Newbie here: Spark Plugs, Fluids + P0133 code

[SubieHo]

Hi there, I'd been reading some of the very helpful info. on this site prior to doing some "routine" maintenance" on my sister's 1996 4.0 XLT with 103K miles on the odometer. She is the original owner of this car.

I replaced all the fluids (coolant, power steering, transfer case, ATF, front & rear differential fluid, brake fluid), fuel filter, pcv valve, air filter, and spark plugs.

With the exception of the air filter, this was the first time that any of these items had ever been replaced. The original PCV valve was really gummed up, causing engine vapors to be pushed back through the vent hose from the oil filler tube into the air intake.

Let me tell ya, the ignition wires were a bear to remove after over 100K miles. The original spark plugs (Motocraft Platinum AWSF-42P) were very worn with approximate gaps of .062 for cylinders 1,2, & 3 and .090 for cylinders 4,5, & 6. Insulator color was normal with no signs of fouling.

Are the gap differences a result of wasted spark ignition?

I also noticed some white corrosion on the connector tips of the old spark plugs from cylinder's 1,2, & 3, almost like the tips were painted white, and found a stored code P0133 for the front O2 sensor on that same side.

Could the corroded plug connections and the CEL code be related?

I cleaned the connection for the 02 sensor and dabbed some dielectric grease on it before hooking everything back up. I also put some on the ignition wire boots to ease future replacement.

After 60 miles of driving the code has not reappeared. If it does, I should probably replace that O2 sensor, right?

 

[Tbirdsims]

Not too sure on that stuff,but the CEL might be for a misfire if the connectors were that messed up, might not be the O2 sensor going. One thing you should def do after doing that big of a tune up is the seafoam treatment, there is a sticky on there here, but the basics (this is what i do, the thread shows another way) i remove the vac line from the brake booster, the put a funnel in the tube, and start the truck up, slowly pour the seafoam in the funnel, use about 1/4 and then stall the engine out with it, dont go past half a can. re attach the line and let sit for about 15-20 min, when you start it up it will be rough at first, but once it gets going dont let it stall out rev it a bit, and you will get a nice smoke show, all the carbon build up from the upper intake and heads will be forced out the tail pipe, and now you completed your tune up

 

[btimm86]

if you do the seafoam put your old plugs back in if you still have them around. seafoam can ruin your new plugs. If your rear diff has a Limited slip (you can find out by looking at the axle code) then you need to add a friction modifier. Autozone has one for around 6 bucks. As for the tip corrosion someone probably just didn't use dielectric.

 

[Tbirdsims]

if you do the seafoam put your old plugs back in if you still have them around. seafoam can ruin your new plugs

Yes good point forgot about that! thanks

 

[SubieHo]

Thanks for the input, guys. My sister lives in one of those fancy, quiet suburbs, and I didn't want her neighbors to phone the fire department so no Seafoam. I did, however, spray some cleaner through the throttle body.

If your rear diff has a Limited slip (you can find out by looking at the axle code) then you need to add a friction modifier. Autozone has one for around 6 bucks. As for the tip corrosion someone probably just didn't use dielectric.

Thanks for the reminder. I read about this in the owner's manual and did put 4 oz. of TransX, purchased from Autozone, in the rear differential.

The plugs were original so it's possible that they forgot to grease that side of the engine at the factory.

As for the the P0133 code: "This involves the front oxygen sensor on Bank 1. This code indicates the engine air fuel ratio is not being adjusted by the oxygen sensor signal or the ECM as expected to do so, or not adjusted as often as expected to do so once the engine is warmed or under normal engine use." (quoted from obd-codes.com).

This may have been caused by the clogged PCV valve, sending oil vapors into the intake chamber and contaminating the intake temperature sensor and the MAF sensor. I cleaned both sensors when I replaced the pcv valve and the air filter, which may have also contributed to the problem.

 

[aldive]

I wouldn't just replace the O2 sensor based on a code(s).

Check the O2 sensor(s) function with a scanner.

Most often the O2 sensor(s) are good and the problem that triggered the code is upstream.

Good luck ....

 

[SubieHo]

I checked out the 02 sensor output and both front ones show good signals with sufficient amplitude.

Thanks for the advice. I'll just keep an eye on it.

 

[aldive]

Good deal.

 

[SubieHo]

I checked everything upstream, but the P0133 code kept coming back. It's a weak intermittent signal so I went ahead and replaced the sensor, and the car is running much better. I'll report back if the code returns.

 

[SubieHo]

After over 300 miles of driving, the CEL is still off. My brother-in-law says it's been driving great and also that he's getting the best mileage he's ever gotten, 23 mpg as opposed to 20 mpg.

Any idea why the front 02 sensor on bank 1 seems to go bad on the 4.0?

 

[sethpdx]

Good question. I would like to know this as well