So ive tried almost everything. Swapping throttlebodies after throttlebodies
i went to mariahs motorsports and they said it had to be a bad thermalwax pellet.
I swapped the complete throttle body off a donor car that idled perfectly at 750 rpm.
Still nada. It isnt the BAC valve either. Cleaned it didnt change anything.
I was told maybe coolant isnt reachng the thermalwax because of a blocked passage but i wouldnt know how to check that.
Any help would be appreciated.
Rx7 fc 87 s4
Milage 140000

 

Throttle cable maladjusted.

You should be able to access at least one of the thermowax coolant hoses without working too hard, undo it and crank the car to check for flow.
If there is doubt, unfortunately a likely candidate will be the steel hose barb screwed into the alloy waterpump housing. Steel+aluminum+hot coolant= corrosion city.
You'll probably need to remove the dynamic chamber/ext manifold to gain access.

 

check AWS sensor on the radiator, or remove that circuit.

 

How do you remove the aws ?

 

...Or you could try unplugging the idle air control valve on the driver's side of the intake plenum, if that doesnt work unplug the valve next to it also. Just cleaning the BAC isnt equal to testing it.

 

or perhaps your thermowax was bypassed but you haven't paid attention to the hose routings. or the passages at the pump housing or rear iron are plugged up where they meet the engine.

a stuck cruise control cable or misadjusted throttle cable would be my next guess. it's unlikely the AWS is at fault and the BAC does not have enough compensation to idle the engine that high even stuck open.

 

Anyone by Santa Barbara ca
Willing to help out?

 

From the perspective of sitting in the drivers' seat.

There is a 2 wire sensor that is in the bottom left hand corner of the radiator, should be reachable from the ground up. If you disconnect the 2 wires from the sensor then tie/splice/solder the two wires together it disables it.

Basically the AWS sensor works as it is normally in the open position then closes the circuit based on temp which turns off the AWS. If you connect these two wires the circuit is closed and AWS is disabled at all times.



However AWS stands for accelerated warm up system, so its quite rare for this to happen after it warms up. It should only go on during cold engine startup.

 

the AWS system is also disabled by tapping the throttle after the engine is running or by starting the car while in gear, so i'm not sure why anyone is continuing to bother considering the AWS as a fault unless the AWS solenoid was bypassed with a straight hose creating a large internal vacuum leak around the throttle plates or is stuck open(something i have never seen yet).

 

Would removing the AWS lead to any conclusions?
Like if I were to remove it and the idle is still high, what would that mean?

 

That it wasn't the problem to begin with?

 

Correct!

If you have done lots of throttle body swaps and no change to concern. I would make sure the cable is mounted properly and not just dangling there somewhere.

 

these days almost every car i see that has a high idle issue it is due to a plugged up thermowax coolant passage, just sayin'.

on some rarer occasions, an air pocket in the system that will not work itself out is an ancillary reason. the root cause for that reason, you don't want to consider.

 

How do you unclog the thermowax passage?

 

he's right.


in order to get to the thermowax you have to remove the upper intake manifold....unless you have a blow gun that doesnt have one of those "vent to atmosphere" style safety's. if you do you can blow air into the hose that comes into the rear/left side of the BAC and try and blow out the crud. if its scale thats blocking it you wont have much luck.

 

it's best to drain the coolant first, then i apply pressure to each side of the 2 hoses to try and force any blockages out, followed by a short length of hose attached to the thermowax passages and blow through in each direction until no blockages remain.

reassemble and leave the top coolant line disconnected, fill with coolant until coolant starts to come out of the hose/thermowax and then reconnect the hose. top off the coolant level by warming the car up and allowing it to cool while keeping the coolant level full at each cooling session. eventually the thermowax should start working and reduce the idle.

you don't have to remove the intake manifold on an n/a car to clean the passages with the exception being a turbo engine, since the thermowax is obscured and mounted under the throttle body.

 

I live in Santa Barbara. Used to work for Mariah Motorsports and currently tune out of their building and on their engine dyno as a contractor. If you just need a bit of help I'm sure we (you and myself) could get it squared away in an afternoon. PM me and we'll talk.

-David Guy