924Board.org

[mustangporsche]

Well the struggle continues to pass crazy CA smog, I haven’t pass yet. So here is whats going on. Now this has me confused. I have got the CO and idle right on not thanks to the net little CO analyzer I got, its right at 5% before cat. and idle at 950, I did have it at .8% because the sticker on the wheel well says .5 to 1 % so I thought .8 would fly but oh no still didn’t pass, I found out that the max. Allowed is .98@ 15mph and .78@25mph, so it can’t even be set to the factory 1% and pass, crazy I say. And the guy said yeah and it is going to be even lower next year, I am ready to move ha-ha. Well here is the current problem I got it set at .5& at idle, but there is something else wrong I think. I can’t get the right voltage when testing the O2 sensor, I am using a good deg. meter set on 2v, but all I get is .008 and once it a while will flash down to .007, now I know this is way off. This is with a brand new sensor, oh and the car is really hot? So does this mean my control unit is out/ I took it out and had a look at the pins they looked pretty good but I cleaned them anyway, but still no difference? Also I have checked, replaced and rechecked pretty much everything else, on the car, so I am stuck/ anyone have any ideas?

[Lizard]

you should be measuring the voltage to the O2 sensor with the - of the tester on a ground point, the + on the O2 wire, if you are not getting a reading from about .2-1 volt then the O2 sensor is I would have to say defective
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3 928s,

[mustangporsche]

yeah that is what i did, well i first tierd with the O2 sensor that was in it many be about 4 months old, was getting .006, than i but a brand new one on and it only was at .008. ? so if both were that far off thats why i thought there was something else wrong?

[Lizard]

try it on a different (20?) volt setting and see if that makes a differnce, also you do have it in DC correct just making sure if not then it is possible that you got a defective out of the box, but also remember that the car needs to warm up first before you will get a real accurate reading.
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3 928s,

[mustangporsche]

Ok well I tried it with a third O2 sensor and still don’t look good. .007. That’s on the DC 2v setting I tired on the next setting witch is 200v and I get nothing too high I guess. And the car is defiantly worm? So I don’t know whets going on, what else would cause this. If the computer was malfunctioning it would not run good are at all right? Because it runs good now? But I can’t get the idle to stay where it is needed, I get the mixture set at .5% and idle at 950 with the O2 sensor unplugged like it says than once I plug it back in it will go on high idle 1200? Why? Do I have to disable the idle stabilizer too? If so where is it? I thought it was the plug on the left front wheel well, but it won’t start with that unplugged?
Thanks for the help this is starting to be a real headache.

hey Lizard how does your 928s five speed compare to a auto, the reason I ask is my twin brother got a 86 928S auto, I would think that the 5 speed would be faster, but I am not saying the auto is slow, this one has 30k in receipts, but I really see what it was all spent on, has chip and nice wheels? not what else. But man does that Porsche v8 feel good, feels a lot better that the 924T, much more torque, I guess it should for having twice the engine.

[Smoothie]

Aha! I see you've cleverly omitted the model year of your car.
As far as know, only '81-up got EIS (electronic idle stabilization).
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[mustangporsche]

oh wow you are right sorry its a 81 931, where is the EIS at?

[Lizard]

in regards to your issue, the reason that your idle goes up is that your O2 sensor is reading too lean and is richening up the mix and this will cause the idle to raise,
is it possible that there is a pretty majour exhaust leak further up that is allowing excess air into the system? it would need to be pretty big for it to read that far out, bad manifold/turbo/wastegate gaskets, cracked exhaust manifold/turbo hot side.

as per the year of vehicle iirc from past posts this is a 81 931 we are working on

in regards to the 928s, I had previosly had an 86.5 928S and it pulled like a bat outta hell on alot of the other cars, and over 220 I havent found another p-car (other than the 993+ turbos) that could keep up, I had it a couple of times upto 310kmph or around 180mph (read NO other vehicle on the road) and it was nuts.
I have ridden in S4 928s and they dont have as much top end as the S3 (85/86 US) cars imo this is due to the cam profile. I have ridden in both S3 and S4 manual tranny cars as well as autos, and the autos do pull hard, but the manual cars have WAY better off the line acceleration, and alot more pull and control throughout the rpm range.
as per my current 928s they are not something that you can really go by in terms of regular 928s as the 81 has an 86.5 wiring, brakes, engine, with an S4 bumpercaps for better air CE. and it has had some weight reduction done, I should be just under the 3000lb range with this car and with the exhaust done up and all the emmisions pulled off I should be able to get roughly 330-350 crank horse, and about the same for torque,
however it is at a shop as they try to find the mystery as to why the engine isnt running properly, they have had it for 4 months and still havent found the issue *curses them* also both cars are Euro cars and slightly lighter than the US counterparts.
the 85 is a 5.0L bottom end with high flowing 16V heads, twin distributors, LH injection and high CR, the factory rating for HP was 310, but it was in the still really light early chassis, this car came with factory sport suspension and the shortest (2.73) final drive that came in the 928s this is the same diff as was in the 928GT all the other cars have a 2.20 final drive. So with the chassis being lighter and the engine having high HP (only 6 less than the S4 and 16 less than the GT) it should be either the same or slightly quicker (definetly quicker after some exhaust work) than a factory 928GT. However I have not driven this car as of yet due to the fact I need to do the timing belt on the car first and replace the windshield.
alot of people have said that the 928 standard is hard to drive with a heavy shifter, I am sorry but the shifter is ANYTHING but heavy, and the hydrolic clutch is a breeze to use. but I much prefer standard, and the 81 will probably be converted over to a manual as well.
I hope that answers your questions
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3 928s,

[Smoothie]

As I recall, that connector on the wheel well affects timing on a DITC equipped car. Unplugging it should retard the timing by something like 7 degrees. It's supposed to be useful in case you end up with some low octane fuel and engine knock.

DITC cars' idle speed has to be set using a timing light (otherwise the EIS will fight you all the way by changing the timing every time you move the idle speed screw). Here's a quick 4 step on the procedure - http://www.924board.org/viewtopic.php?t=14961&start=3
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[mustangporsche]

wow now that you say that as a matter in fast i do have exhaust leak where the turbo meats the exhaust manifold, not sure how big it is, its wierd though it will only make noise right when it is started up and for maybe 5 sec. then it goes away? thats the only time it does it? But now i have been puting this off because it is shch a pain to do, i even have all new gaskets, i just have to get in and do it, now i have to do it. Well thats wierd the haynes doesnt say anything about unpluging the DTIC to adjust the idle, but it sure isnt working this way, so i will try it. thanks guys

[JB1]

Hey mustangporsche:
I just passed emissions this year on my '80 turbo with a CO of .25%. I have never had to pass this car before because of when I baought it it worked out with the year of the car and everything that I did not have to take a test until the third year after I had it. But anyway I was concerned about it passing so here is a trick. Run a full bottle of the full strength chevron Techron fue additive/cleaner. It makes the car burn alot hotter than normal, and make sureyou drive it for a while before having it checked. Pick a checking station abit out of the way, and pull in to the test with the system red hot, right of the highway, and if your car is running properly you will pass. I learned this trick from working at a car shop to help people pass emmisions, and the shevron techron works the best.

Good luck
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1980 924 Turbo 2 tone alpine white, brown

[gohim]

Replace the Cat.

Repeat after me, "A New Cat Covers Many Sins." Repeat over and over again until you get the meaning.

[mustangporsche]

Ok thanks for the tip I will do that, I have replaced cat. But it still didn’t pass. I just got done replacing the exhaust man. Gasket from man. To turbo wow I forgot how much fun that is taking turbo and manifold off, well a day and a half later it is done. I think I was getting air in that leak and that the O2 sensor was sensing a leaner mix that it actually was due to the extra oxygen? Making it too rich. But the flange on the exhaust man. Was half way broke off, there are only three small spot weld that hold it on, so I welded it up good. Now there is no leak sound on start up, but now I have to reset everything, it’s running different now.

Hey JBI how did you get yours down that low .25%? Mine seems to not to like to go that low? This is at idle right? I just had it at .5% because that is what the tag said on wheel well?

[Racing]

Just a thought.
You´re aware that the multimeter that you HAVE to use HAS to be digital when measuring O2 voltage?
Got my attention when you said that you put it in 2V range.
Reason is that the digital doesn´t really crave any current as opposed to the analogue counterpart.

[JB1]

the .25% CO was a average on the test in which they put the car on the dyno wheel, so I guess that is an average percentage over the entire speed range they took the car on. There are some things to keep in mind, the hotter the system is the better the catalyst in the converter can oxidize and reduce the emissions, that is why the chevron techron fuel fuel system cleaner works, it raises combustion tempratures to clean awaay contaminents, thus increasing exhaust temprature, and raising the temps inside the cat which makes the process more efficient. But only while it is fresh in the tank. But not too hot though, making the mixture too rich would result in too high of tempratures inside the cat and buring out the catalyst inside, thus making the cat usless, also oil leaking from the turbo into the system can build up on the catalyist and and make the cat not beable to do its job, and eventually clogging up the honeycomb structure and increasing back preasure which would reduce engine purformance.
just some things to keep in mind.
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1980 924 Turbo 2 tone alpine white, brown