4AGE Low reving problem while driving?

**EB-J** · 13-02-2015, 09:31 AM

I have an AE92 Red and black top 4AGE 88kw in my TA22 Celica. The problem is while driving along in any gear, when the revs drop below 2500rpm it will cut out. The engine is still running but it will not rev below 2500rpm, it will just drop to idle. while the car is in neutral it will rev perfectly through the rev range. But it is idling at 1500rpm warm, and 2000rpm on warm up start. I have check the idle screw and that is wound all the way down. Is this the throttle position sensor playing up or is there an idle sensor that controls the low revs??????

**trdee** · 13-02-2015, 09:39 AM

that generation of 4age does not have an idle speed controller. it just uses a basic wax pellet idle valve. chances are it's your TPS is shot to shit. The 4AG engine manual has a troubleshooting guide which allows you to test if the TPS is fucked with a multimeter and some feeler gauges. Alternatively you can try simply unplugging the TPS and seeing if the car drives any differently. If it doesn't, then the TPS isnt working

**xero** · 13-02-2015, 05:08 PM

as above is one possiblity, also check for vac leaks if the idle screw is wound all the way down and its idling high.
FYI you can also run the car without the idle valve, i ran without for years.

**EB-J** · 14-02-2015, 08:01 AM

Cheers guys, I will have a tinker with it today and check these areas.

**EB-J** · 14-02-2015, 02:00 PM

Well, I had a play around with the throttle body without the pod filter and pipe on today and found that there is a hole that goes down to the power steering vacuum( I think thats what it is). This hole was sucking huge amounts of air, even though the outlets where all blocked off on the outside. so I stuck my finger over the hole and the car ran perfect. So off with the throttle body and off with the cover and made a new gasket to block that hole. Put it all back together and the car idles perfect, and drives smooth without cutting out. I'm exstatic!!!!!!!!! This problem has plagued this car the whloe time. and has made the car very unpleasent to drive. I can see a whole lot more hours behind the wheel now!!!!!!!!!!!!!!!

**worldwalker** · 14-02-2015, 03:26 PM

Good result, in the short time I've been working with the 4A's, if it doesn't have a vacuum issue, there's something wrong with it

Which makes me really worried about my rebuilt GZE.

**xero** · 15-02-2015, 07:13 PM

Originally Posted by EB-J

Well, I had a play around with the throttle body without the pod filter and pipe on today and found that there is a hole that goes down to the power steering vacuum( I think thats what it is). This hole was sucking huge amounts of air, even though the outlets where all blocked off on the outside. so I stuck my finger over the hole and the car ran perfect. So off with the throttle body and off with the cover and made a new gasket to block that hole. Put it all back together and the car idles perfect, and drives smooth without cutting out. I'm exstatic!!!!!!!!! This problem has plagued this car the whloe time. and has made the car very unpleasent to drive. I can see a whole lot more hours behind the wheel now!!!!!!!!!!!!!!!

good shit. get out there and give it a hit with some carby/throttle cleaner, a full tank of 98 then take it for a good strap for a couple of hours. it will love it!