No pun intended! It's been three months now since I done the major and I have found the car to be toooo much fun and quite reliable. My biggest challange was to get it to start properly at various temps since the weather changes in a matter of minutes UP here. After have the WUR apart more times than I care to remember I have a very reliable car. My quest for feedback is on idle speed. I can run her hard without a misfire ,it starts fine and even super-heat re-starts are no problem. The one issue I still have is hot idle, it can vary from 900 to 1700 and I haven't really been able to associate this problem with anything in particular. I would like to hear what other guys that REALLY DRIVE their 308s to tell me if this is commonplace or I need to do some more searching. I should mention that cooling is right on and the temp is stable at any particular driving range. as usual, thanks for the feedback
in my humble opinion the only thing in the k-jetronic that can randomly cause a spread in idle revs between 900 and 1700 is the axiliary air valve. It might move not very well anymore due to dirt/rust ore the contacts to heat it up are giving some random trouble ( not unusual with electrical contacts on a 308)
Brainstorming: The engine compartment gets really hot during/after a hard run, even with normal engine temperatures - and we know matter expands when hot. The first thing that comes to mind is: Do you perhaps have a vacuum leak that occurs only when the parts are really hot? This could be something as simple as an untightened hose clamp or as complex as a failing component (WUR? Aux air valve?) or any other component connected to manifold vacuum... Hummm...
I was hoping for more feedback to my question---------------- is it the actual experience of most that the their idle consistently runs between 9and 11c? I am inclined to think that engine bay temps are causing the WUR to lean a little and raise the idle. Eg, after a 100mi legal run yesterday (the fall colors are peak! any trolls are welcome and our doors open if assistance is needed) when I pulled into the barn the idle was 1800. About an hour later I had to run to the grocery and when I lit her up the idle was at 900. Needless to say an air leak is not the only cause for the unstable idle. eg. while setting the mixture at the fuel distributor the idle will change as the mixture screw is adjusted. Still learning the system. lostbowl
Sorry to have supplied more information than you desired. Here's your answer: Yes. My Mondial QV's idle is rock solid at 1000rpm, hot or cold. (Please remember that cold in Houston is not cold enough for the WUR to even open.)
If the WUR was not open the engine would not start!!! Heat starts the closing of the WUR to lean the mixture. Duh Lostbowl
In my haste to post a reply I typed the wrong acronym. I should have written AAV. Sorry. Answer is still the same: Yes, rock solid at 1000rpm.
No apologies needed here we are all just interested in getting it right. I am now of the opinion I will need to spend a little more time under the bonnet and that's a good thing.I have been trying to drive evry minute I can with snow predicted for Fri. I have spent the summer doing the major and I started stone stupid and now I am only 1/2 stupid and the reward is that the 308 is more fun than my FF was. (many years ago and I had to drive it on track only.) cheers, 1/2 lost
Probably not true. The engine would probably still start, but the idle might be uncomfortably low. Depends on how your base idle is set and any other throttle bypass items you might have. If you have the 2500rpm idle option with the thermo-electro-switch-vacuum-operated bypass then the AAV is less than half of the throttle bypass. You could lose it and not care.
I try and use the manual for specs and ,at least this engine, would not start with a control pressure higher than 1.5 bar. I (at 65F) I like the color of the plugs after a good run so I'm not overly concerned and will drive evry minute I can and start searching for the idle fix after the snow becomes plowable. For the next five months I will stick pins into the likeness of the south west! Yuk, Yuk Need to stay away from people to maimtain sanity!
I had a similar idle speed issue. Turned out to be a hidden cracked vacuum line that only leaked when the engine bay was up to temperature. You can spray starting fluid (ether ?) at vacuum hose connection points to find it (be carefull !!! very flamable stuff !!) Idle speed will change when it ingests the ether @ the leak point. Cracks generally appear at stress points or at or near attachment barbs. my .02
Good advice all around. We have to remember that an engine is essentially an air pump and that engine speed is regulated by how much air is allowed into the pump. A vacuum leak is really just added and unmetered air. I did some testing of my car's AAV. It was 90 percent closed at 80 degrees F and didn't really open much until below freezing (freezer test). I did find that there was an open circuit between the plug and AAV's connector and the internal heater was not working. It was never an issue for me though because at Houston's temperatures, the valve was never really open anyway! Does your car have the air bypass valve around the throttle plate? That guy can drastically affect idle speed and it IS metered air. My car doesn't have one as it's an '83 Euro. All in all, the K-Jetronic is simple - especially on my car because there's no emissions stuff. AAV controls cold idle speed, WUR/CPR controls warm-up and operating charge mixture, modulating for load via vacuum, and of course, the fuel distributor with its pre-set baseline mixture. Another question or two: Does your car have cats? Is it a K-Lambda or straight K-Jetronic? The mixture is modulated under the control of the lambda sensor, by regulating the control pressure which in turn regulates the back pressure on the metering valve via the valve's height (which regulates how much of the metering slits are open to the fuel plenums feeding the injectors. But you guys know that. I'm just brainstorming this morning on other mechanism that can modulate idle speed. BTW, on carburetted cars, a 'searching idle' is a sign of too-lean mixture. regards, rick
Rick, I apreciate your comments. To answer your questions I have a 82 308S and I have removed the cats and air-pump and properly plugged everything while I had the engine out. It is straight K, no lambda! When I first purchased her someone had screwed up the valve settings so bad that one hole on the front bank had a negative clearance and the idle was so rough I did not want to be seen driving it so out the engine came and I replaced the EX valves w/SS and for ****s and giggles I threw the old valves on the garage floor just to see if some of the posts were right about being fragile. They did break off but it did take some effort. Anyway I have peace of mind that I won't be trashing the engine from a valve stem breaking off. Back to the problem------- I have book settings on system and control pressure and she starts fine hot or cold and will run to red if given her head. The AAV is free but I did restrict it's volume to stop the (IMHO) 2500 idle. The first thing I checked was for air leaks by the ole spray some starting fluid everywhere air might get into the system. Idle is a product of A/F ratio so it can be a misbehaving fuel distributor (FD) or WUR. As I said before , NO snow yet so I don't want to take the FD apart until she is garaged so I will continue searching my old brain and this forum and proceed when I can't drive her anymore. Holding out to the bitter end, Tom
PS Rick, Yes I have the air by-pass but it is not ruptured. What I haven't done (the bulb lights up a little slower these days) is to stick the probe up the pipe when I get back from a good run and the idle is up to that 1700 side. I really suspect the WUR is leaning it out too much but the plugs look good. Tom
Thanks for the good words. I think I would attack it by elimination (or perhaps addition). You can plug the hose going from the AAV to the regulator's air duct. You can also disconnect the air valve bypassing the throttle plate and plug both ends. In essence, you can eliminate all the potentially leaky bits. If that doesn't illustrate the problem you can possibly borrow a CPR/WUR from someone here for testing. best luck! BTW, If you can avoid getting into the fuel distributor, it might be advisable. That's a REALLY fine tuned device and a dropped part ends its life. Now I want to go play with my car...
With 130 plus inches of snow I finally attacked the idle problem and found the AAV to be faulty. With a strong 12V DC source it would not close at all for over twenty minutes. Now I am having problems finding one. Everyone lists them but when I order it comes back no loger available. I hate modifying from original but it looks like I will have to eliminate the AAV and control fast idle with the right foot when cold. 1/2 lost
Take it to your local European Car fix it garage that does Jag/Volvo/Mercedes/VW with the WUR. Show it to the old guy there. He'll probably be able to steer you to a part that will work just fine. All the CIS AAVs work the same. The only differences are pretty minor - bore size, mounting holes, maybe close time. Considering what you are proposing (leaving it out) one of these alternate AAVs would be a step in the right direction.
Here's your AAV data (including parts cross-ref): http://www.ferrarichat.com/forum/showthread.php?p=139248388#post139248388
Still not sure which part number is correct but I found a place in the UK called Vauxhaulgreenparts and they quoted 49# and told me they have it on the shelf. Has anyone used this Co. as a source? Tom
