running lean

91cobra5.0 · January 20th, 2008, 11:41 PM

ok so i had to leave off the pipes and run headers until this wed. (ran out of time at the shop and had to get the car home so i didnt get the pipes back on) well now its running lean and i was just curiouse as to why that was happening, is it becuase that there is no back pressure?

White Thunder · January 20th, 2008, 11:58 PM

im guessing but something with the o2 sensor...i might be really wrong so flame away

91cobra5.0 · January 21st, 2008, 12:23 AM

yea i was thinkin that too, that becuase the sensors arent there that the computer is sending the car into a safe mode.

Tony_90fox · January 21st, 2008, 12:42 AM

Off topic but what color is your car? Specific name if you got it.

SALIV8 · January 21st, 2008, 10:09 PM

without o2 sensorsthe stock ecu is setting a preprogrammed "tune" it is in open loopwithout feedback from the sensors

91cobra5.0 · January 22nd, 2008, 12:38 AM

i dont know specific color but its 2 tone silver, a darker silver on top with obviously lighter on the bottom

91cobra5.0 · January 22nd, 2008, 12:40 AM

Originally Posted by SALIV8

without o2 sensorsthe stock ecu is setting a preprogrammed "tune" it is in open loopwithout feedback from the sensors

if i just plug the sensors back in withought the pipes would it fix the no feedback? i mean the engine light will still come on but maybe it wont run lean

JBIGBOOTSY · January 22nd, 2008, 02:43 AM

How do you know it's running lean?

Goblin · January 22nd, 2008, 10:13 AM

Originally Posted by JBIGBOOTSY

How do you know it's running lean?

This is also the question i have.

Iwannagofast · January 22nd, 2008, 10:54 AM

Originally Posted by 91cobra5.0

i dont know specific color but its 2 tone silver, a darker silver on top with obviously lighter on the bottom

i hadnt even noticed the two tone.....but it looks nice

91cobra5.0 · January 22nd, 2008, 10:27 PM

Originally Posted by JBIGBOOTSY

How do you know it's running lean?

air-fuel guage

SALIV8 · January 23rd, 2008, 05:58 PM

Originally Posted by 91cobra5.0

if i just plug the sensors back in withought the pipes would it fix the no feedback? i mean the engine light will still come on but maybe it wont run lean

o2 sensors needs exhaust to give the ecu the correct voltage. it will stay that way until they're in the exhaust

ryans88gt · January 23rd, 2008, 06:04 PM

A wide band O2 or an autometer guage? the autometer gauge reading off of stock O2 sensors is next to meaningless.

I tried using mine to tune my nitrous once. It actually read leaner when I fattened up the fuel jets...

BTW I ran my 88 without O2s for about 3 years with no ill effects other than having shitty fuel economy and it running rich below 2000 rpms. The O2 sensors don't really have much effect above 2500 rpms

91cobra5.0 · January 23rd, 2008, 11:04 PM

its a autometer guage but i dont know if it runs off the o2 sensors and i put th pipes back on and the guage reads fine

jam77 · January 23rd, 2008, 11:36 PM

i wouldn't trust that gauge

91cobra5.0 · January 24th, 2008, 01:47 PM

should i re rout it or something?

Goblin · January 24th, 2008, 01:54 PM

Ditch that gauge, and get a good wideband o2 meter. This is ofcourse, if you can afford it. With the gauge you have now.. if your running on the lean side of stoich, the gauge will tell you your lean.. even though you may only be lean by .02:1 With the o2 sensors disconneted, the car will actually run slighty rich. With the exhaust being disconnected, that doesnt effect the A/F ratios, unless you take the o2s off.

ryans88gt · January 24th, 2008, 01:57 PM

Well, if you didn't have any O2 sensor...think about this...how did the guage now you were running lean??

lol...no O2s means no sensor sending unit.

91cobra5.0 · January 24th, 2008, 05:05 PM

true, but still is the whole guage inacurate or just how it was installed?

Goblin · January 24th, 2008, 05:12 PM

The gauge just isnt accurate.

January 20th, 2008, 11:41 PM	#1
91cobra5.0 Hardcore Enthusiast 98 Cobra Join Date: Jan 2008 Location: Bay Area, Ca Posts: 2,057 iTrader: 0 reviews	running lean ok so i had to leave off the pipes and run headers until this wed. (ran out of time at the shop and had to get the car home so i didnt get the pipes back on) well now its running lean and i was just curiouse as to why that was happening, is it becuase that there is no back pressure?

January 21st, 2008, 12:42 AM	#4
Tony_90fox Banned Join Date: Jun 2006 Location: Bowling Green, KY Posts: 3,803 iTrader: 0 reviews	Off topic but what color is your car? Specific name if you got it. __________________ [SIGPIC][/SIGPIC] [B][U]MM Sapper Squad[/U][/B] [QUOTE=Regency 2007;1676187]MSO's stupidity has never stopped amazing me since the day he joined this forum.[/QUOTE]

January 22nd, 2008, 02:43 AM	#8
JBIGBOOTSY MM Fanatic 1990 LX hatch Join Date: Aug 2006 Location: Hobart Indiana Posts: 4,391 iTrader: 0 reviews	How do you know it's running lean? __________________ Bolt-on Abraham Lincoln Log motor. With extra wiring.

January 23rd, 2008, 06:04 PM	#13
ryans88gt MM Fanatic Join Date: May 2007 Location: Bloomington, IL Posts: 4,737 iTrader: 0 reviews	A wide band O2 or an autometer guage? the autometer gauge reading off of stock O2 sensors is next to meaningless. I tried using mine to tune my nitrous once. It actually read leaner when I fattened up the fuel jets... BTW I ran my 88 without O2s for about 3 years with no ill effects other than having shitty fuel economy and it running rich below 2000 rpms. The O2 sensors don't really have much effect above 2500 rpms __________________ 88 GT CHI headed 351w 10.8 @ 125 - still figuring it out. 03 Cobra 2.3 whipple 10.7 @ 129 - sold it 04 Mach 1 12.7 @ 109 mostly stock - sold it 89 LX procharged 302 515 hp 497 ftlbs 10.7 @130 mph - sold it

January 23rd, 2008, 11:36 PM	#15
jam77 Enthusiast 1987 Mustang GT Join Date: Apr 2007 Location: IL Posts: 685 iTrader: 0 reviews	i wouldn't trust that gauge __________________ 87 GT, typhoon upper and lower,70mm tb, 90mm maf, bbk shorties, bbk x-pipe, flowmaster cat back, 3:73 gear, pro 5.0 shifter, novi blower,afm power pipe, load IO, Trick Flow heads, Anderson B-31 cam, Anderson PMS, 42 lb injectors, t-rex fuel pump.

January 21st, 2008, 12:23 AM	#3
91cobra5.0 Hardcore Enthusiast 98 Cobra Join Date: Jan 2008 Location: Bay Area, Ca Posts: 2,057 iTrader: 0 reviews	yea i was thinkin that too, that becuase the sensors arent there that the computer is sending the car into a safe mode.

January 21st, 2008, 10:09 PM	#5
SALIV8 all motor 92 coupe 9.94@136.40 Join Date: Dec 2006 Location: Chicago Posts: 576 iTrader: 0 reviews	without o2 sensorsthe stock ecu is setting a preprogrammed "tune" it is in open loopwithout feedback from the sensors

January 22nd, 2008, 12:38 AM	#6
91cobra5.0 Hardcore Enthusiast 98 Cobra Join Date: Jan 2008 Location: Bay Area, Ca Posts: 2,057 iTrader: 0 reviews	i dont know specific color but its 2 tone silver, a darker silver on top with obviously lighter on the bottom

January 23rd, 2008, 11:04 PM	#14
91cobra5.0 Hardcore Enthusiast 98 Cobra Join Date: Jan 2008 Location: Bay Area, Ca Posts: 2,057 iTrader: 0 reviews	its a autometer guage but i dont know if it runs off the o2 sensors and i put th pipes back on and the guage reads fine

January 24th, 2008, 01:47 PM	#16
91cobra5.0 Hardcore Enthusiast 98 Cobra Join Date: Jan 2008 Location: Bay Area, Ca Posts: 2,057 iTrader: 0 reviews	should i re rout it or something?

January 24th, 2008, 01:54 PM	#17
Goblin Hardcore Enthusiast 88mm Join Date: Apr 2007 Location: Tucson, AZ Posts: 2,111 iTrader: 0 reviews	Ditch that gauge, and get a good wideband o2 meter. This is ofcourse, if you can afford it. With the gauge you have now.. if your running on the lean side of stoich, the gauge will tell you your lean.. even though you may only be lean by .02:1 With the o2 sensors disconneted, the car will actually run slighty rich. With the exhaust being disconnected, that doesnt effect the A/F ratios, unless you take the o2s off. __________________

January 24th, 2008, 01:57 PM	#18
ryans88gt MM Fanatic Join Date: May 2007 Location: Bloomington, IL Posts: 4,737 iTrader: 0 reviews	Well, if you didn't have any O2 sensor...think about this...how did the guage now you were running lean?? lol...no O2s means no sensor sending unit. __________________ 88 GT CHI headed 351w 10.8 @ 125 - still figuring it out. 03 Cobra 2.3 whipple 10.7 @ 129 - sold it 04 Mach 1 12.7 @ 109 mostly stock - sold it 89 LX procharged 302 515 hp 497 ftlbs 10.7 @130 mph - sold it

January 24th, 2008, 05:05 PM	#19
91cobra5.0 Hardcore Enthusiast 98 Cobra Join Date: Jan 2008 Location: Bay Area, Ca Posts: 2,057 iTrader: 0 reviews	true, but still is the whole guage inacurate or just how it was installed?

January 24th, 2008, 05:12 PM	#20
Goblin Hardcore Enthusiast 88mm Join Date: Apr 2007 Location: Tucson, AZ Posts: 2,111 iTrader: 0 reviews	The gauge just isnt accurate. __________________

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