NO problem (emissions fail)
 

Hello good friends, Blinky didn't have a good day at the office and failed the CA smog. It is only the first run at it so I am not stressing too much. I wanted to bounce a few ideas around and see if anybody can assist me in my endeavour to get back in the good graces of the DMV.

OK here is the short form HC and Co are well below specs. NO is running high.

The car WAS running Hot. In the time she has sat poor blinks seems to have lost the ability to turn on the cooling fans and keep herself cool at idle. If I turn on the AC, the vehicle won't overheat when parked but it does get up above the middle and approaches the red. At least it was there when they tested it. I did mention this to the tech and insisted upon a fan blowing at the front end during the test, but apparently there is some regulation about how close a fan can be during a test and even a regulation as to what fans can be used. Really?

anyhow, first step is to get back to a lower operating temperature. The coolant level and thermostat are fine. I will be focusing on the fan, relay, and temp sensors. any help would be appreciated.

Especially instructions as to how to constant on the cooling fan fro now.


87 924s 2.5 bone stock.

So where should I begin with the cooling problem and does anyone have any other ideas?

raw data: ( ---HC------ -------CO----- -------NO------
rpm co2 02 max ave meas mx ave meas mx ave Mea
1829 14.3 0.3 85 40 22* 0.54 0.13 0.21* 702 445 1110
2942 14.2 0.2 67 29 15* 0.45 0.10 0.31* 746 348 1319

Not sure if the two problems are related, but excessive NO can be caused by a hotter than normal engine, exhaust leaks, bad cat, and a few other things that escape me at the moment.

Both fans come on when you turn the a/c on, right? If so, it is most likely the temp sending unit in the radiator. If you unplug it, you can jump the wires to see if that turns the fan on. If it does, then it is the sender for sure.

Kudos to Shifter
 

Shifter you are right on.

Fan kicks in when sender jumped. Ordering sender and may rig a switch for Smog test. In the meantime, Interrogating the usual suspects and taking the car out for a bit of exercise.

Car was thoroughly warmed, but, these things hate to sit around and this CA gas seems to not age well for some reason. Thinking that burning out the old stuff and some fresh high test combined with some fresh plugs might make a difference.

Try changing your 02 sensor after your tune up and if the car still won't pass I would suspect that your cat is now bad. You can replace the converter with an aftermarket one with some work as I have done it on my 83 944 years ago. You can also adjust your afm but would need a sniffer to do the job correctly.

Sol,

You probably have the stock 80*C thermostat installed.

You could remove the fan switch to be certain of the fan switch temp and just replace it with the same temp. The internal contacts may just be fouled causing poor operation.

Thermo-Fan Switch - replace from the top? - Rennlist Discussion Forums

Pelican only sells 2 fan switches for the early 944/1 or the 924S:
75*C (75*C-70*C)
or
92*C (92*C-87*C)

But the fan switch that would work the best for your '87 924S ---80*C thermostat is the 82*C fan switch (82*C-77*C) if running a little hot and also OK for emissons. I use this fan switch.

BUT..........................................

The BEST fan switch for emissions is the 92*C fan switch, but your car will run hotter-but may pass emissions in CA.

J_AZ

"high test".....

I haven't seen/heard that term since the 70's. Brings back memories.

What about "Ethel"? Now we're going WAAAy Back.

the fight continues comrades.
 

Ok the thermo switch is deader than ceasar. I rigged a toggle switch with some spare 12 ga wire and duct taped it to my air horn. When I want to drive the car, I open the hood, flick the switch, the fans light up and away I go. The car will not overheat when idling. (making progress)

I Will order the thermo switch soon, I promise. I do not intend to drive around like this for long. It is actually kinda humorous, but the novelty is already beginning to wear off.

The plugs were OK but a bit old so I replaced them. The old plugs were unremarkable and it seems that the mixture is good. I gave the car 20 bucks worth of premium, or what passes for it in CA andtook the car for what is called in Jaguar circles "a spirited romp about the countryside" after which it idled for a half hour or so before getting tested. OP bouncing a bit around 4 bars at 925 rpm idle.

Another fail. Boo hoo. the NO is lower but still too high. Poor blinky is discouraged but not deterred. After conspiring with a helpful smog tech we compared theories and the suspect is now the oxygen sensor. If that is not the case then it is looking like a bad capatali$tic converter. (not a pleasant possibility)

zedsn: I wish I had read your post a few hours earlier. however, we really had to rule out the overheat condition first.

OK! so it is O2 sensor time. Isn't there a cross match with a Ford Taurus or something like that? Any suggestions as to whether to go with genuine Bosch or does it even matter?

OH! the data for those of you who like that sort of thing. new numbers

980
1045

The reason that the o2 sensor may be causing the problem is that it may be switching too slowly.

better said: A good O2 sensor should produce an oscillating waveform at idle that makes voltage transitions from near minimum to near maximum. If the sensor doesn't flip-flop back and forth quickly enough, it may indicate a need for replacement.

Thread crawling gives me Advance Auto 13942 generic Bosch or 15735 for the O2 sensor and I might want to do the DME sensor as well.

Ah, "Ethyl", for TetraEthyl Lead, the octane enhancer of choice, back when your parents wanted you to grow up stupid....

I failed NOx a decade ago, and a new to me cat fixed things up for me. Master mechanic told me that was the only fix back then.

If you have a stock exhaust I have a cat you can have for near nothing.

I tried to recycle it and they required a receipt, which I don't have.

It has a small dent at one point, but should not affect much.

$hipping of course might suck....

You are way under on HC & CO.
High NO is usually due to being too lean.

A new O2 sensor is a good idea.
I would also add some fuel via the FQS switch, to enrich the mixture.

The plan
 

K then. Thanks to all for the input.

Replacing O2 sensor with genuine Bosch. Replacing the DME temp sender as well. Going to run good fuel and give the stock system the inputs it needs while hoping the cat is still good after all these years.

Not going to change the FQS setting on the DME just yet, but, good to know I have that option.

The 3 things that I can do.

Adjust the DME (adjust it back after the test)
Adjust the air bypass on the MAF
Replace the cat

Adjust the DME

Actually, it's the FQS (Fuel Quality Switch) in the DME that you're adjusting.

http://frwilk.com/944dme/fqswitch.htm - this tells you about the FQS adjustments. I put mine in position 4, you would likely be looking to position 2.

http://www.geocities.com/motorcity/1760/dme.html - this tells you how to access it.

http://www.promaxmotorsport.com/fqs.htm - everything on one page.


Adjusting the Air Bypass on the MAF

With the car running you need to back probe the O2 Sensor to find out the voltage. Anything over 0.5v means you're running rich. Below 0.45v is running lean (mine was at 0.32v when we started).

On the 944 the by-pass is adjusted using a 4mm allen key to a bolt on the MAF.

http://frwilk.com/944dme/afm.htm - the bolt head can be seen on the first picture of this page, lower right corner. It is covered by default. The cover is removed by screwing into the top of the cover with a sheet metal screw (just a couple of threads into it), then removing gently with a set of pliers or vice grips.

http://frwilk.com/944dme/lambda.htm - This gives you the voltage it should be.

Turning the 4mm allen bolt counterclockwise (I recall) will lower the voltage you read at the MAF. Take it slow and let the reading stablize before continuing to adjust. The reading will also jump around a bit so you need to average it.

Lean times....
 

Status update: Replaced the O2 sensor and temperature switch and it STILL failed on NOX........:mad:

http://forums.pelicanparts.com/uploa...1375230824.jpg

Upper image is before the O2 sensor and temp sensor replacement. I really expected to see more of an improvement. AS you can see we are still running lean WITH a new O2 sensor, so I am thinking that the sensor wasn't the issue, Although everybody agrees replacing it was a really good idea and the next logical step. In consulting with the friendly smog tech, he is of the opinion that the cat is the last thing to be dealt with and with the current numbers I need to do something to richen the mixture. There is plenty of room for more fuel with HC so very low.

SO.... Plan of attack is...

1) I am going to check the settings on the FPS. I have no idea where it is presently, but haven't touched it, ever. Perhaps a PO or tech set it wrong many years ago. God help me I am also going to carefully pull and inspect the DME to check for bad traces and clean the large connector contacts.

Wherever the switch is set now, I was thinking 1 or 2 ticks to richen.

2) I will back probe the O2 sensor to check for voltage and/or adjust the air bypass on the MAF. This brings up rebuilding the MAF, or at least inspecting it. I may have to do that, but don't want to mess with too many components at one time. I think checking the temp sensor within the MAF might be a good idea and possibly cracking the box just to have a peek.

ANY helpful advice is greatly appreciated as I really can't afford a cat right now and this whole business is really starting to get me down. Supposedly, these things can pass emissions without a cat and the smog tech said that getting the mixture correct to begin with is the way to go.

ALternatively, I have a few odd thoughts like checking the fuel pressure or cleaning the injectors in case they have clogged up through the years. The important thing to consider is that testing costs time and money and I am running out of both.

I say just replace the cat and be done with it.

What's your ZIP, I can try to figure out shipping for you.

Another option is that I will be in SD over the Labor Day weekend - there might be a possibility to strap it on the top of the car.....

I had to replace my cat to get my car to pass smog too. There are new laws, as of the beginning of this year that says you have to have a CA approved CAT. The Cat has to have the correct numbers stamped on the bottom and be clearly visible and must be put on by a professional. Even if the cat is from a different year car they will fail the car. I tried installing a New CA approved cat from a different year car and they failed the car because they looked at the numbers stamped on the cat and looked it up in a book to find out it wasn't for my year car. Once I had a shop install the correct cat for my year car it passed smog. Crazy how stupid they get over some things.

Also check for air leaks, both on the intake side and the exhaust side, both will make the NO numbers go up. O2, Cat and air leaks are about the only thing, but I could be wrong.

That is the stupidest thing ever. They failed my 912E here in CO because it was missing the smog pump. I was the only person at the smog testing center and they had 2 techs and the district manager looking over the car and they couldn't quite realize it was missing the fuel injection, EGR, thermal reactors, vacuum advance distributor, carbon canister and PCV. Idiots.

Sol: As mentioned earlier, you might want to try making it a little richer with the fqs. Your have some room to play with...

California is super picky when it comes to smog checks. (and many other things)

Yes! It would be good to have a new cat.
 

Hey guys, I like pussy as much as any guy. I sure wish I could just stroll on up to to the dealer and buy a new one off the shelf. A brand new cat will solve a world of illls, lower NOX being my prime concern. However, the task at hand is one of the correct mixture. By the numbers she is running Uber lean and if I can richen the mixture I can trade off NOX for CO and HC. I have tons of room on that side of the mixture. IF this was an old school carbureted vehicle turning the mixture screw would do the trick, but, this is a Pre-ODBC Jetronic fuel injection.

Greenwater, yes! good thing to keep in mind. I have checked the intake manifold and vac lines 3 times now, but It can't hurt to check again. Also a full fledged inspection of the exhaust system is in order just to be absolutely sure there are no little leaks. When I cover the exhaust it builds considerable pressure but that is just a rough test.

KD, pmed you and thanks for your interest. You are a champ.

I will be checking the above soon and keep you all appraised.

Additionally, Although the cat is possibly original to the car, I do not now if it is truly bad. I mean look at the CO and HC numbers. I am also relying on the theory that these things don't even need a cat to pass smog if they run right.

FQS - Fuel Quality Switch

Easier and more accurate than a carbureted vehicle

(on a side note I would LOVE to have your wonderful L-Jetronic on my carbed p-car)

On the subject of how much can be wrong and the car still runs good, here's a picture of what my intake filter looked like after I had picked the car up in Santa Fe and drove it home to SW Florida:
http://forums.pelicanparts.com/uploa...1375285887.jpg

amazing!
 

Mytrpl7: I have seen worse, but not much worse and not lately. ha ha.

Yea guys, I wanted to know how to set the mixture as best as I can and then adjust with the FQS as needed. The theory is that the computer SHOULD be doing all of the calculations and setting the mixture perfectly for a given set of inputs. The fact that there IS a FQS switch seems to indicate that the computer can only compensate for so much and at this point it may be in over it's head with the current setting. (whatever it is right now....:rolleyes:) It may also mean that there is something out of adjustment or a faulty component like that little temp sensor in the MAF or a bad wire or connector..... It may get ugly from here and I want to do this systematically and logically. The car did pass a few years ago, but it was again, high on NOX back then and the Tech told me that I may need an O2 sensor replacement for next time around.

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

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:
http://www.the944.com/afm.htm

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. Inside the AFM is clean but while I have it apart I might do a refurbish now that i have the cover off.

The intake manifold and all vacuum lines have been checked and are OK. The exhaust manifold bolts were uniformly snug but I don't like the look of the gaskets at the end of the header and it may be leaking at that point. I will test that theory when I get it all back together.

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.

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.

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.

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.

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.

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.

status and update.
 

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

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

How much does a inspection cost up there?

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

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.

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.

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.

voltage variable
 

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.

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.

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.

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! :)

vac test.
 

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.

Vacuum leak FOUND!!!
 

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.:eek:

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

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.

idle speculation
 

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.

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.

I wish I did.
 

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.

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.