[DavidH]

I've had my S4 for a little over a year, and the 'check engine' light has never gone out. I have examined the engine airways for cracks and leaks -- none found. Checked the air intake meter, and it's OK. Have changed the O2 sensor. Still, it burns brightly. Unless there is something else to check, I figure there is just an evil ghost in the machine. So, what's the worst that can happen if I just take the bulb out and, accordingly, have no more "check engine" warning at all?

 

[Tifosi]

Have you tried pulling the codes out of the ECU?

I don't know how to do it myself, but others have gotten away with it and posted about it on the BB.

 

[MrT]

There is a lot of info about this Motronic feature on the digest.net archives. Check out Alfa 164 Motronic Self-Diagnosis for what info may be applicable to you.

 

[aldo]

Try this,

http://www.alfabb.com/bb/forums/spider-1966-up/32095-1993-alfa-check-engine-light.html

Credit to John M. of course

 

[GV27]

The Motronic system has a whole host of sensors. There's crank angle sensors, throttle position sensor, temperature sensor, barometer, etc., etc.. You've checked only two.

I'm sorry, but you sound a lot like one of those "I hate fuel injection - you can't work on it yourself" type folks. To which my reply is always "BS - it's a lot easier to work on because it'll tell you exactly what's wrong!". If you take the bulb out, it can no longer tell you what is wrong and at some point it'll start running poorly (I would suspect that it is not running perfectly now) and you'll be on here posting about how to convert it to carbs.

So look at those links above and let your Alfa tell you what it's unhappy about, then fix it! Then the light will go out and your car will run great. Simple as can be.

C

 

[MrT]

Now, now, Chris, David is only expressing frustration over not being able to identify the problem that makes his CE light turn on. I might express similar frustration over not being able to keep my AirBag light off in the '91 164L. But I have a "bad squib" transient indication and should disconnect the battery and go through all of the airbag connections and clean them. That would probably fix _my_ issue. David just needs a pointer to how to read his problem indication. I'm in that boat myself on the ABS system on the '91 164L, as I don't have the reader that pulls codes from that particular system. I do know how to read the CE codes from the computer, so I can fix those. Maybe when David pulls the CE codes and tells us what they are, we can help with that, too.

Michael

 

[aldo]

David,
Even if you have quessed right and fixed the problem the check engine light won't go out until you reset and erase the trouble codes.

 

[MrT]

I thought there was some long (many tens) of start/stop cycles which would eventually erase it. Maybe not, though.

 

[aldo]

You could be right but I recently lost my O2 sensor and the light remained until I reset it.

 

[Gubi]

At least on mine, the light only comes on when a problem is actually occurring. So if it's an intermittent issue, the light will come on and off as the problem happens. If you fix the problem the light will go out (even if codes are still stored in the ECU).

Fact that the light is on all the time indicates it's something pretty fubared - maybe a dead sensor or cut sensor wire somewhere. Pulling the code would be smart.

 

[DavidH]

Thanks, guys, for the attention. So, here are the freshly-pulled codes -- 1225 and 1223. The shop manual tells me that the 1225 is indeed the air temperature sensor, and that 1223 indicates the O2/Lambda sensor. Interestingly, the comment to the 1223 code says that the "air fuel circuit is operating incorrectly - limit value hit...driveability is irregular." The comment to the 1225 code is that driveability is "almost regular." Frankly, the car does not seem to run "irregularly" -- in fact, it seems to run pretty darned well.

Now, about a year ago, I went through all this and got the same codes -- 1223 and 1225. At that time, I replaced the O2 sensor, and tested the air temperature sensor with a multimeter and found that it was within spec. Since then, I have reset the check engine light (hold the button for >10 sec until the light goes out) several times. The light stays out for about one trip to the hardware store and then comes back on. Grrrr. So, what's a guy to do? Might there be something else lurking in the ECU that is setting off the lights?

 

[papajam]

...and that 1223 indicates the O2/Lambda sensor.

Well, not the O2 sensor proper. Code 1223 indicates that the sensor has sent a value to the ECU that is out of range. Either a lean or rich mixture. Possibly the result of a bad air temp sensor/circuit.

Contrary to the standard practice of addressing the lowest code first, I'd test the air temp sensor readings at ECU pins 6 & 22 against the values listed in the service manual.

 

[Gubi]

Yeah, what Jim said. Lots of things will throw a 1223 code but it doesn't mean the problem is with the sensor. Likely the 1225 problem is causing the mixture to hit a limit.

 

[DavidH]

Jim and Tom, thanks. I understand your advice and will try to check the air temp sensor this weekend and report the results. D.

 

[DavidH]

After pulling the codes and resetting/erasing them, the car drove for a while without lighting up. But, after about five or six miles, the light came on again. I don't know what that signifies, but I thought I'd report it.

 

[he3r0]

It may not be relevant, but, guy from NC Inspection Station, told me that after reseting the codes, you have to drive about 30-40 miles, then computer does checkup again and if the problem is not fixed it will light up engine check light again.

 

[DavidH]

Code 1223 indicates that the sensor has sent a value to the ECU that is out of range. Either a lean or rich mixture. Possibly the result of a bad air temp sensor/circuit.

I haven't tested the air flow meter yet, but I did notice that there is a "hiss" when I opened the gas cap today; tank was about half full +/-. If this is a partial vacuum in the tank, then could this make it hard for the fuel pump to get gas to the engine and make it run lean? If so, might this explain the Lambda code (1223)? There was a thread on hissing fuel tanks a year or so ago, but it didnt reach this issue.

 

[Gubi]

No, that's not your problem. Even with the tank vent system properly working the tank will still hiss a little at times.

The 1225 code is your smoking gun. Lots of things can cause a 1223, but the 1225 means either you have a bad temp sensor or bad wiring from the sensor to the ECU. Fix that and the 1223 should go away.

 

[La Voce]

Problem: 1991 Spider, driving home from a road trip, hesitation at throttle tip in, warm engine, half tank of fuel. However, little or very brief hesitation, if one becomes aggressive on throttle from a standing start. Also becomes difficult to start, with intermittent rough idle. By the way, none of these symptoms were evident with a full tank of fuel.
In the driveway, the Check Engine light illuminated briefly twice whilst trying to hold 2,000 rpm (she was running raggedly, with rpm fluctuating). Pulled a 1223 code.
1223 Code Troubleshooting:
1. Check to ensure there are no intake duct air leaks
2. Check the air filter for proper functioning
3. Check to ensure fuel pressure is correct
4. Check the electric injectors and airflow meter for proper functioning
Examining under the hood, I found the fuel pressure regulator vacuum line torn open on the underside at the regulator, out of sight from any casual visual inspection. Replaced the hose, and on a hunch, tried to directly power the in-tank fuel boost pump from the battery. No joy. So, new pump on the way. Will advise as to results.

 

[spiderserie4]

By the way, none of these symptoms were evident with a full tank of fuel.

because of that, you need to also carefully check the little stepped hose on the in tank pump.
http://www.alfabb.com/bb/forums/1059625-post22.html