Rich bank 2 and 1, Bank 2 is worse. I have a LTFT of around 29%

[TonyG1989]

I ordered new heads and a complete gasket kit. I have good compression all the way around and I still can see crosshatching, original 110,000 miles on this engine. I am no rich man, and I know it's a gamble not rehoning and installing new rings and pistons. No connecting rods seem bent, all pistons are the same height when TDC on each particular cylinder so I THINK the bottom end is ok. Two main questions. Does a clogged or even partially clogged cats cause a rich condition? Or could it be possibly my hunch about the exhaust valve seats being recessed cause of this rich condition? And even if it was the rings how would that cause a rich condition? I've changed my o2 sensors two times, the same thing, even switched their positions to see if the trims changed, nada, same thing. Is it the cats? Changed Injectors (MOTORCRAFT U TYPE) they are the correct ones without a doubt. MAF readings in spec as far as I can tell. IAC reads normal. The Coolant temp sensor reads normal. No intake leaks (which I was told would cause a lean, not a rich condition) No air restriction to the cylinders for sure. I even poured oil into the cylinder to see how fast it would leak through the ring gaps, held water like the hoover dam. Could it be the exhaust valves letting raw fuel/air mix into the exhaust during the compression stroke? Causing the o2 sensor to read rich? It seems the engine is fine other than that. The motor runs FINE at high rpm, STFT evens to 0 at 1000 RPMs. It is just at idle she stumbles and jerks. And it isn't the IAC valve, she is in spec and probably the only reason she doesn't stall altogether. Anyway, newbie here, thanks for any wisdom!

 

[franklin2]

Have you checked your fuel pressure? Does your fuel pressure regulator have a vacuum line going to it? If it does, does it have any fuel in the line?

 

[TonyG1989]

I unhooked the hose going from the tank to the EGR valve solenoid (Which I just replaced due to an air leak) and couldn't see any evidence of fuel. Is that the wrong place to look? I plugged up a fuel pressure gauge at the rail and got 50 psi. But it was leaking (at the gas gauge connection) so I shut it off as soon as the fuel pressure gauge stopped at 50psi and the needle didn't anymore.

Theory: Because the exhaust valves leak, during the compression stroke its pushing the fuel/air mix into the exhaust, telling the O2 sensors that it needs to trim fuel. Causing an actually "lean" condition even though the computer says it's too rich?

Here are photos of each exhaust valve, and both heads valve side up. Sorry, some are a little blurry. Any thoughts?

 

[franklin2]

Not sure why you are stuck on the mechanical part of the engine for a rich condition. Do a compression check on the engine. If it's good, then move on away from a mechanical problem with the engine causing it.

Is 50 psi good for your setup? I am not up on all the different years and their pressures, but I know 50 psi is high for a older model fuel injection system.

 

[Rearanger]

Rich bank 2 and 1, Bank 2 is worse. I have a LTFT of around 29%

Just to clarify. Do you mean +29% or -29%? A rich condition would show computer subtracting fuel = -29%.

 

[RonD]

If an engine is actually running Lean it will ping/knock
If an engine is actually running Rich it will blow out grey smoke from tail pipe, and Cat converters would be RED HOT

But that's not what Lean or Rich "codes" mean
Lean and rich codes mean computer has reached a 20% mark, + or - , in calculation errors
So -20%(rich) or +20%(lean)

And the % has to do with calculated open time for each fuel injector
The engine is never actually running lean or rich because computer is adjusting the injector open time, the codes are to let the driver/owner know there is a calculation error that should be checked

O2 sensor voltages are what initiate the lean or rich codes, computer has no other way to "test" if exhaust is lean or rich
O2 sensors can only "see" Oxygen, not fuel
High oxygen in exhaust is lean, 0.1volt from upstream O2
Low oxygen in exhaust is rich, 0.9volt from upstream O2
Sweet spot for upstream is 0.4volt, but it changes fast, 0.2 to 0.6volt range

Downstream O2s(after Cat converters) SHOULD see Low Oxygen exhaust since the Cats burn up most of the remaining oxygen cleaning the exhaust, so they should run steady at 0.7 to 0.8volt

2002 Ranger should be running 55psi fuel pressure so your 50psi is fine

If the engine computer is showing same type of error code for both banks of a V6 engine then it has to be an issue that BOTH banks share, something in common for both banks

Yes, a clogged exhaust, if its SHARED could cause codes on both banks
This could be tested for with Vacuum gauge

EGR system issue can effect both banks

If MAF sensor was OVER reporting AIR WEIGHT that would effect both banks, longshot


You did change fuel injectors, well got new ones, and that "may" be the issue
Computer is programed for the injector size, i.e. pounds of fuel that will flow out in an hour, like 19lb/hr

If you put in 24lb/hr injectors then more fuel will flow out each time injector opens, so computers calculation will be off, on the RICH side
In 2002 3.0l Ranger gas only or flex fuel "should" use the same size injectors(2001-2008)
In the VIN the 8th digit will tell you what COMPUTER you have
"V" is a gas only 3.0l computer
"U" is a Flex Fuel 3.0l computer

You need the injector size that the computer expects
Injectors are NOT like Jets in a carburetor, larger injectors just cause Rich codes, same as smaller would cause lean codes, no change in power just get ODB2 codes, lol

Maybe you got shipped the wrong injectors, labelled wrong

 

[TonyG1989]

Rich bank 2 and 1, Bank 2 is worse. I have a LTFT of around 29%

Just to clarify. Do you mean +29% or -29%? A rich condition would show computer subtracting fuel = -29%.

-29% - And to clarify it was pretty even as far as LTFT goes on "Both Sides" -29% bank 2 - -22% Bank 1

 

[TonyG1989]

If an engine is actually running Lean it will ping/knock
If an engine is actually running Rich it will blow out grey smoke from tail pipe, and Cat converters would be RED HOT

But that's not what Lean or Rich "codes" mean
Lean and rich codes mean computer has reached a 20% mark, + or - , in calculation errors
So -20%(rich) or +20%(lean)

And the % has to do with calculated open time for each fuel injector
The engine is never actually running lean or rich because computer is adjusting the injector open time, the codes are to let the driver/owner know there is a calculation error that should be checked

O2 sensor voltages are what initiate the lean or rich codes, computer has no other way to "test" if exhaust is lean or rich
O2 sensors can only "see" Oxygen, not fuel
High oxygen in exhaust is lean, 0.1volt from upstream O2
Low oxygen in exhaust is rich, 0.9volt from upstream O2
Sweet spot for upstream is 0.4volt, but it changes fast, 0.2 to 0.6volt range

Downstream O2s(after Cat converters) SHOULD see Low Oxygen exhaust since the Cats burn up most of the remaining oxygen cleaning the exhaust, so they should run steady at 0.7 to 0.8volt

2002 Ranger should be running 55psi fuel pressure so your 50psi is fine

If the engine computer is showing same type of error code for both banks of a V6 engine then it has to be an issue that BOTH banks share, something in common for both banks

Yes, a clogged exhaust, if its SHARED could cause codes on both banks
This could be tested for with Vacuum gauge

EGR system issue can effect both banks

If MAF sensor was OVER reporting AIR WEIGHT that would effect both banks, longshot


You did change fuel injectors, well got new ones, and that "may" be the issue
Computer is programed for the injector size, i.e. pounds of fuel that will flow out in an hour, like 19lb/hr

If you put in 24lb/hr injectors then more fuel will flow out each time injector opens, so computers calculation will be off, on the RICH side
In 2002 3.0l Ranger gas only or flex fuel "should" use the same size injectors(2001-2008)
In the VIN the 8th digit will tell you what COMPUTER you have
"V" is a gas only 3.0l computer
"U" is a Flex Fuel 3.0l computer

You need the injector size that the computer expects
Injectors are NOT like Jets in a carburetor, larger injectors just cause Rich codes, same as smaller would cause lean codes, no change in power just get ODB2 codes, lol

Maybe you got shipped the wrong injectors, labeled wrong

"U" type and "V" type engine injectors are completely different flow rates. I have OEM "U" type in, the original injectors were in and still had the same issue. I bought a brand new set and literally the same conditions were present. I appreciate the fuel PSI feedback. Im gonna throw the new heads in and if that doesnt fix her im replacing fuel pump assembly and regulator. Any comments on the valve photos? I am suspecting recessed exhaust valve seats.

 

[RonD]

Yes up to 2000 3.0l V and U did use different sizes, 2001 to 2008 used same injectors gas only or flex from my understanding
Which I think was 19lb/hr or 21lb/hr

Earlier were 14lb/hr gas only and 24lb/hr for flex, if memory serves

Ford ditched the "Fuel type sensor" in 2001 and changed the computer software to allow for wider range of mix ratios

 

[TonyG1989]

Yes up to 2000 3.0l V and U did use different sizes, 2001 to 2008 used same injectors gas only or flex from my understanding

Ford ditched the "Fuel type sensor" in 2001 and changed the computer software to allow for wider range of mix ratios

Injectors. I "did" change them. BUT, the condition started with the original injectors. I put some RPMs on her hard to check her out when I first bought her. Could a leaking exhaust valve cause fuel to bypass during the compression stroke and cause the O2 sensor to read rich and force the engine to adjust lean?

 

[RonD]

O2 sensor can't "see" fuel just oxygen

Leaking exhaust valve would cause lean because of unburned air leaking out into exhaust manifold

Is the engine pinging under load?
Thats a sign of Lean

Is it smoking out tail pipe or are CATs making noises(metal expanding too much) or running Hot?

Lean and Rich codes are computer calculation error notification not actual condition of engine operation

 

[TonyG1989]

Yes up to 2000 3.0l V and U did use different sizes, 2001 to 2008 used same injectors gas only or flex from my understanding
Which I think was 19lb/hr or 21lb/hr

Earlier were 14lb/hr gas only and 24lb/hr for flex, if memory serves

Ford ditched the "Fuel type sensor" in 2001 and changed the computer software to allow for wider range of mix ratios

And I really dislike texting, I have upmost appreciation and respect for you.

O2 sensor can't "see" fuel just oxygen

Leaking exhaust valve would cause lean because of unburned air leaking out into exhaust manifold

Is the engine pinging under load?
Thats a sign of Lean

Is it smoking out tail pipe or are CATs making noises(metal expanding too much) or running Hot?

No disrespect, I just went through this 2002 3.0 V6 Vulcan Flex (V) and Gas (U) Injector fiasco, and it's a thing. No disrespect. I finally got "U" type in and it runs way better than the flex-fuel type. the flex v type (RAN HELLA RICH, DEADLY), and now I've got brand new U type, and I'm back to where I started. Injectors did nothing

 

[RonD]

Always like new information so always like it when any of my answers are questioned
"the more you know, the more you realizes how LITTLE you know"

Are you running the original 2002 computer as far as you know?

Reason being there are not alot of things that can cause Rich codes on both banks
High fuel pressure, over 70psi in a 2002, fuel pump can go to 80+ PSI
Wrong injector size
TWO or more injectors sticking open, one on each bank, extreme longshot
Clogged exhaust, but that tends to set lean codes

EGR valve leaking, but that would set DPFE sensor code, for sure

And of course failing computer

 

[TonyG1989]

Yes sir its the original "U" type computer. Today I put cyl 1 on TDC and timing seems spot on as far as damper marks show, doesnt seem to be any play so I dont think its timing chain issues or anything. I just got the heads today. I'll install them and report back. I took out the o2 sensors and it ran the same except the trim went lean as all get out.

 

[RonD]

You are down to
Mis-labelled injector size, and if these are 2nd set with same issue then not likely
or
The computer, which would make sense if you had same issue before engine work

Yes, O2 sensors would be at 0.0 or 0.1volt when out in the "fresh air", lol