Trouble with idle speed

[JonAE86]

Well I have this strange problem with the ae92 i just bought the other day.

It has 4A-GE just like my 86's so i own all parts that might be required.

It idled about 1500 rpm when i got it. Brougt it home, adjusted the idle screw. Got it to idle at 800rpm. Then the next time i started it up it was back to around 1500rpm while hot. When cold it idles little above 2000rpm.

Seems like i cant adjust the screw any lower so the problem must be elsewhere.

Might there be a problem with vacum lines?

Any faulty sensor?

Can the ecu control the idle speed?

All ideas accepted.



And one last question....

Is there any power diffrence betwean fwd and rwd ecu?


Thx.
Jón M

[Ivan141]

You might have a vacuum leak...and you might want to have a look at the adjustment of your throttle linkage etc. if you still cant solve it.
There might be a small difference in the fwd and rwd ecu's..I think the RWD 4AGE's have a higher output officially. Might have something to do with the difference in drivetrain losses. Is it a TVIS engine?

[JonAE86]

Yes it has T-vis.

Its the same engine. The only diffrence is that it has the throttle on the other side of the intake cuz its a fwd.

[Ivan141]

Why did you ask about the ECU if I may ask? Feel a big difference in power between the 2?

I have an AE92 TVIS engine in my AE86 since the old one blew up, so I have had the pleasure of trying both on the same ECU. My old AE86 engine revved more freely than the current ae92 one I have.. Havent opened up one of these late TVIS engine's but some sites said that these may have the same bigger big and small ends as the smallport engines, which could explain why my old engine revved faster.

[JonAE86]

Well, i dont know if there is any diffrence in the 86's engines or the one that is in the 92.

Just wandering if i might get improved performance from my ae92 if i jused one of the rwd ecu's i have lying around.

It seems to rev ok, all the way to 8k rpm. The T-vis seems to be a bit late though. At least the engine sound changes about 5k rpm, so it must be when the butterflies open up. Think it was about 4500 rpm in my parts 86.

Havent driven my ae86 cars much, guess about 2000km max in an 86. Spent more time restoring than driving.

Just bought this ae92 5door GTi to replace the st205 Celica GT-4 i just sold the other day.

The Corolla seems to be ok and in good shape, although it has done 273k km in its 17 years. I am really amazed how good it runs really. The oil pressure is good, it warms up really quick and drives fairly nice, although the springs are bit to soft for my taste.

[JonAE86]

These past days i've also been wandering, since it has been quite cold outside, that the coldstart might not be going off properly. Was cleaning the car yesterday inside my garage. Had it then running for awhile and then it started idleing just fine at 800rpm. The temp reading was a bit higher than normaly, but it was still very good. Then i started driving and the car cooled down a little and the idle was up again to 1500 rpm. Note its minus degries here.

Any suggestions?

I myself is suspecting the thermostat to be faulty. What thermostat can i fit so the car runs maybe warmer that stock?

[JonAE86]

So there is none who might now if any of this might be the problem?

[Ivan141]

I dont know any thermostat that will raise the temps, but you can use pretty much any corolla thermostat for 4A engines, they're all the same.
How far do your temperatures drop? On my car the coolant got cold while driving on the highway, and my heater also had zero effect. That was due to a broken thermostat. But you should notice the meter going down to around 1/4 of the scale and lower if that's the case.

[Pesh]

I've got the exact same problem with my AE101 engine. BTW stupid question but where is the idle screw?

[banpei]

Pesh Wrote:I've got the exact same problem with my AE101 engine. BTW stupid question but where is the idle screw?

For TVIS engines it should be on top the auxilary airvalve. Dunno about throttle bodies though.