Manual choke idle

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Manual choke idle

Post by arctichotspur »

Hi.

I have been having trouble with cold starts since I got my MK1A one year ago. Once the car warms up it idles great at 800-900 rpm. I have tried several things regarding the cold start issue, but not much have worked. I have checked and adjusted the tps, checked the csi, replaced vacuum lines, cleaned the throttle body etc. Last attempt was doing the manual choke conversion.

Since the conversion the car is definitely better and will idle roughly, but not kill it self like it used to do. If I turn off the choke before warm the car stutters and dies. My VSV(picture) which I got off eBay has a ID of 6,5 mm and gives me an increase in rpm of approx 300.

What increase in rpm are you guys experiencing with your manual choke conversions and what ID does your VSV have?

Any other tips I should check which could be root of my problem?

Thanks.
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Re: Manual choke idle

Post by jimi »

300 rpm isn't enough, needs to be more like 1500. Mr T's stock setup will have the engine revving at up 2500rpm
Try this, start the engine from cold and then pull the pipe from your VSV to the throttle body off at the throttle body, what happens to the rpm when you do this ?
Couple of other things, have you blanked off the AAV inlet port on the throttle body ? ( normally done with a tyre valve cap) How long are you letting run before switching it off ( whats the ambient air temperature ?) How long do you have to run it beforeit will idle on its own with the choke off?
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Re: Manual choke idle

Post by jimi »

What's csi ?
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Re: Manual choke idle

Post by arctichotspur »

I will check by removing the pipe to the throttle body.

I have blanked off the inlet port using a tyre cap and gasket silicone blocking it completely.

I normally need to help the car idle at around 2000 rpm for approx 3-4 mins. I can then let go off the throttle and let it idle with the choke for another minute or two before turning off the choke.

Now in winter I am only starting it in my garage so temp would be around 15c.

And I forgot to mention that I feel it has small misfires until the engine is warmed up.

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Re: Manual choke idle

Post by arctichotspur »

Csi=cold start injector ?

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Re: Manual choke idle

Post by arctichotspur »

Could the pipe on the throttle body that the vsv connects to be somewhat blocked/dirty and restricting air flow?
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Re: Manual choke idle

Post by jimi »

Ahh didn't twig with the abbreviation.
The car should manage 2000 rpm on its own with the manual choke.
The vsv I used is an aircondtioning one from a MK2, this has an adjustment that regulates the amount of air passed through it. If I set it near maximum restriction (very little air passing through) then my car won't idle when cold.
If I set it to minimum restriction ( maximum airflow) then the car will idle at around 2000 rpm, gradually rising to around 2500rpm as it warms up.
I have it set to idle around 1500, rising to around 2000 rpm if I leave it on, which I don't. I have a timer that switches it off after 3 mins, car will idle on its own after that.
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Re: Manual choke idle

Post by arctichotspur »

Is that the vsv recommended in the know your 2 section?
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Re: Manual choke idle

Post by jimi »

Yes its possible, if you restrict the airflow bypassing the throttle butterfly then the idle won't rise enough. That's the reason for my suggestion, its to prove there's no restriction to the airflow going into the throttlebody.
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Re: Manual choke idle

Post by jimi »

I wrote the KY2 article and pictures are of my car/installation
https://www.mr2oc.co.uk/know-your2/mk1/ ... tions.html
It's Paul Woods concept, originally I bought a kit from him, which I used for a couple of years. When he discovered the adjustable vsv he sent me one to try out, The article was the result of my experiments, it's still in use on my car today
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Re: Manual choke idle

Post by arctichotspur »

I managed to get around to start the mr2 today. It started as normal and idled around 900-1000 with the choke on. I then removed the tube plugged into the throttle body. The rpm immidiately increased to around 2700 which means that there is no blockage at least.

It also makes me believe that the 10 euro vsv I bought on eBay is probably not capable of providing more air...I think I will try the vsv you use and Paul Woods recommended.

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Re: Manual choke idle

Post by arctichotspur »

Update/Solution:

Got the VSV recommended by Jimi and Paul Woods in the mail today and connected it to the car. With this VSV the engine idled at 1600 rpm gradually rising to 2000 rpm. It finally works and I don't have to worry about cold starts anymore.

If you are doing the manual choke conversion; Don´t try other(cheaper) VSV´s. Just use the one that actually works and does the job!
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Re: Manual choke idle

Post by jimi »

Excellent news, well done for persisting and getting it sorted :th:
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