ses code, lean banks - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mudboy · 02-07-2010, 02:35 AM

I got a 98 chevy 3/4 ton 4x4 has the 350 vortec engine in it. it has a miss to it when trying to hold the rpm's, like when the cruise is on or just maintaining a steady speed. I have had it into a dealer and said it need a tune up and injector flush, put in new plugs, wires, cap, and rotor and have run 2 fuel tanks of seafoam, 1 tank of lucas injector cleaner and 1 tank of stp injector cleaner through it and I run 91 octane gas. still has a miss and still has the ses light(have cleared it twice) with a lean left and right bank code on it 171 and 173 i think they were. from what i have found it can be anywhere from mass air sensor, timing, fuel pressure(is good), O2 sensors but can't get any specific answer on which or what it might be.... anyone have or heard of this problem???

ChevLoRay · 02-07-2010, 11:05 AM

Just be patient and someone will jump on here with what you need to know. It doesn't always happen as quickly as we'd like, but it will.

Oh, and

to the board!

95 S_Trucker · 02-07-2010, 03:04 PM

could also be a vacuum leak

i had a similar problem

my 98 had had a p0173 an p0171, but it also had a O2 sensor code

ERASER5 · 02-07-2010, 03:22 PM

I fixed a car with a lean bank code. In this case it was the MAP (manifold absolute pressure) sensor. The case was split and therefore leaking. If you have a MAS, I do not think you have a MAP, but I may be wrong.

ChevyTech · 02-07-2010, 03:52 PM

If you have lean code on both banks and no other codes you should test the fuel pressure.

**bwood** · 02-07-2010, 04:31 PM

You said that you checked the pressure, but what was it? Anything below 60 running is low. You truck does have both MAP and MAF sensors. An air leak could be the answer also. There are only a few vacuum connections on the upper intake, brake booster and EVAP solenoid, but the upper intake plenum can be a source of air leaks itself. It is sealed to the lower plenum with a large Oring type seal and the is another oring around the injector body. If you wouldn't mind post your fuel pressure readings. Also, has there been any recent work done besides what you mentioned (intake gaskets fuel filter).

mudboy · 02-08-2010, 11:08 AM

when i checked the fuel pressuse it was at 66 psi and the intake gasket has been changed 5 years ago. I have sprayed around on the engine, down both sides where intake connects, all the vacuum connections, and the upper and lower plenum with carb/throttle body cleaner looking for a vacuum leak. I didn't find one...

mudboy · 02-28-2010, 05:16 PM

central port injection? doesn't that have the one injector with the "spider legs" going to the cylinders? mine has the single injectors for each cylinders

mudboy · 03-01-2010, 01:59 PM

decided that i would check the compression on my truck and it was averaged between 180 for the lowest and 188 for the highest...

02-07-2010, 02:35 AM	#1
mudboy Registered User Join Date: Sep 2003 Location: jasonville,indiana Posts: 5	ses code, lean banks I got a 98 chevy 3/4 ton 4x4 has the 350 vortec engine in it. it has a miss to it when trying to hold the rpm's, like when the cruise is on or just maintaining a steady speed. I have had it into a dealer and said it need a tune up and injector flush, put in new plugs, wires, cap, and rotor and have run 2 fuel tanks of seafoam, 1 tank of lucas injector cleaner and 1 tank of stp injector cleaner through it and I run 91 octane gas. still has a miss and still has the ses light(have cleared it twice) with a lean left and right bank code on it 171 and 173 i think they were. from what i have found it can be anywhere from mass air sensor, timing, fuel pressure(is good), O2 sensors but can't get any specific answer on which or what it might be.... anyone have or heard of this problem??? __________________ '78 chevy 3/4 ton with 7" lift on 38" super swampers 85 toyota(shh) 4x4 3" lift, 33" super swampers 98 chevy 3/4 ton 4x4, 33" mud terrains

02-07-2010, 11:05 AM	#2
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: ses code, lean banks Just be patient and someone will jump on here with what you need to know. It doesn't always happen as quickly as we'd like, but it will. Oh, and to the board! __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was. Last edited by ChevLoRay; 02-07-2010 at 11:05 AM.

02-07-2010, 03:04 PM	#3
95 S_Trucker Registered User Join Date: Oct 2009 Location: . Posts: 2,187	Re: ses code, lean banks could also be a vacuum leak i had a similar problem my 98 had had a p0173 an p0171, but it also had a O2 sensor code Last edited by 95 S_Trucker; 02-07-2010 at 03:04 PM.

02-07-2010, 03:22 PM	#4
ERASER5 Registered User Join Date: Jun 2006 Location: Indiana Posts: 4,859	Re: ses code, lean banks I fixed a car with a lean bank code. In this case it was the MAP (manifold absolute pressure) sensor. The case was split and therefore leaking. If you have a MAS, I do not think you have a MAP, but I may be wrong. __________________ '70 GMC C1500 LWB Power disc brakes. WooHoo! Posi 6 Lug Dana 60

02-07-2010, 03:52 PM	#5
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: ses code, lean banks If you have lean code on both banks and no other codes you should test the fuel pressure.

02-07-2010, 04:31 PM	#6
bwood Registered User Join Date: Jan 2003 Location: Denison, Texas Posts: 1,919	Re: ses code, lean banks You said that you checked the pressure, but what was it? Anything below 60 running is low. You truck does have both MAP and MAF sensors. An air leak could be the answer also. There are only a few vacuum connections on the upper intake, brake booster and EVAP solenoid, but the upper intake plenum can be a source of air leaks itself. It is sealed to the lower plenum with a large Oring type seal and the is another oring around the injector body. If you wouldn't mind post your fuel pressure readings. Also, has there been any recent work done besides what you mentioned (intake gaskets fuel filter). __________________ 1998 GMC Sierra SLE 1/2 ton 2WD 305 Vortec -Gibson Stainless Cat Back Swept Side -SS Wheels 2005 Honda CRF250R 2006 Honda CRF150F

02-08-2010, 11:08 AM	#7
mudboy Registered User Join Date: Sep 2003 Location: jasonville,indiana Posts: 5	Re: ses code, lean banks when i checked the fuel pressuse it was at 66 psi and the intake gasket has been changed 5 years ago. I have sprayed around on the engine, down both sides where intake connects, all the vacuum connections, and the upper and lower plenum with carb/throttle body cleaner looking for a vacuum leak. I didn't find one... __________________ '78 chevy 3/4 ton with 7" lift on 38" super swampers 85 toyota(shh) 4x4 3" lift, 33" super swampers 98 chevy 3/4 ton 4x4, 33" mud terrains

02-28-2010, 05:16 PM	#8
mudboy Registered User Join Date: Sep 2003 Location: jasonville,indiana Posts: 5	Re: ses code, lean banks central port injection? doesn't that have the one injector with the "spider legs" going to the cylinders? mine has the single injectors for each cylinders __________________ '78 chevy 3/4 ton with 7" lift on 38" super swampers 85 toyota(shh) 4x4 3" lift, 33" super swampers 98 chevy 3/4 ton 4x4, 33" mud terrains

03-01-2010, 01:59 PM	#9
mudboy Registered User Join Date: Sep 2003 Location: jasonville,indiana Posts: 5	Re: ses code, lean banks decided that i would check the compression on my truck and it was averaged between 180 for the lowest and 188 for the highest... __________________ '78 chevy 3/4 ton with 7" lift on 38" super swampers 85 toyota(shh) 4x4 3" lift, 33" super swampers 98 chevy 3/4 ton 4x4, 33" mud terrains



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