it will make a clean rev and sounds healthy as can be until it warms up and this clean rev sweep was with the maf tube unhooked from the throttle body and maf so runs good until comes up to temp.

I have changed the coolant temp sensors and caps and rotors as well as sent the ecu to tannin auto for a rebuild which they did the new caps although they did not appear to be leaking visually.

it is showing a maf code from being unplugged and a #1 knock sensor code which I do not think it can cause all of these issues?

I am at a loss on this one does anyone have any ideas or is there anything I have overlooked?

 

[Zuffen]

First you need to clear the MAF code.

Unhook the battery for 5 minutes then reconnect it and start the engine (with the MAF hooked up) and check it for codes.

I suspect it could be the IAT/MAF unit.

These aren't easy to find in good condition and buying new is big $$

 

[xspsi6]

OK I will do that, Just curious how could the iat/maf cause this condition?

 

[sideshow]

seriously get rid of the car
when they get about 15 to 20 years old the soarers start to play up
suspension steering ecus etc etc they all start failing
they are one of the worst cars Toyota has made when it comes to reliability when they get old and they will cost u a shitload to repair

 

[xspsi6]

That's what everybody has been saying thus far even my die hard Toyota friends however I know it is a small issue that can be fixed as I am sure its just something simple.

 

[pwd]

got to disagree with sideshow, had mine since 2001, done over 500,000 kilometres in it and wouldn't have it if it wasn't reliable. Might as well not own any car over 10 years old with that logic.

 

[xspsi6]

My wifes 95 ls400 has 437k miles and runs flawlessly everything works however this sc really has me wondering about my stance that the 1uzfe is the most reliable engine ever made .

Trouble shooting info seems to be vague and distant.

 

[pwd]

the engines are good mine has been supercharged since 2007 and it gets a hard time. have you checked the timing belt for wear, or even the possibility that it is maybe one tooth out on its markings. I did this to mine one night at the drags, you can see how badly the rotor button was damaged and the cap as well, still ran, missed like a pig, but still ran and started, took me a while to find the fault because it felt like an electrical issue.

 

[xspsi6]

the engines are good mine has been supercharged since 2007 and it gets a hard time. have you checked the timing belt for wear, or even the possibility that it is maybe one tooth out on its markings. I did this to mine one night at the drags, you can see how badly the rotor button was damaged and the cap as well, still ran, missed like a pig, but still ran and started, took me a while to find the fault because it felt like an electrical issue.

View attachment 13467

Wow that is crazy but I did change the rotors and caps.

 

[xspsi6]

Update:
I got the car to run much better and drive up to 70mph today turns out it was 2 bad maf sensors in a row so revs clean now but still has a low rpm stumble and over fuels some what almost seems like a bad or out of adjustment tps but it seems way worse in gear at low rpm but load almost makes it die.
will an out of adjustment tps do this? Also if I hold the rpm at say 3k steady it will drop down and hunt even though my foot is the exact same spot on the pedal.

still shows knock sensor codes not sure why that would be and does not show up until you rev it over 2500 rpm

Any suggestions on where to go next?

 

[ugp]

Sounds a lot like a failed coolant temperature sensor.

Unplug it and see if the situation changes.

 

[pwd]

I believe the tps can cause issues similar to what you say with the revs hunting, proper way to set the tps is with a voltmeter, but you can also do it by holding the revs steady at about 2000 and if it is hunting, adjust the tps till it stops hunting and runs steady. The knock sensors, if faulty, I think should put the engine into a sort of limp mode, where the engine cant be revved to hard to protect till the problem can be fixed.

 

[xspsi6]

the engines are good mine has been supercharged since 2007 and it gets a hard time. have you checked the timing belt for wear, or even the possibility that it is maybe one tooth out on its markings. I did this to mine one night at the drags, you can see how badly the rotor button was damaged and the cap as well, still ran, missed like a pig, but still ran and started, took me a while to find the fault because it felt like an electrical issue.

View attachment 13467

Sounds a lot like a failed coolant temperature sensor.

Unplug it and see if the situation changes.

tried that today with no real results