weird throttle problem

hey peoples i am new to this forum so i say hello to you all, recently my friend bought a '85 s12 gazelle with a ca20e.
It runs okay it just does this weird thing where when you are driving around every now and again when you will have the car in neutral or with the clutch in it will stay at 2000 rpm with no throttle on, you tap the throttle a bit and then it goes down to normal idle again. apart from these freak occurances it idles normally, I was thinking it was the throttle cable or butterfly getting stuck but my question is, could there be any other reason for this problem?

Check the throttle position sensor and also check the throttle body and make sure nothing is sticking on it. Other than that i'm not sure of anything else that would cause this.

Honda Acords from the same era as our cars are know for doing the same thing. My first guess would be to take off the TB, and actually use carb cleaner to clean it out. While you are at it, I would clean the intake manifold so that your fuel mileage is a bit better.

how's his battery?

The ECU is supposed to bring up the revs when the battery is reading low, but only when in neutral or with the clutch in.

thanks guys i will check those things out these holidays (next week) me and my friend have finals for uni (college in american speak) right now.

yea, you need to make sure that the throttle plate is seated right in the throttle body. if it is dirty, it wont sit right and the ecu will think that the TB is slightly open, thus give it an increase of fuel. that could cause the idle problem.

mine is doing slightly the same thing with the idle being high and when I tap the pedal is goes down. This only occurs sometimes. How would you check a TPS or adjust it if it needs to be adjusted? I changed out the TPS for the ca18et one so i would have matching electronics.

I'm not sure how to check a TPS, but if they start to go, they can do some pretty funky shit...I thought that the TPS on our cars was either on or off, and that is why the ones off the S13's won't work (they have a variable resistor), and if this is the case, then they would be easy to check...8)

well here is what the wiring diagrams look like. Ca20E's have an on/off, but the ca18et's (turbos) have the variable resistors.

what about the V6? ive had that weird problem with the dropping of revs when hitting the gas at idle...

cool we should be getting the TB out soon to have a look my mate ordered in a gazelle work shop manual but they are in high demand so we have to wait until september. in the mean time we have a pintara (i think) manual for the CA20E. i am guessing we clean it with carby cleaner?

on another note we just solved some problem where none of the lights inside the cabin worked with the doors open the dash would go dark and the clock would switch off..... stupid guy we bought it off put a fuse that was too big (15A instead of 10A i think) in the accessory fuse slot :laugh:

.....note..i have the 60mm KA24e TB..it is polished, cleaned..and polished again..the plate is lines up perfect, with nothing in the areas that move...seems like a TPS problem, or MAF leak??