Rough Idle, Smell of Gasoline and Ocassional Backfiring

[Smokey Bones]

Good evening Gents,

Here is what the problem is. Recently purchased a 2003 MM. It had ConRods in 4 and 8 go through the block. I managed to find another MM motor.

Motor was rebuilt to spec, and the donor parts (Intake, Headers, etc.) were reused to assemble the new motor. This is the configuration that the engine was in when it blew. The vehicle had been driven like this for several years, as I knew to owner and the vehicle. (Tune?, I don't know)

The assemble motor has a K&N cone filter, long tube headers, cat delete, and X-pipe. Other than that, everything else is stock.

So, the other day after putting the finishes on the motor, I started the engine, and it shook pretty bad. I plugged in my Snap-On computer and noticed that cylinder 1-4 were missing pretty bad at idle and would occasionaly backfire. However, above 2000RPM, all of the cylinders fire without any misses. The code I am getting is P2195, Bank 1 Sensor 1 excessive lean.
What I have done thus far:

Intake Manifold leak test via carb cleaner- No Difference (no leak detected)
Vaccum Leak test via carb cleaner - No Difference (no leak detected)
New PCV Valve - No Difference
Cleaned IACV - No Difference
Compression Test - All cylinder read equal.
EGR Valve cleaned and tested - No Difference
Fuel Injector Pulse Test - Pass
Swapped Spark Plugs- No Difference
Swapped Coils - No Difference
Spark Test - Pass
Spark Plug Gap - Within spec
Fuel pressure reads 39PSI (According to computer)

Spark Plugs, and O2 sensors are new.

I am at a loss, I cant seem to think of anything else to check. It idles like crap, but above 2KRPMs it screams and doesn't miss a beat. I put the old O2 sensors back in and still no difference. When I check the plugs on cylinders 1-4 after a short idle, they are all wet and smell of fuel.

How can one side of the engine function fine and the other be faulty?

Does anyone have any suggestions or maybe any ideas on where to start? This is starting to aggravate me. Am I missing something? Please Help

Smokey Bones

[Smokey Bones]

Gentlemen,

Just a thought, but could I have installed the timing 180 degrees off on the passenger side? If so, how do I go about correcting it with the motor in the car?

[ByronRACE]

How does it run when the engine is dead cold and the scan tool indicates it is running open loop? What are your short term and long term fuel trim values? Have you done anything to the oxygen sensors? Any chance you have reversed the left and right bank HEGOs? Were the oxygen sensors and cats replaced after engine failure? How much oil got into the exhaust? Long-tubes already create HEGO related issues due to sensor location and lack of heat at idle; if they were ever oil contaminated...you might have one that no longer functions. You say you replaced the O2s, but did you foul another one? How long was it running before you swapped them? Since it's the entire bank, I'm betting on a hego related issue.

[Smokey Bones]

Well, I took the front end apart and noticed that bank one was not in sync with bank two. I disassembled all of the timing components, and then reassembled.

The engine manually turns over much smoother. When I use the starter to roll it over, it is smooth and rhythmic. Whereas before is was like I was trying to crank a high compression engine.

I will be putting the finishes on it tomorrow. I will keep you updated as I go.

Just a foot note, I did not have any PTV contact so this should be pretty straight forward from here.

But, I think I was 180 off.

[GetMeMyStogie]

I'd have suggested either of the two chains on that side were off by a tooth on either cog.

[Zack]

It is almost impossible to time the car incorrectly.
Are you sure the intake and exhaust cam didn't get switched?

[Smokey Bones]

Well the verdict is in! I was off 180 on the main sprocket on bank 1 (passenger side). She runs like a Swiss watch now. O2 sensors are performing as expected and no codes.

BTW, the long tube headers sound ferocious! And I love it.

Thanks for all of the help.