[flash]

yes, but when the car is built, the standards to which it is subjected are much tougher. for example, even in california, the standards are 10 times less strict at biannual testing than they are for certification. this is to anticipate worn engine and converter conditions at 100k miles. i would venture to guess that your testing stations are attempting to do the same thing by telling customers to have their cars warmed up, so as to give them the best chance of passing.

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[Bulti]

A nice fact: since catalytic converters are mandatory for petrol cars from 1993 onwards (in Belgium), my '92 doesn't even have to rev when doing the test... Would be a different story when maintaining 4000 rpm with a '93 :-)



Sorry Dry, hijacking the place :-)

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[paulzebo]

Did you find the problem yet?

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[tryan]

hmmm....maybe just jousting at windmills but see if your throttle plate bushings and seals are ok. (be thankful you don't have MFI stacks). bruce at arnworxs has a video on the 944 style throttle body teardown and rebuild. count your spring windings first.



if they check out, see if you can get the <acronym title='throttle position sensor'>TPS</acronym> set to .5V and note any cold/warm/hot idle changes. the computer wants to see .5 at idle. per the workshop manual, you can add the 1k jumper to pull the O2 sensor out of the loop and go to the base map.



I would try a point or two lower octane and put those silly multiple electrode plugs back in. I chased a negative fuel trim problem for months that was resolved by changing gas stations. I was pretty anal about not using corn in my tank but corn is good with butter and salt. i think audi started with the multiple electrode plugs on some early 80's CIS Quattro models but i am not a fan.



another option would be to remap your timing up 5 degrees at idle after she starts when cold.



flame me but carb cleaner is not so nice to sensors and seals.

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[dry664]

[quote name='paulzebo' timestamp='1411491118' post='162467']

Did you find the problem yet?

[/quote]



Thanks for asking! Not yet, haven't had any time to investigate ideas in this thread just yet. Will have some time this weekend, in between watching some Ryder Cup action!

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[dry664]

I've still got this issue and I'm losing my mind!.



Since my last post I've cleaned up the distributor cap and rotor, replaced the O2 sensor, replaced the airbox with an unmodified version and have done another vacuum test. Still does the same thing.

The car starts up and idles perfectly. As soon as I use the throttle the car starts to run rich. It behaves like an old car that has been over-choked and can stall. After about 4 mins when its all warmed up it drives perfectly.

Its worse when its cold. When it gets down to just above freezing, that's when its susceptible to stalling out. Above maybe 50degF there no symptoms at all.

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[flash]

is there a coding plug installed?



is the chip stock? i know you had a promax in there, but have you tried it with the stock one since you changed the other things?



other than that, i think you have a MAF problem

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[dry664]

Coding plug?



The car has a Promax currently but it did this exactly the same before when the standard chip was installed.



I'm thinking the <acronym title='mass air flow'>MAF</acronym> is a possibility but does it sense temperature? I'm just wondering what info it could give that could mean the car run great when warmer but crap when colder?



Aside from that Im thinking FPR or ECU?!? <img src="/forum/images/smilies/968/whine.gif" class="smilie" alt="" />

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[flash]

yes - coding plug.



near the ECU, on the harness, there is a 2 pin connector. if somebody plugged in a resistor there, like they do in countries that have leaded fuel, it disables the O2 sensor. that would absolutely do what you are talking about.



so would a bad MAF. if it think there is more air flowing over it than really is, then it will add fuel to keep the mixture correct. the temp thing is related, but different. the ECU alters mixture based on a few different sensors. temp is one of them. even in normal operation, the ECU adds fuel at cold start. then after about a minute, it leans it out. yours just sounds like it's confused when it's cold.



clean the MAF with MAF cleaner



look for the coding plug. if it's there, unplug it.

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[dry664]

Cheers Flash.

I will have a look for the coding plug but the car reacted so well to the new O2 sensor I would be surprised.

I've actually cleaned the <acronym title='mass air flow'>MAF</acronym> with <acronym title='mass air flow'>MAF</acronym> cleaner twice now. Think I will try borrowing another <acronym title='mass air flow'>MAF</acronym>.

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[flash]

good idea.



other than that, i am at a loss to explain why it is so cold blooded. like i said, my first thought was vacuum leak, but if you've managed to pressurize the system, and show no leaks, then that rules out that issue.



have you hooked up an air/fuel meter yet?

have you plugged into a durametric or bosch hammer yet?

how many seconds between cold start and the symptom going away?

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[dry664]

Its been hooked up to a hammer three times now and shows no faults (aside from running with an unplugged O2, which I did to see if the O2 made a difference).

My mechanic ran it with the air fuel meter hooked up and confirmed it runs 'very rich' on warmup, but perfectly fine after that.



Like I said, no problems starting it but once I set off the symptoms begin. Usually takes 3-4 minutes before the symptoms disappear completely.

What else is strange is that the car doesn't really do this twice in one day even if its really cold.



The issue is when pulling up to a junction during that first few minutes, when I dip the clutch the car tries to stall.

Its like once I close the throttle, it cant get enough air in via the opened ICV to cope with the amount of fuel. The just before stalling, it figures this out and something pulls the fuel back. If it does stall it can be really hard to start after, like the engine is flooded. Weird!

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[flash]

yeah - clearly the ECU is not seeing what it want.



bad ICV or connection to it would be one guess. it should definitely be able to run on the air from that. durametric test on the ICV would rule out the connection.



bad MAF would be another.



bad temp sensor could be sending the wrong signal too

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[dry664]

Temp sensor would make most sense but I've tested two sensors in water with a thermometer to make sure they are putting out the right reading, then put the most accurate one in the car!!

I will have another look at the ICV. Maybe plugging probes into it to check its actually getting the a signal? <acronym title='throttle position sensor'>TPS</acronym> is definitely working and calibrated with a DMM.

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[flash]

tech tip: when checking temp sensors or thermostats in a pot of water, do not let them touch the pot. when they touch the pot, you get a false reading.



the ICV is basically a gate valve. it opens and closes abruptly and can easily be heard. the durametric has a test procedure for it that is quite effective.



as another test, see if the engine running condition changes at idle after cold start, when it is exhibiting the symptom, and you get under the hood and just crack the throttle a hair. if it smoothes out, then you know that you are not getting enough air in there.

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[Bulti]

Trying to think out of the box, at the risk of talking complete nonsense:



Maybe it has something to do with the cat back being clogged? Maybe when it heats up it allows the gasses to escape better than when cold?

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[flash]

should be the reverse

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[dry664]

Cheers guys. Some stuff to think about!

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[kwikt]

Still sounds like the(blue)water temp sensor. I had the same problem last year...although you also have an oil temp sensor also which is between fuel injector 3&4 and connects to the DME. Worth checking out.

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[Ab54666]

[quote name='dry664' timestamp='1421355513' post='165144']Cheers guys. Some stuff to think about![/quote]



We aren't far away dry (both London although can't recall exactly where you are, i'm SE12). Happy to try a few swapsies etc. I've got my old standard FPR and temp coolant switch if you wanted to borrow those to try out, we can relatively quickly swap <acronym title='mass air flow'>MAF</acronym>'s to try, a few of us are around mine of Waylanders (NE London) this Thursday to whip out my starter and refurbish it if you wanted to join in a spanner day - might be more than one 968 to borrow parts from! I've got a standard chip and Promax (RS Barn stage 2 in at the mo) but looks like you have checked that.



I remember reading a few people with a similar problem with the water temp which is why I changed mine. Type911 is only a couple of miles from me also if you need parts (assuming he has in stock).

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