OK, the car is a 1990 NA. And what it does is once it warms up, and if it is in netral/park (it's an automagic....) the engine will every now, and then. Just start reving it's self. It's just annoying, I having noticed anything else wrong, but the RPM's will just jump, up and down about 250-500 RPM's. But if you get out and hold the main TPS in, it stops. Does it just need adjusted? If so, is the S5 TPS any different than adjusting the S4 TPS?



Or is it something else??? https://www.nopistons.com/forums/pub...DIR#>/ohmy.png

It might be your Water-Temperature Sensor actually. On my '86 Corolla GT-S when I first bought it, the idle was NEVER constant because the sensor was broken and the car never knew what temperature it was. Check yours, and see if it works. A replacement was only $10 at Autozone. It's worth trying. Once I replaced the sensor, the car idled fine, therefore fixing the problem.

Anyone else have any idea's?



I would go down and buy a new one, but if it didn't fix it I would kick my self for wasting $20 bucks on it, when that's not the problem.....



I might do it anyways https://www.nopistons.com/forums/pub...#>/biggrin.png But my temp sensor works fine. It always parks it's self right in the middle of the guage. Maybe it's broken https://www.nopistons.com/forums/pub...IR#>/dunno.gif

mine has just started doing that too

is yours auto also shane?



my automatic did that, but my 5 speed never did.

yeah it is

It's not the tranny, because I have had a manual that did it...



But the automatic doesn't do it in gear...

Set the TPS anyways. It doesn't take long.



Are you sure there isn't a vac leak or something somewhere?

set the tps and idle speed first before you do anything else

I don't want to screw with the idle... It's bad to https://www.nopistons.com/forums/pub...1047683358.gif



It idles at about 1500.... But when it is in drive, or any other of the automagic gears, it sits perfect at 750! So it's fine with me, I'm not out of gear that much.



Also is it the BAC valve that makes the engine RPM go up when you put it in gear? I'm thinking that is for the AC, but it may serve a dual purpose on the automatic... But one of the valve's must be stuck open for it to idle this high out of gear.





And I'll go tinker with the TPS https://www.nopistons.com/forums/pub...#>/biggrin.png

i've got a 1990 NA with a 5-speed and it does the same thing but only when its cold. It will rev up to 1500 rpm and then when it hits 1500 drops down to about 1000 and does the whole thing over again. up and down, up and down. after its run for about a minute though it goes to 750 and never changes. It used to be much worse (it would do it all the time) but then i did the tb mod and its a lot better.



if you play with the tps adjust screw while its reving like that you can usually get it to stop but i've found that the next time you start the car its usually out of adjustment again.

umm this is a longshot but is it like the neutral switch on a manual car. I remember i unplugged mine when I was having a problem like this. rev like crazy in nuetral but when I put it in gear the revving slowed a lot. I think its called an Inhibitor switch on auto's. Just crawl under the car and se if its connected. Should be right up by the starter.

HA! this is weird. I did the TB mod, then my TII started doing exactly what you said. Revs up to 1500, then drops to 1000 and starts surging up and down over and over. Mine does it all the time still, I can't get it to stop, but I'm gunna fiddle wit hthe TPS adjustment screw while its doing that and see if I cant get it to stop.

STock efi BLOWS!



Yes i've had way to much to drink tonight https://www.nopistons.com/forums/pub...IR#>/smile.png

Yup https://www.nopistons.com/forums/pub...IR#>/smile.png

Does anyone have a chart, or anything that will lable the sensors on the tranny?





This sounds like a rather common problem.... There must have been someone here that has fixed it!



Could it be the ECU?

LMAO



Yes, yes it does

Get a weber downdraft manifold, and a carb. Problem solved!!

I'm going to try and get 2 40mm mikuni carbs, and make a manifold!



No weber.... Mikuni's have been said to be much better at atomizing the fuel. And easier to set....

the inhibitor is on the pass. side of the tranny and you have to pull the exhaust to get to it.

My buddy had that same problem and we messed wih the idle screw, but all that did was make things worse. we think it might still be a small vacuum leak somewhere

ahh thats right, its on the other side of the tranny, but mine draps over the tranny so the actual switch is on the drivers side.

Ok---It sounds like alot of us are having the same problem.Mine was surging alot when it was cold as **** outside,I played with the throttle,now it takes forever for it to come down from about 1500 rpm.But if I adjust it to lower it,when the motor gets good and hot--its to damn low.I never had this problem before untill the winter came.I am tired of dicking with it.Running the rpms so high does make shifting when its cold a bitch though.When some one finds out what the **** it is let us know.

Mines a 86 5 speed

i had the same problem. it was cause by my removed BACV instead of blocking the line i recconnected it to the hose coming from the tmic, this made my car rev itself from 1000-1500rpm.



just so you know its not the TB mod or anything that causes it, unless its done incorrectly.



my car has a lot done to it (and a lot removed from it) and still idles perfectly at 750rpm.



kevin.

well mine idles high when i start it up, and doesnt start surging until it warms up. At one point the other day I had been driving for awhile, stopped at a stop light and it went down to 950 and idled solid. drove to the next light and its surging again. Thats the only time ive seen it have a proper idle. When I figure it out ill post what it was.

Not sure if its the related but my 87 T2 was idling at almost 1400 rpm and seemed to sputter. I went to do a compression check but after pulling the plugs and battery I decided to give it another shot. (Dont ask why I removed the battery... Long and painful story). Anyway. I put everything back and she fired right up and idled at 700.....



BTW... The comp check was due to the thing not starting later when I tried.....