Whats Making My 1.9 8V Idle So High? :s

[johnhenry 20]

Afternoon all

 

Ive basically had a real mare with the car, the idle is way too high, I've got the idle screw all the way in and its still sitting nicely at anywhere form 1250-2000.

 

in the last few weeks i have

> replaced the SAD with a known good unit - and have ran the checks to make sure it is not stuck open - it is fully working and shut off.

> had the distributor completely rebuilt by H&H Ignition, including new advance vacuum

> replaced the AFM (have tested the problem on both my old AFM and the new AFM, same problem)

> replaced the throttle body as I noticed mine had the Throttle stop screw broken so i assumed it had been messed around with. The replacement unit TPS clicks as it should when the butterfly is shut.

> all the pipework connecting bits is bakerBM silicone, not new, but good condition

> New ECU temp sensor (blue connector)

 

I have tried to starve the engine of oxygen to check for leaks and it does stall if my had goes over the AFM nozzle

 

THIS IS ALL WITH THE IDLE SCREW FULLY SCREWED IN (and AFM screwed out 7 turns as i have read you do for a base level of setup)

 

The car when first started will idle at about 1200 rpm (i guess this is due to the SAD valve being open)

Once it starts to warm up, the SAD shuts, and the engine revs drop down to about 900

As soon as I start actually moving the car the rpm's start to rise. eventually after about 1-2 miles it up to about 1500 rpm.

 

> NO hunting at all, bang on solid idle

> the engine runs nicely through the rev range

> If i blip the throttle, the revs drop down and then pick up immediately back to the solid idle.

 

Ideas welcome. will respond to everything and check everything anyone suggests as I just want to drive my car at weekends now, I work away in the week and haven't been able to enjoy it the last 2 due to this problem.

 

Cheers in advance

John

[farmer 328 1 Cars]

Any air leaks ?

[welshpug 1,662]

air leak, or you just need to back the throttle stop off further, TPS may be holding it open, or the throttle cable.

[DamirGTI 343]

Id also check the SAD heater connector .. use an multimeter and see if theres voltage present on the connector with the ignition ON , should be battery voltage or at least near .

 

Have you tried pinching the SAD hose when the revs climb up ?

 

I had almost identical issue before , and it turned up to be the SAD heater connector with zero voltage (wire breakdown somewhere inside the loom) , all was fine until driving in high gear on a flat straight road with minimum engine load then the idle started racing up to the 2000 rmp ... stopped and tried pinching the SAD hose and it dropped down immediately . I just rewired heater connector and was fine afterwards .

 

D

[Slo 283 1 Cars]

Check that bolt on the inlet manifold that holds the oil filler neck its infamous for causing this if its loose

[johnhenry 20]

Welshpug & Farmer - I have had a good look for air leaks, have tried to starve the engine of air by covering the AFM with my hand and the engine stalls, no huge sounds of engine leaking. Regarding the throttle cable ill slacken it off bait and see if it makes a difference, weirdly It was fine and I haven't adjusted the length before/after this problem has occurred, ill look into non-the-less

 

Damir - I have checked the SAD pipe when running it isn't clogged, I haven't checked the readings coming off the connector wiring - the wiring isn't great!

 

Slo - I'll check this tomorrow morning, sounds like it could be a possibility. not sure though as it usually starts off with a decent idle and gets worse

[Slo 283 1 Cars]

Thats because when the engine is cold its using a lot more fuel than when it is warm so the air leak (if it has one) will match the amount of fuel going in and when its warmed up the fuel amount will drop and it will run weak and idle like a bar steward.

 

If you cover the afm up it will stall, not just because its where it breathes from but also because its where it monitors how much fuel to use so no air no fuel no idle

[johnhenry 20]

knowledge dropped right there! thanks, ill have a real look at this tomorrow.

[Slo 283 1 Cars]

Just put some thread lock on the bolt and tighten it up then you can forget all about it

[johnhenry 20]

Checked inlet oil neck filler bolt. tight as, no movement whatsoever.

 

there was no reading on the wires to the connector leading to the SAD with the ignition on, there was a fluctuating reading when the car was being cranked over however. from 0-14 volts

 

I then covered the sad inlet on the side of the large bend pipe that goes into the throttle body to see if by there being no air in from the sad this solved the problem. It didn't kept idling at 1500 , so this would mean that this bears no relevance to the problem? (the SAD was connected up at this stage.

[welshpug 1,662]

did you block both SAD pipe and the elbow between AFM ant throttle body when checking that?

[johnhenry 20]

yeh I blocked off the pipe from the sad to the elbow pipe, and the pipes opening on the elbow.

 

baffled :/

[welshpug 1,662]

so you have ruled out the SAD, time to look at what I suggested then.

[johnhenry 20]

I've loosened off the throttle some more, and I hear the 'click' from the TPS when as the butterfly snaps shut.

 

Its done the same thing with Two separate Throttle bodies, which would rule out the TPS?

 

As for air leaks, next weekend I'm just going to take everything apart, and put everything back together, maybe find the issue.

 

Is there anything electrical that is inside the car (Tach relay) or ECU that it might be? the loom has been bodged in the past which I have tried to rectify.

[jackherer 543]

Its done the same thing with Two separate Throttle bodies, which would rule out the TPS?

Not if both of the TPSes are knackered, do you have a multimeter you can use to test them? If not you can use a battery and bulb.

[welshpug 1,662]

did you back the TPS off as well as winding the throttle stop off?

[minimaniacwhyard 17]

Little tip finding an air leak. Buy a can of break cleaner and spray round suspect areas if there is a leak the mixture gets into the airflow and causes the engine to blip. Great method saves a lot of time fault finding sometimes.

[johnhenry 20]

I tested the old TPS and it read correctly, but i saw the Throttle stop screw had been broken so I was concerned it had been bodged previously. so replaced.

Stupidly haven't tested the current one,

 

on the new Throttle body, the throttle stop screw is wound back a fair bit so its not holding the butterfly open.

 

Will be getting some brake cleaner next weekend! Great tip thanks!

[welshpug 1,662]

 

 

on the new Throttle body, the throttle stop screw is wound back a fair bit so its not holding the butterfly open.

 

 

 

 

so you haven't backed off the TPS and the TPS is holding the butterfly open.

[johnhenry 20]

no the butterfly is shut, and as it shuts the tic clicks

 

sorry I'm not making a great deal of sense

[johnhenry 20]

right - progress.

 

Had a K&N i57 system in the garage i completely forgot about, thought it would be good to change over to completely know that there were no iffy parts there.

Swapped it over, (happy with the sound )

 

the problem was still there after about 10 mins of driving, then i remembered to do the holts easy start test (thanks Minimaniacwhyard) - sprayed everywhere, nothing changed until ispraying the SAD body,, revs shot up, time for either new SAD or good used.

 

will keep updating.

 

Cheers

John

[welshpug 1,662]

You have an air leak then!

[johnhenry 20]

I do yes, and its to do with the SAD, which contradicts my two points earlier in the thread, normal service has been resumed :/

[welshpug 1,662]

check the hoses properly, unlikely its the SAD itself, they're a very simple device.

[johnhenry 20]

Ive whipped the sad out as getting to things round there now is a breeze as I don't have the AFM bracket, or battery getting in the way

 

the housing is actually loose :S like the two parts are not snug, to be honest, It can't be good for it, even if it is a known good unit, trying to source a new one is being difficult :/