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WUR resistance...13 ohms
around 10°C now |
Go visit your friend.........
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Jan, Ask your friend to check the WUR resistance of the WUR-072 in his car when the engine is cold. And compare the values (Ohms) between these WUR-072's. Post the data. Your WUR is out of spec. and would always cause this erratic cold idle. This problem will not go away until you install a good working WUR. Lastly, stay away from tinkering your mixture setting because it has nothing to do with your erratic cold idle problem. Keep us posted. Tony |
my friend doesn't know how to measure that, will have to go by his place and do it myself. :)
in the meantime, been digging a bit further while waiting for a duty cycle meter to arrive: - checked the 15°C sensor: OK - then i wanted to check the air flow sensor position (which is OK) and by taking off a couple of things (cruise control cable etc), i noticed that the throttle lever did not touch the 15 degree position switch! so the switch was open all the time...this is a cold enrichment thing, so i guess that has not helped my cold running issues. I managed to reposition it, and bend back the throttle lever to it's original shape, and now it's functioning properly. The switch itself measured OK. - next up the list is the butterfly: the base positioning looks too crooked as far as i can tell (need smaller mirror), probably 2 or 3mm height difference between both sides of the butterfly...i think this should be a little less. Can anyone confirm that the closed butterfly should be following the horizontal edge in the throttle body more closely? I know it shouldn't hit the housing. |
ok guys, started the car this morning at around freezing temp, starts first time, but idles at 500rpm. It seems to start and run a bit easier now i have corrected the 15 degree switch. It holds the 500rpm without any problem, not fluctuating, not stumbling.
In order to further troubleshoot: can anyone explain me why i can simply raise the cold rpm by turning the idle air bypass screw and i cannot raise the rpm by using the (working) AAR? These things both give bypass air, right. Is it because the AAR takes the air from the boot and maybe changes the air flow sensor position slightly? when the car idles cold i've checked the following: - unplugged the fat aluminium AAR vacuum line, plugged both sides. no difference in cold running. - When i take off the plug on either side, the engine stalls immediately. so the lines are definately not blocked and pulling air. - when the engine is idleing, when i push or pull ever so slightly on the air flow sensor, the engine dies. thanks for thinking along, cheers, Jan PS it seems anal to be bothered about such a small problem...'i could simply hold the rpm's up with the throttle for 30 secs and done'...but by searching for problems and causes you really get an understanding of the system, which IMO is definately worth the effort. |
The aar uses air that is already measured
It does not increase the lift of the sensor plate The idle valve does increase the lift of the sensor plate as it increases the drawn air The aar only Lets through air following the amount of opening but does not suck in more air then already present in the systeem |
OK, my buddies US 80 SC 072 WUR has 11 ohms at approx. 7°C...
doesn't really matter right now, took the valve covers off for setting the clearance, and found 3 broken headstuds, guess we found the reason for the oil leaks. the engine is already been dropped, disassembled and brought to specialised firm to overhaul...full cylinderhead revision, cleaning up of pistons and cylinders (they luckily still look good), and they're going to take out the headstuds, and open the case and have a look at the crank for good measure. No vacation this year :D |
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Sorry it's unrelated but where did you purchase the RUF CTR front bumper? How is fitment? It looks great, I intend on putting one on my SC. |
hi there,
i don't know which brand the bumpers are, nor where the PO bought them...they were on the car when i bought it. Fitment is OK, but it is FG so you can't compare it to OEM stuff. in the meantime, the engine has been professionally overhauled from top to bottom, 12K € but it doesn't really matter...brand new engine now, also brand new clutch kit, etc etc...the full list is 2 pages long. Sortof lucky too, as we discovered that the clutch was almost worn to the rivets, and also we found a broken valve spring in one of the cylinderheads. So it was time to look at it. :) i still have the cold start issues, but for now, i'm gonna leave it be and just drive the thing. It always starts but runs like **** for 10 seconds. After that it is fine. It drives wonderful by the way, much smoother sound (now that the cylinders are effectively airtight :D ) , much less vibrations, no leaks, and after about 600 miles she appears to use 0,0l oil. I've run it in perfectly, next week oil and filter change (porsche classic oil). |
Though completely over my head, this is an amazing thread.....so many super smart guys on here.
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check the AAR. it should be open when cold and it should close when heated.
sounds like it might be stuck. if it is remove it and try some carb cleaner in it.. both the AAR and the idle adjustment use air that has already been metered by the AFM., if you increase the idle with either one it is just like putting your foot on the gas. same goes for the AAV. that is open only when cranking. it closes after it is started. may not be related but since you have a new motor you have the injectors cleaned and checked. I saw something about vac advance. that does not do anything at idle. |
the AAR works correctly, i checked that a while ago.
The car drives perfect after one minute, and when fully warm, etc... i adjusted the WUR both leaner and richer (cold control), but both ways have no impact on cold low idle. how can i easily check if the csv mounting is unblocked? I've read a couple of stories about the csv mounting flange with blocked air outlet...which means that AAR and decel valve etc...would not have any effect. |
i could disconnect the vacuum line from the back of the boot to the AAR/decelvalve and see if the engine pulls vacuum from that line, correct? (close the hole in the boot while trying)
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OK, got myself a duty cycle meter, and with cold engine i'm getting 35 on the readout...which means 65% duty cycle i guess.
Pushing the throttle slightly temporarily reduces the reading to 25, then back to 35, so that is very correct for now. Gonna go out and warm the car up thoroughly in an hour or so, then do some more measurements. I have a O2 sensor on order as well, gonna get it tomorrow, wire it in, and see where we go from there. |
yapp, i like the color very much :)
just went out for a drive, engine nice and hot, 50% duty cycle, so that's all working OK, let's see what the mounting of the 02 sensor will bring. i made the WUR adjustable, and fooling around with that changes cold starts from very poor and stuttery to 'sort of OK'...but always with low idle. after less than a minute the car idles fine, and accepts throttle very nicely. Once warm, it is brilliant. I've finished running it in too, checked all the valves (all perfect) and changed to Porsche Classic 10W-60 oil. It hasn't used or lost a drop of oil since rebuilding. I have to say, touching 6500rpm is an almost lifechanging experience :) |
OK, i wired in a bosch 501 one-wire 02 sensor, warmed up the car and checked mixture and duty cycle.
i was not far off with my 'setting on hearing'...maybe 1/8th of a turn. great to see the duty cycle change when you turn the mixture screw, i saw it nicely dropping and rising by turning left or right on the screw. I have set it now at ca. 50%. I think i picked up some low down horsepower too, it feels more crisp from 2000 to 3000...i think i lost a tiny stumble through slow acceleration which was there before. Maybe it's because it's colder out today, maybe it's in my head...anyway, got a great feeling to have tackled another little item and learned along the way. (and it's great to see that the computer is working as it should.) |
now let's see what mpg's i will get, not that i care :D
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Jan, I've been having the exact same symptoms with my car since I refurbished my CIS. The thing is, about once in every 12 starts or so it starts up perfectly. And before the rebuild I did not have this issue (just very high idle due to a blown air box), so I don't think it's the WUR. All my components seem to check out perfectly, all my pressures are within spec. My o2 sensor is new and connected. My gut tells me that this is an electrical issue. The wiring on these cars is old. I noticed that there was a fair smount of corrosion on the terminals of my WUR. That connection shouldn't effect the cold start idle, but perhaps one of the others might? Just a thought.
I've been living with it. 30 seconds of slop is tolerable, since the joy of driving isn't effected, but it would be nice to resolve this issue. I'll hopefully have some time in the next couple of weeks to play around, and I'll post if I find anything interesting! |
Hey Jan,
I may have made some progress, check this out: http://forums.pelicanparts.com/porsche-911-technical-forum/912358-82-cis-cold-start-issue.html#post9100276 Try it out and let me know you get the same results. Groovy |
hi groovy, yeps, 20 seconds of spluttering is not that hard to live with, especially since i need like a minute to get out of my garage, open the gate, close the gate, hug the dog, etc :) so by the time i'm out in the street the car runs great...
i'll try your throttle tap to see if it catches more quickly. We're still having very cold nights here (almost 0°C) and morning starts mean 5 seconds cranking before she catches. |
on a side note: i think the car feels a bit less smooth with the O2 sensor connected, especially driving steadily. Not a big issue, because i'm used to a very nervous KTM motorcycle, but just noticing it.
If i had a working km-o-meter i might discover some changes in mpg, but for now it's gonna be guesswork. |
Things to check.........
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Wreckah, Your WUR is still suspect to me. What is the WUR's heater resistance (Ohms) when engine is cold? Have you checked and tested the spray patterns of the CSV injector and the six (6) fuel injectors? I have successfully started engines and cars well below freezing point temperature many times as tests. Keep us posted. Thanks. Tony |
Hi Tony,
i'm aware that the WUR is still a very possible culprit...but where can you find a new one? i've been looking around for a while...nothing yet. And i don't feel like sending it off for a rebuild, that would mean a couple of weeks off the road...maybe next winter... Will check the injectors when i feel like another testing session, but for now, i'm focused on driving the car for a little while, just enjoying it :) cheers, Jan |
fuel distributor test OK, next up is injector test
distributor test = - injectors taken off - fuel lines in bottles - bridge FP relay - ignition on - no leaks when airmeter is not touched, not a drop - push the airmeter up, fuel starts coming, this is after about 30 seconds i would say - all bottles are as good as identical https://scontent.xx.fbcdn.net/v/t1.0...8f&oe=579D4B6D |
injector test: full open, big spray
https://scontent.xx.fbcdn.net/v/t1.0...e6&oe=579EB3B9 injector test: small spray, barely open, they all seem to open at the same time and spray very similar https://scontent.xx.fbcdn.net/v/t1.0...1f&oe=57E5C746 i have a non-starter now, it's the green cable that is now brown and finally has given up after trying to wiggle it into a bend that works...new cable on order. |
Same color as my '79 Targa! I had a lot of CIS adventures this past summer. My car also has the "wrong" WUR, a Euro on a California car, but with proper setup it works fine. http://alturl.com/jk6cy http://alturl.com/iak49
http://alturl.com/m6rnt |
hi guys, i'm trying to get my head around the vacuum cleaner leak test.
i've attached the blower hose to the exhaust pipe, and can't find any leaks around the injectors or airbox, but one thing is confusing me very much: when i turn the engine by hand, all of a sudden i have a huge airleak coming from the valve cover seal at cyl. nr 1. It happens of course when one of the valves from cyl 1 opens, but surely the valve seals should stop air getting past, no? Brand new revised engine by the way (12K € revision) , fully revised heads, valves, seals, chains, etc...etc...basically everything is brand new in there. No smoke, no oil comsumption, 5000kms since the revision. Any ideas? cheers, Jan |
Where do you live.?
It is very hard to get good cold start if you have a mix and match of components. I know how to find good used WURS ... The WUR are interchangeable but they also work together with the FD and many FDs exist. I think Tony (Boytsc keeps a list of FD/WUR relationship.) Also some of the references out there are not accuarte for EURO SC's (if yours is a EUro). What is your CO setting when fully warm? |
Hi, i live in Dikkelvenne, near Ghent, Flanders,
these are my components: WUR 0438140072 FD 0438100077 1981 USA SC cold start issue is 99% WUR related, so if you could get a good one, that'd be great. After 1 or 2 minutes, the car runs and drives fantastic. Never checked CO. This vacuum test was to make sure all lines etc...are good before i change parts. The air leak from the valve cover seems very strange. |
Wur-072............
Jan,
It has been a year since you started this thread. What you have not shared with us is the heater resistance (Ohms) value. Or I have missed it. When the engine is cold, measure the resistance and post the reading. Thanks. Tony |
Hi Tony, it was 11 ohms, i posted this some time ago. Should be higher, so it's out of spec. :)
As far as i can tell i need a 090 WUR, but apparently the 072 would be close in specs...i've looked around but can't find anywhere to buy this. (I'm not risking 500€ on ebay for a 35yr old 2nd hand part which probably has the same faults). |
Not surprised........
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Jan, That is what I was expecting to see. The resistance at 10~11 (Ohms) is out of spec and will always give you an erratic cold idle. Another PP member (Mike in FL) has exactly the same problem like yours. He has a newly rebuilt WUR-090 with 10 Ohms resistance. He sent it back to the rebuilder and came back with 10 Ohms again. Rebuilder insisted there was nothing wrong with the WUR-090. And this rebuilder is a well known company and an authorized Bosch rebuilder(?). Mike installed the second WUR and found the cold idle problem still persisted. Now, I have this questionable WUR-090 and did the test yesterday. At 10 Ohms reading, it would be able to start and run the engine but would have this erratic cold idle. To fix this problem is to install a WUR has the correct heater resistance of 25~26 Ohms. Look at the picture below. That is what a good WUR-072/-090 should read when cold. http://forums.pelicanparts.com/uploa...1476453232.jpg Do you know a friend visiting USA? I could lend you a WUR for you to test. You are not buying it. Just a loaner so you experience how a good working WUR contributes to your engine's performance. PM me. Tony |
Hi Tony, that's a very nice offer, thanks. I'm gonna put some effort in finding something locally, and if that fails i'll pm you and maybe we can work something out. Big Porsche breaker's place is looking for 090's as we speak.
Do you know if it is normal to have air pressure under the valve covers if you put pressure onto the system (reverse vacuum cleaner through exhaust pipe)? Maybe it comes from the breather pipes? To me it seems weird that the airleak past the valve cover seal changes when turning the engine by hand... |
FG Porsche ? Did not know they where still selling parts to individuals.
I can fix the heater element if it is not compeltely shot. But as I work at a leisurly pace your car will be off road for a while ;o) |
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yapp, it's FG Porsche, they used to sponsor my big trip to China with the 69T, so i can still get parts there (bought targa roof spare piece couple of months ago)...i did not know they stopped b to c ? i drive the thing quite regularly, but wouldn't mind a week or 2 delay...you think that's possible? |
Ah you are the Carrera to China guy....
I think FG is using the parts for their own resto business. I am not sure they can help you with a 090. But if you can get a bi-metal from them it is fairly easy to do. I have got 2 myself but I am attached to them ;o) 2 weeks should not be a problem. We could mix the internals with the 072 you have today...and that is going to work. Pretty sure about that. |
yes, one of them, my buddy stayed in Cambodia :)
alright, will try to get the bi-metal. |
okay, just found an 090 in Germany, 25,3 ohms, should be here in a week or so, i will keep you guys updated, thanks, Jan
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I'm biting my nails on this one as I have a similar problem... Even after sending out both the WUR and the FD to CIS Flowtech for rebuild. I have not checked my OHMS across the WUR, but I will this week.
Thanks for taking the time to share your progress |
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