240 Idle control problem?

Hi all,

I noticed something whacky happening a few weeks ago, happened once so I ignored it, but Something Odd happened again this morning, so I thought I'd throw symptoms on the table & see what people think, as I won't be able to look at it before the weekend (might not even be then).

[How do I format stuff like bullet points, newlines without new paragraphs & indents without BB Code?]

(*) redblock managed by MoTeC running Motorcraft (XF) IAC, cam is a little too big for static CR & MAP-sensed operation

(*) the idle was tuned, and this was ~5yrs ago, without IAC and than IAC was switched on - ie. so it will mostly idle itself, and IAC just needs to help occasionally

(*) car has recently been to a mechanic to have all my leaky Hyster/Crown spec oil-filter & cooler hoses replaced with something more relevant to a car

(*) cold start worked fine, but VERY doughy on light throttle to roll it out of the garage (ie. as soon as I tocuhed the throttle it bogged down & felt like it was heading towards stalling)

(*) 30s of cold idle mostly fixed that "bogging down"

(*) when warm, I did need to catch it with the throttle or it wanted to stall

Having typed all that out, it does smell a bit like idle control doesn't it? Although I thought it would need IAC for cold start to idle properly (which it did until I touched the throttle), maybe that's being done totally by fuelling?

I guess my first step is to check the plug & see if the ECU can detect whether a valve is connected ... ? Any other suggestions before I start trying to diagnose?


  • So what car, year model and type do you have?

  • edited March 10

    I don't think it will help 'cos I think the stuff that's relevant is that ECU is MAP-sensed MoTeC & it's a RedBlock ... it's a 5spd 1980 model-year 242GT but there's not a lot in the realm of possible causes that was originally fitted to a 5spd 1980 model-year 242GT (come to think of it not even any wiring).

  • edited March 10

    I think you might need to get the car on a dyno or at least to a tuner to find out exactly what's happening.

  • edited March 10

    Well that escalated quickly! 😀 I think that's a bit extreme without having done any diagnosis myself ... was just looking for suggestions. 😉

    I think it may be intermittent though, which is annoying ... seemed to want to stall when I was slowing down & let the revs drop while in neutral, and was kinda stally. But when I got home & it was in the garage, gave it a rev up to ~4000 (this is a redblock so of course it sounded like redline OR someone tilling a field) & completely released the accelerator - no probs. And then pumping the brakes a bit to try & suck all the pressure out had no effect.

    I don't really remember what it used to look like but the plug for the IAC has more exposed wiring (poking out from the heat-shrink) than everything else does, which is a bit odd, and that part of the loom is also a bit loose so the plug vibrates around a bit ... I think I'm gonna have to look on the weekend & see whether the ECU can detect & log an actuator that's not connected for a period of time.

  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress

    Did you know the pilcrow has been a formatting symbol for over 600 years?

  • If running a motec with the icv etc if may well be failing.

    You should be able to get a read out on a laptop to see how its running.

    Nice gear btw the old motec. Are you running wide band?


  • Thanks @Cam205 , I’m hoping that the ECU might have an error-code ready for me to see once I hook the laptop up to it. 😁

    It’s got a wideband connected for tuning & logging purposes, but the guy who tuned it (the late & much respected Jerry of A-Class) wasn’t a closed-loop believer, he reckoned tune it right & not rely on a bandaid to cover holes in a tune.

    Thanks @jamesinc , I hadn’t previously realised you could click on that newline character to the left of the current line.

  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress

    @Forg that's okay, I fixed it with sarcasm 😛

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