P0420 and fuel consumption

runner19 · 02-02-2004, 08:10 AM

I have a MY02 WRX with a AF531v3 map switch rom(ecutek).

Ambient Temp 87 F

My cars fuel consumption has increased by 80% recently. My car has a SPT bosal exhaust with a gutted uppipe(full decat). It is throwing a P0420 cel. The car runs fine other than the increase in fuel consumption

I have had it checked for boost/exhaust leaks and there were none.

1. Can the P0420 code be causing this increase in fuel?
2. Is the Ecutek temp compensation causing the increase in fuel consumption becasue of high ambient temps?

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mouserWRX · 02-02-2004, 09:05 AM

I remember hearing that your car runs in some kind of "safe mode" when you get a CEL thrown, and so yeah I believe it's running rich. I threw a P0420 code for about a couple of days however, I didn't really notice THAT big of a difference. I'm not sure about #2, but I doubt #1 would cause an 80% increase in fuel consumption.

mick_the_ginge · 02-02-2004, 11:29 AM

The P0420 cat code will not effect which ecu map you are running. Other codes can, not this one.

Of course your ECU could have seen enough knock that your ignition advance multiplier has dropped below 8 and you are running the safe and rich map.

Do you have delta dash to check the IAM?

jland67 · 02-02-2004, 06:52 PM

I ran with a P0420 for months on end with no problems.

Jeremy

Uncle Scotty · 02-04-2004, 02:55 PM

Stuck/sticky injector....???

motoxphil · 02-04-2004, 04:27 PM

Could it be that you are WOT 80% more than before

Things like this tend to happen when new performance parts are installed

Phil

Rally Performance · 02-04-2004, 09:40 PM

I agree with Mick. Try an ECU reset, and see if it clears up your problem... if you have Delta Dash, you can download the latest version at www.ecutek.com and can see the advance multiplier. The P0420 code won't cause the car to switch to the hi detonation fuel map, but low advance multipliers might.

You may be having another problem, but see if a reset clears it up.

Regards,
Ken
Rally Performance

WiredWRX · 02-15-2004, 07:56 PM

I noticed the same thing when I threw the PO420. Never had the numbers to prove it, but I noticed that as soon as I threw the code, my gas mileage would suck.

I just figured that the ECU was trying to compensate for the cat innefficiency by running the car rich. Why, I don't know, cause I would think that running rich would have the opposite effect, but, my gas mileage deffinitely sucked when I had the cel.

Got the PDE DP, no more CEL, no more crappy gas mileage.

Problem solved.

Michael

marto · 02-17-2004, 05:56 PM

I have high gas consuption too.
1.8 impreza 200 miles with a full tank
please help?
already change air filter and actually the old one had a grissy spot in the middle.
02 sensor maybe but how do I check it?

I like my suby I drive it hard even when it is tainy.
new with subys

02-04-2004, 09:40 PM	#7
Rally Performance Vendor Member#: 16588 Join Date: Mar 2002 Location: www.rallyperformance.com	Agreed I agree with Mick. Try an ECU reset, and see if it clears up your problem... if you have Delta Dash, you can download the latest version at www.ecutek.com and can see the advance multiplier. The P0420 code won't cause the car to switch to the hi detonation fuel map, but low advance multipliers might. You may be having another problem, but see if a reset clears it up. Regards, Ken Rally Performance

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02-02-2004, 08:10 AM	#1
runner19 Scooby Newbie Member#: 39562 Join Date: Jul 2003 Chapter/Region: MAIC Vehicle: My02 WRX Sedan 5MT WR blue	P0420 and fuel consumption I have a MY02 WRX with a AF531v3 map switch rom(ecutek). Ambient Temp 87 F My cars fuel consumption has increased by 80% recently. My car has a SPT bosal exhaust with a gutted uppipe(full decat). It is throwing a P0420 cel. The car runs fine other than the increase in fuel consumption I have had it checked for boost/exhaust leaks and there were none. 1. Can the P0420 code be causing this increase in fuel? 2. Is the Ecutek temp compensation causing the increase in fuel consumption becasue of high ambient temps? * Registered users of the site do not see these ads.

02-02-2004, 09:05 AM	#2
mouserWRX Scooby Specialist Member#: 48960 Join Date: Nov 2003 Location: Austin Vehicle: 2006 TL Anthracite	I remember hearing that your car runs in some kind of "safe mode" when you get a CEL thrown, and so yeah I believe it's running rich. I threw a P0420 code for about a couple of days however, I didn't really notice THAT big of a difference. I'm not sure about #2, but I doubt #1 would cause an 80% increase in fuel consumption.

02-02-2004, 11:29 AM	#3
mick_the_ginge Citizen Mick Member#: 27646 Join Date: Oct 2002 Chapter/Region: NWIC Location: Portland, Oregon Vehicle: 2003 Sleeved 2.5 Oil Dry Sump Goodness	The P0420 cat code will not effect which ecu map you are running. Other codes can, not this one. Of course your ECU could have seen enough knock that your ignition advance multiplier has dropped below 8 and you are running the safe and rich map. Do you have delta dash to check the IAM?

02-02-2004, 06:52 PM	#4
jland67 Scooby Specialist Member#: 14427 Join Date: Jan 2002 Chapter/Region: South East Location: Cary NC Vehicle: 2002 09 Mazdaspeed 3 Grey	I ran with a P0420 for months on end with no problems. Jeremy

02-04-2004, 02:55 PM	#5
Uncle Scotty NASIOC Supporter Member#: 16200 Join Date: Mar 2002 Vehicle: OK Houston we have an Uncle	Stuck/sticky injector....???

02-04-2004, 04:27 PM	#6
motoxphil Scooby Newbie Member#: 5094 Join Date: Mar 2001 Location: Gaithersburg, MD, usa Vehicle: 2002 11.96, 1.64, 115mph!	Could it be that you are WOT 80% more than before Things like this tend to happen when new performance parts are installed Phil

02-15-2004, 07:56 PM	#8
WiredWRX Scooby Specialist Member#: 20768 Join Date: Jul 2002 Location: Los Angeles, CA Vehicle: 2009 IS-F Black	I noticed the same thing when I threw the PO420. Never had the numbers to prove it, but I noticed that as soon as I threw the code, my gas mileage would suck. I just figured that the ECU was trying to compensate for the cat innefficiency by running the car rich. Why, I don't know, cause I would think that running rich would have the opposite effect, but, my gas mileage deffinitely sucked when I had the cel. Got the PDE DP, no more CEL, no more crappy gas mileage. Problem solved. Michael

02-17-2004, 05:56 PM	#9
marto Scooby Newbie Member#: 51538 Join Date: Dec 2003 Location: philadelphia Vehicle: 1994 impreza red	I have high gas consuption too. 1.8 impreza 200 miles with a full tank please help? already change air filter and actually the old one had a grissy spot in the middle. 02 sensor maybe but how do I check it? I like my suby I drive it hard even when it is tainy. new with subys