Bank 1 and 2 running rich
#1
Bank 1 and 2 running rich
My truck is running rich on banks one and two and its idles rough when stopped at lights and such I cannot find the fuel injector pressure regulator under the hood I'm at a loss I have a 98 ranger 4.0 Both two wheel and four wheel
Last edited by Rangerdangur; 3 Weeks Ago at 03:09 PM. Reason: Left something out
#2
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Join Date: Aug 2018
Location: Winston, Ga
Posts: 107
a. Are you using a live data scanner to see the rich trims? Is it always rich, idle and cruise and snap throttle?
b. Sounds a little like a stuck egr which you may be able to test by unplugging it and see if the rough idle goes away
b. Sounds a little like a stuck egr which you may be able to test by unplugging it and see if the rough idle goes away
#3
#6
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Join Date: Aug 2018
Location: Winston, Ga
Posts: 107
Have you thrown the filter out or can you post a picture of it?
#9
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Join Date: Aug 2018
Location: Winston, Ga
Posts: 107
I strongly suggest you check this filter every day for a week or so to make sure the new filter isn’t getting oily. If it does you need to do some deeper digging!
edit: I wonder if this could be related to a stuck open pcv valve...?
edit: I wonder if this could be related to a stuck open pcv valve...?
Last edited by kenhigg; 3 Weeks Ago at 04:57 AM.
#10
I had troubles with actual motor oil on my K&N filter on my 4.0 SOHC. It was coming from the valve cover ventilation tube attached to my air intake hose. I changed my PCV, and it seemed to help.
I cleaned out the intake tube and washed my filter out with the K&N recharging kit (cleaner and filter oil), and I thought it would be fine.
I oiled too much and the excess was traveling to the MAF sensor. Lesson learned.
Go lightly. Very lightly
I've also been reading that the K&N filters aren't good for vehicles with MAF sensors because of the filter oil they use to catch more of the dirt and particulates. Older carb'd engines eat that stuff up no problem, but those MAFs are sensitive.
Out of the box, my K&N was fine with my system. It's when I cleaned it and re-oiled it...
I cleaned out the intake tube and washed my filter out with the K&N recharging kit (cleaner and filter oil), and I thought it would be fine.
I oiled too much and the excess was traveling to the MAF sensor. Lesson learned.
Go lightly. Very lightly

I've also been reading that the K&N filters aren't good for vehicles with MAF sensors because of the filter oil they use to catch more of the dirt and particulates. Older carb'd engines eat that stuff up no problem, but those MAFs are sensitive.
Out of the box, my K&N was fine with my system. It's when I cleaned it and re-oiled it...
#12
All it takes is a little MAF spray cleaner on the MAF wires about twice a yr. It's a way overblown concern.
Also, I rebuild / modify engines. And on the engines that used K&N for yrs prior to being rebuilt the wear looks perfectly normal as compared to ones that used paper filters.
IMO the carbon from EGR contributes 1000% more to buildup in the intake, valves, and bore scuffing.
#14
Bank one running rich
I replaced the air filter on my 98 and that cleared up the bank 2 running Rich now it still reads bank one running rich it's not the egr or the pcv valve I'm at a loss of where to go from here
#18
On a V6 or V8 engine one bank running lean or rich can be an upstream O2 sensor issue on that bank
O2 sensors use a chemical reaction like the battery does, so they do use up the chemicals and start to fail, 100k to 150k miles is recommended change period
BUT............if there was an engine problem that caused oil or coolant to go into the exhaust then that can shorten the O2s life
Air filter, MAF sensor, temp sensor, air temp sensor, PCV Valve, upper intake manifold vacuum leak, all effect BOTH banks
Lower intake vacuum leak, injector issue, leaking valve stem seal, would just effect one bank
O2 sensors use a chemical reaction like the battery does, so they do use up the chemicals and start to fail, 100k to 150k miles is recommended change period
BUT............if there was an engine problem that caused oil or coolant to go into the exhaust then that can shorten the O2s life
Air filter, MAF sensor, temp sensor, air temp sensor, PCV Valve, upper intake manifold vacuum leak, all effect BOTH banks
Lower intake vacuum leak, injector issue, leaking valve stem seal, would just effect one bank
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