Won't let me hold engine at ~2000rpm

[ru486]

I first noticed this when I had a flat battery and I was sitting in the car giving a few revs to try and charge it up a bit. If I tried to keep it sitting on around 2000, the revs would continually drop back down to idle speed, even though pedal position was unchanged. Had to take my foot off the pedal and push it in again to get revs back, but then after a few seconds it would happen again. This also happens when I'm crawling up my driveway trying not to tear the bottom out of the car.

Is this abnormal? or is the computer thinking the idle is too fast and adjusting it back down?

[Dish]

I've noticed this in mine. I've got the JDM 4age. I never really thought much of it at first, only happens when I'm just trying to keep it at revs, haven't noticed it anywhere else.

[mattysshop]

what happens if you accelerate more as it dies down?

[ru486]

The revs drop back to idle very suddenly, so haven't tried accelerating while its actually dropping. When driving normally and shifting up through gears its fine, only happens when trying to crawl around at a constant low rpm. Will mess around with it tonight and pinpoint exactly when it occurs.

[mattysshop]

sounds bizzare.. but yeh.. see what happens.. http://www.ae86drivingclub.com.au/forums/emoticons/smile.gif

[devolutio]

check the tps - if it thinks you have closed throttle, if the idle contacts are closed, but you foot is a little bit on the throttle bringing the revs up, it will rev cut back down to idle. do a search for 'hunting'.

[selk]

does it do this when the engine has warmed up

[rthy]

i had a similar problem... found out my fuel filter was the wrong way...

[ru486]

Lol, I'll check that, but reckon its the TPS - have seen a couple of other similar threads now that I know what to look for.

Have just done some playing around and found out that the revs cut out at 1700rpm - dropping back to idle of around 1000. If the throttle is open exactly the right amount, the revs go up and down repeatedly. If you open the throttle while the revs are dropping, it almost causes a stall.

After reading this thread http://www.toymods.net/forums/showthread.p...9&highlight=tps (http://www.toymods.net/forums/showthread.php?t=6159&highlight=tps) I'd say its the same problem - TPS needs adjusting as its not registering the throttle as open until after a certain amount.

[StockAE86]

Yeah sounds quite similar.. Try adjusting the TPS, and then borrowing someone elses to see if your tps is knackered

[driftism]

Mine was really jerky when the TPS was out, sounds similar to this problem.

[devolutio]

you can adjust it with guesstimates... or read the 4age workshop manual on how to set it... but i hate feeler guages so i just put a throttlebody on that had tps set to it since factory. honestly i think yours is working fine, and it might even be worth taking it to an auto electrician with a workshop manual (or a printed page from the pdf version).

just for fun, unplug the tps and go for a drive. I bet the problem goes away.

http://img110.imageshack.us/img110/392/fi352ja.jpg
http://img210.imageshack.us/img210/8471/fi860px.jpg

[ru486]

Will try it with TPS disconnected, but I'm sure that will stop the problem. Thanks very much for the pages from the 4age manual - I've been downloading them, but it is a very painful process on dialup!