yet another p1151 code

[Brandyn85]

hey guys im new to the site and have been searching like a mad man about this p1151 code that pops up every now and then on my 98 explorer sohc 4.0 i've only had this explorer for about a month and a half. everything was great until about 3 weeks ago. driving about 20 miles on the freeway i exit and come to a stop and accelerate again and it bogs down check engine light comes on, "jam" the gas and it goes fine. next day on the way to get the code read it turns off as i pull into the parts store, few days later same thing happens so i rushed right to the parts store and they pulled a p1151 bank 2 lean blah blah i forgot exactly. anyway i have been trying to figure this thing out and what to do. i've searched for leaking vacuum lines havent seen any yet. cleaned the mass air flow sensor with MAF cleaner. i have been on the freeway since i did that stuff but not nearly as far as before. my gas mileage is slowly decreasing. i have yet to do a tune up on the ex. but considering the information im thinking i need to just go throw a o2 sensor on it and see what happens. i will be kind of mad it that doesnt fix it though... at one part store the guy told me "for sure its the 02 sensor" i said what about MAF sensor, dirty or bad?" he said "no way, it wouldnt only effect ONE 02 sensor". a guy at another part store told me not to put a 02 sensor in it but instead have my catylitic converter checked as it may be clogged.

this thing is starting to drive me nuts, seems like it runs worse when its warm. today searching for vacuum leaks after i got home from work it was loping between 500 and 1200 rpm. i just drove it about 5 minutes ago about a half mile while it was cold and it didnt do it.

anyones input would be great.

thanks guys

 

[robertoa1a]

When you say freeway I think California emissions. You sound frustrated enough.

I know I sound redundant when I say "did you clean the plugs and inspect them for tell tale signs of engine wear or malfunction". There are times when one bank runs too rich and it can be a bich to detect.

I use a scanner that can provide a detailed print-out on how the engine performs and what the 02 sensors are reading both before the cats and after.

I don't live in your area but places like auto zone will kindly do it for free knowing you may buy buy from them in the future.

With the type of problem that you are having a printout would be gold in resolving the issue as there are many people whose replies will save you money and time.

 

[coonerboy]

I would replace the O2 sensor. Being that it is only bank 2, its unlikely there is a vacuum leak after the maf. It would be possible there is a intake manifold leak on that bank, so it wouldn't hurt to check for leaks there.

Also, remember that intake manifold vacuum is highest when at idle. If you are getting a stumble at part throttle when vacuum is much lower, it is not indicative of a vacuum leak. A vacuum leak is more likely to cause problems at idle. Also noticed you said it didn't seem to do it when it was cold. This is most likely happeneing when the pcm is running in open loop and not recieving any feedback from the O2 sensors. Once it warms up it will switch to closed loop where the air fuel ratio is determined by the O2 sensors, the problem may become more prevalent.

This being said, it would help greatly in diagnosing the problem if you had or knew someone with a scanner who could check o2 sensor operation as well as fuel trims. You are going about this the right way in diagnosing the problem instead of just replacing a part and seeing if it fixes the problem. Thats the right way to go!

 

[Brandyn85]

thanks for the imput guys, yeah im trying to do it the right way... i have alot of cars growing up... im only 24 and i believe this explorer is number 60ish... i never had a lot of money to buy "nice" cars so i'd buy em and fix em up then trade them or sell them... im pretty familiar with cars but this ford is something else... its actually making me think a little. im thinking i will throw a sensor on it and see what happens, i guess if thats not it then we'll go from there.