Help! Right Bank running rich!

[MoabB2]

Ok, here it goes. This has been an ongoing battle for a year now and no one seems to know what the problem is.

I have transplanted a 1997 Mercury Mountaineer 5.0L V8, GT-40p heads, along with stock AODE 4r70w transmission and all stock wiring and computers into a 1989 Bronco II. Basically, the Bronco II thinks it is a 97 Mountaineer and the only code I am getting is P0453. The motor is all stock except for Advanced Adapters Headers, K&N filter, and Dual Flowmaster exhaust. I should also mention that I run 33 inch tires with 3.73 gears.

Now for the problem. The right bank is running rich. It is not throwing any rich codes, but you can smell the exhaust on the right side is very gassy! Also, the engine seems to run well for the first couple minutes when it is cold(closed loop), but then when it warms up it will run horribly. It usually idles fine, although idle is getting worse. Under acceleration it bogs down really bad and has no power at all! It kind of surges in and out of power. On the highway it has a hard time keeping speed and on hills bogs down really bad. When I down shift the engine revs...but still, no power. It will accelerate slowly, but not as much as it should for how hard the engine is laboring. I also hear the occasional backfire in the exhaust system.

I have checked fuel pressure, it is in spec.
I have cleaned the MAF, and replaced it, no change.
I have cleaned the TPS also.
O2 sensors have been replaced and swapped time and time over. No change.
Injectors have been pressure tested, no leaks.
I have plugged in two different stock 97 computers, no change.
Street Performance created a custom wiring harness, no change.

Does anybody have a clue as to what may be the cause of my problem? Is it something internal in the engine? Thanks in advance for any info!

 

[spindlecone]

Actually, when first started cold it should be in open loop, if your running in open loop warm (unless at WOT) could be the problem

 

[MoabB2]

I must have had that reversed then. Whichever loop it is, it runs better when cold, but when it gets warm it runs worse....

 

[Turdle]

Could be a stuck or leaking fuel injector?

 

[Rhett]

Maybe you have a clogged cat.

I would have said O2s as well, but you said you changed them.

What I would do is put a brand-new set of Motorcraft plugs in it, and a set of Motorcraft wires. And also I would change the fuel pressure regulator and fuel filter and air filter just for kicks. All of that is easy and relatively cheap to do.

 

[glfredrick]

Those 5.0s are notorious for having leaky intakes...

I'd check that avenue.

Also, which plugs are you running? You must run a double platinum plug in the Ford motors becasue they use a "lost spark" system, where the coil fires through the positive side on one bank and the negative side on the other. Single platinum plugs will give an out-of-balance condition.

Generally I like Bosh Platinum plugs, but in the Ford motors, I recommend Autolite plugs.

 

[MoabB2]

All of the spark plugs and wires are brand new. Motorcraft Double Plats.
New air filter, and FPR has been checked and is working properly. All the injectors were pressure tested at the fuel rail and none of them were leaking. New O rings were added also.

The cats were new about a year ago, but they haven't been checked since. Wouldn't a clogged cat throw a code in the computer?

Could this be an exhaust leak? I'll have to check the intake for leaks also. What's the best way to do that?

 

[Rhett]

Could this be an exhaust leak? I'll have to check the intake for leaks also. What's the best way to do that?

What headers did you use when you dropped the 302 in? Yes the 302 has been known to have exhaust/header leakage.

Did you open up the engine at all before install? Or did you just pull it out of the Mountaineer, and drop it in? I assume it ran fine in the Mounty.

I assume also that your wires going to the O2's are not shorting out somewhere, and the plug wires are also not chafed or shorting or arcing. I assume you checked all of that really well.

Rich on the one side...hmm. Did you pull the plugs...do certain plugs look blacker than others?

 

[410Fortune]

He used the Duff headers which are the Advance Adapters conversion headers.
I think they were also modified to clear the 4r70w

The plugs on the rich side were also wet with fuel.

 

[MoabB2]

The Plugs On The Right Side Were Very Black.

I Never Looked Inside The Motor Before The Swap. I Was Only Told That It Ran And That All Cylinders Were Tested For Compression. I Don't Think That Is An Issue Though Because When I First Dropped In The Motor It Ran Like Heck! This Problem Came On A Few Months After The Swap....after I Overheated It One Time.

 

[MoabB2]

I assume also that your wires going to the O2's are not shorting out somewhere, and the plug wires are also not chafed or shorting or arcing. I assume you checked all of that really well.

I thought this was a problem too. Since then I have completely rewired the whole truck with a brand new harness.

I should mention that injectors were also swapped sides to see if that changed anything....no change.

02 sensors have been swapped sides, no change.

 

[MoabB2]

Apparently part of my issue was that my headers had burned up one of my spark plugs. I have replaced it and it runs better now, but still rich on the driver's side.

My mechanics have advised me to just go get emissions tested and see if they can diagnose anything. I may just take it to a SCT shop where they can put it on the dyno and tune the engine. Any suggestions?

 

[Rhett]

In other words, your mechanics are at a loss. Well, I don't blame them, I kind of scratch my head too. Something is causing the plugs on your drivers side to be black...something is causing it to run rich on that side. You switched O2s and no change. Maybe both upstream O2s are bad? But it's not throwing codes. You tested the fuel press. and it's fine, so that makes me think there's no leak at the rail or FPR. But if they're wet, then there's too much gas there. Are you 100% sure there's no leak on the rail? I'd be interested to know how it does with emissions.

 

[MoabB2]

I will double check the rail and intake for leaks. I will also be checking for an exhaust leak. Emissions will be done early next week. I'll let ya'll know how it goes.

As a side note, I am not sure if this relates...I washed down the engine compartment yesterday. It still had red mud splashed all over. Then I let it dry and air out for about an hour. When I started it up after about 10 minutes it started to run VERY bad. The Check Engine light came on, flashing at first, and then solid. It almost wanted to die and sort of felt like only a few cylinders were running. I have no idea though.
When I returned home I pulled the battery cable to reset the computer. Ive been over 40 miles since and problem hasn't returned, nor has the CEL returned. Maybe it was just because the engine was wet or something...I didn't pull the code from the computer though.

 

[410Fortune]

A wet engine can cause issues, with the MAS, with arcing with standing water on the coil pack, battery, etc.

you have to be careful when you wahs your engine bay and should remove and puddles or standing water (compressed air is GREAT for this) before starting.

Do not get the alternator soaked and cover your air filter, etc.
the ppower steering cap likes to collect water and headers can cause puddles of water at the base of your spark plug wires.
If you are having increased arcing issues when its wet (mis fire) then you need to check your wires, make sure they are seated and routed correctly. die electric grease is used on the boots to keep moisture out.

header leak should be obvious (ticking noise) and will cause a rich condition on that bank.
my BII runs slightly rich as well, but I do not have the power issues you are having.
I have a header exhaust leak on the passenger side, I have not had the opportunity to tear into it and replace my TM headers with the re-designed set Robert sent me months ago yet, I will fix the leak at that time and expect the rich condition to go away.

Also the ethenol gas we are getting here in CO right now with the warm weather is not the best thing for this or any engine IMO, in fact it plain SUCKS, it is my understanding this winter blend will kill the cat converters even more quickly then a better unleaded blend, it can cause detonation (pinging) and well I can tell the difference between winter blend and are usual gas, this year they extended the ethenol blend to keep prices down (yeah right)

 

[Howard]

The Plugs On The Right Side Were Very Black.

This Problem Came On A Few Months After The Swap....after I Overheated It One Time.

I think this is the clue. I would get a compression test done and see if you have damaged anything when it overheated. My guess would be that it now leaks un-metered air in on the left bank and the computer is trying to enrich it causing the right bank to run rich.

 

[MoabB2]

So it is possible that the Overheating episode did some damage to the internals...? I hope this isn't the case.

410, There is a noticeable ticking noise on that same side. You can hear it in the engine compartment, and if you listen right by the rear exhaust on that side you can hear the same ticking. It only happens on the problem side. Is my header leaking?

 

['97 V8]

if its a noticable ticking from the the exhaust then yes, your header is most likely leaking

 

[Howard]

A badly leaking exhaust manifold will also cause the computer to enrichen the mixture as the O2 sensor will not be reading correctly (because of the leak before the sensor)

 

[410Fortune]

I suspect this is your issue, remove the header and re-seal with a new gasket.

Make SURE you completely clean both mating surfaces and use a good sealing gasket.
The TM headers get torqued a bit then torqued again when hot.
all bolts get thread locker. You may contact Robert and see what gasket he recommends.

This is assuming you have pin pointed your leak to the header/blcok gasket, not at the collector, ball flange....