lunaboy

I have searched the threads, tried most of it and still havent fixed it.

My car is a C4 1990, has a "hot film" air flow meter with "FilmStar" signal convertor. Modified exhaust ( all done by PO)

I have replaced the dist caps, coils and tested readings for temp sensors etc. In the process found that there is no O2 sensor (leads jumpered out).

Car has been rough with intermittant stuttering, but last week it just refused to start. With a fair bit of throttle I can start easily, but cannot idle . Car is driveable , with lots of throttle !!

The mechanics I consulted said, replace the hot film with std flap/vane unit and all will be well. Borrowed a unit, put in on and no change !!

I decided to "muchanic" a bit again (boredom?) and removed distributor caps , coils etc to check for anything again. This time I found a rotor very badly burnt out ! this was fine 3 months ago!! Ah Ha, i thought, got it !!

Well, got new rotor and cap (traces of arcing) and put them on. Double checked everything twice and looked forward to idling around again.

AAAAAHHH no change to idle , still not there !!

Have to wait till next week before putting car into hospital !

Does anyone have a suggestion (clean !) as to what to look at next whilst waiting. Given that I dont have too many practical skills !!

cheers

springer3

The damage to the rotor and cap are a clue that something very bad is happening. How old are the spark plugs? Worn plugs raise the system voltage. Shorted plugs cause high current in the ignition system. Both conditions cause running problems and age the electrical insulation and electronic components. It is probably not a good idea to drive until this is resolved. Expensive parts could get damaged.

Laurence Gibbs

Whilst this is unlikely to be your problem .....have you checked that both rotors are running i.e. you don't have a broken belt? (you mentioned one burnt out rotor!)

lunaboy

Hi Guys

I have checked the dist belt, and it appears to be in good condition and in one piece. Have now booked in P for the expert touch next week.

I now believe the ISV is at fault as its operation appears to be the only thing not double checked, for the non start problem.

The rotor problem ??? hope the experts can find out if anything drastic going on .

In Adrians book, it talks about resonance valve sticking open/closed. Is this an easy look see, or do u need to dismantle too much stuff??

Will report back if/when any resolution

lunaboy

No progress !! Mechanic is busy trying to fix another P car with same issues !! Waiting to see what happens there.

I do now believe that something is afoot with the ISV itself (as in Adrians book, failed closed)

Is there any way to test the ISV unit itself, other than replacement ?

Symptons are, no start unless throttle part open and no idle at all. Runs steady at part throttle ie 1500 rpm, but hunts badly as get closer to 800 rpm until dies.

Have pulled off the harness to ISV and get exactly the same . Presume this indicates the issue is here somewhere.

Has any one tried to start and idle with the ISV disabled?? Do you get the same effect ?

Would appreciate any feed back

cheers

JasonAndreas

If you connect a multimeter (set to Voltage-DC) to pins 1 & 2 of the ISV connector in the engine bay wiring harness you should get whatever the battery voltage is (with the engine running). If you think there is a problem with the actual valve itself you can cycle it with a 9-volt battery. When you apply power the little door inside the ISV should move all the way closed, you can hear and see it.

The car will continue to run if you unplug the ISV but I can't remember if it will start with it already unplugged.

lunaboy

Have not been able to check voltages with engine going due to lack of idle and no one to assist !!

But did remove ISV and have put 9 volts across the two contacts. Nothing at all happened !! on both polarities.

Unit appears to be "closed", when I cleaned unit some months back it was not like this, but appeared to be partly open and able to pass wind, when blowing into it.

I presume this means the unit is compromised ! Will look to get replacement now

lunaboy

Further update
Aske another P service man who suggested the following tests on the ISV

First, with unit off the engine, "rotate" between hands like making fire, should hear the armature moving
(and I cant!!)

Second, attach unit back to wiring and with assistant turning over motor, look into unit and see the valve moving
(and i havent been able to do this yet, no assistant)

My unit seems moe and more destined for the bin !!

Anyone have recommendation for best place to get replacement for overseas shipping to NZ ??

lunaboy

Well, the no idle is now resolved ! Received a new ISV from Paragon and fired up first time n no hesitation !

Have done a DME reset , following recommendation from P car mechanic.
He reckons after disconnecting battery for short time, start car to idle do not touch throttle or any thing else and leave to idle roughly along for at least 15 mins until it gets real hot with cooling fans coming on . Next time you start it will be perfect !

He reckons as good as an adaptive reset with hammer.

Now just need to move all the rest of the cars and get it out onto a dry road for a final road test !!

Now the rest of the niggly bits can be started on !!

Thanks to those who helped

jimq

You need to take it out for a spirited drive to complete the reset after doing the idle part.

lunaboy

Hi jimq

Have now done the spirited drive !

All is still well, keeping fingers crossed that it stays that way!

Cheers
nigel