1997 4.0 SOHC p0171 and p0174

[Scout3]

Hello everyone,

I posted a while back about my son's 97 4.0 SOHC having the 171 and 174 lean codes. It only does it in cold weather and only once in a while. I have given it a good visual and checked all the vacuum lines and all appear good. Friday I reset the codes and he took it on a weekend trip of 126 miles. The weather was even colder than before. I checked it when he got home and no cel light and no pending codes. I was suspecting leaky intake gaskets but now I am not so sure. What else could be so intermittant? My scanner has a compatibility problem with this year and will not monitor fuel trim levels in live data mode but it will display the trim levels in freeze frame once a code has been set. I believe the values were around 13 for the short term and 22 for long term, so it must be a vacuum leak issue. Any ideas on something that would come and go like that? Thanks.

Ed

 

[swetrid]

Intake gaskets for sure.

 

[AppFire]

I have a '99 4.0 OHV with the same codes, been dealing with it since I bought it in October. Traced and inspected vac lines, replaced maf sensor, plugs, wires, etc... and still throws the codes about once a week. I will be replacing the gaskets next. I am leaning towards them being the problem. Codes come and go just like yours.

Chris

 

[Scout3]

Chris,

Son drove it to school less than 5 miles away and the light came on. Go figure. I quess it is intake gasket time.

Ed

 

[2000co]

I'm having the same problem on very cold days. Last cold day we got was -7f, on warm days no codes. I'll do the entire recommended tests and if they all come ok I will replace the gaskets.

 

[AppFire]

If I reset my code after the motor warms up, it will not come back on until another cold start. That is why Im leaning toward the gaskets. When the motor is warm they expand and seal off any leaks and I can drive it all day with several starts and stops and no codes, when its cold they shrink allowing air to enter and throw the code.

Chris

 

[jordan101]

i have the p0153 p0171 and p0174 codes so o2 sensor and lean on both sides is this the intake gaskets?

 

[muhl5443]

with thise codes it is most likely the intake manifold gaskets both upper and lower. especially if they hae never been done before.

@ jordan yes you most likely have the intake manifold gasket problem and a bad O2 sensor. the O2 snesor is probably bank 2 sensor 1.

 

[AppFire]

with thise codes it is most likely the intake manifold gaskets both upper and lower. especially if they hae never been done before.

@ jordan yes you most likely have the intake manifold gasket problem and a bad O2 sensor. the O2 snesor is probably bank 2 sensor 1.

I agree, still waiting for the weather to warm up just a bit before I replace mine.

Chris

 

[jordan101]

today it is 16 degrees outside it was idling at 500 when i sprayed carb cleaner around upper gaskets it moved to 900 and stayed for bit drove to town shut it off and then started it it did same thing idle at 500 so it must be the gaskets since its so cold. will they expand back in the spring and summer.

 

[ucluglee]

My '00 XLT 4.0 SOCH just recently started throwing 171 and 174 codes, but it didn't start doing it until I replaced the thermostat housing and both temp sensors. All (the ones I could get to) the vacuum lines have need inspected and checked and the intake gaskets were replaced in '05 due either a recall or a TSB while I had it in for service. When I replaced the tstat housing I also replaced the throttle-body-to-intake spacer and the spacer-to-intake O-ring gasket.

It's not throwing the codes on a regular basis so I'm going to start with replacing the fuel filter (192k miles and I can't remember when I ever changed it) and going to clean the MAF sensor.