Intermittent smoke with codes

[magoo454]

I will start off by asking you to forgive me for any mistakes in terminology, I am a fifteen year G.M. master tech (don't hate me from the beginning).
I have a 94 explorer with a 4.0L and manual trans that I just picked up. This is my first Ford. It had a cracked head so I replaced. both with new heads. Found with leak down test and then by visual inspection after removal.

The problem.
Sometimes when starting up or even after driving for a while, out of nowhere I will get a lot of smoke from fuel out of the tailpipe and check engine light. There on no KOER codes for a cylinder imbalance. Checked codes and have both a 157 MAF signal low or grounded and a 158 MAF signal high or shorted to power. Heres the kicker what ever is happening is happening in the right bank only. Also if I pull the plug wires 1,2,or 3 for any plug on that bank there is no audible change in the rough running engine. The heads were new with rockers and valves.
Here is what was replaced
Left and Right heads
Water pump (cause of cracked head)
All Lifters (found one that had collapsed) Ford Parts
Plugs From Ford
Wires From Ford
All upper motor gaskets also from Ford
Fuel Filter
PCV
Air Filter
Also replaced crank sensor ( the people who owned it before me took it to the dealer ship for diagnosis and the tech did not put it back on).

Here is what I have done so far
Checked wires (power ground and reference) for MAF, EGR back pressure sensor, Intake air temp sensor, cleaned MAF and Idle control valve. Checked for any Vacuum leaks.
None of the wires are shorted going the sensors.
Did vacuum check on EGR and it checks fine.
Did find minor corrosion on #1 coil tower but like I said it does not matter which wire is unplugged on the coil from that bank.
Fuel pressure regulator operating within spec no leaks.
Did back pressure check on cat at O2 sensor and it checked fine.
I do not think this is a bank two O2 sensor since this are heated O2s and would not effect cold start, I am new to ford but I would only think they would come into effect after they warmed up.
All roads have led to a MAF but I do not what to shot gun the repair.

What I think
I am leaning toward replacing coil pack and MAF
Any input would be appreciated.

 

[Explorer_Joe]

Hi I am having the SAME EXACT issue with my 93 XLT, Only codes it throws are 157, 158. I figured it I would also get codes from the cylinders because it is definitely misfiring. I was leaning towards the MAF as well, but have been learning that its possible the PCM may be fried or partially fried.

Lets keep each other updated, I may go ahead and buy a brand new MAF and if that solves it I'll definintely let you know.

 

[magoo454]

Hi I am having the SAME EXACT issue with my 93 XLT, Only codes it throws are 157, 158. I figured it I would also get codes from the cylinders because it is definitely misfiring. I was leaning towards the MAF as well, but have been learning that its possible the PCM may be fried or partially fried.

Lets keep each other updated, I may go ahead and buy a brand new MAF and if that solves it I'll definintely let you know.

So heres the deal being a 15 year technician sometimes karma, god, the car gods or the universe in general decide that as you get really good at something (such as the gift of being able to listen to or pick up a certain smell on a vehicle and know exactly what is wrong with it) you will be humble so that you do not get a head so big that you will always be able to get into the cars you are trying to fix.

The problem with the vehicle, I am ashamed to say, was my own doing. The MAF was bad but that did not solve my smoking problem but it did cure my check engine light.

Proper diagnostics tells you that when you have fuel coming from the tail pipe that you check the fuel system, the electrical systems, emissions and of course compression. Being as the heads were brand new, the cylinders were not scored (did not suspect a broken piston ring) I did not believe that compression was an issue. Well last Sunday I was on the john when it dawned on me that these were new heads and that the valve may have been to tight in the valve guides. This would be a simple fix, air up the cylinder remove the valve spring and turn the valve with a drill a couple of times. I could not sleep so at three in the morning I went out pulled the truck into the shop and ran a compression test, sure enough #1 cylinder had zero compression. So I pulled the valve cover on the bank with out compression. This is the humbling part, when I got the valve cover off I looked at the valves to make see if the rocker arms were making contact with all of them. Then I noticed it the reason for my problems was the push rod was not lined up properly when I put the rocker arms on. Lucky for me it got wedged between the intake gasket and the head. Fixed the issue and the vehicle never ran better.
Before you replace any thing make sure that you have check every wire in that system (power, ground, and reference)