cold idle, just won't idle when cold ?

[Nuttynotty]

Hi Guy’s Looking for assistance, car been starting great for months, however the past few days she is being a pig, she will start, well fire up no problem (so the cold start valve is OK), but she will not idle when first started when cold, she will splutter and die, turn the key, fires right up, but wont idle ( only when cold) once she has been running for about 30 seconds she will start to idle but the revs are all over the place ( 500~ 1500rpm) once she is warm 5 minutes she idles great I have checked the micro switch on the fule body ( both WOT and Idle both are OK), the ISV is clean and checks out , the only thing I notice is that when you first start her up in the morning, she used to smell rich from the exhaust ( un burnt gas) , now she does not smell !!! I believe that the injectors are not enriching the fuel when cold, would that be the Enrich relays job ? if so where is this sucker???

[Nuttynotty]

Ok, I think the problem is the warm up regulator, I think its stuck on hot, any idear where it is, just point me in the right direction...

Cheers

[audi-driver1126]

could be an air leak on the rubber "boot" on your cars throttle body. it tends to crack over time from the engines constant heat. That will cause a funky idle at cold start.


or, ive had recent odd running behaviour caused from a failing temperature sensor (located under the upper rad hose. its on the right side of the engine block if you look at it from the front of the car) unplug it and then plug it back in. Give it a go.

[Rogviler]

Originally Posted by Nuttynotty

Ok, I think the problem is the warm up regulator

If you have one you'll have two extra lines coming off the fuel distributor that run down to the driver side of the engine block where there's a small box. That's the warm up regulator. If this is for the Coupe GT in your signature line then I can't recall if they have them or not...

It could still be the cold start valve even though it does start. I would verify by testing it in a jar to make sure it sprays.

The warm-up enrichment check procedures are in the Bentley, but they all end with replacing the ECU rather than something to be adjusted, which isn't very helpful.

However, it could be a simple problem between the cold start valve and the sensor (thermo-time switch), which you can test by doing the following:

-engine coolant temperature should be below 59 degrees F (do it at night or early morning, before any driving)

-unplug coil wire from distributor cap and connect to ground with jumper wire

-unplug connector from cold start valve

-connect multimeter to terminals (of the connector that you removed)

-actuate starter, you should see 8v minimum

The thermo-time switch is the one at the top of the top radiator hose where it goes into the engine. Replace if bad.

That's about it as far as something that would present only during the warm-up phase, other than vacuum leaks or the like, as mentioned above.

-Rog

[Blewtoon]

I don't think it's the cold start valve. It only sprays fuel for a few seconds to give the initial start.
More likly it's the temp sensor or a vac leak or a combination of the 2. Unplugging the temp sensor should trick the icu into thinking that the engine is cold, calling for a rich mixture, after it warms up plug it back in & it should run ok.
If that works it's time to replace the sensor

[Rogviler]

I'd still at least rule out the CSV. If the engine is needing to run longer to warm up in order to overcome a faulty cold start system then that would be the exact symptom being presented.

Alternatively, you could simply unplug the CSV and see if it starts any worse. If it's worse but the same symptom it could just be dirty. If it's worse but completely different then you could probably rule that out. If it's the same then you have your culprit.

-Rog

[Nuttynotty]

Cheers Guy's


After checking the engine bay for a warm up regulator and not being able to find one, even tho the manual said I have one ?? and reading Rodgers comments, yes it’s a CGT so I don’t have a warm up regulator. I spent a good few hours checking for air leaks and spraying carb cleaner around the boots on the intake when running………, So tonight I will check the Cold start valve and the temp sensor, The Only ECU I have is for a Auto and I don’t think that is compatible. Temp Sensor mentioned I believe is the single sensor on the top of the engine right hand side, as I have two one on top of the rad hose and one below the top rad hose, will remove the electrical connection on both and see what happens…… Cheers guy for you help, will post me results.

[Rogviler]

FYI, I've recently converted to the "cheap cigar" method of finding vacuum leaks. It works so much better than carb cleaner or propane, and doesn't have the chance of ruining injector seals.

If you smoke already it's easy, otherwise just get a $1 gas station cigar and blow a few puffs into the vacuum line of your choice. Did it yesterday and found that the brake booster line on my Fox leaks and there was a massive split in a line hidden under the airboot on my 4kq. I never would have pinpointed those with the other method. It works so slick I can't believe I didn't try it before. Doesn't work on a windy day is all.

-Rog

[audi-driver1126]

thats different, sounds like a good idea though! becuase i dont smoke, and probably shouldnt due to my age, could i do this with any other smoke producing item?

[Rogviler]

I was trying to think of another way to do it, but of course it wouldn't be as dead simple. They do make machines that do it, but you'd either have to buy it or rent it...

I would find someone who smokes or wouldn't mind pretend smoking for you. It only takes a minute. I don't smoke either, but it's easy to draw enough smoke into my mouth to make it work.

-Rog