System too lean...????

[LancerEVA06]

I'm totally clueless on fords here... My girlfriend owns a 1999 Ford Explorer Sport (4.0L SOHC) and after 30 minutes of clearing DTC's I keep getting a "System Too Lean" code. Checked everywhere for vaccum leaks, also check the IM gasket. MAF is clean, and new air filter and the cylinders are all free of carbon. Her truck has very erratic idle but other then that it doesn't have any driveability problems. Only thing I can possibly think that it could be is O2 sensors... but don't want to spend the $100+ on new ones if that isn't even the case. Any suggestions?

Btw, Sorry about not using SEARCH... I'm coming from a 06 Mitsubishi EVO IX, so I have absolutely no idea what I'm searching for.

 

[BrooklynBay]

Welcome to this forum! Was the TSB 00M12 ever performed? What was the DTC code #?

 

[LancerEVA06]

Welcome to this forum! Was the TSB 00M12 ever performed? What was the DTC code #?

I have no idea what the TSB 00M12 is... and I have no idea what the DTCs are.... My code reader is Mitsubishi specific, so I had to go to Advance Auto Parts to pull the codes. I know that is was "O2 UP SYSTEM TOO LEAN" and "O2 DOWN SYSTEM TOO LEAN". Those were the only two codes. I've had other vehicles I've work on where it threw up those codes and it wasn't the O2 sensors but something else, and I know Explorers have this problem.

 

[BrooklynBay]

That TSB refers to the intake gasket kit from Ford. Ask them what code numbers came up, not only for a description of the code.

 

[Tbars4]

let me ask a dumb question....does the truck have a regular engine and did she put e85 fuel in it? e85 would give you this reading...

 

[LancerEVA06]

I hooked up my MUT tool to read the DTCs.... however since it's a Mitsubishi tool I have no idea what they mean. Anyway, the codes I got from it were P0171, and P0174.

I checked out the TSB 00M12 BrooklynBay was talking about... I'm not sure if it was done since her truck was bought used... but I've tripple checked both plenum gaskets and IM gaskets and they're both good.

tbars4 no e85 wasn't put in. Around here we only have a handful of gas stations that offer e85, and barely anyone uses it since it's about 20 cents more then premium and get maybe 80% the mileage.

 

[Tbars4]

i took a shot when i seen you were in the corn belt...from what i hear in the midwest, e85 was 20 cents less but what i hear on the forums, i wouldn't touch it if i had the correct motor...anyway, i was hoping my answer would be your simple solution...the codes as i read them in order are,system adaptive fuelto lean(bank1), and the next is the same for bank2...thats all i know...

 

[LancerEVA06]

I just thought about this... she does have an exhaust leak... are these O2 sensors in the manifold or in the exhaust piping itself?
Also, I used to own an 85 Mustang and it would run the same type of way on start up... it was due to a carboned up EGR valve... can anyone tell me where the EGR valve is on the explorer? Better yet show me a picture?

 

[BrooklynBay]

You might find this thread useful: http://www.explorerforum.com/forums/showthread.php?t=183944. Check the link in post # 9.

 

[LancerEVA06]

You might find this thread useful: http://www.explorerforum.com/forums/showthread.php?t=183944. Check the link in post # 9.

I didn't see an EGR valve... or one even mentioned.... On her truck I see what looks to be an EGR valve but it's not connected to the intake or head... instead it's hooked into the exhaust then going up to the IM... and a vaccum fitting on top. The way it's hooked together kinda reminds of the old GM A.I.R. system. Am I describing the EGR or something else?

 

[BrooklynBay]

Maybe it's the DPFE sensor? Is it made out of plastic? Does it look like this:

 

[LancerEVA06]

MIL light is on again... throwing same codes... I've tried everything. I'm about to give up.

 

[Tbars4]

i take it you fixed the exhaust leak?? even though it is ann exhaust leak, cool fresh air can be coming in which would tell your o2 sensors its to lean...you have an 2- o2 sensors on your exhaust pipe...also, if you have a donut, a place where exhaust manifold and piping meat, that may be your sorce for the leak...

 

[CDW6212R]

I have a similar issue, mine's a code P0171, just that. I have had my engine down for timing chain repairs, so I am doubtfull that my new upper gaskets are leaking. Mine I'm thinking is a vacuum leak around the rear plastic lines, there are several, and they are very fragile. I'm assuming that yours is a SOHC, look on the intake cover.

There are four O2 sensors, over $75 each at Ford. Unless the mileage is high(125k+), I'd not suspect those yet. The upper intake gaskets are evidently very prone to leaking, they cost less than $10 for the upper set. Buy those from Ford and spend an hour or two to carefully change them.

The EGR is on the front driver's side of the engine(in front of oil fill cap), it and an exhaust leak should not create a full lean code set. I think you should be looking for an upper engine vacuum leak. Good luck,

 

[LancerEVA06]

Well if they are that cheap I guess I'll pick them up and install them. Does anyone have a diagram for the tightening sequence and torque specs for the upper intake?

 

[CDW6212R]

The "screws" are torx headed, about a size T30. They have very coarse threads, the hard part is getting to them, mainly the rear ones. Lubricate the blue gaskets(o-rings) with something like lithium grease, before installing them.

 

[LancerEVA06]

The "screws" are torx headed, about a size T30. They have very coarse threads, the hard part is getting to them, mainly the rear ones. Lubricate the blue gaskets(o-rings) with something like lithium grease, before installing them.

do you happen to have the tightening sequence? I'm trying to download the Service Manual, but as of right now it's saying about 9 days remaining.

 

[CDW6212R]

Sorry, no, I didn't use a manual very much for my engine work. I know that most sequences alternate from side to side and inside out, in steps. Do find the proper sequence if you need to. I chose to trust my skills of evenly tightening many bolts as a unit. I've been threw a bunch of valve bodies, and those are very sensitive to improper torquing. I've never had any issues with any valve body work that I've done. Regards,