7 replies to this topic

[R F Developments]

Hi everyone,

I would like to start by thanking you all for your help on the previous "Wont idle post".

I have decided to start a new thread as my symptoms have become less irratic.

The car is a 1994 Cooper SPI. Engine modifications as follow

1293cc, self modified head and inlet manifold. Swiftune vernier adjustable SW5i cam, Hi lift rockers, K&N air filter, LCB and Play Mini single box system. (inc CAT)

The car starts on the first turn of the key, hot or cold and runs for about 5 seconds(1000 RPM) fine. The idle then slowly increases to about 1500 RPM and then falls back below 1000 and cuts out.

With application of throttle it will run all day and responds well. I suspect over rich as it is very fumey and black smoke is apparent from the exhaust.(not confirmed though)

The car does drive and pulls well, although on one ocassion a missfire was present on hard acceleration at about 4000 RPM in second but this cleared immediately.

When the idle is changing no movement of the stepper or throttle is apparent so I presume it is a mixture issue.
If the return fuel line is nipped the car does not cut out and will tick over.

The throttle cable has been replaced and set up.

Any ideas or help will be greatly received.

Cheers Steve.

[Sprocket]

Idle speed is controlled with ignition advance. If there is an air leek allowing too much air into the engine, the stepper motor will closee the tthrotle right off. the ignittion idle control will then retard to bring tthe idle speed down.

I would be elooking for an air leak, but the stepper, of its not moving at all (watching the throttle linkage when some one turns the ignition off, stepper should operate the throttle) could also be faulty, usualy dry solder joints on tthe motor itself and easily fixed.

Coulkd just need tuning up, but i deffo recon there could be an air leak

[R F Developments]

Cheers Sprox.

The stepper is working as it moves on shutdown.

It looks as though the idle adjustment stop has been moved at some point as there are witness marks on the peg and threads indicating movement. I do not know when this was done or how. (if diagnostic kit was used)

I called some local garages and when I informed them of it being modified they shied away from the work.

I did try interigating the ECU with a Rover MEMS diagnostic kit,but the card was for a 820i SPI and it would not run the test.
I have a CO meter also, but have yet to check the emmisions.

All the dubious vacuum pipes are new as is the fuel trap. I will check again but I have found no air leaks previously anywhere.

Any ideas about the following?

- What areas do think require special attention?

- How would I go about tuning the car and does anyone know of someone who could do this in the Mansfield area?

- I did wonder if it would take time for the ECU to adapt to the new engine spec and a decent run would cure the issue.
Only a guess though?

Thankyou for your time any other suggestins or inputs are greatly appreciated.
Steve.

[BoyracerAU]

I've been told a run of about 35km would be enough for a newly introduced ECU to become acquainted with the car.

I wonder, if the stepper motor's not moving, throttle cable's not moving and the idle is erractic, is it possible your problem is to do with the regulator?

Just wondering.

[ICAM]

What is the temp reading during the problem

[R F Developments]

I have finally cracked it!

Hooked up an ACT diagnostic and checked the flags and had a MAP sensor fault. Cleared this and ran engine for 2 mins and rechecked flags. MAP fault had reapeared!!

Upon checking live data vacuum level was down and so air leak was confirmed.

I had previously replaced the sense lines so turned my attension to manifold again.

I ran the car and sprayed WD40 around the manifold and the car picked up confirming a manifold leak.

When I removed the manifold everything appeared normal with nothing obvious. On close inspection there was soot around a small area under the manifld heater? I removed the circlip and found a small nick in the rubber seal. This had initially obviosly been sealing up as the engine warmed and thus been giving me the random tickover and associated issues. As it worsened the car started to cough through the inlet and produce the soot I saw (and probably blew more seal away hightening the problem.)

I replaced the seal started te engine with great results.

ACT confirmed no faults and tests ran well, without any flags.

The only thing is that the idle is a tad low and ocassionally the engine will stall after revs.(800 RPM)
Is it a case of adjusting the idle screw out? Live data indicated idle at 27 steps.

My co2 is also a tad high at 1% (Haynes says 0.5% max at idle). Can this be adjusted?

I am now very happy and would like to thank you all for the help.

In paticular Sprocket, BoyracerAu and DaveRob, thankyou Steve.

[BoyracerAU]

Well done. Nice to get a good result with your own hands!

[DaveRob]

Hi Steve

well done mate..... its all a learning experience this SPi stuff. lol

To be honest every car Ive plugged my gear into has had a MAP fault.....people dont realise how CRITICAL this part of the system is.... the tinyest air leak causes problems. As for your idle....27 steps sounds about right so its going to be down to tuning the idle air but before you do this consider the explination re cat and decoke first as Ive indicated below....... and this will prob resolve the stalling issue.... I cant remember if your car has a cat.... is emmisions high with cat or without... It might be that if you have a cat and emmisions are high then because of the air leak your car has been running rich.... and so destroyed the cat elements...just a posibility. If it HAS been running rich I would suggest taking the head off and lapping the valves and doing a full decoke.... as if you have a couple of burnt seats this could be the cause of BOTH idle stalling AND emmisions problems..... Its a Sat morning job to strip decoke and rebuild and costs a head gasket set of about £10 so well worth doing.

Keep us updated

Rob