4a-ge Idle Problems

[webers4x48]

Hi to all,

 

i have a AE82 twinky with problems :hmm: . when it is idle-ing, it will idle at 2000rpm then drop down to 1300rpm then back up to 2000rpm. it continues to do this several times then the revs will increase to 2500rpm then drop down to 2000rpm and then back to repeating the up's n downs with the revs. the engine check light is not on and i have done the diagnostic check which told me everything is normal. neither the service manual or the max ellery manual tells me whats going on. please help

[Des]

Vaccum leak ?. Ive got a 4afc and when it had a vaccum leak it reved up and down at idle.

[webers4x48]

thanks mate, i'll have a look to see where abouts it is. i did check some of the hoses around the throttle body today but i couldn't see any perished hoses so it might even be the throttle body gasket.

[Trev]

Check your water level and your temp senders, Its hunting which is usually caused by the ecu receiving a false signal to say its cold and then when water comes through it goes to normal temp which explains the constant rise and fall, I have actually experimented with mine one day when i did a cooling system flush.

[Medicine_Man]

This problem sounds similar to what my AE86 is doing. I think its a problem of the spring not returning the throttle body to being 100% shut. Also possibly an adjustment on the throttle body and throttle position sensor.. Let me know what you find..

[trd]

this could be anything

 

cam belt timing

t.p.s

idle not set correctly eg: locking out the ecu before setting idle

cold start control leaking

idle screw out to far (see idle not set correctly)

 

have you done anything to it or did it just start happening?

[TheNOBBLER[RL]]

He flogged the arse off it! Webbers will tell all, but I'm pretty sure it started on a cruise not long ago.

[webers4x48]

He flogged the arse off it! Webbers will tell all, but I'm pretty sure it started on a cruise not long ago.

 

 

:) Right you are, Nobbler. It started on the first cruise i took it on but then came good after a few days and was good till the next cruise. Its been doing it since and that was about 3 weeks ago. I'm going to spend a little time on it today with all the good feed back from this thread (thanks guys :jamie: ) and then i'll keep you people posted.

 

I'll start with your advice Trev because thats the only thing I haven't done yet since I bought the car 3 to 4 months ago.

 

Thanks, Leigh.

[towe001]

Check your water level and your temp senders, Its hunting which is usually caused by the ecu receiving a false signal to say its cold and then when water comes through it goes to normal temp which explains the constant rise and fall, I have actually experimented with mine one day when i did a cooling system flush.

It happens cause there's no coolant at the throttle body.

[Trev]

It happens cause there's no coolant at the throttle body.

 

No it happens for neumerous reasons, The 4AGE has 3 temp senders/sensors (1 guage, 2 ECU), This has been covered on TC.org a couple of times, Here's 1:

 

Link To Unstable Idle

[webers4x48]

Hey Guys, I did the coolant change and it didn't improve anything. Checked the vacuum lines and fixed a couple of suspect ones but still didn't fix it. I took the pod off and blocked the hole at the bottom of the throttle body and that fixed it. So what does this mean? Do I have to take the throttle body off and thoroughly clean the cold start section or do I have to get another throttle body? My Bro-in-law had the same dramas with his and he replaced the throttle body but that was a bit costly.

 

Thanks for the help so far, Leigh

[MRMOPARMAN]

hey leigh, mines doing the same thing atm.. sounds pretty common. i traced mine down to the idle bypass valve under the throttle body too, although i havent fixed mine yet (need to get the engine going)

 

just try a few things..

pull the bypass valve off (should be a few phillips head screws from memory) and check all the vacuum lines to and inside arent blocked

 

the coolant lines inside arent blocked and coolant is getting to it

 

the air lines through and in the throttle body arent blocked.

[webers4x48]

hey guys, i solved it YAY!!!! :y: I pulled the throttle body off and gave it a thorough clean. pulled the idle bypass valve off and gave that a thorough clean and then blew out the coolant lines that go to throttle body(which covered me in coolant :y: ) with the air compressor. put it all back together and it works a treat :y: A big thanks to all who gave me good suggestions :y: I don't think it was actually the throttle body itself, but I thought I would give it a good clean anyway while it was off. I think it was the coolant lines that were blocked even though i flushed the system.

 

Hey cam, how'd you go at jarrods the other day. Is it running yet?

 

cheers to all, Leigh

[Trev]

Hey good to see you resolved it, How many k's to a tank were you getting?

[MRMOPARMAN]

hey leigh, yeah jarrod got it going, but hasnt driven it yet coz the water pump was pissin out!

 

i went again today to pick up the old bottom end (thanks jarrod, its in pretty good nick) and he was just about to start. i held him up for ages spinning shit though.

 

it sounds shit hot so far, should be a fun cruise down the great ocean road :y: