Too Lean??

Comatose · 11-20-2001, 04:01 PM

86 GT w/HO 5.0, 5spd.

What would cause this car to run lean only when the engine is warmed up. When the engine is cold, it has excellent throttle response, after it warms up, the throttle response is still good, but has a bit of a lag to it. Also, when the engine is revved when it's warm, the pipes have an odd cackle when the engine decellerates. Only in nuetral does the cackle occur, not while driving and gearing down.

byrnech · 11-20-2001, 04:08 PM

What mods does your car have?

Comatose · 11-20-2001, 10:20 PM

Stock.....

I ran a bottle of fuel injector cleaner through it recently, that helped with the surging idle. The other symtoms are minor, but they still bother me....any ideas.

Thanks

Jeremiah

Phantom5oh · 11-20-2001, 10:33 PM

try checking your fuel filters... they could be clogged and need replacing... but what makes you think its running lean??? just curious??? but it could also be your injectors... try that for a start see what the results are and we can go from there...

steve

2FastLX · 11-21-2001, 01:52 AM

That doesn't sound like a fuel filter or injectors to me. It only does it when the car warms up so if it were either of those it should do it all the time. Have you tried pulling codes yet?

PKRWUD · 11-21-2001, 02:52 AM

Popping in the exhaust when free revving the engine is a symptom of a lean mixture. Only being a problem when the engine is warmed up means it's not injector or filter related, as mentioned. When cold, it's in open loop, and rich. That's normal. I am suspicious of the O2 sensors, but you really should run a KOEO and KOER self test and see what codes come up.

Take care,
-Chris

Comatose · 11-21-2001, 11:42 AM

Could you tell me more about these self tests......Thanks.

I am new to EFI, Sorry for all the questions.

Thanks for the help.

Jeremiah

byrnech · 11-21-2001, 04:12 PM

My guess would be the O2 sensors. The surging idle, and unusual air to fuel ratios are common indicators.

2FastLX · 11-21-2001, 11:59 PM

O2's would be my guess too, but I'd try to get some codes first. There are a few ways to pull codes. A code scanner which you can buy from Auto Zone (get one), or using a jumper wire/ohm meter/engine light. Here's some more info for you:
http://ratnin.home.mindspring.com/eec_test.htm

11-20-2001, 04:01 PM	#1
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	Too Lean?? 86 GT w/HO 5.0, 5spd. What would cause this car to run lean only when the engine is warmed up. When the engine is cold, it has excellent throttle response, after it warms up, the throttle response is still good, but has a bit of a lag to it. Also, when the engine is revved when it's warm, the pipes have an odd cackle when the engine decellerates. Only in nuetral does the cackle occur, not while driving and gearing down. __________________ Jeremiah 1986 Mustang GT K&N Filter, Removed Air Silencer, Black Magic Fan, 65mm Explorer TB, 110lph BBK Fuel Pump, F/M Force II Cat -Back, O/R h-pipe, U/D's Timing@14* 1986 Mustang LX SSP--new project car AOD, 3.27's, Dumps, 238k miles

11-20-2001, 04:08 PM	#2
byrnech Registered Member Join Date: Jun 2001 Location: Anderson, TX. Posts: 166	What mods does your car have? __________________ 331 10:1, AFR 185's, TFS-R intake

11-20-2001, 10:20 PM	#3
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	Stock..... I ran a bottle of fuel injector cleaner through it recently, that helped with the surging idle. The other symtoms are minor, but they still bother me....any ideas. Thanks Jeremiah __________________ Jeremiah 1986 Mustang GT K&N Filter, Removed Air Silencer, Black Magic Fan, 65mm Explorer TB, 110lph BBK Fuel Pump, F/M Force II Cat -Back, O/R h-pipe, U/D's Timing@14* 1986 Mustang LX SSP--new project car AOD, 3.27's, Dumps, 238k miles

11-20-2001, 10:33 PM	#4
Phantom5oh Registered Member Join Date: Mar 2000 Location: Boston, MA Posts: 334	try checking your fuel filters... they could be clogged and need replacing... but what makes you think its running lean??? just curious??? but it could also be your injectors... try that for a start see what the results are and we can go from there... steve __________________ 95 GTS 03 DR 650SE Sgarzi's Machine Works

11-21-2001, 01:52 AM	#5
2FastLX The Photoshop Guru Join Date: Feb 2001 Location: Mecca, Indiana Posts: 1,419	That doesn't sound like a fuel filter or injectors to me. It only does it when the car warms up so if it were either of those it should do it all the time. Have you tried pulling codes yet? __________________ Project: 1988 Coupe - EFI 5.8L Twin Turbo with Victor intake, Canfield heads, F303 cam, March aluminum underdrive pulleys, TKO (or T56 if funds permit), PBR twin piston calipers and 13" rotors up front, 94 Cobra rear calipers and 12" rotors on the rear, 3.73's, Griggs K-member, tubular front control arms, torque arm and panhard bar, polished 99 Cobra wheels. "The GR-40 kit installation is now complete, and the humble Fox-chassis car will now out-corner and out-stop a ZR-1 or a Viper, and support massive horsepower additions with perfect balance." Griggs Racing ICQ# 42269241

11-21-2001, 02:52 AM	#6
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Popping in the exhaust when free revving the engine is a symptom of a lean mixture. Only being a problem when the engine is warmed up means it's not injector or filter related, as mentioned. When cold, it's in open loop, and rich. That's normal. I am suspicious of the O2 sensors, but you really should run a KOEO and KOER self test and see what codes come up. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

11-21-2001, 11:42 AM	#7
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	Could you tell me more about these self tests......Thanks. I am new to EFI, Sorry for all the questions. Thanks for the help. Jeremiah __________________ Jeremiah 1986 Mustang GT K&N Filter, Removed Air Silencer, Black Magic Fan, 65mm Explorer TB, 110lph BBK Fuel Pump, F/M Force II Cat -Back, O/R h-pipe, U/D's Timing@14* 1986 Mustang LX SSP--new project car AOD, 3.27's, Dumps, 238k miles

11-21-2001, 04:12 PM	#8
byrnech Registered Member Join Date: Jun 2001 Location: Anderson, TX. Posts: 166	My guess would be the O2 sensors. The surging idle, and unusual air to fuel ratios are common indicators. __________________ 331 10:1, AFR 185's, TFS-R intake

11-21-2001, 11:59 PM	#9
2FastLX The Photoshop Guru Join Date: Feb 2001 Location: Mecca, Indiana Posts: 1,419	O2's would be my guess too, but I'd try to get some codes first. There are a few ways to pull codes. A code scanner which you can buy from Auto Zone (get one), or using a jumper wire/ohm meter/engine light. Here's some more info for you: http://ratnin.home.mindspring.com/eec_test.htm __________________ Project: 1988 Coupe - EFI 5.8L Twin Turbo with Victor intake, Canfield heads, F303 cam, March aluminum underdrive pulleys, TKO (or T56 if funds permit), PBR twin piston calipers and 13" rotors up front, 94 Cobra rear calipers and 12" rotors on the rear, 3.73's, Griggs K-member, tubular front control arms, torque arm and panhard bar, polished 99 Cobra wheels. "The GR-40 kit installation is now complete, and the humble Fox-chassis car will now out-corner and out-stop a ZR-1 or a Viper, and support massive horsepower additions with perfect balance." Griggs Racing ICQ# 42269241

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