Reasons for Running Rich?

[ocduff]

Well, I've searched through the forums and found a lot of information about Air Flow Meters, O2 Sensors, Idle Adjust Screws, and Throttle Position Sensors and how they correlate to gas/fuel mixture -

If any of you looked at the thread I started about my throttle linkage problem, you know that I've checked everything but the Air Flow Meter to address a problem that turned out to be my throttle linkage - so here is my current situation:

I purchased my 91 Spider two weeks ago and it was running fine then with the exception of the throttle linkage (which is another, isolated problem which has been addressed).

Anyway, the problem I've been having is that the car has been running slightly rich. The only evidence I have of this is a faint burnt gas smell in the fresh engine oil and lightly sooty deposit on the outside of the spark plug rings (electrode is white, tip is chalky white). I'm not sure that my gas mileage is that much affected - basically, thats the evidence I have supports that I'm running rich - yet I have no way of knowing how rich.

As I said, I'm new to the car and I don't know if this was an issue before I bought it but I think I recall smelling the oil that was in it before I changed it and it seemed OK. I passed emissions last week but failed because of a cracked center tailpipe, which was worsened by the guy yanking on the tailpipe with a towel over his hand (another story). But it was failing anyway, and is very bad now (though patched with a poor patch kit).

So, I'm not certain that my new exhaust leak is the cause of my over richness or not, but I plan on replacing it soon (my car doesn't have a center muffler, only a center "pipe" - which I like, but can't find one anywhere). I'm thinking of ordering a center muffler and trying to get it on there myself (if the mounting screws aren't too rusted) otherwise just take it to Meineke and have them make a pipe. Maybe this will help.

I'm not sure if the Air Flow Meter has been messed with by the Previous Owner, but if I was to adjust it, how many clicks and in what direction should I adjust it to get me running at the proper mixture? I seem to be reading that clockwise enrichens, counter clockwise leans. Is this correct?

Thanks in advance for your advice -

[Gubi]

Well, you really need to spend more time figuring out what the problem is before you randomly fiddle with things. The Motronic AFM (unlike the L-jet) is not supposed to be adjustable. If you mess with it without knowing it's broken first, you're probably going to screw it up.

I think you need to get the cardisc manual (www.cardisc.com) and go over all the Motronic sensors. The AFM flap and AFM temperature sensor are *very* easy to test with a voltmeter. You also need to clear/check the computer and see what codes you're getting. If the car is really running rich and your O2 sensor is working correctly, you should be getting check engine codes. If possible, you should also get your exhaust gas analyzed to see what your %CO level is...that will give you a hint on the level of richness, if any.

Also, you mentioned that you had adjusted the idle screw on the throttle to try to fix your earlier problems. Before you start chasing the richness problem, get the calibration procedure for the throttle idle adjustment and make sure you've put it back into spec. On the Motronic I'm reasonably certain that the idle speed is controlled by the computer, so it's not an RPM target you're trying to hit by adjusting the screw, it's an air flow rate target. It's all in the cardisc manual.

Most of all, remember that the computer is your friend. The Motronic can correct for a reasonable amount of irregularity in the system, but if it gets overwhelmed it will tell you. If your O2 sensor is working correctly it should not be possible to run consistently rich without getting a code. If the sensor is bad you may or may not get a check engine light.

Good luck.

[ocduff]

gubi -

thanks again for your advice - It seems to me as if everything is working fine - as for CO2 levels - I passed emissions, so it was below normal levels. As for clearing and checking engine codes: I can clear them, I just don't know how to check them.

The car runs great no issues beside the exhaust and richness (related). Yes, I'll have to break down and get the cardisc manual - however the question whether I'm running rich or not aside, there is gasoline in my fuel. I've only had the check engine light come on and that was when I'd set the idle screw high and that was only for 30 seconds, going down a hill with my foot off the accelerator.

This and the cracked center exhaust are my two issues, I was wondering if they could be related. I have no way of knowing how much fuel is getting into my engine and that is a concern of mine.

[alfaloco]

Are you getting any Check Engine warning light with the engine running? Do you know how to check for fault codes?

[ocduff]

Alfaloco -

No, I only got the Check Engine light for 30 seconds a week ago going down a hill - that was it. That was when my exhaust was begininng to go and after I'd set the idel screw a little high. It hasn't happened again.

No, I don't know how to check the fault codes.

Thanks

[alfaloco]

On the rear shelf, right side, there's a small panel which pops out. Under there is a red button. Turn the ignition on, and press the button. Note the flashing pattern of the "Check Engine" light. The number of grouped flashes indicates a digit, i.e. X XX XX X = 1221 code. The groupings repeat four times after an introductory sequence.

Unless someone on the BB has a link handy, I can fax you copies of the pages from my manual on interpreting the codes. Got a fax number?
I could send you on a search or onto the Alfa Digest, but by the time you do all that I can fax you the info tomorrow.

[ocduff]

Alfaloco -

Thanks for the offer to fax things over but unfortunately, I'm going to have to drive it until I get some another "check engine" light - I had to disconnect the battery last week after the light came on. So I'd imagine that erased whatever codes were in there.

What possible codes are in there? I could manipulate it to get another one of those codes up possibly.

Thanks again.

[ocduff]

Also - does anyone know any reason why there would be gas in my oil if the engine was not running rich?

[Craig]

Gas in the oil I will have to think about but this link should help with the codes http://www.digest.net/alfa/FAQ/164/diag.htm

[John M]

Hey OCDuff:

First....I need to welcome you to the board and give a big congrats on getting your Alfa. Sounds like you have a pretty good one with just a few bugs to work out.

On the check engine codes, I don't believe removing the battery cable will erase the codes. Take a look at this thread for the procedure:

Electrically problems???

On the running rich....a little fouling around the base of the plugs could signify a few things. Hard driving for one......but thinking back to your original thread when you discussed how the car was stumbling, I imagine with you trying to compensate for the TPS being off with the gas pedal you built up some of that carbon on the plugs. If you were punching on the gas pedal to try to clear the motor a bunch when she was hesitating.....that's likely the source of the carbon on the plugs and perceived gas in the oil.

I would take Gubi's advice and hold off on the tinkering until you get the cardisc manual. More than likely with the TPS correctly set, you are good to go. One thing about the motronic computer that is superior to the Ljet.....the motronic CE light will quickly let you know when things are out of wack.

On the middle exhaust, the previous owner must have removed it. Not uncommon. So any Midas...etc..should be able to put a new straight pipe in. Otherwise, IAP, Centerline, Vickauto....all would have the center muffler. Could a leak down stream from the O2 sensor result in a rich condition? I suppose its possible but unlikely. A leak upstream of the O2 sensor could more easily cause a rich running situation. But in any case...I would expect to see the CE light come on if that was going on.

A few things that I suggest you can do with your new ride.
1. Fill electrical connections under the hood with dielectric grease
2. Check all the air/vacuum hoses and replace as necessary.
3. Check the motor mounts and replace as necessary.
4. Change all the fluids.

I am of the opinion that the series 4 spider (91-94) is the best of the best. Its a very reliable car. And I believe its the easiest to diagnose. So sit back and enjoy your new ride.

Best Regards,
John M

[turbolarespider]

How old is your catalyst?

If it's new, then you could be running rich, even still, that is a stretch.

If you are passing emissions for both CO and HC, then you are not running rich. It's very hard to actually pass if it's really rich (really as in not a large amount, but actually rich).

The dark ring on the plugs is probably the quench zone in the combustion chamber, so it won't burn there well, anyway. Especially with the white, chalky tip. As for the gas in the oil- no idea unless you've been cranking and running cold a lot recently...

Eric

[Ianc]

I agree that white plug tips and passing the check indicate that the engine is not running rich. And in order to get gas in the oil it would have to be REALLY rich. I think you must have flooded it at some point. All you need is once, and the oil will smell like gas until you burn it off, which would require getting the engine hot for quite a while. Plug tips are the best indicator of mixture - if they're tan, you're ok.

[ocduff]

Hey guys -

Well, it sounds like you've explain some reasons why there might be gas in my oil - plus given me a reason to relax a bit.

As for the exhaust pipe - I went to Meineke and got them to weld a new section on the bend in the pipe near the rear muffler that was cracked This, believe it or not, seems to have cured about 85% of my complaints about hesitation, idle problems, etc. The car runs smooth and quietly now - I guess that exhaust leak had gotten worse over time without me noticing. Hesitation/poor running is gone. Also any annoying ticks and buzzing in the engine is gone.

And Gubi and John M - thanks for the info on the codes. Here's what I pulled from my computer (there were only two codes in there):

4 short flashes - those kept repeating after a pause in between.

When I pressed the button again for the next code I got:

One Long Flash and One Long Delay and One Long Flash and One Long Delay.

Not sure how to interpret those or what they mean but looked at some interpretation charts above and found nothing (incidentally, my battery was unplugged last week for a good amount of time (( this was after the check engine light came on)).

And Here's the results of my emissions test (looking for rich readings):

Standard My reading
N0X 1088 52
HC 141 120
CO% .79 .52
CO2% - 12.4
O2% - 3.3

If anyone has any input here, I'm all ears - and thanks again everyone for all the help. It's sounds like I'm being totally paranoid about the gas in the oil - I drive it relatively hard at times, but not sure how I could have flooded it. Well, I'm glad my car isn't dying!!

[alfaloco]

Thanks to both big John and Gubi for the link to the codes. It's been so long since I fiddled with a 164 (sold ours in 2001) that I didn't think of the 164FAQ site. Ah, those senior moments...

(don't you laugh you young whippersnappers... your time will get here!)

OcDuff- the Motronic codes are the same for both the series 4 Spider and 164. The four short flashes mean "no codes stored". It does not sound to me like you currently have any fault codes in memory, frankly. My experience has been that a minimum 30 minutes of disconnected battery will indeed erase them, also.

I agree with the others on the state of your plugs, if the engine were truly running rich the plugs would be downright sooty and damp, probably too fouled to fire reliably. I'm curious about your comments on the gas smell in the engine oil. Have you noticed the oil actually thinning with use? I suppose you can tell, I'm not convinced you DO have gas in your oil! I have not heard of that happening on a Motronic Spider, unless it is connected somehow with the vapor separator circuit.

Dave Jarman

[Ianc]

The Alfa exhaust system is a true header system, tuned to extract gases. If there is a break in the tailpipe inthe first 1/3rd of the system, all sorts of bad things happen to the tuning. My guess is that you've found most of the problem. Meanwhile, I pulled the plugs on my neighbours Alfetta. I wish I'd taken a picture. Black, sooty, fouled, yechh. Can't see how it ran at all.