try this one

pbouffard · 05-09-2007, 07:33 PM

hers one for the pros, got a 88 c2500 king cab long bed with a 350, bored .030 a mild cam and a holley tbi, nothing special. when the truck is cold at any outside temp, the truck runs rich, i mean RICH, smell it see it out the pipes and all, and runs rough, now this is at idle, when the engine is cold, but when you go to drive the roughness clears up, then when the truck warms up to about 150 the idle is fine and it is not rich. i replaced coolant temp switch, and put a hotter plug in, no luck. i put a factory tbi on it and i couldnt get it to idle right at all, ran good down the highway but idle really sucked, put the holley back on and delt with the cold idle since. the only engine code i get is from running at highway speeds for about 20 min and a egr code is set. dont know if its the valve or egr sensor but it is dealing with the egr. any ideas, i thought of putting a hotter coil and removing the fusible link feeding the coil so the input volts are not reduced , i havnt done this yet but its my idea. oh and also the manifold vacuum is good and the tps is set to the correct ohms at idle according to holley, mine is adjustable. anyway any different suggestions? thanks

mrjohnwayne · 05-09-2007, 08:28 PM

Do you have 02 sensor(s)?

75K30 · 05-10-2007, 10:00 AM

That is a sensor problem. It is reading improperly, and telling the ECM to run it fat when cold. The hotter plugs are actually not helping too much, and depending on the heat range you have stepped up to may cause detonation troubles at higher rpms or temps.
Either low end ECM parameters are off (scale is too low), or you have an inop sensor.

pbouffard · 05-11-2007, 10:24 AM

the sensors are fine, most are new, i have on o2 sensor on the driver manifold, the egr is the only code.

mrjohnwayne · 05-11-2007, 11:46 AM

You can pull the EGR off and try cleaning it with some carb cleaner. I'm also wondering if you might need another 02 sensor as well. Do you have a dual exhaust or single outlet. If single wonder if you could move the 02 after the y so it can get a more accurate reading.

436'd skylark · 05-12-2007, 10:03 PM

well its supposed to run richer when cold. I'd guess that it runs rich all the time, just way more in open loop mode. what are you running for a computer.

pbouffard · 05-15-2007, 07:04 PM

my truck has single into dual. cat foward is a stock set up

72'CaminoKid · 05-16-2007, 03:42 PM

definately sounds like a sensor issue. maybe the whole computer itself.

pbouffard · 05-16-2007, 07:48 PM

computer is new, been like this since i bought it and the owner sez its been like that since the rebuilt motor

scottie · 05-16-2007, 08:14 PM

keep it simple..... gap your plugs, check continuity of your wires, you might just have a dead cylinder, and if it has been dead for as long as it sounds, it could cause a buildup in the EGR, enough to trip a code. or i'd go as far to say a bad EGR. i'd say clean it and test it with a multimeter. word of advice, dont waste your money on a hotter coil, and definitly DO NOT take out the fusable link. it doenst restrict voltage, its just there to protect from frying something very expensive.

05-09-2007, 07:33 PM	#1
pbouffard Senior Member Join Date: Apr 2007 Posts: 100	try this one hers one for the pros, got a 88 c2500 king cab long bed with a 350, bored .030 a mild cam and a holley tbi, nothing special. when the truck is cold at any outside temp, the truck runs rich, i mean RICH, smell it see it out the pipes and all, and runs rough, now this is at idle, when the engine is cold, but when you go to drive the roughness clears up, then when the truck warms up to about 150 the idle is fine and it is not rich. i replaced coolant temp switch, and put a hotter plug in, no luck. i put a factory tbi on it and i couldnt get it to idle right at all, ran good down the highway but idle really sucked, put the holley back on and delt with the cold idle since. the only engine code i get is from running at highway speeds for about 20 min and a egr code is set. dont know if its the valve or egr sensor but it is dealing with the egr. any ideas, i thought of putting a hotter coil and removing the fusible link feeding the coil so the input volts are not reduced , i havnt done this yet but its my idea. oh and also the manifold vacuum is good and the tps is set to the correct ohms at idle according to holley, mine is adjustable. anyway any different suggestions? thanks

05-09-2007, 08:28 PM	#2
mrjohnwayne Senior Moderator Join Date: Apr 2005 Location: Texas Posts: 3,722	Do you have 02 sensor(s)? __________________ John Wayne 2000 F-350 7.3L Powerstroke 4x4

05-11-2007, 10:24 AM	#4
pbouffard Senior Member Join Date: Apr 2007 Posts: 100	fuel prob still the sensors are fine, most are new, i have on o2 sensor on the driver manifold, the egr is the only code.

05-11-2007, 11:46 AM	#5
mrjohnwayne Senior Moderator Join Date: Apr 2005 Location: Texas Posts: 3,722	You can pull the EGR off and try cleaning it with some carb cleaner. I'm also wondering if you might need another 02 sensor as well. Do you have a dual exhaust or single outlet. If single wonder if you could move the 02 after the y so it can get a more accurate reading. __________________ John Wayne 2000 F-350 7.3L Powerstroke 4x4

05-12-2007, 10:03 PM	#6
436'd skylark Senior Member Join Date: Mar 2007 Location: Buffalo Ny Posts: 661	well its supposed to run richer when cold. I'd guess that it runs rich all the time, just way more in open loop mode. what are you running for a computer. __________________ Joe 89 K2500 Chevy, Wee-Oh-five 285K miles, completly rebuilt needs a motor, bad 1962 IHC Scout All Wheel Drive (Scout speak for locking axles) 152 ci, dana everything else

05-10-2007, 10:00 AM	#3
75K30 Senior Member Join Date: Jul 2006 Posts: 2,992	That is a sensor problem. It is reading improperly, and telling the ECM to run it fat when cold. The hotter plugs are actually not helping too much, and depending on the heat range you have stepped up to may cause detonation troubles at higher rpms or temps. Either low end ECM parameters are off (scale is too low), or you have an inop sensor.

05-15-2007, 07:04 PM	#7
pbouffard Senior Member Join Date: Apr 2007 Posts: 100	my truck has single into dual. cat foward is a stock set up

05-16-2007, 03:42 PM	#8
72'CaminoKid Senior Member Join Date: Jun 2005 Posts: 2,756	definately sounds like a sensor issue. maybe the whole computer itself. __________________ 99 suburban xlt 96 silverado 91 wrangler (my baby ) 08 Honday shadow 750 (my mistress)

05-16-2007, 07:48 PM	#9
pbouffard Senior Member Join Date: Apr 2007 Posts: 100	computer is new, been like this since i bought it and the owner sez its been like that since the rebuilt motor

05-16-2007, 08:14 PM	#10
scottie Senior Member Join Date: Jan 2006 Location: South Florida (Palm Beach), originally from south of BOSTON Posts: 644	keep it simple..... gap your plugs, check continuity of your wires, you might just have a dead cylinder, and if it has been dead for as long as it sounds, it could cause a buildup in the EGR, enough to trip a code. or i'd go as far to say a bad EGR. i'd say clean it and test it with a multimeter. word of advice, dont waste your money on a hotter coil, and definitly DO NOT take out the fusable link. it doenst restrict voltage, its just there to protect from frying something very expensive. __________________ im a straight shooter with upper management written all over me

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