Check Engine Light

Mach.1 · 03-13-2000, 02:34 PM

I had a 80mm mass air flow system with a K&N air filter on my 96GT last year and everything worked fine. Then my intake manifold went out and I took it to Ford for them to fix it since it was a recall part. The next day when I got it back the check engine light came on. I took it back to them and they said they would check it out. They told me the the mass air flow sensory got shorted out by the oil from the K&N filter. They said since it was aftermarket they would not replace it. So I bought a new one and it did the same thing. I put the old sensor on with the stock air filter system and it worked fine. So I guess the sesory had not shorted out after all! Anyway it has been a year now and I wanted to try my K&N filter again. I put it on and it ran like a champ for about 2 weeks and now the check engine light is on. Does anyone know what might be causing this? Did Ford do something to my computer to make do this with a K&N? Just do not understand why it worked before but not now!! Thanks for the help!

fixer · 03-14-2000, 01:09 AM

YOUR DEALER IS EXACTLY RIGHT!!!! no matter how many mass air flow sensors you install, as long as it sucks that K&N oil past the two filaments it will short out the sensor in no time flat. OR, if you leave your air cleaner stock and never change the filter.
i ran into the same problem and so did the Bondurant School in Phoenix. they pulled all the K&N filters because they were "shorting" out the sensors. its no joke and is an idiosyncrasy with your car. the old ones worked because of the way the air flowed over the sensor; it did not promote oil covering the sensor. with the new ones even a little bit will create problems. my suggestion as well as many other dealers suggestion is to leave your air cleaner stock and change the filter regularly.

Mach.1 · 03-14-2000, 02:18 PM

First thanks for you reply! But what I do not understand is if the K&N filter caused the sensor to short out then why does it work again as soon as I but the stock air filter on with the supposed shorted out sensor? Seems to me that I would get the same result unless I replaced the sensor.

Ripper · 03-14-2000, 03:49 PM

Will this happen to my 99GT? I'm getting ready to clean my K&N filter. I have the stock mass air meter.

BLK99GT · 03-14-2000, 11:53 PM

I've had a K+N on my 99GT for 15K + miles and havent had the check engine light come on

Ripper · 03-15-2000, 08:10 AM

BLK99GT:
Have you cleaned your K&N yet?

03-15-2000, 08:51 AM

I have had my K&N air filter on my '97 Mustang for a year and have yet to see a check engine light (knock on wood). If it is the cleaning oil that screws everything up, then I'm just not going to use it to clean the filter.

lewillie · 03-15-2000, 09:33 PM

My 99 4.6GT is equiped with a K&N and has been for the past 15K miles without any problems as described. Be reasonable when you oil the filter, this may be the cause of the problem.

P.S. Listen up guys. I've read many posts stating this engine does not respond well to shorty headers......Well your big time wrong.
They will make your 99 run like hell. The cast iron exhaust manifolds are no gift.
That is unless the Canadian version differs from it's U.S. counterpart

lewillie

------------------
99/ Silver GT 4.6 SOHC
M.S. headers 3.27

BLK99GT · 03-16-2000, 11:58 PM

Ripper:
I havent cleaned the K+N yet and i just put on a MAC fenderwell kit with a new cone filter so i wont know how the cleaning affects the MAF for a while

------------------
1999 GT AODE ,MAC cold air kit,ATS-III seq. turn signals

95GTS · 03-21-2000, 07:31 PM

Welcome to the world of the 4.6. Mine comes on, then goes off after about 4 cold starts just like the manual says it should, then stays off for a while, then comes back on. Seems to be a routine almost. Mostly does it when I get on it, though. I know of others that have the problem and don't have the K&N. And yes I do have the K&N and had it on there for probably over 15-16k miles before it started doing the check engine light thing. Dallas Mustang sells a deal that shuts off the check engine light or tricks the computer some how so it doesn't turn on that feature and screw up engine performance. You practically have to get one or live with the light when you put on offroad exhaust with the 4.6 cause of the new OBD-II computer.

ShinyGT · 03-24-2000, 12:20 AM

I have a '96GT and have the same problem with my K&N. I took the battery terminal off and let it sit for awhile and tried again. The light stayed off for a day and then came back on so now I just live with the light, it isn't hurting anything is it? <g>

96GTBYYOU · 03-27-2000, 10:28 PM

Mine never came on 'till I installed the Vortech - Now it just stays on.....and I don't care!

------------------
96GT, Vortech S-Trim,C&L 80mm mass air,30# injectors, MSD DIS-4, 3.73, Bassani X, Flows, 70mm TB, Subs, Mega-Bite Jr.Lower rear Ctrl Arms, FMS Uppers, Ripper, and a bunch of other $tuff I can't seem to remember!

97snakedriver · 03-28-2000, 06:16 PM

I have never heard of this happening. How oily is your filter? Have you done anything else? You don't supose your dealer screwed anything up.

It could be some sort of weird computer thing, but I wouldn't think a K&N would flow enough to throw the computer off that much. Weird.

By the way, your warrentee can not be voided because of a K&N, unless there was something wrong with it. Too much oil or something.

------------------
'97 Cobra, K&N, Flowmaster, subframes, 4.10 gears, Steeda Tri-Ax shifter, Steeda G-Trac 3, Cobra R wheels w/ Goodyear F1s

03-13-2000, 02:34 PM	#1
Mach.1 Registered Member Join Date: Jan 2000 Location: Alpharetta, GA. USA Posts: 4	Check Engine Light I had a 80mm mass air flow system with a K&N air filter on my 96GT last year and everything worked fine. Then my intake manifold went out and I took it to Ford for them to fix it since it was a recall part. The next day when I got it back the check engine light came on. I took it back to them and they said they would check it out. They told me the the mass air flow sensory got shorted out by the oil from the K&N filter. They said since it was aftermarket they would not replace it. So I bought a new one and it did the same thing. I put the old sensor on with the stock air filter system and it worked fine. So I guess the sesory had not shorted out after all! Anyway it has been a year now and I wanted to try my K&N filter again. I put it on and it ran like a champ for about 2 weeks and now the check engine light is on. Does anyone know what might be causing this? Did Ford do something to my computer to make do this with a K&N? Just do not understand why it worked before but not now!! Thanks for the help!

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03-14-2000, 01:09 AM	#2
fixer Registered Member Join Date: Aug 1999 Location: mesa,az,usa Posts: 457	YOUR DEALER IS EXACTLY RIGHT!!!! no matter how many mass air flow sensors you install, as long as it sucks that K&N oil past the two filaments it will short out the sensor in no time flat. OR, if you leave your air cleaner stock and never change the filter. i ran into the same problem and so did the Bondurant School in Phoenix. they pulled all the K&N filters because they were "shorting" out the sensors. its no joke and is an idiosyncrasy with your car. the old ones worked because of the way the air flowed over the sensor; it did not promote oil covering the sensor. with the new ones even a little bit will create problems. my suggestion as well as many other dealers suggestion is to leave your air cleaner stock and change the filter regularly.

03-14-2000, 02:18 PM	#3
Mach.1 Registered Member Join Date: Jan 2000 Location: Alpharetta, GA. USA Posts: 4	First thanks for you reply! But what I do not understand is if the K&N filter caused the sensor to short out then why does it work again as soon as I but the stock air filter on with the supposed shorted out sensor? Seems to me that I would get the same result unless I replaced the sensor.

03-14-2000, 03:49 PM	#4
Ripper Registered Member Join Date: Jan 1999 Location: Danbury, CT, USA Posts: 273	Will this happen to my 99GT? I'm getting ready to clean my K&N filter. I have the stock mass air meter.

03-14-2000, 11:53 PM	#5
BLK99GT Registered Member Join Date: Jul 1999 Location: rocky point, NY ,USA Posts: 65	I've had a K+N on my 99GT for 15K + miles and havent had the check engine light come on

03-15-2000, 08:10 AM	#6
Ripper Registered Member Join Date: Jan 1999 Location: Danbury, CT, USA Posts: 273	BLK99GT: Have you cleaned your K&N yet?

03-15-2000, 08:51 AM	#7
crumbie Guest Posts: n/a	I have had my K&N air filter on my '97 Mustang for a year and have yet to see a check engine light (knock on wood). If it is the cleaning oil that screws everything up, then I'm just not going to use it to clean the filter.

03-15-2000, 09:33 PM	#8
lewillie Registered Member Join Date: Oct 1999 Location: Ste, Catherine, quebec, Canada Posts: 23	My 99 4.6GT is equiped with a K&N and has been for the past 15K miles without any problems as described. Be reasonable when you oil the filter, this may be the cause of the problem. P.S. Listen up guys. I've read many posts stating this engine does not respond well to shorty headers......Well your big time wrong. They will make your 99 run like hell. The cast iron exhaust manifolds are no gift. That is unless the Canadian version differs from it's U.S. counterpart lewillie ------------------ 99/ Silver GT 4.6 SOHC M.S. headers 3.27

03-16-2000, 11:58 PM	#9
BLK99GT Registered Member Join Date: Jul 1999 Location: rocky point, NY ,USA Posts: 65	Ripper: I havent cleaned the K+N yet and i just put on a MAC fenderwell kit with a new cone filter so i wont know how the cleaning affects the MAF for a while ------------------ 1999 GT AODE ,MAC cold air kit,ATS-III seq. turn signals

03-21-2000, 07:31 PM	#10
95GTS Git jiggy Join Date: Oct 1999 Location: MO USA Posts: 865	Welcome to the world of the 4.6. Mine comes on, then goes off after about 4 cold starts just like the manual says it should, then stays off for a while, then comes back on. Seems to be a routine almost. Mostly does it when I get on it, though. I know of others that have the problem and don't have the K&N. And yes I do have the K&N and had it on there for probably over 15-16k miles before it started doing the check engine light thing. Dallas Mustang sells a deal that shuts off the check engine light or tricks the computer some how so it doesn't turn on that feature and screw up engine performance. You practically have to get one or live with the light when you put on offroad exhaust with the 4.6 cause of the new OBD-II computer.

03-24-2000, 12:20 AM	#11
ShinyGT Registered Member Join Date: Mar 2000 Location: Greenville, SC Posts: 19	I have a '96GT and have the same problem with my K&N. I took the battery terminal off and let it sit for awhile and tried again. The light stayed off for a day and then came back on so now I just live with the light, it isn't hurting anything is it? <g>

03-27-2000, 10:28 PM	#12
96GTBYYOU Registered Member Join Date: Dec 1999 Location: Reseda, Ca. USA Posts: 32	Mine never came on 'till I installed the Vortech - Now it just stays on.....and I don't care! ------------------ 96GT, Vortech S-Trim,C&L 80mm mass air,30# injectors, MSD DIS-4, 3.73, Bassani X, Flows, 70mm TB, Subs, Mega-Bite Jr.Lower rear Ctrl Arms, FMS Uppers, Ripper, and a bunch of other $tuff I can't seem to remember!

03-28-2000, 06:16 PM	#13
97snakedriver Registered Member Join Date: May 1999 Location: Blacksburg, VA Posts: 1,526	I have never heard of this happening. How oily is your filter? Have you done anything else? You don't supose your dealer screwed anything up. It could be some sort of weird computer thing, but I wouldn't think a K&N would flow enough to throw the computer off that much. Weird. By the way, your warrentee can not be voided because of a K&N, unless there was something wrong with it. Too much oil or something. ------------------ '97 Cobra, K&N, Flowmaster, subframes, 4.10 gears, Steeda Tri-Ax shifter, Steeda G-Trac 3, Cobra R wheels w/ Goodyear F1s