idle issue

After chasing a fluctuating idle I found a toasted AAV and a sticky electrovalve. I am passed those issues (I replaced the AAV) now and after reading Steves' post (extremely helpful, thanks Steve) on the two electrovalve circuits I found the vaccum lines reversed. OK now for the issue at hand. Under cold start conditions (ambient of 60-70F) I have to hold the pedal down a bit or the idle stumbles around 500-800. After the light goes out and the cold-start air valve closes the idle stabilizes at 1000 and all is spec after that. I have no issues with other than the low idle at start up. I checked control pressure cold and found it to be too high and I looked in the Bosch manual and it suggests a cold pressure of 1.2 bar. Is 1.2 correct for a 2V engine? Any suggestions on anything else to look at will be most appreciated.
Thanks again to those few who have educated replies! less but still lost

 

There are several different WURs used on different models so the "1.2 bar" value may be appropriate for some models (when fairly cold), but I believe the US i 2-valve WUR has a somewhat higher cold control pressure -- see the graphs on page D39 in the Mondial8/QV WSM 281/83 (if you don't have a copy go here: http://ferrari.cdyn.com, and you can download it).

PS You should also compare the 10-digit Bosch PN on your WUR to the one given in the US i 2-valve graph -- not uncommon for people to make an incorrect substitution when replacing (although there may be a different, but correct, supercession -- your homework, if so ).

PPS Need to do a little "mea culpa" here. There are two different cold start valves, that have different operational logic, so the connections to the electrovalve are different depending on which cold start valve you have. I didn't realize this when making some prior posts about the electrovalve vacuum line connections so my advice would be to verify physically that the cold start valve is indeed "open" when your cold-running light is "on", and "closed" during warm-running.

 

Before you start chasing more complex stuff make sure the system is airtight. The CIS warm-up/idle all goes to hell in a hand-cart if there is air finding its way into the system where it shouldn't. When was the last time you had the seals replaced on your injectors?

I found a hole in the long vacuum hose that goes back to the ignition box under the trunk floor in my 328 - only found it when I had the inner arch liner off for something else. Aside from allowing air into the system it also meant I was getting no vacuum advance.

If you find an air leak then also get your mixture checked using a gas analyser after you have fixed it.

 

Thanks for the advice. To answer a few questions---I done a major this winter including SS valves. All new injector seals and all injectors were pressure checked. I have removed the AIR system and properly plugged the same. I have been chasing this high idle hot problem and found the AAV would not close at all and vaccum lines were reversed on a sticking electrovalve replaced both and yes I have an open air valve until the light goes out and the air valve closes. This has been driving me nuys and the fact still remains that after I nurse the right peddle to keep the rs up everything is perfecto---idle all day long at 1G. This evening I looked at the CO values and it was running 2.0 (Gunnson single gas ) if I read the Quatro WSM correctly it should be 1.0 +- .5. @900-1100rpm. for a 2V. I don't see the logic of a slightly rich condition being the culprit here. Steve, is there a flaw in my thinking here? I even checked the cold control using the graph and with the given ambient I should have a reading of 1.5 and I did so I let her go to cooling fan temps and the control went up to 3.2 (my old brain says it read the spec was 3.1) I don't see the tenth causing my issue either. I really don't mind warming it up but I cannot tolerate some system running a miss. Thanks in advance for the time some of you guys spend helping us idiots.
PS It took 25yrs. of playing with Jags--------- what is it they about making the same mistakes over and over------- I had to have a Ferrari---------- and I love it.

 

Depends on where you are measuring this 2% CO value -- if it is upstream of the cats (or you have no cats) = shouldn't be that much of a runability issue. The stock CO value is a bit on the lean hairy edge to get the low emission numbers, and 1.5% CO will probably run better (and 2% should be A-OK from a runability standpoint -- I can't recall the upper CO limit where it would be so rich that a cylinder would stop firing, but even 5-6% CO runs OK -- even if MPG goes down and the cat catches on fire). However, if you are measuring 2% CO after a catalytic converter, that would imply that you are way, way rich (that it might be so rich, that when cold, cylinders are misfiring).

(Assuming warm-running is good) If the WUR is doing the right thing, and the AAV & cold start air valve are open, your cold RPM should be increased -- are you sure that the air lines in the cold start air valve system are unblocked/unkinked?

 

Same issue I have. Car runs great when it is started up and later when warm,but thanks for the hint looking for an air leak in the line somewhere. Like living with my wife, there are some things I have learned to live with.....since the cold start works well every time with the throttle down, guess I will stick with it. But then it sure would be nice if I could find the glitch. Pride I guess

 

Thanks again for your input Steve. When I done the major I replaced the cats with "test pipes" and cleaned out the bits from the muffler. I had the gas pipe stuck up the tailpipe and the fuel dist. responded as expected when the mixture screw is turned. I was questioning the 1.0 book spec.------------ thanks for the validation on the 1.5-2 CO. I am so bored with the cookie cutter cars ,that I am used to, that I never gave a thought to the very possible issue with having the wrong WUR and or AAV. I will check those numbers this morning. In desperation I am going to remove the entire cold start system and inspect every valve and hose. As a matter of habit I would do this as I re-assembled the engine this past spring but I am begining to show signs of memory lose and I have to admit that time is catching up tp me! Just to be sure when I done the major I replaced all the wires with new stuff from Dave Helms and checked the resistence as per Daves' reccomendation. I just have that feeling that the gremlin is right in front of me and most likely self induced. I will be sure to post the fix when I find it. After reading every thread I could find pertaining to the CIS system I can ,with certainty, say that there is allot of misinformation out there and thanks to guys like Dave, Steve, Rifledriver and Fastradio I have made it this far but close only counts in horse shoes! Don't mean to leave anyone out so let me say this forum is the best. still LOST

 

OK ,as I predicted I found another bad part that I thought was OK. The cold start valve was closing in appearence only. After I removed the whole system I found that the cold start actuator was moving to the closed position but the valve did not seal. OK I plugged the plenum and air box. I aligned the fuel distributor as per WRM loosened a delivery line and tightened the adj. screw until fuel just filled the cavity and then backed it off 1/2 turn. Now before all of this the car ran fine but did not have a fast idle and I had to hold the pedal down to start and warm but once the light went off the idle was a perfect 1G all day no matter how far or long I drove. I just was not happy with the cold start system not working. I also found the sensor plate not centered and corected that. I believe that I am reverse engineering what the PO did or had done to compensate for the bad AAV and cold start valve. NOW---------- I went to start the engine and I had to pedal it to keep it running and the exhaust was sooo rich I was choking. I suspect that someone tried compensating for the extra air by adding more fuel but what the hell did they do?? I checked the WUR again and it coinsides with the graph in the WRM both cold and hot. If my thinking is correct I need to obtain the free play that the manual calls for. Any suggestions are appreciated. Yesterday with the bad cold start valve I had a CO reading of 2.o hot. I don't need to check it today---------- its way rich! Lost

 

There's no "freeplay" in your K-Jet FD (see your other thread).

The good news is that you've maybe explained why you didn't have an increased RPM during cold-running -- i.e., if the cold start air valve was letting in X amount of air during cold-running and warm-running, there would be no increased cold idle RPM.

The bad news is that if you've now fixed the cold start air valve to not let any air in during warm-running, you'll need to increase the amount of air entering the engine via the throttle plate adjustment and/or the air bypass screw to reachieve the 1000 RPM warm-running idle speed that you had when some air was (wrongly) entering via the cold start air valve -- read Chapter D in the Mondial8/QV WSM 281/83!

 

Steve I damn sure am not questioning you but everything I read says that the sensor plate should not protrude more that .5mm above the upper end of the flat in the bore. The fix is to drift the guide pin. My thinking says that the PO had to find a way to richen the mixture so it would run. Now it will not start so I am going through the steps as per WSM.
Than you again for taking the time to help! Tom

 

Now I get it------------ I was making an association between free-play and the stop position of the sensor plate!! A couple of taps on the guide pin and a mixture adj. and all is well with the world. It would be impossoble for me to get this right without a gas analyzer!
I can't pass along exactly what the problem was but I found these items bad--AAV, electrovalve and the cold start valve. Along with the bad bits I also found the air sensor plate off center and the stop height of the sensor plate was way too high and the vaccum lines to the electrovalve were reversed.
My thanks to Steve again for his time and knowledge. I read through the chapter D many times but with all the conflicting info (I found on the internet) I lost sight of what to do. A few words pointing me in the right direction from Steve made things happen and she is back on the road. Tom