Running rich

AP1995V6 · Jun 13, 2007

So far I've replaced O2 sensors, EGR, and ECT. I also replaced those 2 sensors next to the EGR valve. I forget what they're called.

I checked fuel pressure. I got 30psi at idle, and 40psi at wot.

I get a bit of a gas smell during start up, and is more noticable after I have been driving. I got a strong exhaust smell when driving.

I'm running out of ideas.

The code reads that, on both banks, it's too rich for the computer to adjust. Those are the only 2 codes.

Thanks

chuck943 · Jun 13, 2007

unplug vacuum line on fuel pressure regulator and make sure there is no raw fuel there,it is probably ok since fuel pressure readings are normal but look to be sure. Do a fuel pressure leak down test, see how long fuel pressure holds after engine shut down,shouldn't loose no more than 10 PSI in about 10 minutes or so,if so you may have a leaking injector. Make sure air filter is not restricted and make sure no critters(bugs) found their way to the MAF sensor. Have you had any recent exhaust work? Exhaust restriction could also cause this.

final5-0 · Jun 13, 2007

Just a thought here

There are some codes that indicate the pcm has reached its adaptive
rich limit. If you are talking about these kinds of codes you would be
lean as the pcm is trying to compensate.

Why not give specifics as some members are pretty good with those
codes and maybe some have had the same codes as yours.

Grady

AP1995V6 · Jun 14, 2007

It's ODB-II but the codes are P0172 and P0175.

AP1995V6 · Jun 14, 2007

Would crapped out catalytic converters cause enough restriction to cause this?

I've had exhaust work done, but the eec was tossing this code before hand.

I've also cleaned out the MAF and it's voltage is within parameters.

chuck943 · Jun 14, 2007

did your fuel pressure leak down test pass?

Usually a dirty MAF will set lean codes P0171/P0174 but I have seen like moths or bees get sucked up inside MAF and they seem to set rich codes if they get stuck on the sensor bulbs.

To check for restricted exhaust you can use a vacuum pressure guage. It is easier on the 4.6L that use a DPFE sensor because you can just hook it in the hoses that go from DPFE sensor down to exhaust, but on vehicles that do not have a DPFE sensor you will have to rig up a fitting to put into the O2 sensor holes in the exhaust. If you still have one of your old O2 sensors that will work good just cut off the ends so just the center tube is left in the sensor then remove one of the front O2 sensors and screw this into it and hook up your vacuum pressure guage then take some readings. You should have around 1 psi or less at idle and no more than 3-4 psi at WOT. If your exhaust is restricted you will see probably 6-8 psi at wot.

JNeidlinger · Jun 14, 2007

Maybe an exhaust leak somewhere? Maybe not since your computer knows it is rich, but its worth a check. Crapped up catalytic converters could cause this too. Be gone with them!

AP1995V6 · Jun 15, 2007

chuck943 said:
You should have around 1 psi or less at idle and no more than 3-4 psi at WOT. If your exhaust is restricted you will see probably 6-8 psi at wot.

Is there a way to simulate wot? Or do I have to actually open the throttle all the way up?

The MAF is definitely clean. I've taken it out a few times to make sure.

What's the leak down test? Seeing how long it holds pressure?

I'm betting its the catalytic converters. As soon as I get home I'm going to take off my exhaust manifolds and check for cracks jic.

chuck943 · Jun 15, 2007

No you can't simulate it because you will be measuring pressure so you have to give it some throttle but don't just rev it up there and hold it it will show up quick if that is what it is, just take it up to about 2500 rpm then goose it to wot while you watch the guage.

AP1995V6 · Jun 15, 2007

Thanks. I'll check it out sometime this weekend. I hope this is the end of the problem.

AP1995V6 · Jun 16, 2007

I ran the vacuum test on both sides.

At idle, needle moved rapidly between 1 and 0. As I increased the throttle, the pressure evened out at 0. 0 at WoT as well.

Exhaust leak?

chuck943 · Jun 16, 2007

I would expect to see lean codes with an exhaust leak.
Do you know if these codes are a hard fault or if they are continuous memory codes?
You took the exhaust pressure readings at the O2 holes/or DPFE hose(this is a V6 right?)? If so thats good readings,your exhaust is flowing pretty good with 0 PSI at WOT,usually see around 3 PSI at WOT with cats still on vehicle.
With normal fuel pressure readings and no restrictions in exhaust I would suspect electrical like maybe a bad MAF or PCM. You did do a fuel pressure leak down test didn't you?

AP1995V6 · Jun 16, 2007

I believe the codes are continuous memory.

Yeah, it's a V6 and I used both DPFE hoses and got the same result on both sides.

The leak down test passed.

The MAF is cleaned and has the proper voltage readings.

I also bought a new Cam position sensor and checked to make sure the cam was aligned properly while I was at it.

I guess I can go back through looking for vacuum and induction leaks. Have any suggestions on how to check for these?

Could I use the vacuum gauge to test manifold vacuum to see if there's a leak? If so, what sort of pressure readings should I see?

chuck943 · Jun 16, 2007

yeah but a vacuum leak usually causes lean codes not rich. Unless you are loosing vacuum to fuel pressure regulator, but you should see increase in fuel pressure if that were the case.
Do u have a way to look at live data?
You said you cleaned MAF and replaced Cam shaft postion sensor,did you change oil and filter after that and do a reset on the PCM. You could have possibly fixed problem but maybe oil is contaminated from running rich,also have you replaced PCV valve?

AP1995V6 · Jun 16, 2007

I checked the PCV system, and it seemed to be fine. But I guess spending a few bucks on a new valve wouldn't kill me

Yeah. I reset the computer everytime I mess with the car and it keeps coming back on.

chief44 · Jun 17, 2007

I had the same codes on my son's 94 six cylinder just this past week. I replaced the two pre-oxygen sensors, but it still ran rough, on a hunch, I pulled the cold air intake apart. I found the car ran better with intake off. My problem turned out to be the sensor on the intake. Car has never run this good.

AP1995V6 · Jun 18, 2007

I replaced the PCV valve, and that fixed my rpm start up problem (the car would shoot up to around 2000-2100 rpms when it turned over).

I drove it around town and paid attention to the symptoms...

It sounds like it is missing. I checked the coil pack and I have spark from each wire. So I guess hesitation?

The car seems like it has absolutely nothing below 2400 rpms or so. After I hit that rpm area, the car actually picks up and feels like its supposed to. This is all at partial throttle. No complaints about WoT. (The eec reads a pre-determined a/f for wot right?) Partial throttle at 3000+ rpms, the car hesitates before shifting and bucks a little.

Cruising speed or anything to do with the lower region of the rpm belt, the car has no guts whatsoever.

chuck943 · Jun 18, 2007

AP1995V6 said:
No complaints about WoT. (The eec reads a pre-determined a/f for wot right?) Partial throttle at 3000+ rpms, the car hesitates before shifting and bucks a little.

No u are thinking about fox body mustangs,SN95 and OBDII use fuel allocation tables even at WOT.

I wish you had a way to look at data, I would be curious to know what the Air Charge Temp sensor is reading, what your Long and Short fuel trims were doing, and the Baro reading on the MAF. And what DPFE voltage is reading.
You might want to go ahead and bite the bullit and get some one to run a good diagnosis on it, unless you can get some way to get data readings. I would hate to see u keep throwing parts at it.

AP1995V6 · Jun 18, 2007

What sort of device would I need to check those data?

Would something like this http://www.diydiagnostics.com/advanced_specs.htm be sufficient?

I could probably swing something like this http://www.diydiagnostics.com/COM327_specs.htm as well.

chuck943 · Jun 18, 2007

I am really only familar with Fords diagnositc scan tools and software. There are several guys on here that have diagnositic software they are running on their laptops that maybe could give you some good ideas there, but you would need something like this.

http://www.amazon.com/ELM327-Diagnostic-Tool-Auto-Scanner/dp/B000LG4BN0

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