81 FI rough idle when cold

[Jazgeek]

Howdy....

81 FI CS0....

when engine is cold it idles pretty rough and at times almost dies (but not completely). After engine up to temp it idles fine and sounds great. What should be the first things I should look at?

[So Cal Mark]

what is the cold idle speed? If it's too low the idle will be rough. Cold idle speed is controlled by the aux air valve. It acts like a fast idle cam on a carburetor. It opens when cold to allow air flow around the throttle plate and gradually closes as the engine warms up, slowing the idle down

[ga.spyder]

Jazgeek,I just had exactly the same issue on my 82 F.i. Mark is correct (as usual!).I had to change out the aux. air regulator ,and the problem was solved.You can check by pulling both hoses going to it ,and temp. splice them together.I used another piece of hose ,and just wrapped it w/ electrical tape.If it starts and idles up,the regulator is bad.Once it warms up,it wont run right w/ the splice in place,so re connect the 2 hoses.Hope this helps.
Craig ps...its the least I can do after you turned me on to the Gord's!

[rlux4]

Craig, you dirty dog you! I am experiencing rough idling at start up, sometimes it even dies if I don't baby it for a few minutes. I read your post and figured OK, I've got about everything else taken care of, I'll do the aux. air regulator now, I mean Craig did his after all. Then I priced it. $230 to $369! Man, for that much I'll keep babying it cold. Hmmm, maybe bypass the expensive little bugger and splice in 3/8" ball valve. OK, I'd have to raise the hood and open it, then close it a minute later, but I'd sure be saving money. Only until I win the lottery though.
Ron

[ga.spyder]

Hey Ron ,I went to Jon Logans Midwest 124 site and he had some used a.a.r.'s for $25.A price even a builder in a housing slump(can you relate?) could afford.But ,he didnt have any left .He did find a nos part on his bench that he sold me for $50!! YEAH JON!! Anyway it fixed the problem,I had been driving it like that for a year. Brad Artigue told me how to diagnose and test it.As usual ,a lot of help from the Fiat community.
Craig

[rlux4]

Thank you very much Craig. I think I can pass up the trip to Lowes for the ball valve now.
Yes, I can relate. Luckily, this go-round I stayed away from building spec homes. Because of the market though, I'm actually having to strap on the old tool pouch and do some of the work. Oh well, helps keep me from getting decrepit, hopefully.
Ron

[ga.spyder]

Hey Ron we also didnt get sucked into the spec house craze.There are a lot of guys here that are dying w/ interest payments ,or are letting the banks take the spec houses.We are surviving on a couple re models and garage builds.I also have ''strapped on the bag'',although with just me and my partner we have always been pretty hands on.We have a big home to build in the fall ,so we should be ok until then.
good luck ,Craig

[YVFiat]

I'm having the same problem with my 82. However, I've already replaced the auxiliary air valve and still have the problem. Any other ideas?

[domdommm]

I have the same problem car won't idle when cold, when it warms up its fine. I suspect its the same issue as the other members on this post aux air valve. I wanted to know if there is a way to test the AAV and can it be cleaned. thanks guys

[focodave]

Hey domdommm,

Use the "search" feature on tab above and simply search on "aav".
You will find a ton of good posts showing how to inspect, troubleshoot, and repair the AAV.

Dave

[spider2081]

I think the aux air regulator uses a bi metallic strip to open the airway and power from the Dual relay along with a ground that comes from the ECU to close it. If it is not opening when cold it might just need to be freed up by cleaning with carburetor cleaner.

[PhillySpider]

The FI system is very basic and easy to work on. I highly recommend the "FIAT Fuel Injection Diagnosis and Maintenance Manual". I have an original copy, but you can find it for download...sorry, dunno if i can link to or reference the mira page.
It's an excellent guide to completely understand the system and EASILY perform a total system tune up. We had no cold start, rough idle, sputtering, misfiring, and stalling...of of which resolved going through the tune up process.

[RRoller123]

FUEL INJECTION DEBUGGING
http://www.hiperformancestore.com/Ljetronic.htm
http://www.njfiats.org/joomla/images/st ... BoschL.pdf

FUEL INJECTOR CLEANING:
WWW.OKINJECTORS.COM
www.witchhunter.com

FUEL INJECTION MANUAL
http://www.mirafiori.com/faq/fiatFI_may2002.pdf

FUEL INJECTORS CHART
http://users.erols.com/srweiss/tableifc.htm

L-JETRONIC MANUAL
http://www.hiperformancestore.com/Ljetronic.htm

L-JETRONIC
http://mastertechmag.com/pdf/1988/11nov ... ronic2.pdf
http://jenniskens.livedsl.nl/Technical/ ... tronic.pdf

L-JETRONIC FI MANUAL (FROM VW)
https://www.type4.org/manuals/ljet/index.html

BOSCH L-JETRONIC MANUAL – BEST ONE:
http://foxed.ca/rx7manual/manuals/BOSCH ... Manual.pdf

[domdommm]

Would anyone know if the bosh aux air valve 0280140120 in terchangable with the Bosch 0280140126 they look identical

[BryanHubbard]

I’ve got the same issue. I replaced the aar with a used one I bought off of ebay, same issue. One of the posts says to disconnect the 2 hoses and splice them together. If it starts up, the unit is bad???? So I’m assuming if it doesn’t start up, the unit is good?