Warm starting problem

douglas851 · Post by **douglas851** » Thu Nov 05, 2009 6:06 pm

My 16v starts instantly and idles fine when it cold and when it is hot (after 20 mins drive).

However, when it is warm it refuses to idle and dies on a closed throttle, but runs as it should above 2000 rpm.

If you try and start it at this point it takes several attempts, eventually starting on two but once all four join in it is fine above 2000 rpm.
All this is repeatable and predictable.

Any ideas?

Vanny · Post by **Vanny** » Thu Nov 05, 2009 6:42 pm

fill the idle control valve with WD40, leave for 10 minutes, drain WD40, leave to try, refit. If its not the ICV then i would imagine it is a fault with the ignition, check cap (spec tightness), arm, leads and plugs. Has this started recently or been arouund for a while?

I'd recommend asking the same question on the BX16valve.co.uk forum
http://www.bx16valve.co.uk/forum as there are a greater proportion of valver owners, its also a semi common problem.

Post by **docchevron** » Fri Nov 06, 2009 2:37 am

/\ what he said.
Also worth checking that the idle switch clicks in when the throttle is returned to rest.
Also, check that BOTH butterflies open and close properly.
It's not unknown for the second butterfly to get a bit sticky ont he return cam (especially if you dont open the throttle wide that often) which then makes the ICV close up ALOT since there is air being passed through the not completly closed second butterfly.
When the second butterfly does close it can stall the motor since the ICV doesn't allow enough by pass air through quickly enough.

Happened on mine, and took me bloody ages to find it!

douglas851 · Post by **douglas851** » Fri Nov 06, 2009 1:38 pm

Ok, I have checked the ICV and it is working fine. Rotates freely and moves to open when the engine turns over.

Will now check the butterflys...........

douglas851 · Post by **douglas851** » Mon Nov 16, 2009 9:14 am

A bit more detail;

The car runs fine until the water temp reaches about 60, then only runs properly above 2000 rpm and dies with the throttle closed. Once water temp reaches 90 it runs perfectly and idles happily.

Post by **docchevron** » Mon Nov 16, 2009 1:35 pm

Does your car have the two row or three row ECU?

Also, does it have a K light on the dash??

Sounds more and more like ECU temp sensor is giving erratic readings as it warms up.

Just as an experiment, start the car from cold, let it warm up until it starts to cut out, then unplug the sensor.. Does it die immdiatley or idle at about 900RPM?

douglas851 · Post by **douglas851** » Mon Nov 16, 2009 6:31 pm

As far as I know it has Motronic ML4.1

There is no K light, or any other engine management light.

I shall try the removing the temp sensor wire.

prm · Post by **prm** » Mon Nov 16, 2009 10:41 pm

Well done Doc with the rows on the ECU. Funny how you seem to easily slot into 2 row units.
You’ve prompted me to finally finish the K-light wiring mod and fault code read-out for non equipped 16v’s.

Might be worth checking the resistance on ATS and CTS, hot and cold at warm up stages with the engine stationary.
Both types of sensors have almost identical resistance readings at identical temps –stationary. The ATS element is exposed within the AFM intake tract, variations in ambient intake temp (resistance readings), are almost instant when compared to the CTS. Variations in ATS and CTS switch resistance alters the pulse duration on the injectors.

As a rough guide … Cold, 0 to 5?C, 3-4k?. 30-40?C, 1-2k?, 80-90?C, 250-350?.
If it’s got air con?? Gently hold the throttle cable quadrant against the stop to see if idle rpm remains reasonably constant.

What happens when you remove the ICV plug with the engine on idle and warm?

Regards

Post by **docchevron** » Tue Nov 17, 2009 1:45 am

Thats interesting!
How have you modded the wiring to make the K light work mate?

Mines got the 2 row, the diagnostic plug is dead and I have no way of reading the thing at all..

Have thought about getting the K light working many times in the past, but never quite sussed how to, although I know it must be possible since the old white P1 valver I had also with 2 row ECU had a K light that worked, albeit with some VERY heath Robinson wiring that was spliced into the main ECU loom...

DFF53 · Post by **DFF53** » Tue Nov 17, 2009 3:11 am

Clean all the points at the distributor. May sound sill but worked on my car with similar symptoms. Grease and sirt build up on the connections . Worth a try.

prm · Post by **prm** » Tue Nov 17, 2009 9:50 pm

Doc

I’ve never tried connecting a fault code reader to the 2 pin plug by the fuel pump/ECU relays. Any members used this socket?
Plan of campaign is to utilise one of the redundant dash warning light coloured window for the K-light, and incorporate on board circuits for in-car diagnostics. A few problems to overcome. Depending on make of consol, most of the dash lights can be group negative or positive.

Been trying to complete for some time. thanks for the push. Will try and complete over the next 3-4 weeks. If I give a call for a spare 119 ECU you will know its back to the drawing board.

Over the years I thought I’ve nearly sussed all the electrics on a 16v, but the bloody French and their wiring methods. I suppose the UK main wiring and ECU connections are quite basic when compared to US, Asian and some European specs, they appear to have utilised one loom for all regions, makes economical sense, there seem to be quite a few unused connections around the ECU.

Just finished a mod on the overhead consol. Connected those p . . poor spot lamps to operate with the door courtesy switches, also to operate individually with the ignition off. Incorporated a solar panel to keep the battery topped up, as the car seems to spend its current life parked up - in bits.
Will post if any members are interested.

Regards

Post by **docchevron** » Wed Nov 18, 2009 3:26 am

The K light is present on all cars, whether used or not, it's the bottom left lamp on the rev counter (veglia instruments)..

I foolishly assumed that I could runt he K light from the diag socket, but it's dead, and every other two row car I've ever tried to read with the Proxia, Lexia, Gunson or bulb and a bit of wire has PHAILED!

I guess there must be a way of reading it?????

I'm sure we'd all be interested to read anything you have to post mate.
Any mod is a good mod!

douglas851 · Post by **douglas851** » Wed Nov 18, 2009 8:23 pm

Ran up the car until it started running rough.

Took off water temp sensor plug, no affect.

Put it back on, no change to engine running.

Does this mean it is faulty?

prm · Post by **prm** » Wed Nov 18, 2009 10:10 pm

It depends on the water temp at that particular time.
Forgive me for mentioning it;

you are removing the ECU –CTS plug, with two wires attached.
As you’ve got the car running with the plug removed. Remove the plug, attach your meter leads, analog or digital, and monitor the resistance of the CTS up to normal temp. You may find the idle rpm gets erratic around normal temp, as the mixture will be extremely weak at this point, as the ECU will reduce the injector pulse time to the absolute minimum if the CTS is way out.
The resistance readings previously mentioned should give you an approx guide.

Found very few problems with CTS’s, just the readings are inclined to get slightly wayward with age. More inclined to go with ATS on the AFM.

If resistance readings are present, you need to inspect the wiring back to the ECU.
One point to mention. They can sometimes be right sods to detect exactly what componet is causing the problem. Just need to work through one section at a time.

Best of luck

Regards

BX Bandit · Post by **BX Bandit** » Fri Nov 20, 2009 10:48 am

If you disconnect the CTS on mine, the revs rise to about 1500 at a guess. I suppose it's a 'get home fail safe' thing. I guess therefore it may be odd that Dougs car doesn't do this????

That said, I have a 3 row which may work differently.

I have used the diagnostic socket btw and you have to be methodical in using it. By that I mean, after you connect the reader, you have to flick the switch (close the circuit of the tester) for 3 seconds and then open it again. That should prompt the ECU to enter diagnostic code readout mode. Each time the ECU gives you a code, you have to flick the switch again for 3 seconds, then back and it'll give the next code.

It's easy to make a reader, effectively it's just a light and a switch! I think the K light flashes the same as the reader light.

Surely if you disconnect a sensor like CTS, the K light will come on (assuming the bulb isn't blown)