CIS won't idle when cold

I have a 76 2.7 euro that won't idle when cold, engine RPM varies from 0 - 2000, the car never struggles to fire but the only way I can keep the engine running is to feather the throttle. When warm the engine doesn't miss a beat and idles at a constant 900rpm. Engine is in good condition - any suggestions as to where I shoukd start looking ?

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76 2.7

try the warm-up regulator and/or aux air regulator.
81'SC

I had the same problem...it was running lean, adjusted the mixture and it was corrected...

You need an exhaust gas analyzer to fix it,,,,

[This message has been edited by mikez (edited 09-08-2000).]

I adjusted my mixture by ear. Go for the smoothest, not fastest, idle. Maintain idle at about 950 using the idle adjust screw while adjusting mixture. Mike is right though, the proper way is with a co monitor, but this should at least tell you if mixture is your problem.

Leon 78SC

I adjusted my mixture by ear. Go for the smoothest, not fastest, idle. Maintain idle at about 950 using the idle adjust screw while adjusting mixture. Mike is right though, the proper way is with a co monitor, but this should at least tell you if mixture is your problem.

Leon 78SC

This may be a stupid question, but how do you get a hold of a CO meter? If you were to purchase one, would it be worth it?

The reason I'm asking is because I have owned, tweeked and driven 911's for 30yrs and have yet to come across a CO meter for my toolbox.

Besides, I doubt if most people would know where to measure the CO on their catylized exhaust system if you were to ask them.

As long as I have been adjusting my mixtures without the aid of a CO meter, I have never had a problem passing the Calif. smog inspection and my cars run clean and strong.

So who has access to a CO meter anyhow?

Regards,

Joe

"Sniffers" are expensive I believe. Shops have them.

My guess is a device has failed. Lagoon mentioned Auxilliary Air Regulator. There is also the Auxilliary Air Valve and I'm trying to understand these devices. One serves the purpose of increasing the idle during warmup. It does this by opening an air passage when cold, and slowly closing it due to voltage applied at an electrical plug on the device. If it's broke then it's probably oppen all the time rather than closed all the time, so your idle is actualy probably set too low.

Easy to test. The Haynes manuyal give some tips in the Supplement on Later Models. It calls this stuff a "choke."

Leon would know better, but I suspect that all those larger (just under an inch) air hoses shoudl be handling no air when the engine is warm and idling. Taht is, you coudl pinch those hoses, and there shoudl be no change.

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'83 SC

You can get them here. Look at either of the two "GasTester" items on this page http://autoexpertproducts.webjump.com

Or JC Whitney has them here. http://www.jcwhitney.com/catsubpic.jhtml?CATID=3295

Leon 78SC

Thanks in advance guy's for taking the time to help me out, off out into garage - could be some time !.

there are several air devices on the CIS cars

The first is the bell shaped auxilary air device, according to the factory manual you check it by removing the filter housing and cartridge and duct, next you disconnect the hose leading to aux air device above thenthrottle valve on the throttle valve housing and then you tightly seal connector and hose, next you reinstall duct start engine and check idle , if a change in rpm is noted the auxilary air device is leaking and if it leaks considerably it will not be possible to adjust idle speed.


As far as trouble shooting automatic choke aka aux air regulator or or aux air valve

you 1st disconnect top control line at aux air valve and plug
If the problem is corrected you have a bad aux air valve if prob unchanged aux air valve is good

the problem with the factory manuals they assume you are a trained P car tech already but they are better than nothing

[This message has been edited by jryerson (edited 09-10-2000).]

Is the engine popping when giving extra throttle at warm up? If so, the warm up regulator is not inriching the mixture when cold. I had the same problem. I CAREFULLY took apart the WUR, cleaned everything and everything is just fine now. 81'sc

HI, the control pressure regulater is the problem (most likly)at cold start and for about 3 or 4 min. during warm-up, control pressure must be about 1.8 to 2.3 bar.after a few min. this will rise to about 3.1 bar .
when this unit fails it fails high, so not enough fuel during warm-up.
also you better hope it doesnt backfire while you are feathering it. airbox replacement is way more expensive than a control pressure reg.
have fun.