NO problem (emissions fail)

[GreenWater]

Ha ha, nice air filter. A plugged air filter would make the car run rich, I believe.

I can't remember now, but I think the CAT was around $200 from local autoparts store.

[zedsn]

If you want to adjust your afm you are going to have to remove the round plug on the body itself and from there you can make adjustments but best to have a tialpipe sniffer when adjusting. You will have to drill a hole in the plug and use a sheet metal screw to thread into the plug then remove it. Should be a write up some where on this.

[DannoXYZ]

Originally Posted by SolReaver

So... In adjusting the mixture, does one adjust the [AFM] first, and then adjust the FQS? OR do you step the FQS to a best guess and adjust the [AFM]?

The flapper-door bypass adjustment screw only adjust mixtures at idle, the amount of air adjusted is tiny and won't make a bit difference in your 1500 & 2500rpm tests. Don't waste your time with this adjustment.

Originally Posted by SolReaver

Lastly, is the O2 sensor voltage between 0.45 and .5 v the best way to set mixture and is back probing at the O2 sensor junction the best way in??

You need to datalog this signal and graph it to really know what the actual mixtures are. It swings between 0 and 1v very quickly and a voltmeter will not give you useful data. You want average of 0.5v with 50% of the time above and 50% of the time below (use calculus to integrate area beneath-curve, Excel has a function that can do this). Can't see that without graphing it.

Originally Posted by SolReaver

checked AFM temp sensor resistance at ambient temp and it is 1.81K, and the AFM is getting 4.7 v power, which seems to be within specs per:Air Flow Meter (AFM) - from "The 944 Motronic DME" by FR Wilk* ©2001 www.the944.com

Measure AFM-output at pin-7 of DME-plug. It should be around 0.7-0.8v at 950rpm idle. It's a possibility that the spring-tension on the AFM flapper-door was adjusted and it's now reading too lean across-the-board. The 944-spec racers often do this adjustment as it's allowed by the rules. Remember that '60s saying about power and mixtures.

Originally Posted by SolReaver

The FQS had it's original cap in place on the DME and was set to stock position (1?). I have fashioned a tool by whittling a golf Tee and it works great. The DME is an 0261 200 007, 944.618.121.04, Type 944MWN-01, 078 and the AFM is a 028020264.

I like to think of stock most counter-clockwise position as 0. Then count clicks to set other positions, 1-click clockwise = position 1, then 2-clicks clockwise = position 2, etc. Easier to keep it straight that way without the off-by-one error.

Personally, I would just set the FQS to position-7, full clockwise, for a +6% fuel-enrichment and -2.77 degree ignition retard. You have more than enough HC leeway for this and the richer mixture and less ignition advance will lower combustion-temps and lower NOx emissions. Very quick adjustment, 5-10 seconds max and you're ready to pass the test. Don't waste time with anything else.

[SolReaver]

Thanks much Danno, I did just go over the car and re check everything, FQS set to 7 and it runs nicely. we will see what the smog guy says.

AFM output is 0.9 v at idle. I hope I am reading it correctly. Wiper arm (7) to ground (6) is where I am tapping the voltage with the AFM cover off and the vehicle with the car fully warmed. As this is a little high per your test.....a) am i doing this correctly? b) what would a slightly high voltage indicate, and could that be a problem?

thanks all

[1982_928]

Just get out of California and move to Texas. No emissions testing for 25+ yearold cars..

How much does a inspection cost up there?

[Gawernator]

Lol they don't even safety check or inspect the car... all the *******s here care about is smog, they could care less about accidents killing /people/ lol. Anywhere from $30-$60 I see... depends on area and ghetto-ness of facility

[GreenWater]

That's what I'm saying. It's expensive living here, in more ways than one. But the weather is very nice. It was a great 75 deg day again today. I would be out of here fast if it wasn't for that, and the beach. Testing isn't too much, but repairs can be expensive if you can't do them yourself.

[1982_928]

With all the greenies up there, the EPA, and everything else that goes on, I don't see how anybody could stand to live there.

Sure, It's hotter than hell here in Texas, but there are a lot of car guys. If you have AC you'll survive.

A safety inspection here for a 25+ yearold car is a whole $12.. They still want you to have the emissions stuff on the car, but most people will look the other way. As long as your tires have tread, and the lights and wipers work, it passes. My pickup passed with 4 lug nuts on one wheel the other day.

[DannoXYZ]

Originally Posted by SolReaver

AFM output is 0.9 v at idle. I hope I am reading it correctly. Wiper arm (7) to ground (6) is where I am tapping the voltage with the AFM cover off and the vehicle with the car fully warmed. As this is a little high per your test.....a) am i doing this correctly? b) what would a slightly high voltage indicate, and could that be a problem?

Slightly high voltage from AFM, but within specs if your idle was faster than 950rpm. Was the car warmed up? It could have been doing the cold-start higher-RPM idle.

This really sounds like you've got a vacuum leak sucking in extra air into the engine. This would cause leaner mixtures, higher combustion temps and higher NOx readings. Hook up a vacuum gauge to the intake-manifold and see what vacuum you have at idle with a warmed up car, should be in the 25-30 in.Hg. range. Lower numbers could indicate a vacuum leak or worn-out rings. There's threads on pressurizing the intake and spraying soapy-water to find leaks.

And of course, a sure fix is new cat, but that's a last-resort step.

[SolReaver]

Danno:
Car was fully warmed and rpm is 925 (ish)

I was thinking vac leak as well and will try the leak test with soapy water. Have visually inspected several times but might have missed something. Good excuse to wash down the engine and spend some Quality time under the hood.

82_928: Just came back to CA. FROM TX. Yes, the sunshine is expensive here. IMHO, Totally worth it. Have had cars inspected in TX and have been failed for wiper blades.....sooooo.... gonna disagree with ya there. Those roads are long and there is a lot of nothing between towns so I always heeded those signs by the road that said to "maintain your vehicle". In that spirit, please make sure all your lug nuts are on there.

50 bucks a pop or thereabouts. The CA BAR is on a jihad to rid the state of older cars it seems. This is to encourage new car sales.

[DannoXYZ]

Yeah, auto-manufacturers & dealer have powerful lobbies and many senators in their pockets. They pass stricter laws for imports, such as amber taillights and other standards while not requiring them of domestics. Or 25% tariffs on light trucks. Or lobbying to have the fleet CAFE standards repealed because they couldn't meet them (while Toyota & all other imports created hybrids that got double MPG ratings). All these favoritisms to help the locals "compete". HAH! All that does is drive up the cost of autos for everyone and the domestics just raises the price of their inferior products and pocket a bigger profit!

Although it is realistic to expect older cars to be able to meet the emissions regulations from the era they were produced.

[1982_928]

I'd rather my car be failed for a $5 wiper blade than some stupid emissions stuff that could cost hundreds of dollars to fix.

Just my logical opinion.

[DannoXYZ]

Originally Posted by SolReaver

I was thinking vac leak as well and will try the leak test with soapy water. Have visually inspected several times but might have missed something. Good excuse to wash down the engine and spend some Quality time under the hood.

Be sure to pressurize the intake before squirting soapy-water. If the engine's running or have vacuum in the intake, you'll suck the water into the engine instead of having the leaks bubble out (you'd be amazed the numbers of people who've done that).

Also don't forget the vacuum-gauge test with real numbers.

Good luck!

[SolReaver]

Hey guys.
re-checked the manifold integrity To my great surprise, there were no leaks. hmmm...go figure...

I did some thinking, which for me can be a dangerous proposition, and reasoned that a vac leak would mean less air coming through at the idle RPM not the slightly higher amount of air that was indicated buy the slightly higher voltage.

In a fit of inspiration and insanity, I reasoned that the high voltage was a result of more than the correct amount of air passing through the AFM and that perhaps my IAB was at fault. I really don't like messing with such things but figured I could turn the IAB hex down until it stopped and then up again the same number of turns to bring it back to it's original position. It refused to turn down. I tried turning it up a bit (counterclockwise) a few turns and noticed that the .9 voltage was going down. After 4 and a half turns up, the voltage was within specs.

So, my friends, I have this dillema, and this riddle for you. HOW on earth did my IAB hex screw wind up all the way down??? Up until this wonderful adventure under the hood, my knowledge of that adjustment was "leave it alone" and I can assure you that I never messed with it. Is it possible for that hex screw to just sort of settle itself down over time?

lastly, is setting ones IAB by way of the AFM voltage an OK way to go? the funny thing is that in watching the voltage it almost seemed like the car was adjusting itself slowly to the new setting and through about a rotation and a half it made little to no difference as the car ranged around that area. I left the IAB in the middle of this comfort zone.

Sorry don't have a vac gauge with real numbers right now, but will check when I can.

928: yea I wasn't too upset but wiper blades cost a lot more than 5 dollars.

Danno: yea, I do think that even older autos need to meet some reasonable emission standards, My actions are currently speaking for me. My main concern is that it is so darned expensive for re tests. and the whole potential converter purchase that looms over all my efforts is not easing my mind.

[SolReaver]

Hey folks, I am happy to report that I FOUND a problem with my car.
The very lean mixture may be due to an Idle Control Valve (ICV) that is leaking like you read about from the top where the connector goes on. Why am I happy about this? Because it explains everything so far. The good point is that I can prob fix this, the bad point is that i will prob need to remove the manifold to do so and I am going to bet there is a bunch of WYAIT to be done as well.

I hate to admit that I missed it previously, but that is what happened. It is kinda hard to get to and i just didn't drench the top of it where it leaks with soapy water.

Anyone with a spare, good ISV and advice on doing an intake manifold chime in.

[Volhv]

I thought that vacuum leaks would only be an issue at idle......

Read somewhere that the ICV can be changed without removing the intake manifold. Haven't attempted that myself yet.

[SolReaver]

Volhv: well, at idle the vacuum is higher, so a vac leak would be more OF an issue, but un-metered air going into the system kind of defeats the whole purpose of the computer adjusting the mixture based on Lambda voltage derived from position, oxygen and temp sensors. The math is all off and the computer just can't adjust for the added and unknown quantity of air. Therefore, and with all due respect, your thoughts are not entirely correct in this matter and in this instance. Additionally, this appears to be a rather large leak and not getting smaller with time. In fact, I theorize that it may be increasing with time and began leaking several years ago. At the last smog a helpful tech was able to get a pass by adjusting(or rather closing down) the air bypass on the AFM.

I look forward to resolving the issue and finally determining if my Cat is going to need replacement.

OH joy of joys! a new ICV is only 200 dollars! My how I just love dumping endless streams of hard earned money at this emissions difficulty. Perhaps i can rebuild the old one. It functions beautifully except for the slight whistling and screwing up my mixture.

[Volhv]

That sounds about right than. Thanks, I will take your advice, and look for leaks there.

Unfortunately I did not check my ICV when I had the intake manifold off. I merely checked its operation, cleaned it, and replaced the hoses.

[SolReaver]

Volhv: yea, You have to douse the entire system with soapy water with the intake manifold under pressure and I missed the part on top where the connector goes in the first time around. I even removed the J boot and pressurized directly into the Throttle body after capping the two lines that went into the J boot. I had no idea that an ICV could fail in this mode or that it could fail so dramatically.

[mytrplseven]

I am happy to hear about that. I just did a re-check of my vacuum system a couple of days back and it looked tight, but now I'm wondering if perhaps I'm dealing with the same problem (slight stumbling on accel, but perfect idle and WOT). I did have the intake manifold off to fix a few things but didn't really examin the ISV.