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Discussion Starter · #1 ·
Attained a 1991 Alfa Romeo 164 V6 QV manual ths week, i have had heaps of autos but this is my first manual, very fast 164!!!

She has been idling on 2000rpm on startup (sometimes 2500) for around 30 second to a minute then she would drop down to normal, now startup, warm and hot she is always idling on 2000rpm or more and will not drop no matter what!

Is this a common 164 manual fault??? Never had a problem with the autos always baby bottom smooth idle.

So far i have replaced the IDLE ACTUATOR, AIR FILTER and FUEL PRESSURE REGULATOR and these items have made no difference whatsoever!

Could the MOTRONIC ECU have a idle fault???

Any ideas Steve or any 164 manual owner to save me diagnosis time???

Thankyou VeeSix :confused:
 

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Me thinks you need to reset the min max switch on front of throttle body. There are two 6 or 7mm screws holding it in place.

Adjust is so it clicks on/off between 0<1 degree of throttle movement.

Report your findings/results.
 

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My 91 164L did this and that was the fix. Does the later engine use a minimax switch or a potentiometer?

I thought that the QV (Quattrovalvole, four cam) engine was much later than 91 model year. QF (Quadrafoglio, 2 cam high compression version) maybe? Equivalent to our S version. If so then they both used the same throttle switch. Easy peasy to adjust correctly.
 

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Discussion Starter · #4 ·
Hello Steve and Michael
Thankyou very much much for your prompt replies

Yes i know that part Steve it is a little black unit opposite side of throttle cable attachment, yes attached by two bolts, i will go and try that now Steve and e-mail you back, i think i even have a couple of these spare so can definantly rule whether this is the problem, never adjusted one though, guess i will see how i go, why do these go out and need to be reset Steve???

Yes they are stamped here in Australia 164 QV Michael, which i believe stands for Quadrifoglio Verde, yes i believe they are equivelent to your S version, i think the same thing just different names different countries, imported here 1991 thru to 1993 i believe, same as your S version, i think i saw one of your threads last year Steve and you purchased a run down one off some lady, i will go back and check your threads Steve later, anyway down to the garage to try and sort this idle problem out, would love to take the kids for a spin today after school

Thankyou David VeeSix :)
 

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That minimum switch can be tricky: I found its adjustment hardly made a difference when I had a vacuum leak. Once the leaks were fixed and I got the idle back to its proper speed (750 rpm) the adjustment of that switch became crucial.

I'll build a smoke machine this weekend. I've still got to check why the turbo pressure is low.
 

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Waiting with rum tainted baited breath for VeeSix's response. I have been laying weed blocking paver cloth, aggretate and paving sand and pavers today so even after a stint in my hot tub I R whipped.
 

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Discussion Starter · #8 ·
Hello Steve, Spiral & Ital
Thankyou for your replies
I had about an hour or so yesterday afternoon before work to play with it and just ran out of time, sadly i did not get to take the kids for a spin in it

Anyway here is the run down Steve, played with the min/max switch on it, no difference, removed that one and put another one on, started to play with that one, with the bolts in loose i moved it all the way to the right and presto idle dropped down to normal, yeehah i thought! was going to send Steve a kiss in the mail, was nice to hear her idling on 900 rather than a constant 2000, then i thought well i will just double check, turned her off, started her again and rrrr back to a 2000rpm idle, dam, played with the switch a few more times, got the idle down started her again back to 2000, went thru this process about 5 times, same thing, play with the switch, idle down, turn off restart back to 2000rpm idle, that was it had 5 minutes for a VB schooner left, what do you make of that Steve & others???

Dam that lower switch bolt is hard to get back in, pity someone with fat fingers, not working today but will still not get a chance to play with her today, wife is going to a Friday night royal wedding party, good luck, can not wait for it to be over so the news gets back to real issues, not these people who waste millions on crap, anyway back into the 75/Milano V6 3.0 today, i promised the kids a bushwalk and a train ride, will check back in in about 6 hours Steve to see if you have replied, will get a chance tommorrow of about 2 hours to work on her before work, dam Saturdays 12 hour shift!!!!!
The only thing that keeps me sane is that i get to drive a V6 Alfa Romeo thru the hilly countryside to and from work, 40 minutes of V6 top gearing!!!!!

Thankyou VeeSix
 

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I think you need to reverify min max throttle switch is set correctly with engine off so it clicks off/on between 0<1 degree just as you move throttle off stop using a small screwdriver is inserted inside plastic cover opening to just move it off factory preset stop.

That being done try starting engine again and let it warm up and see if idle correct.

Now if you press accel to rev up and it won't go back to idle correctly verify throttle arm is resting on factory preset stop under plastic cover if not you have a binding throttle either in min max switch, at butterfly inside throttle body or under plastic cover or accel cable inside it's housing.

You may have to remove clamp screw holding clamp over hoses on top of plastic cover to investigate for binding condition.

Report your findings.
 

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Discussion Starter · #10 ·
Hello Steve
This is possibly going to be a "overlook the obvious" one, to start with the accelerator housing was missing the plastic cover, a common thing i have found as i have purchased quite a few 164s over the years, i sarted playing with min/max switch a bit more as you mentioned, i could hear the click and there seemed to be nothing wrong, then i started noticing the other side as i was turning it, it seems the accelerator cable was coming/loose at the end, readjusted the accelerator stop as i was turning it up and down to try and get a idle and now shes idling great, took it to work and back not a problem yet, ran out of time again but there maybe something missing from the end of the accelerator cable area, will check today against the other 164s, being uncovered the accelerator cable could have been getting caught on something, makes sense as when i first recieved the 164 pressing down on the accelerator pedal would sometimes bring the idle down, sort of like the cable was going back into place.
Anyway it was another great learning curve plus i learnt about the min/max switch which i never really payed much attention to before.
Maybe i need to stop having a schooner everytime i work on the 164.
Thankyou VeeSix.
 

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R&C my excuse but I worked on Black Beauty earlier in the day and hope for success with my radiator leak and tranny issue.
 

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Discussion Starter · #12 ·
Metal clip missing!!!

Hello Steve and others
Finally found time last night to see what was missing or playing up!
The accelerator cable has a small metal clip at the end that sort of holds it in place, very small and fragile, drop it in the car and you would be lucky to find it again, noticed it as soon as i checked the 164 against this one!
Do you know the clip i am talking about Steve?
 

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