m20 very high idle.

[steve_k]

afternoon folks looking for help & advise (again).

this time i's to do with a high idle problem,
it's a m20b27 (hartge based),

basically when i start the car it sits at 1500rpm then climbs to 2000rpm before i shut it off for safety,
it has had all brand new inlet manifold gaskets incl the T/B gasket, the AFM is a recon item,
i know there's no air leaks.

the ICV is buzzing when i first turn the ignition on,
it's had a brand new TPS (old one was full of gunk/crap, a brand new CPS as the old one was miles out, new dizzy cap & rotor arm.

a few months ago i replaced the head with a fully rebuilt one (griffin stage 3 copy) & changed the cambelt/waterpump at the same time,

when it was all back together i started the car & it idled perfectly, left it a few weeks while i did a few other jobs,

came back to it today & it's no idling at 1500 - 2000rpm.

i'm stuck, really can't work out why it's doing it.
does anyone have any ideas??

i'm at the end of my tether with this car i really am.

[steve_k]

also, i've checked the stop on the throttle & there's an audible "click" soon as the throttle comes off it's stop,

the ICV is buzzing away with the ignition on, & when i remove the ICV i can clearly see the valve inside moving freely when i rock it about.

[steve_k]

probably not related but i've just noticed that neither the battery or handbrake lights on the dash come on with the ignition on.

[paultv]

Has the battery been disconected whilst the car was left alone?

Maybe the ECU needs to re learn the idle setting....

Start the engine and pull the AFM cable then re plug it....if no change try this a couple of times to see if it settles down.

Check daft things like the accelerator cable metal spigot is correctly seated in the plastic retainer on top of the T.Body, sometimes it spins 90 degrees if you've been doing under the hood manual throttle at the T.Body .. this opens the throttle and it's tough to detect.

Paul

[paultv]

Hows the battery voltage with no load?

Paul

[steve_k]

Cheers paul will check that tomorrow (got to pop out till late )
As for the battery iirc it's about 12.5v & yes it was left off for a month or two.

[steve_k]

Just to add,

I'll have a poke round later to see if the throttle cable has got snagged anywhere along its route.

[paultv]

Every time my battery is disconnected I find the idle cones back high or high and erratic - it takes about 20 minutes of driving around for it to settle correctly, also appears true if you fit a different ICV ... sometimes I have to do the AFM plug thing to get it to sort itself out. Once done it stays fine for good until I pull the battery again.

Paul

[steve_k]

Cheers for that paul,

Only problem is I cant drive it at the moment as there's no mot on it,

I'm trying to get it sorted so I can get it in for mot.

I'll give the afm plug a go tomorrow when I've got more time & daylight.

And I'll clean the ice out again just to be sure.

But as I said above, when I fitted the new cps & TPS after the head swap/Campbell replacment it idled perfectly around 850+rpm & the battery had been off for over 6 months at that time.

[paultv]

Our cars are great hey? They can be a real pain in the ass sometimes.. I've just driven to Berlin ..a great drive with a few autobahn bursts of 110mph...but I can hear a rear wheel bearing getting worse, so it's back on the stands when I get home at the end of the week!

Good luck and don't give up, doesn't help getting dark earlier does it?

Paul

[steve_k]

Tell.me about it lol.

When it's running it's fantastic but soon as there's a problem................

I'll try what you've suggested tomorrow (if I get chance) & report back.

As for getting darker earlier it's a real pain in the ass

[steve_k]

As for long runs,

Once took it from grimsby to Swindon & back in a weekend,

Mansfield to great yarmouth for a week & used it as a daily in all weathers for a couple of years without any problems at all.

But soon as I pull it off road to sort a few bits it throws a monumental paddy.

[steve_k]

I forgot to say in the first post.

When the engine rises from 1500 - 2000rpm the "idle" is smooth, no jerky ness, or miss fires just a very smooth but very high "idle".

[HJ1981]

also, i've checked the stop on the throttle & there's an audible "click" soon as the throttle comes off it's stop,

the ICV is buzzing away with the ignition on, & when i remove the ICV i can clearly see the valve inside moving freely when i rock it about.

This, but do not forget, anytime the TPS is adjusted, stop changed or TPS removed the DME has to be reset. Basically disconnect power to the DME for at least 10 seconds (either unplug the DME or disconnect the battery).

[steve_k]

also, i've checked the stop on the throttle & there's an audible "click" soon as the throttle comes off it's stop,

the ICV is buzzing away with the ignition on, & when i remove the ICV i can clearly see the valve inside moving freely when i rock it about.

This, but do not forget, anytime the TPS is adjusted, stop changed or TPS removed the DME has to be reset. Basically disconnect power to the DME for at least 10 seconds (either unplug the DME or disconnect the battery).

thanks, i'll give that a try today.

[steve_k]

right, anyone else got any suggestions for me to try to get this sorted today?

[steve_k]

Well so far I've had the inlet manifold off & replaced the gaskets with new 2mm thick rubber ones (had them in stock ages) as the ones on there didn't look to clever. Also took the icv off & sprayed it internally with carb cleaner.

The valve inside moves freely when you shake the icv side to side like a rattle.

Started the engine up again & it idle was now down to 1300rpm.

While it was running (only briefly) I went round the whole inlet side with carb cleaner to see if there were any more splits/vac leaks.

I found none.

So started it up again & as paultv above suggested I pulled the plug for the afm, engine dies straight away.

Also pulled the afm & the checked the "barn door, no binding or sticking.

So now I really am at a loss as to what could be causing it.

& I really dont fancy leaving it to idle at 1300rpm for anymore than 30 seconds on a stone cold engine.

So, any ideas??

[paultv]

Did you let it run a while? Shouldn't do any harm at all.

Paul

[steve_k]

Did you let it run a while? Shouldn't do any harm at all.

Paul

Not yet, will be trying that tomorrow.

Didn't fancy running a stone cold engine at 1500 - 2000rpm for any length of time.

Also rechecked the ICV & even though its had a (BIG) blast of carb cleaner through it the valve was still a bit stiff as in it would only move a bit when I shook it.

Got a new one on the way so fingers crossed.

[paultv]

After changing the ICV you need to let the ECU re learn the idle... itll take a while, let the engine run and hopefully settle down.

Didn't find any odd throttle cable issues?

Paul

[steve_k]

After changing the ICV you need to let the ECU re learn the idle... itll take a while, let the engine run and hopefully settle down.

Didn't find any odd throttle cable issues?

Paul

Will do.

As for the throttle cable. Nope none as I could see, no snagging it all seems to be in order.

[paultv]

Has the butterfly stop screw been messed with?

What does the car do if you remove the ICV pipe to the throttle body and block it ( at the throttle body pipe )

The engine should idle but lower than 700 rpm and roughly. If it still runs fast the butterfly is too open ( assuming no other air ingress ) and needs the stop screw re setting and the tps re setting.

But if the car ran fine 2 months ago I can't see how this can be the problem really.

What a bummer!

Paul

[steve_k]

Has the butterfly stop screw been messed with?

What does the car do if you remove the ICV pipe to the throttle body and block it ( at the throttle body pipe )

The engine should idle but lower than 700 rpm and roughly. If it still runs fast the butterfly is too open ( assuming no other air ingress ) and needs the stop screw re setting and the tps re setting.

But if the car ran fine 2 months ago I can't see how this can be the problem really.

What a bummer!

Paul

As far as I know the butterfly stop screw has not been messed with (looks to have a glue type residue on it) & I know I've never messed with it.

As for the icv pipe being removed, not tried that yet so will try tomorrow.

I know it's strange, the car has been off road for the past few years while I did a mini resto.

The engine was built by someone else & run in before being fitting in mine. It was running perfectly then.

When I changed the cambelt/water pump/tensioner, I put it all back together as was,

I changed the cps & tps not long after as they were both causing problems (non start etc) & it started & idled perfectly after that.

Really cant work it out.

[steve_k]

well i better update this.

car now idles as it should,

when i checked the ICV the internals seemed to be a little stiff, so i gave it a good soaking in carb cleaner, & in the mean time thinking that it was on it's way out i bought another ICV, (came this morning), fitted that went to start the car & i could hear a faint buzzing from it,

started the car & it died straight away, tried again, same thing,

so after swearing enough to make a macalpine navvi blush, fag & a brew, i thought to try the "old" ICV again (couldn't hurt to try).

& lo & behold!!!!
when i started the car it idled a little high for about 30 seconds then dropped down to 1100rpm then again to just over 900rpm where it stayed till i shut the engine off.

it was a little smokey as it's not been run in over 6 months but at least it's back to were it should be.

now just to sort out a leaky brake union.