So I just got done rebuilding the top end of my 4.6 disco and she ran great for a few days. It started off with a code p0130 bank 1 sensor 1. I cleared it a few times thinking all the stuff I did needed time to reset. Today driving home she started stumbling at idle. Now I have p0130 bank 1, p0303 cyl 3 misfire, p0171 bank 1 system too lean.

Here's what all was done: All new or reman

New plugs (NGK) Wires STI 8mm New coils
Oil Pump new
Camshaft new
rocker assemblies New
lifters new
pushrods new
cylinder heads (completely rebuilt)
inline egr valve mod
all new gaskets (valve, head, exhaust, valley, front cover, oil sump etc..)
timing gears (camshaft and crank)
timing chain
injectors reman.


Any ideas on what I could have screwed up?
I did all of this because of an annoying tick when warm and cyl 8 misfire.
It seemed to be running smooth, great and quiet at all temps until today.
Super bummed!!!!

Thanks for any advice

 

p0130 is an O2 code, are those new?

Check the wire for cyl 3 and or pull the plug to check it.

 

Think I replaced bank 1 sensor 1 last fall and I never drive the rover so it may have 2k miles on the sensor. Could a bad O2 sensor cause a misfire? Ill take a look at the wire and plug.

 

I've had some bad luck with NGK spark plugs. Recommend Champion RC11PYPB4. And gap them, don't trust them out of the box.

 

Silicone gasket maker can kill O2 sensors, as can lots of other fluids. After all that work I would have invested in 4 new sensors, but at minimum the front 2 would make sense to replace. They control AFRs.

 

Old mechanic proverb..."02 sensors don't just die, they get murdered".

So, if you see an 02 sensor that has failed, or keeps failing after replacement, look upstream...most likely...something is causing it to fail. This all hinges on buying quality parts to begin with, yes, cheap parts are exactly that.

Since you are getting a misfire code, l'd focus my attention there...correcting this issue may solve issue. Yet, you may have to replace 02's also...since it may have been murdered in the process.

Brian.

 

The Deputy's advice makes sense, but yes, I have seen a bad O2 cause misfires. I don't think that's the case here, however, since your truck has a misfire on only one cylinder.

Four years ago I had misfires crop up suddenly on cylinders 2, 6 and 8 plus a P1300 (random/multiple misfires detected). There were no typical O2-related codes.

It didn't make sense to me that 3 of 8 plug/wire combos would fail simultaneously, nor are they paired on a coil or on the same coil, so the next thought was what else do the even-numbered cylinders share? The answer was the O2 sensor. I installed a new sensor and the misfires disappeared.

I've since shared that info a few times on this forum with others having multiple misfires on one bank and it's worked for them. My theory about how this happens is that the failed O2 causes the mixture to be so lean or so rich on one side that the misfires are triggered. I don't know how else to explain it, nor why there were no standard O2 codes.

 

Have you done a compression test?

 

Not yet Sixpack. I haven't had anytime since the post to work on the rig. However I did crank it up today. Got the code for cylinder #5 misfire now and multiple cylinder misfires pending.

 

Doing a quick look this morning and the wire to the knock sensor on the drivers side has been somewhat melted on the exhaust manifold. That would be bank 1. Could a bad wire to a knock sensor cause my problem? The misfires and o2 are all on that side.