Also suffering from an idle problem:

Starts and idles okay from cold, but once I've been driving and come to a stop, the revs rise to about 3500 rpm then drop back down. This happens when cold or hot. It is a slow and gradual increase to 3500rpm not a sudden rise, takes a couple of seconds.

My first thought was sticky ISCV? Maybe TPS?

Have had a quick check and found no air leaks.

 

This could be the VSS, have you checked for leaks around the vacuum hoses?

Martin

 

Hi Martin,

Thanks for your reply. There were no leaks nor had any of the hoses collapsed and sucked themselves flat.

 

It's worth checking the VSS, it could also be a gummed up ISCV, as you say.

Martin

 

Cheers Martin,

I'll try cleaning the ISCV and then check the VSS.

 

I think your trottle cable is getting stuck, i may be wrong but im quite sure its that, best way to check is rev the car from the bay and then pull the throttle cable right back to where its supposed to be, if that doesnt fix things then replace the throttle position sensor (£10ish) and see if that fixes things.

Mine sits just under 1000rpm and sometimes revs up a tad but not much and instantly goes back down, the sensor is what i think is up with mine, that and the lambda sensor, im checking both anyway.

http://en.wikipedia.org/wiki/Throttle_position_sensor

 

When breaking for a junction my revs will come down as normal, until my speed hits 0, then my revs will rise slowly to about 3.5k, sit there for a while then drop down low (almost stall) then rough idle for a bit, then be fine. Of course I have normally pulled away before all this has happened and it behaves fine when I pull away.

If the cable was stuck it I would of thought it would act like I had the pedal slightly pressed all the time, not just when stationary. If it was the TPS I would of thought be playing up whilst driving not just when stationary.

 

Cleaning the ISCV made no difference, I also switched for one I knew to be working fine, again no difference. I intended to have a another look yesterday as I had the day off but I had to change my front springs as one snapped and the top mount bearing were fooked so did them and the arb drop links. Anyways, the top of my n/s strut was fooked making it impossible to get it undone, so had to replace, and then the bottom of the strut just didn't want to go back into the hub, so ended up taking all fooking day and I didn't get chance to have another look at my idle problem .

 

Loom toward the VSS, although I guess your speedo has no issues?

Martin

 

Speedo works fine, but it's still worth a check. Cheers.

 

Right,

I removed the vacuum hose that comes out the back of the inlet manifold, blew air down to make sure it wasn't blocked or sucked flat or leaking, and it's all good.

The outer sheathing on the accelerator cable has melted/dissolved along one section, so I cleaned that up.

I removed the TPS and checked the resistance across the pins, and it's right for throttle fully open and closed and it changes smoothly with no sudden jumps throughout the range, so I think that is okay.

I'm thinking the throttle cable is the most likely cause atm, but if it was getting stuck I would expect the engine to rev as soon as I put the clutch in, but it doesn't start to rev up until I have almost come to a stop?!?

I suppose the MAF is the next thing to check, or could be an air leak on the actual inlet manifold or TB somewhere, will have a squirt with carb cleaner to try and find leak.

 

Just a quick update to say: problem solved!

It was a vacuum leak, which got worse, and therefore easier to find. There are a couple of vacuum connections on the inlet manifold which are not used and capped off, these caps had got brittle and started to split, split got worse and I was able to pinpoint. Just replaced both caps and now have a nice smooth idle.

The throttle cable was sticking slightly as well, so I replaced that too.

Thanks for all the helpful suggestions.