930 CIS Issue - Low Idle and Hard Cold Start
03-15-2006, 10:42 PM
#47
Rennlist Member
Glad to see it's fixed!!
Yea Chet, what the hell. I can not even say anything after that. Too many new things and not noticing the obvious as I've replace that cap each year for many years.
In any case, only did the initial 20min run in. Probably will not be a few weeks until I take a quick run on street. ...it's so noisey and kind of a spectal running down street.
Yea Chet, what the hell. I can not even say anything after that. Too many new things and not noticing the obvious as I've replace that cap each year for many years.
In any case, only did the initial 20min run in. Probably will not be a few weeks until I take a quick run on street. ...it's so noisey and kind of a spectal running down street.
03-16-2006, 12:41 AM
#49
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The question I have is why did a PORSCHE MECHANIC put that stupid filter on the AAV, and why did I think it he should know what he's doing so that's OK?
Now in retrospect I can see why the Tripstermobile had such a hard time starting - it essentially had a massive vacuum leak. Problem is when the AAV closes the leak goes away - yet the motor is still running very rich and backfiring on shutdown. How is this related? Remember, my car has no AAV and it runs just fine with the CO set at 3%.
Now in retrospect I can see why the Tripstermobile had such a hard time starting - it essentially had a massive vacuum leak. Problem is when the AAV closes the leak goes away - yet the motor is still running very rich and backfiring on shutdown. How is this related? Remember, my car has no AAV and it runs just fine with the CO set at 3%.
03-16-2006, 06:58 AM
#51
Drifting
I've known for a while now that Rarely has been running around with no AAV (I learned about it on Pelican doing some research on the decel valve). In my never ending quest to get rid of things not needed and overly complicated, what is the consensus on removing the AAV and plugging the connection on the I/C? Good idea? Bad idea?
03-16-2006, 09:23 AM
#53
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I removed mine after it broke. ...but it's a race car, so not a big thing holding foot on gas for two mins until it'll idle on its own. I would be a pain on street car because first time you let foot of gas going down driveway it'll stall.
03-16-2006, 10:50 AM
#55
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I removed the AAV (3 years ago) because I don't need it now that I live in a state that never sees snow.
On a "cold" winter day (below 32*F) the AAV had a nasty habbit of screaming the motor if I started it up in a parking lot after the car sat for an hour. Apparently the engine oil was still warm but the AAV was cold and open. It would fire up at 2500rpm then take a minute to close off to a normal idle. Couldn't stand it.
The car starts up just fine without the AAV, I have seen no adverse affects to removing it in my climate.
As for the Tripstermobile, at this point it looks to me like the total idiot mechanic that sold him this motor must have "tuned" the mixture to run with that filter on the AAV. That would explain the 8% the engine has when warm (with the AAV closed). Stay tuned - we'll adjust the mixture on Friday.
On a "cold" winter day (below 32*F) the AAV had a nasty habbit of screaming the motor if I started it up in a parking lot after the car sat for an hour. Apparently the engine oil was still warm but the AAV was cold and open. It would fire up at 2500rpm then take a minute to close off to a normal idle. Couldn't stand it.
The car starts up just fine without the AAV, I have seen no adverse affects to removing it in my climate.
As for the Tripstermobile, at this point it looks to me like the total idiot mechanic that sold him this motor must have "tuned" the mixture to run with that filter on the AAV. That would explain the 8% the engine has when warm (with the AAV closed). Stay tuned - we'll adjust the mixture on Friday.
03-16-2006, 10:54 AM
#56
Rennlist Lifetime Member
Keep in mind that most do not actually check CO or AFR. I still find most wrenches winging it then they can't figure out why the car is not running right. I get at least a dozen emails a week about starting, running issues with the CIS and when I ask about control and system pressures and what the CO or AFR at idle is they all say " dunno" I set it by ear. ARGH...that is like saying I can map EFI by ear.
03-17-2006, 03:31 PM
#58
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Just did some fine tuning on the CO, here are the results.
Drove the car in today to work, car ran pretty good but not great. Rarly8 put his CO tester on it and we found the CO @ 13%. He adjusted it down to 3% and the car sounded great, we drove it and it ran great, then when we turned off the engine it popped back thru the exhaust (loud). Then after setting for 30 min's in 60 degree weather it acted if it were very cold. He then set the CO back up to 5.5%, car runs great again but still pops, sounds like a mild shotgun.
Right now I am letting it set for an hour to see if it cranks cold nature again.
Can this be because the control pressure is set on the low side? Car had a very mild pop until we brought the CO down, almost not noticeable.
Drove the car in today to work, car ran pretty good but not great. Rarly8 put his CO tester on it and we found the CO @ 13%. He adjusted it down to 3% and the car sounded great, we drove it and it ran great, then when we turned off the engine it popped back thru the exhaust (loud). Then after setting for 30 min's in 60 degree weather it acted if it were very cold. He then set the CO back up to 5.5%, car runs great again but still pops, sounds like a mild shotgun.
Right now I am letting it set for an hour to see if it cranks cold nature again.
Can this be because the control pressure is set on the low side? Car had a very mild pop until we brought the CO down, almost not noticeable.
03-17-2006, 03:42 PM
#59
Rennlist Lifetime Member
Hook the pressure gauge to it and watch what it is doing during this time. I wonder if it has a problem. The Head might also be an issue. Is there smoke when it starts? Does it sound like each cylinder is lighting off or do they all sound like they are hitting when this happens? What are the rest pressures? Do you have an accumulator in the line. This also acts as a dampener and holds system pressure. If this is not present you will drop pressure and worse yet have inconsistent pressures from the pumps. The internal regulator can not handle the pressure influx by itself.
03-17-2006, 07:13 PM
#60
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Start-up is normal, CIS is not like Motronic - he will have to get used to it.
The only issue remaining is the "POP" on shutdown. We had no time for further testing today. I told him to get some seat time and see if anything changes or any trends develop. The engine is not running overly rich and does not smoke on startup. We're real close - thanks all!
The only issue remaining is the "POP" on shutdown. We had no time for further testing today. I told him to get some seat time and see if anything changes or any trends develop. The engine is not running overly rich and does not smoke on startup. We're real close - thanks all!