FC idling problem

[banana-man666]

Hi there everyone. I picked up my first rx7 last night and it seems to have an idling problem where the idle revs fluctuate from 1000 rpm to around 1500 rpm.

I was just hoping some of you on here might have some insight on what could possibly be causing this!

Any help is greatly appreciated.

BTW the car is a 1988 UK manual non-turbo (EGI?)

Thanks
Dave

[sadgoth]

What is the spec of the car? Is it standard, has the engine been ported in any way? etc

There are a number of possible reasons for this and it depends a lot on what has been done to the engine

[Brett]

Not a white car is it?

[banana-man666]

As far as is known to me the engine is standard but. I have no real way of knowing as the guy I got it from only had it a week and couldnt afford insurance so I kindly took it off his hands

[banana-man666]

Yes brett it is white from coventry

[Brett]

Yeah the guy who brought it the other week is Slimer on here and retrocarclub.  I\'d start by looking at the inlet system and ensure there are no splits or air leaks past the AFM, after that its time to start checking the idle up system...

[banana-man666]

Yes it was through retro rides that I found the car actually and swapped my 79 celica for it.
So I need to check for leaks from the AFM?

[Brett]

From the AFM backwards to start with - if unmetered air is getting in it may cause some problems.  But I suspect it will the cold start assist - if you in the 2nd gen section you will find links that take you to the factory service manuals

[banana-man666]

Downloading them as I type this. Lets hope this sheds some light on the situation

[Brett]

Usually things get stuck with age - you might find yourself with most of the UIM apart at the weekend freeing things up

[banana-man666]

At the moment I have no clue what a UIM is or even the AFM you mentioned earlier. Thats why im grabbing the manual

[Brett]

Or right - sorry!

AFM = Air flow meter
UIM = Upper inlet manifold (Contains the moving parts of the inlet, such as the throttle etc)

[banana-man666]

Ah cool cheers. I have just spent a couple of hours playing with the wiring and left the engine idling as I did. After around 15-20 mins it stopped messing around and sat at a steady 1000 rpm.

So I turned engine off left half an hour and it did same thing jumping from 1000 to 15000 rpm and after 30 seconds or so it stopped again.

What is there in the way of a choke or cold start valve on these engines and could that cause a problem like this?

[Brett]

Sounds like its behaving once its properly warmed up? (Although the car should be idling at around 750rpm - idle can be adjusted via the screw on top of the throttle body)
 Give Rmagictastic a look on this forum - he is having the same issue at the moment.

[banana-man666]

Ok just thought I would give you all a little update on this one.

The car is now on the road after thinking I had sorted the problem.
It now idles perfect with the lights off but when you switch them on it goes back to the same old trick!!
Im now thinking that I have some form of electrical fault along the lighting circuit that is interfering with the throttle wires.

Is this possible?

Dave