Hey,

My 01 L truck has had a problem for months now. The "Service Engine soon" light comes on after a minute or so after starting it up. Looked up the code at my local Ford dealer, It said banks 1 and 2 lean, which means both sides of my engine are running lean. It has been doing this for months, I thought I had a vacuum leak around the fiberglass power tube, but no leaks.

Hooked the truck up on a Dyno this weekend to have some new programs burned and the truck showed lean on the graph, no matter what we did. We could get it down some but , not enough to tune.

I installed new larger fuel pumps and 50 lb injectors this weekend while dynoing, still the same problem. Some kind of electrical gremlin not letting the truck get more fuel? You can hear the fuel pumps activate, Maybe one fuel pump is working and under WOT the other pump is not? Also, sometimes it will start hestitating during cruising around, like it is starving for fuel.

Codes from this weekend was 1639, 0703, 1780, 1408, 1232, 1000... Checked the relays, seemed OK, Fuel press is 54 -56 lbs under WOT?? I've heard someone else on the boards had similiar problems, they took a resistor out of the fuel pump circuit, which allowed the fuel pumps to run wide open all the time, I would rather fix the problem, then remove parts.

Anybody have any suggestions? I'm going to the dealer on Tuesday.


tks

 

what is your MAF voltage and BARO frequency?

also what kind of percentages are you getting for long and short fuel trims?

BTW:
hope this helps.

I'd say check your low speed fuel pump relay (check your owners manual for location).

later,
chris

 

Hey Chris,

This may not sound right, but I think sometimes the fuel trim would be like up to 30% lean under WOT??? We used a Ford tool, looks like a big T to check the codes. I'm trying to get in touch with him now, so I can post more info.

tks

 

look above DL, sounds like maybe one of your fuel pump relays is bad.

P.S. "the big T" is an NGS or "new generation star tester", but I may start calling it "the big T" at work now. I like the way that sounds better anyway. I'll run it past the other guys in the shop. just messin' with ya. good luck on your problem.

later,
chris

 

Hey Chris,

Is that the two relays together beside the fuse box under the hood on the drivers side?

We checked them with a voltmeter and swapped them all around.

 

Hey glad I could help you out..It's cool.. My local Ford dealer tech has the Big T(He!He!) and another one that looks like a big touch screen monitor (portable like a Lap top) I don't remember the abbrev names for the test equipment..

 

Hey Chris,

We tried a new processor, still did the same thing. Must be the relay, I hope.

Can you shoot me an E-mail at dplynn1@bellsouth.net ... tks

We pulled 305 and 306 out, my friend checked them with a Volt meter, then we swapped them back in the opposite number slot? Maybe we didn't check the relay properly? We swapped them, the other should have been good??

 

you need to put more fuel to the carburator

 

Is that what JDM told ya?

 

DL,

I think you need to install bigger jets in the carb.

Seriously, I'd recommend testing it by bypassing the resistor. Just let both pumps run and see what happens. Also, did you try swapping MAF's from another truck?

 

Hope you come up with the answer to this because I have a 03 with the same problem. 1500 miles on it I went to get it dyno tuned and it had the same problem, it would rich up a little but it still showed it running lean. Nobody has come up with a answer for me. I hope you get a answer so I will know where to look.

 

"I thought I had a vacuum leak around the fiberglass power tube, but no leaks. "

David: I HAD a REM intake, 'hard' pipe installed on my 01. I never got any "lean codes" but when I took it off to check for any intake oil, I found two of the three rubber grommets(on the bottom--for the PCV tubes) of the pipe cut or torn. This would certainly allow for unmetered/extra air getting into the mixture. Check them out carefully.

Dan

 

"I thought I had a vacuum leak around the fiberglass power tube, but no leaks. "

David: I HAD a REM intake, 'hard' pipe installed on my 01. I never got any "lean codes" but when I took it off to check for any intake oil, I found two of the three rubber grommets(on the bottom--for the PCV tubes) of the pipe cut or torn. This would certainly allow for unmetered/extra air getting into the mixture. Check them out carefully.

(Note: REM replaced the grommets quickly but I don't trust that the new grommets will do a better job of staying tear-free due to the design and the sharp edge of the holes.)

Dan

 

Put a brand new MAF on the truck last week at my local dealer, two new 02 sensors. At the Dyno, we threw alot of fuel at it, it didn't lower the air/fuel ratio enough to be safe. I shouldn't have to bypass the reistor, It used to work fine. My local Ford tech said it wouldn't be a good idea to run without the resistor for a long period of time.

Got a appt with my dealer for either tomorrow or Wed. , we'll see.

Thanks Dan, we checked for vaccum leaks, I'll check there also.

 

The real meaning behind the code is that the truck is running too rich and the computer is trying to lean it out. If you have an oil breather cap try putting the stock cap back on. Not referring to DL's problem directly.

Justin@JDM