FAO: 16v owners with low revving problem

[Tom_16v]

There seems to be a lot of us on here that have this problem, that the revs suddenly drop to about 500rpm on idle and then pick back up, and then repeats.....

Has anyone actually cured it if they had this problem?

So far, Ive replaced;

Lambda Sensor (twice - 1st time with a universal one, now has a genuine Reanult/Bosch one on)

Coolent Temp Sensor

Idle Speed Control Valve

HT Leads

Dizzy cap/Rotor arm

Ive also had the potentiometer and Thottle postion altered numerous times....

& still not cured!

The thing I cant understand is why the problem is so intermittent. Some days it runs fine, some days its slightly hesitant, and others its really runs badly for the first couple of minutes.

Also, I went out today in it and it was fine. Drove about a mile and had to stop for two minutes. Got back in, started it up, and it just stuttered once as I drove off.... I noticed this happens the other way round too, re-starting sometime cures it. Why would re-starting the engine cause this?

Ive run out of ideas of what the problem is now, and getting a bit pissed off to be honest!

Any help would be greatly appreciated.....

 

[king.stromba]

Could it be a fuel problem?

 

[RenaultFreak]

cleaning the idle speed air valve always sorted those for me



you can also get busy cleaning the throttle body and its passages.

 

[rasp]

I replaced my rocker gasket to get rid of oil on the sparks and so far I have not had this problem since, if anything it now sometimes revs a little higher on idle.

 

[Natalie]

mine used to do it at times, and now doesnt anymore...??? think it might be a case of sh*tty petrol ???



-ben j

 

[JAY172]

have you removed the injection computer and had a look inside.old clios quite commen for water to get inside and damage the ecu.

 

[BenR]

Speedo information for the computer.

Behind the dash where the speedo cable plugs in is the hall sender....wiggle it. It may cure it, or you may need to replace it.

CAn you hold the rpm at a steady 2000rpm spot on?

Does it fluctuate when moving and the clutch is dipped and your coasting?

 

[Tom_16v]

Ive cleaned out the odd bit of oil in a couple of the chambers, but theres not enough to cause problems. Still does it straight after.....

Cant be cr*p petrol, been using optimax for 16months ever since I bought it.

Wheres the injection computer Jay? Does seem worse when it rains, although this could just be a coincidence and my imagination!

Ben - If it is playing up, if I hold it at 2K RPM the revs will still die.

If I coast along, it will still drop down to 500rpm and then pick up again.

 

[DeanRSi]

mine does exactly the same mate, as soon as the temp dial moves past the bottom it usually is fine but i stil get a splutter soemtimes when it is warm and i have turned the ignition off and started it again.

Could it be anything to do with having low temp coolant sensors fitted? making the engine think its colder than it is so the ECU chucks more petrol in? on mine it feels like its overchoking(i know they dont have chokes) but its that sort of problem.

 

[Tom_16v]

Dont think itll be the low temp thermostat, as I dont run one. No need with my oil cooler.

 

[Adams_16v]

Mines same! i changed road speed sensor, ISCV, cleaned Tb etc, tried another ecu, slightly better but still same!

iv bought a whole TB with potentiometer, ISCV, etc so gonna fit that next week and see if that cures it!

remember what was said about changing the iscv though! if not done correctly the new one will be damaged straight away!

if i hold my revs at 2k its fine, if i hold them at 1200rpm then it revs up and down on its own!

also it used to be intermittant, now its all the time! it refuses to pop and flame when its playing up! does it on demand when its running fine!

 

[DeanRSi]

yeah, dont forget to disconnect the battery etc mate.

 

[BenR]

the injection computer (ECU) is under the drivers side scuttle panel, under the jack.

 

[Tom_16v]

thanks ben...

 

[Pete-W]

how do u go about replacing the ISCVcorrectly then? have a new one to put in mine!

 

[BenR]

unconnect batt, unbolt it, undo the connection, replace.

 

[JAY172]

sometimes the learnt values for the idle valve that the computer has learnt need to be erased or it wont be long before your new valve is faulty again.

injection computer is under the jack beneath a metal bracket.its housed inside a plastic case.remove the computer and have a look if its corroded(you can unscrew the back and have a look inside it as well)