2000 rpm idle after cleaning TB & IACV

[docdread]

All hoses/vac pipes seem to be in place, recet ECU, cleaned TB and IAC valve again, drove for two days both times engine getting to operating temperature... but the idle remains high. 1600 on cold initial start, 2100+ after engine is warm.

Checked previous threads already. Gentlemen, my 91 mx83 is now in your hands. HELP

[zero_gravity]

i'd try adjusting the throttle position sensor

[docdread]

Adjusted the throttle position sensor, idle speed now a BIT lower, throttle seems to be SLIGHTLY open, I can use my hands to forcibly shut it down all the way and the revs will get to 1100 but as soon as I drive the rpm's dont come down; 1500-2000. Throttle body is clean, cables are in place. Is there a screw or something to adjust the idle speed?

[zero_gravity]

start here and go forward

http://www.cygnusx1.net/Supra/Librar...ction=FI&P=100

thats the supra repair manual which is the identical engine for non turbo. this procedure is how to properly adjust the TPS and yes you should remove the TB to do this. i thought i could do it on the car once, that was a big mistake. made my car run like crap. all you need for this is a set of feeler gauges and a multimeter.

also, if you don't have another TB gasket put a bit of blue RTV silicone on there. good luck.

also make sure both sides of that TB are clean.

[docdread]

Thanks. A little bit more progress, apparently because the ISCV was really dirty so previous owner compensated bad idle by adjusting the cables at the TB to keep the throttle slightly open. Fixed that by slackening them a bit. Idle speed now down to 1400 and more importantly, not sticking at 2000 after driving. Now to get down to 900rpm, will look at the link thanks

[zero_gravity]

sounds like you're hot on the trail of the problem. the dirty ISCV is very very common with the 7M. that and a dirty throttle body. usually a clean and readjustment is all that is required. also, you might want to flush out the PCV pipe while you're there, it gets blocked up easily. just use whatever cleaner you're using on the TB and ISCV. you'll be amazed at the crap that comes out of that.

best of luck and let us know how it turns out. if you find any of those parts damaged i have a few working spares around.

[docdread]

PCV pipe was coated with oil/carbon whatever it is and I'ld say air flow was restricted by about 40%. Rubber connectors were so old and brittle they crumbled as I removed them...replaced with a new $2 rubber hose. Engine sounds a little bit more responsive. When I initially cleaned the TB I noticed in the intake manifold, just in front of the cold start injector, there is a passageway and it was caked SOLID with the infamous black stuff. Cleaned as best as my figures would allow in the restricted space but to do the job nicely would mean removing the intake manifold... not in freezing Michigan weather, I will do it in a few months or an a really warm day. Idle is still a bit high, anything else I can try before removing and checking TS?
Another question, how hard is changing the driveshaft support bearing, mine is gone.

[zero_gravity]

good job with that pipe, its always bad:p

and yeah the intake manifold always gets dirty. its from that PCV pipe venting back into the intake. you'd want to do some sort of home brew catch can to eliminate that, but its not necessary if you don't mind cleaning that stuff every year or two.

you can check all the vacuum tubes, a leak might cause this but i'd imagine it would cause a low/unstable idle. either way its easy to replace that stuff, just get a bunch of tubing from any auto parts store and replace one by one to avoid confusing them. cut the tubing with just a regular pair of scissors. beyond that yeah its time to recalibrate that TPS...sounds like the last guy might have messed with it anyhow.

as for that carrier bearing its not a terrbily hard job but i don't know if you'd want to do it in the winter (i'm up in canada so i understand . you'd have to remove that propeller shaft and press the old bearing off and the new one on. other than that its pretty straght forward just watch your torque specs. the part isn't cheap though, over $100. i recommend www.1sttoyotaparts.com from my past experience. great prices and they're great to deal with. if you cant find the part on their web cataloge just call them, it doesn't list everything.

[docdread]

Got the center bearing for $40 new, suspiciously cheap or a gift from the gods? Now how hard a press are we talking here, the old one is so bad the driveshaft moves 2.5inches sideways and up and down, dont know how I never realized it. Any special tools required and will I lose any trans fluid?

[zero_gravity]

trans fluid? no the front half of the driveshaft will slide out, its a splined end. as for the press we're talking something along the lines of a hydraulic press...there are other ways however.

bearings like this are press fit on meaning that the diameter of the shaft is actually very slightly larger than the inside diameter of the bearing. this creates an interference fit meaning it isn't going anywhere easily

its possible to rig something up with hand bearing pullers, maybe even some kind of rig and use a hammer if you're careful. getting the new bearing on is easier. simply leave the driveshaft outside in the cold, do this first thing in the morning when its coldest. warm up the bearing a bit with something like a toaster oven (be careful of the rubber seal) and then if you're quick enough it should slide right on.

beyond all that if you have access to a secondary vehicle i would just take that front half of the driveshaft to a machine shop and ask them to remove the old one and press the new one on. its a no fail approach and i doubt they'd charge much.

[kamesama980]

dammit, it didn't record my post yesterday... I was gonna say check the throttle linkage/cable, throttle stop screw, and idle adjust screw.

The driveshaft carrier bearing is NOT press fit. the only bearing I ever had trouble with welded itself to the driveshaft because it was bad and overheated. I just cut the rubber part off and hammered it off. the other 3 I've changed just slipped off after removing the nut.

[docdread]

FIXED!!! By accident really. Previously I removed the EFI fuses to try to reset the idle speed, didnt work. Today the car wouldnt start and I realized the +ve terminal on the battery cables needed replacing, I disconnected it put a new one in and car starts, now revs perfectly at 900 park and 600 in drive. Thank you fellaz. Now for the center bearning, bolts are on so tight wish me luck.

[kamesama980]

Originally Posted by docdread

FIXED!!! By accident really. Previously I removed the EFI fuses to try to reset the idle speed, didnt work. Today the car wouldnt start and I realized the +ve terminal on the battery cables needed replacing, I disconnected it put a new one in and car starts, now revs perfectly at 900 park and 600 in drive. Thank you fellaz. Now for the center bearning, bolts are on so tight wish me luck.

Oughta be 650 in park or in gear but beggers can't be choosers. so what is the +ve thing? would that be the + battery cable clamp? Might have a look at the rest of the grounds in the engine bay and consider removing and cleaning them.

[docdread]

Yes the battery clamp on the positive cable, the threads on the bolt were worn, so it was couldnt be tightened.
Well I finally got new the center support bearing on. The old one was really bad and somehow got stuck on, so it had to be pressed off. Unfortunately I drove the car quite a bit before replacing it and I think the ujoints on the front half shaft might be bad. Car now has a slight vibration in the 30mph range.

[docdread]

Update: My thermostat was dead. Temp gauge wouldnt go higher than cold line -20 celcius in Michigan, put a new one and works fine. Noticed that the idle came down even more.. sounds perfect now.