Issues after header install

razzamagoo · Thu, Feb-10-2011, 01:54:09 AM

Okay I have some issues after a header install. I was expecting some o2 issues but it doesn't seem to be so. If you crank car up it idles just fine. But if you go to drive it it severely limps and the SES light comes on.

I use Carsoft 6.5 to scan my codes. According to Carsoft I'm throwing HFM sensor. What in the world? The MAF? So I take it off and clean it and try again. Same thing. If I drive the car it'll run very rough and idle rough. Turn car off and the SES light is gone. Idles just fine until you drive and the cycle starts again.

Now I haven't even touched that dang sensor or the intake. Weird. Any ideas people? Does this sound like the MAF is indeed bad? How can I test it without spending a ton of money on a sensor I may not need?

2002 M3 SMG here with 97,000 miles.

Hu///mmell · Thu, Feb-10-2011, 01:58:12 AM

Are your o2 sensors in the right places?

razzamagoo · Thu, Feb-10-2011, 02:00:00 AM

I'm pretty sure they are as I labelled them. I will double check though.

Don't understand why carsoft said HFM/MAF sensor if it is the o2's.

razzamagoo · Thu, Feb-10-2011, 02:18:14 AM

Just confirmed that the sensor with the 1 tag on it is going to the front long header (cyl 1-3) and the other is going to the shorty header (cyl 4-6).

razzamagoo · Thu, Feb-10-2011, 03:18:01 AM

Will a dead o2 sometimes throw the MAF code?

Can I take the two post cat sensors, splice them into the front ones and see if it fixes it?

mksnwbrd8 · Thu, Feb-10-2011, 09:23:35 AM

what was the code exactly?

sometimes the o2 sensors can throw a code that is very similar for the maf sensor, but it would usually be lean/rich fuel or unable to adjust fuel

the post cat o2 sensors don't control the fuel, they simply compare the voltage to the pre cat sensor to see if the cats are working properly, they would not cause any idle or running issue.

razzamagoo · Thu, Feb-10-2011, 10:45:34 AM

Carsoft wasn't much help in showing the code or I just don't know how to interpret it....I'll run it again and grab a snapshot for all to see.

razzamagoo · Thu, Feb-10-2011, 10:45:37 PM

Those number on the yellow tags on the sensors don't mean jack! Swapped o2 and voila purrs like a kitten!

Hank Cohn · Fri, Feb-11-2011, 12:52:13 AM

That had to be the case. Glad you figured it out. It is amazing how messed up the car will run with just a little mistake. Which headers did you put on your car? Are you running catless? What did you do with the post cat 02 sensors?

razzamagoo · Fri, Feb-11-2011, 12:52:35 PM

I'm running the ebay catless headers. Secondary o2's are tied off in the drug bin away from any wires and plastic for the time being. I have o2 simulator but I haven't thrown a CEL yet.

I also did 4.10 gears at the same time. All I gotta say is OMG! PERFECTION.

Thu, Feb-10-2011, 01:54:09 AM	#1
razzamagoo Registered User Join Date: Mar 2010 Posts: 207 Reputation: 0	Issues after header install Okay I have some issues after a header install. I was expecting some o2 issues but it doesn't seem to be so. If you crank car up it idles just fine. But if you go to drive it it severely limps and the SES light comes on. I use Carsoft 6.5 to scan my codes. According to Carsoft I'm throwing HFM sensor. What in the world? The MAF? So I take it off and clean it and try again. Same thing. If I drive the car it'll run very rough and idle rough. Turn car off and the SES light is gone. Idles just fine until you drive and the cycle starts again. Now I haven't even touched that dang sensor or the intake. Weird. Any ideas people? Does this sound like the MAF is indeed bad? How can I test it without spending a ton of money on a sensor I may not need? 2002 M3 SMG here with 97,000 miles.

Thu, Feb-10-2011, 01:58:12 AM	#2
Hu///mmell Registered User Join Date: Oct 2009 Posts: 1,547 In the garage: '03 BMW E46 M3 Reputation: 0 Location: Charlotte - Plaza Midwood	Re: Issues after header install Are your o2 sensors in the right places? __________________

Thu, Feb-10-2011, 02:00:00 AM	#3
razzamagoo Registered User Join Date: Mar 2010 Posts: 207 Reputation: 0	Re: Issues after header install I'm pretty sure they are as I labelled them. I will double check though. Don't understand why carsoft said HFM/MAF sensor if it is the o2's.

Thu, Feb-10-2011, 02:18:14 AM	#4
razzamagoo Registered User Join Date: Mar 2010 Posts: 207 Reputation: 0	Re: Issues after header install Just confirmed that the sensor with the 1 tag on it is going to the front long header (cyl 1-3) and the other is going to the shorty header (cyl 4-6).

Thu, Feb-10-2011, 03:18:01 AM	#5
razzamagoo Registered User Join Date: Mar 2010 Posts: 207 Reputation: 0	Re: Issues after header install Will a dead o2 sometimes throw the MAF code? Can I take the two post cat sensors, splice them into the front ones and see if it fixes it?

Thu, Feb-10-2011, 09:23:35 AM	#6
mksnwbrd8 Registered User Join Date: Aug 2008 Posts: 130 In the garage: '03 BMW M3 Reputation: 0 Location: Chicago	Re: Issues after header install what was the code exactly? sometimes the o2 sensors can throw a code that is very similar for the maf sensor, but it would usually be lean/rich fuel or unable to adjust fuel the post cat o2 sensors don't control the fuel, they simply compare the voltage to the pre cat sensor to see if the cats are working properly, they would not cause any idle or running issue.

Thu, Feb-10-2011, 10:45:34 AM	#7
razzamagoo Registered User Join Date: Mar 2010 Posts: 207 Reputation: 0	Re: Issues after header install Carsoft wasn't much help in showing the code or I just don't know how to interpret it....I'll run it again and grab a snapshot for all to see.

Thu, Feb-10-2011, 10:45:37 PM	#8
razzamagoo Registered User Join Date: Mar 2010 Posts: 207 Reputation: 0	Those number on the yellow tags on the sensors don't mean jack! Swapped o2 and voila purrs like a kitten!

Fri, Feb-11-2011, 12:52:13 AM	#9
Hank Cohn Registered User Join Date: Mar 2008 Posts: 139 Reputation: 0 Location: Atlanta	Re: Issues after header install That had to be the case. Glad you figured it out. It is amazing how messed up the car will run with just a little mistake. Which headers did you put on your car? Are you running catless? What did you do with the post cat 02 sensors? __________________ __________________ 2003 ///M3 Carbon Black 1990 ///M3 Brilliant Red

Fri, Feb-11-2011, 12:52:35 PM	#10
razzamagoo Registered User Join Date: Mar 2010 Posts: 207 Reputation: 0	Re: Issues after header install I'm running the ebay catless headers. Secondary o2's are tied off in the drug bin away from any wires and plastic for the time being. I have o2 simulator but I haven't thrown a CEL yet. I also did 4.10 gears at the same time. All I gotta say is OMG! PERFECTION. Last edited by razzamagoo; Fri, Feb-11-2011 at 12:58:27 PM.

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