fuel problems

[redreatta]

hello all, i have a 96 xlt with the 4.0 litre, it has been giving me problems for some time now, i was recently on here with the DPFE sensor problem and thought i had it fixed, now my check engine light is back on and it is stuttering really bad.
roughly 7 days ago i was driving a distance and the light came on. the next morning the battery was dead. i went out and got a new battery a couple days later and installed it, when i stared the car and drove it, it started stuttering. went to auto zone and had a free engine diagnostic done and it said, 1. PO174 fuel trim bank two condition 2. PO171 fuel trim bank one condition 3. PO402 Egr system fault( the ECM has detected too much flow on the Egr system. i have replaced the DPFE sensor and cleaned the throttle sensor about 2 months ago. before all this if i was to drive the explorer long enough to get it at running temp and turned it off long enough to go into a store it would not want to start back up. acted like it was not getting enough gas so i would hold the pedal down about half way and it would eventually start. any help or ideas anyone has would be greatly appreciated

 

[robertoa1a]

Are you still on the original spark plugs? When the book says to do regular maintenance at certain intervals. The 4.0 is pretty forgiving. The odds are none of that has been done in 2 to 4 times the specified time. What does the air filter look like? Ever thought about changing the fuel filter.

I heard a guy bragging about how he hasn't changed his oil in 60,000 miles. "The thing is still running". Thats pretty cool. I guess.

 

[redreatta]

yes i changed the fuel filter, air filter and sparkplugs about a year ago. i change my oil roughly every 3000 miles

 

[robertoa1a]

I think that a likely cause may be a vacuum leak. Half the time these problems are solved simply by cleaning the MAF with an approved MAF sensor cleaner. Its real sensitive and will cause the problems you are talking about.

 

[budwich]

As stated, your problem is probably an "onion"... first skin is probably a vacuum leak and the second skin is probably associated somewhat with the egr which might be related to a "large vacuum leak" as I think the system "imagines" that you are "open throttle" (ie. low vacuum) which means that the egr should be opened for "environmental reasons".... I don't believe cleaning your MAF with do anything for these types of problems. Check hoses and such. Try the "spray test" to see if you can find the leak.

 

[chance942]

check your fuel PSI.

 

[robertoa1a]

In case your fuel pump is going out I wouldn't fill the tank up till you know.

 

[4x4man]

Hi guys.

Should both of the MAF sensors have the same color?
In my case the one is almost white and the other one more brown/black.

What can I use to clean the sensors? ...I got CRC electronic cleaner and Break Cleaner from Aerosol by hand.

What do you think?

Cheers
Frank

 

[4x4man]

Ok...I could'nt wait, so I used CRC and now the both sensors got the same bright color.
A lot of "****" on the "dark" one, and I used a small soft brush.
Too bad I don't got the right torx to get all around both sensors.

Update after a test drive:
All I can say...I got a new car
The guilty one was the dirty MAF sensors, and I never got a oxygen sensor problem as I first tought.
Voltage on both upstream 02's now showing the the right readings between 0.1 - 0.9V.
The engine idle's more smoothly now, and whith wot it acts like a plane...HI

Tomorrow I hopefully will get the right tool to disconnect the MAF sensors again to clean the "backside" as well, and I really looking forward to measure my fuel milage

 

[robertoa1a]

You only have one maf sensor. Are you sure we are on the same page?

 

[4x4man]

You only have one maf sensor. Are you sure we are on the same page?

Inside my MAF there is two sensors (see picture)
http://www.floranett.no/temp/MAF.jpg

...and today I got the right torx tool and did a new clean :

 

[robertoa1a]

OK. Good attention to detail! I almost want to say that something is wrong with that picture. I think a new one cost about $100. I don't want to ask you to gamble that much. Will your Auto Zone let you try a known good unit or have a return policy?

There is a trouble-shooting process in my books but It seems detailed and not real clear on readings since you cannot simulate driving conditions while checking. check between (+&-) for open circuit. It looks like two elements look like they are in a parallel circuit with only one working. That would seem to give the PCM erroneous data. The resistance would double.

 

[robertoa1a]

Are you in Norway Sweeden?

 

[4x4man]

OK. Good attention to detail! I almost want to say that something is wrong with that picture. I think a new one cost about $100. I don't want to ask you to gamble that much. Will your Auto Zone let you try a known good unit or have a return policy?

There is a trouble-shooting process in my books but It seems detailed and not real clear on readings since you cannot simulate driving conditions while checking. check between (+&-) for open circuit. It looks like two elements look like they are in a parallel circuit with only one working. That would seem to give the PCM erroneous data. The resistance would double.

Hi Roberto

As I wrote above, my sensors (specially one) was full of oil and dirt....so after cleaning everything is 100% ok
I earlier got an lean oxygen sensor code P1151, but all caused by the MAF the dirty MAF sensors. I remeber the voltage (before cleaning) on the one HO2S showed max 0.05....and now it act like the other between 0.1 - 0.9 V
It was hard to get focus (as you can see on the pic) on those to little ones, but you see it's two of'em.

Cheers
Frank

 

[4x4man]

Are you in Norway Sweeden?

Norway...is my english that bad...(sorry)

 

[robertoa1a]

There's supposed to be two elements.

I get confused every time a post starts under one name then seems to continue under another. This doesn't appear to be the original poster. The American English sounds normal.

 

[4x4man]

There's supposed to be two elements.

Yes...there is two elements as my picture hopefully shows
I wrote two sensors....sorry

 

[robertoa1a]

Well if it is as dirty as you said then there is a good chance that unit is bad. Those are heating elements and the heat varies with engine conditions. The engine measures how much air is coming in by how they cool. It's a delicate thing.

Fuel is provided by the computer based on this information.

Dirt on a hot element could burn it up.

 

[robertoa1a]

I would clean the IAT sensor too. The duct is provably got a lot of dirt in it too.

 

[4x4man]

I would clean the IAT sensor too. The duct is provably got a lot of dirt in it too.

The elements looks great after the cleaning and the IAT sensor is cleaned as well
I'll get back how my milage is later....and I belive it's better now