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.