High Idle Speed (intermittent)

[PistonBroke]

Hi Guys,

I really dont know what I would do without the BB. It really is great having all this expertise at hand. So thanks in advance to one and all (once again).

This one seems a little strange to me. When I start the car ('79) first thing the idle speed will sit around 1500 rpm until it warms up a bit and drops to just below 1000 rpm which to me seems about right???? However after driving for a while especially in traffic if I pull up at a set of lights the car often idles at somewhere between 1500 rpm and 2200 rpm. Drive on another couple of miles pull up at another set of lights and the car will be idling again at around 900 rpm.

Is this possibly just a sticky throttle cable and if so how and where do I sort this? Or do you think this could possibly have something to with the cold start microswitch I have read about on here, I do have an issue with popping during deceleration so wondered if these things are related.

While on the issue of fuel systems I cannot for the life of me find the one way check valve around my vapor seperator in the trunk. Am i being really silly and its hidden somewhere or is there a possibility that a PO has removed this? If so are replacements available? And is it dangerous without it?

Thanks again

Piston Broke

'79 Spider Veloce (currently)
'81 Alfasud 1.5 ti (previously)
'88 33 Cloverleaf Sportwagon (previously)
'89 33 Cloverleaf Sportwagon (previously)
'91 33 1.7 ie (previously)
'91 164 V6 Lusso (previously)

[Roadtrip]

It's possible that the throttle cable is not adjusted correctly or that something is sticky. The throttle cable should have a slight bit of slack in it when at idle so that the relay crank is sitting firmly on the idle stop screw. If the throttle is being held open slightly, that could very well cause some burble and backfiring because the fuel delivery is never being cut off during engine decel.

My recommendation would be to do a soup-to-nuts tuneup, which would find and correct such problems.

[usatrade]

Hi
I have the same phenomena with my 79. Cold it 'runs between 1500 and 2500 RPM until warmed up. If Hotter outside (65 to 75°) cold is about 1500 RP? until engine hot. Then iddle is perfect. Throttle cable is ok.
I do not have the answer but woukld love tpo have it like PistonBroke
Claude

[74rally200]

Air Leak? Do you have carbs or injection? Either way, bad sealing on the intakes would seem likely to cause these symptoms.

[usatrade]

Hi
I have Spica.
But if I had an air leak the car would not iddle perfectly when at temperature.

Presently I have removed everything on the intake and will put it back shortly. we will see.

Claude

[PistonBroke]

Hi,

Yeah mine is fuel injected too. When you say leaky intakes are we talking into the SPICA unit itself? And if so could it be just a case of tightening a couple of hose clamps?

Thanks

[PistonBroke]

John,

Thanks for your reply also. When you say " a soap to nuts tune up". What do you mean!!!! I am hoping its just a phrase I havent heard before but I presume it will involve the full SPICA tune up/ troubleshoot from the guides you sent me recently (and I am still pouring through, even though they make me really nervous).

Thanks

[KTMARINER]

I have the same problem with my '78 fuel injected alfetta sedan..super high (2000rpm) idle until it comes up to temp..once it reachs temp it settles down and runs absolutey perfect..
Any suggestions are appreciated

[jclark]

Quote:

Originally Posted by PistonBroke John, Thanks for your reply also. When you say " a soap to nuts tune up". What do you mean!!!! I am hoping its just a phrase I havent heard before but I presume it will involve the full SPICA tune up/ troubleshoot from the guides you sent me recently (and I am still pouring through, even though they make me really nervous). Thanks

[Roadtrip]

Yes, soup-to-nuts . . . alluding to all the courses of a meal. Favorite expression of a previous commander of mine . . . sort of like . . "Ok Gentlemen, I want a soup-to-nuts briefing on this deployment 10 hundred Tuesday morning."

No need to be nervous. There are only a few adjustments that can be made and if you follow the directions to the letter and in lockstep, it's really pretty easy. You want to be familiar enough so that you understand what you are actually doing on each step. Keep reading.

With regards to the evap system, yes the one-way check valve is pretty important because it prevents a vacuum from forming in the tank and possibly causing a fuel flow stoppage.

If you're missing a check valve, try an auto parts store for a generic one. Lots of them are used on modern cars in the emissions tubing.