Check Engine Light? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

edevlin · 07-18-2006, 03:43 PM

Hi all, I have just started getting a "check engine" light on the dash. I suspect it has something to do with the mods I have done to my 2000 2.7L Boxster. Got an cold air intake, ECU chip and Fabspeed secondary cat bypass.

The mods I had done are not supposed to effect the check engine lights as the bypass pipes are downstream of the two sensors around the first set of cats.

There were no lights for the first few weeks following the mods, so I am not sure what is going on. Any ideas, thanks,

Ed

PorscheDoc · 07-18-2006, 04:13 PM

Which ECU flash did you get?

Get the code read down, but I am going to guess it is a dirty Maf. Did the cold air intake use the K&N filter?

07-18-2006, 05:53 PM

If its a dirty MAF it might cost you 150 to get it cleaned at a dealer (I had a dirty MAF). But im pretty sure I could of done it myself...

PorscheDoc · 07-18-2006, 06:34 PM

Quote:

Originally Posted by boggtown

If its a dirty MAF it might cost you 150 to get it cleaned at a dealer (I had a dirty MAF). But im pretty sure I could of done it myself...

Very easy to clean the maf, I suppose this calls for a write up with pictures? I will see what I can do in the morning

blinkwatt · 07-18-2006, 06:39 PM

Quote:

Originally Posted by PorscheDoc

Very easy to clean the maf, I suppose this calls for a write up with pictures? I will see what I can do in the morning

Yes it may be easy but do not forget that you need torx bits to remove it if memory serves me right.

MNBoxster · 07-18-2006, 08:46 PM

Quote:

Originally Posted by PorscheDoc

Very easy to clean the maf, I suppose this calls for a write up with pictures? I will see what I can do in the morning

Hi,

You're right, it is very easy to clean the MAF if you know what you're doing. But a note of caution, it equally easy to destroy the MAF if you don't...

Happy Motoring!... Jim'99

edevlin · 07-19-2006, 05:55 AM

The cold air intake I got does use a N&K filter. When I was thinking about getting a cold air intake, I checked with the Porsche mechanic that has done work on my car. He warned about oil from the filters mucking up the sensors.

When I talked to the folks that installed the intake with the N & K filters, I tolk them that I was concerned about oil on the sensor. They said that was very rarely the problem (except for me?), that the only time they had seen a problem was when folks cleaned the filters, reoiled them and put way too much oil on them.

What is the role of the sensor on the intake? I am wondering how a malfunctioning sensor can mess up the operation of the car, or is it just an emissions sort of thing. I know just enough about this topic to be dangerous.

Ed

MNBoxster · 07-19-2006, 07:00 AM

Quote:

Originally Posted by edevlin

The cold air intake I got does use a N&K filter. When I was thinking about getting a cold air intake, I checked with the Porsche mechanic that has done work on my car. He warned about oil from the filters mucking up the sensors.

When I talked to the folks that installed the intake with the N & K filters, I tolk them that I was concerned about oil on the sensor. They said that was very rarely the problem (except for me?), that the only time they had seen a problem was when folks cleaned the filters, reoiled them and put way too much oil on them.

What is the role of the sensor on the intake? I am wondering how a malfunctioning sensor can mess up the operation of the car, or is it just an emissions sort of thing. I know just enough about this topic to be dangerous.

Ed

Hi,

The MAF (Mass Air Flow Sensor) tells the ECU (DME in Porsche Parlance) how much air is entering the engine so that the ECU can select an appropriate Fuel MAP to determine the Flow and Duration of the Fuel Injectors to get the proper A/F Mixture.

The MAF uses a thin piece of conductive film (think Mylar) which is heated by an electrical current. As more Air passes over this film, it takes away some of the heat generated by the current. The film posesses different resistance qualities at different temperatures and it is this difference in resistance which the ECU uses to determine the Mass of the Air passing over it - the resistance measure is directly proportional to the amount of Air flowing past it. If the Film becomes dirty or covered in Oil, it's ability to retain heat is increased and the resistance in the current is no longer a direct correlation to the amount of Air passing over it.

The resistance signal exceeds either the upper or lower pre-set limit and the ECU cannot get the A/F mixture right. It then goes into a pre-set default mode, sometimes referred to as Limp Mode to both protect the engine and to keep emissions as low as possible. It cuts the amount of fuel being delivered in an attempt to establish the proper mixture. So, you're engine is being starved for fuel and this is what causes the drop in performance.

The K&N filter has been shown to be a problem on these cars. Not only that, but they're not really any better than the OEM on a stock engine. They clog in less time and they release a fine aerosol of Oil into the mix which settles on the MAF, causing the issue I described. Personally, I'd pitch it, because not only does it cause MAF problems, but it allows more dirt to pass into the engine increasing wear and necessitating a shorter Oil Change interval because much of this dirt gets retained in the Oil. Hope this helps...

Happy Motoring!... Jim'99

edevlin · 07-19-2006, 10:52 AM

Yikes, I took the air filter out of my aftermarket cold air intake, and found it is a BMC filter that is to be cleaned and recharged (not an N&K). I have about 2K on the filter and it was quite dirty when I cleaned it. Also, I can now see how an overapplication of oil can muck up the system.

I am interested to see if my check engine light is due to a dirty sensor. I would be very interested in how to clean the sensor to see if that is my problem.

Also, a fellow poster asked what the error code was. Is there an relatively inexpensive diagonostic tool that would allow me to plug into the port on the car and check the error codes? I could have it done at the Porsche shop, but would like to be able to check these things for myself as they come up.

Ed

fab · 07-19-2006, 11:44 AM

I had installed an K N filter not too long ago. Then I asked around if it will do any harm and I got mix bag of response. At that point, I iimmediately removed the filter and purchased a stock item.

edevlin · 07-19-2006, 12:47 PM

So I went to Advanced Auto Parts and 150.00 later, I became the owner of a OBD II Autoscanner, ouch. I figured with the messing around I seem to be doing to this 2.7L 2000 boxster, I am going to need to know what the fault codes mean.

It looks like you guys were right on the money on predicting my problem. I only got one code and that was P0102 which according to the Boxster service manual is "a mass air flow sensor - short to ground/below lower limit/lean mixture threshold".

So, for the short term, I need to be able to clean the maf, if possible. For the long term, I need to decide if I should dump the cold-air intake that seems to have caused the fault code.

Even thought it appears to have given me this fault code, I am still inclined to try to keep the cold air intake. The reason being that the Autoauthority Pitstop chip I got for the car is dialed in for this cold air intake, and the performance of the car is great, much better than before the chip and intake.

Also, I was planning on getting the crew at Autoauthority Pitstop to install german headers and high flow cats, as they have worked for quite some time to dial in a chip for the 2.7L boxster with their intake and exhaust rig. I am loving the performance of the car, especially after chipping.

As a little background, this car is my first Porsche (but have lusted for one since my 1958 Karman Ghia I had in the late 1960's). I have had it for about 2 months, and 2,000 miles (trip to Florida to see mom), so I am quite new to the game. When I got the car I had some modest funds set aside to do some mods if it seemed they were warranted. So any advice and/or comments to my situiation are welcome.

Ed

2000 2.7L Boxster
45,000 miles
Silver/Black
Fabspeed Secondary Cat Bypass pipes
AP custom chip
AP cold air intake (AKA: MAF eater)
17" wheels
Pioneer CD/JL Audio amps and speakers
Power Seats

PorscheDoc · 07-20-2006, 04:10 AM

Just clean the maf, and the filter (don't oil it), and you should be fine. The cold air intakes move so much more air through the system than the stock filter, that it will literally suck out any excess oil out of a filter (or microscopic dirt particles) out of the filter immediately on start up, and there goes your MAF sensor.

I will do a write up before the end of the week. Crazy crazy week, track event today, and a couple cars that need to leave town by friday, so it is a little crazy, though I will get it done

What you will need:
Can of CRC maf sensor cleaner (any auto parts store) or CRC QD electronics cleaner
Torx security bit (though with the cold air intake system, this probably has been removed and replaced with a small 2.5 or 3mm allen)

edevlin · 07-20-2006, 06:22 AM

The last time I did any work on cars was back in the points-plugs-distributor-adjust carb days. So learning about this Boxster has been both frustrating and kinda fun so far. I have been trying to trouble-shoot the check engine light, I got my code reader, read code, identified MAF sensor as probably the problem. On advice of forum members, got no-residue contact cleaner, disconnected the battery, poped the MAF sensor out, found the mylar film and resistor contacts, sprayed to clean, poped unit back in.

Started car 3X to give the error code a chance to come up if it was going to rear its ugly head again, and beauties of beauties, no check engine light. Who would have thought that a black span at the bottom of the dash with no fault lights could look so good. So there I was, top down, driving down the road, the sun was shining, the day way young. Ed Devlin, master mechanic, trouble-shooter extraordinary, a simple piece of german machinary is no match for my wits......

Steped on the gas, took it up towards redline and thought to myself, man this car is running great. Then it happened, my house of cards came crashing down with the appearance of a little orange light on the dash that said "check engine"...... The car is still running great, seems to be as good as ever, but that little light has got to go.....

Ed

2000 2.7L Boxster, 45K
5-speed manual
TTP cold air intake, BMC filter
Fabspeed Secondary Cat Bypass Pipes
Custom AP ECU Chip

MNBoxster · 07-20-2006, 08:14 AM

Quote:

Originally Posted by edevlin

The last time I did any work on cars was back in the points-plugs-distributor-adjust carb days. So learning about this Boxster has been both frustrating and kinda fun so far. I have been trying to trouble-shoot the check engine light, I got my code reader, read code, identified MAF sensor as probably the problem. On advice of forum members, got no-residue contact cleaner, disconnected the battery, poped the MAF sensor out, found the mylar film and resistor contacts, sprayed to clean, poped unit back in.

Started car 3X to give the error code a chance to come up if it was going to rear its ugly head again, and beauties of beauties, no check engine light. Who would have thought that a black span at the bottom of the dash with no fault lights could look so good. So there I was, top down, driving down the road, the sun was shining, the day way young. Ed Devlin, master mechanic, trouble-shooter extraordinary, a simple piece of german machinary is no match for my wits......

Steped on the gas, took it up towards redline and thought to myself, man this car is running great. Then it happened, my house of cards came crashing down with the appearance of a little orange light on the dash that said "check engine"...... The car is still running great, seems to be as good as ever, but that little light has got to go.....

Ed

2000 2.7L Boxster, 45K
5-speed manual
TTP cold air intake, BMC filter
Fabspeed Secondary Cat Bypass Pipes
Custom AP ECU Chip

Hi,

Disconnect the Battery (Radio Code in Hand), wait 5 min. and reconnect, this will clear the code. Then drive one Drive Cycle to re-educate the DME (idle will be rough until you do). This will probably clear the code or you may have a bad MAF, they cannot always be cleaned satisfactorily - they do fail eventually and require replacement. Hope this helps...

Happy Motoring!... Jim'99

edevlin · 07-23-2006, 06:16 AM

I have been reading some threads about needing to reprogram ECU for new MAF sensors. I was going to get one and replace it, but I am now concerned that I may have to have the ECU reprogramed so that it recognizes the new mass air flow sensor. Anyone know if reprogramming is necessary when replacing MAF sensor in a 2000 2.7L boxster?

Ed

2000 Boxster 2.7L
45K
BMC cold air intake
AP Chip
Fabspeed bypass pipes