Code 41 *FIXED

[Nadams01]

Hello, I got an issue. I have a 91 ex that I just waterlogged the motor and slapped in a brand new LKQ engine with a professional. It had a slight idle problem before the motor the rpms would increase or decrease ever so slightly. After the motor the truck will run great cold with no issues and idle like a champ. I can drive 40 to 60 miles with out a problem but as soon as I stop to idle for more then 5 or 10 minutes it will start to stutter and idle rough. IAC, MAF FPR 02 ICM TPS crank sensor has been replaced. No obvious vacuum issues and good fuel pressure. If I idle it for a bit then go drive off the CEL turns off. Its intermittent and extremely frustrating. I work at a shop and my mastertech specializes in classic car restorations and I will be working with him on the issue aswell. Anybody got an ideas? Thank you.

 

[Centaurious]

Code 41 relates to a lean condition (engine running code) or the system was lean for 15 seconds or more (no HO2S switching) (memory code).

Inspect the wires from the O2 sensor and the connectors. There may be damage or you may have dislodged a pin or socket while doing up the connection leading to an intermittent connection. You might have damaged wires while installing the engine into the body.

Carefully inspect the Air Hose between the MAF and the Throttle Body. It is known to crack at the bellows or wear through on the underside.

"I can drive 40 to 60 miles with out a problem but as soon as I stop to idle for more then 5 or 10 minutes it will start to stutter and idle rough." This sounds like a heat soak problem. If you can fairly consistently get this to happen, drive about 40 miles, stop and let it idle but open the hood and see if the problem goes away. These intermittent problems are commonly electrical related to sensors. If you still have the old parts try swapping in the old MAF and see if it changes anything. I've bought new parts that were bad.

 

[Nadams01]

Code 41 relates to a lean condition (engine running code) or the system was lean for 15 seconds or more (no HO2S switching) (memory code).

Inspect the wires from the O2 sensor and the connectors. There may be damage or you may have dislodged a pin or socket while doing up the connection leading to an intermittent connection. You might have damaged wires while installing the engine into the body.

Carefully inspect the Air Hose between the MAF and the Throttle Body. It is known to crack at the bellows or wear through on the underside.

"I can drive 40 to 60 miles with out a problem but as soon as I stop to idle for more then 5 or 10 minutes it will start to stutter and idle rough." This sounds like a heat soak problem. If you can fairly consistently get this to happen, drive about 40 miles, stop and let it idle but open the hood and see if the problem goes away. These intermittent problems are commonly electrical related to sensors. If you still have the old parts try swapping in the old MAF and see if it changes anything. I've bought new parts that were bad.

A quick brake clean inspection of the intake tube past the MAF increases the idle. I have replaced all sensors and all cooling components the engine never gets hotter then the n of normal on the heat gauge. Still possible for heat soak? Thanks for your help.

 

[Nadams01]

A quick brake clean inspection of the intake tube past the MAF increases the idle. I have replaced all sensors and all cooling components the engine never gets hotter then the n of normal on the heat gauge. Still possible for heat soak? Thanks for your help.

Also I missed spelled. I drive 30 mins to my shop at 65mph roughly and no issues. Asoon as I let it idle then it will idle rough. May be installing after market intake due to me not having emissions for 2 years.

 

[Centaurious]

As far as I know there is not an aftermarket kit to replace the intake tube. NOS replacement intake tubes are available but they are not cheap. The intake tube could well be your problem.

Good luck and please let us know what happens.

 

[Nadams01]

As far as I know there is not an aftermarket kit to replace the intake tube. NOS replacement intake tubes are available but they are not cheap. The intake tube could well be your problem.

Good luck and please let us know what happens.

replaced the intake kit. note this is a problem after waterlogging the prevoius motor. to get everyone updated the 02 sensor has been replaced and there are no vacuum leaks. I took my vape mod and blew it into a vacuum line and no vapor out of anywere but the cone. I hooked up a snap on scan tool to like at live data at idle and driving, mainly looking for fuel trims in %. the trims stayed at 0 at idle and went up to 17% under full throttle driving. The 02 sensor was updating as it shoot and read anywere from 28 and 38 mili volts. under full throttle tps was reading 4.6 volts when it therotically should be at 5? anyway i replaced my fuel filter as it was an oe and was slightly clogged and apears to have increased throtte response but the iradic and low idle seems like its almost missing. I unplugged the IAC and it feels like the miss was gone and i could smell it running rich. Im going to ohms test the IAC and make sure water could not have damaged it. I will test my MAF sensor as well. My ICM has been replaced and all voltages and Ohms have read in spec. I unplugged the SPOUT connecter and it feels slower to responde as if the timing is slightly retarded. acording to LD my spark advanced timing was from 12 degreese to 18 degreese full throttle. I will continue to post updates. I have read through other code 41 forums but none have gone into exact detail besides vacuum leaks.

 

[Nadams01]

replaced the intake kit. note this is a problem after waterlogging the prevoius motor. to get everyone updated the 02 sensor has been replaced and there are no vacuum leaks. I took my vape mod and blew it into a vacuum line and no vapor out of anywere but the cone. I hooked up a snap on scan tool to like at live data at idle and driving, mainly looking for fuel trims in %. the trims stayed at 0 at idle and went up to 17% under full throttle driving. The 02 sensor was updating as it shoot and read anywere from 28 and 38 mili volts. under full throttle tps was reading 4.6 volts when it therotically should be at 5? anyway i replaced my fuel filter as it was an oe and was slightly clogged and apears to have increased throtte response but the iradic and low idle seems like its almost missing. I unplugged the IAC and it feels like the miss was gone and i could smell it running rich. Im going to ohms test the IAC and make sure water could not have damaged it. I will test my MAF sensor as well. My ICM has been replaced and all voltages and Ohms have read in spec. I unplugged the SPOUT connecter and it feels slower to responde as if the timing is slightly retarded. acording to LD my spark advanced timing was from 12 degreese to 18 degreese full throttle. I will continue to post updates. I have read through other code 41 forums but none have gone into exact detail besides vacuum leaks.

Lol found it. The brand new MAF was giving improper voltages but not out of range enough to trip a code. Love ond1