Rough Idle codes say too lean

[dgalvin66]

97 Expedition XLT 4.6 227k miles
Runs rough at idle still has exhuast leaks, will be fixed in next few days.
What has been done so far:
replaced all 4 O2 sensors some improvement
replaced pcv valve and line to TB some more improvement
replaced all plugs and wires alot of improvement
replace both exhuast manifolds and all studs (just got it back today) more improvement

The truck runs great but does not idle very well. When I first got it the idle was terrible and I thought it would die but never did. All of the work that has been done has made a great improvement but it still has the check engine light on and is throwing too lean codes. I do not have them right now, the shop did not give them to me and my code reader is at a friends house at the moment, I will update what the codes are tomorrow if I can.
There are exhuast leaks at both cats and the muffler that I hope to have fixed in the next few days. I know the muffler needs replaced and hopefully the cats do not.

I have a few other problems with the truck that I will mention here that may or may not play a part in this problem but I will start another post on those issues later.
Both the Oil pessure and water temp gauges jump to max high within less than half a block of driving (about 6 house lengths) down the street. I have never seen this happen on any vehicle I have ever driven before. I do not know if this could be defective sensors or something more serious, I hope not the later.

I thank you all in advance for your help.
Dave

 

[JUST4FUN]

follow the PCV hose to the tbody and look for a hole in that boot connection

 

[Kevo]

you might want to clean your IACV or replace it but i dont think it can cause lean codes and also check out your EGR and EGR controls

 

[CARO'S98EB]

check your intake hose from the t/b to the a/f. make sure it does not have any leaks or hoses not attached. IF that is ok use a pair of pliers to squeeze each vac hose shut or cap them off.

 

[tonydiv]

Another thing that can cause a lean code is the Mass air flow sensor. It can be dirty, or if there is a leak between it and the TB. They make a special cleaner for it, or if you have a spare $70, you can just replace it.

Grab a can of starting fluid, start the truck and spray around the intake tube, between the MAF and TB. Also spray around some of the other vacuum lines. If the idle picks up, you've found your vacuum leak.


It also can't hurt to clean the air charge temp sensor that is in the intake tube.

 

[dgalvin66]

The EGR was checked by the shop when they replaced the exhaust manifolds (so they say) I will check it again.

I have a can of MAF cleaner in the shed, will try it.

Also have a spray can of TB cleaner to try.

The PCV and the entire line all the way to the TB has already been replaced (there was a major leak) the plastic line and elbow were both shot, I just replaced with a few feet of 3/8" PCV hose routed so there are no kincks. Very 1st thing done.

I had read about the IAC and will look at that and see what I can do with it.

What is the A/F coming off the TB?

What is the Air Charge Temp Sensor? I am not familiar with that either.

I am off to take the wife to the farmers market then play with this stuff afterwards.
Thanks

 

[dgalvin66]

Ok here goes.
The codes are P1131 and P1151
As I said I do know that there are some exhaust leaks that need to be repaired, I am hoping to get it in tomorrow to have this done.

I pulled the IAC and cleaned it. It was filthy.
Rechecked for vacuum leaks and could not find any. Used a can of carb cleaner and sprayed all around the intake, TB, vacuum lines and any place that could possibly leak.

Cleaned the MAF and what I believe to be the Air Charge Temp Sensor.

It is idling pretty nice when it is in park at about 800 rpm and fairly smooth. If I apply the brake while in park no change, but when put in reverse or drive with the brake on it drops to about 550-600 rpm with a stumble almost like a missfire? not sure how to describe it. But it is still rough, nowhere near as rough as it was when I started and is almost acceptable now. But I do need to get the CEL and codes taken care of or it will not pass the emission inspection so that I can register it.

 

[JUST4FUN]

both banks lean
Causes

A code P1151 and P1131 may mean that one or more of the following has happened:



Electrical:


• Short to VPWR in the harness or HO2S
• Water in the harness connector
• Open/shorted HO2S circuit
• Corrosion or poor mating terminals and wiring
• Damaged HO2S
• Damaged PCM



Fuel System:


• Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system



Induction System:


• Air leaks after the MAF
• Vacuum Leaks



PCV system:


• Improperly seated engine oil dipstick



EGR System:


• Leaking gasket
• Stuck EGR valve
• Leaking diaphragm or EVR



Base Engine:


• Oil overfill
• Cam Timing
• Cylinder compression
• Exhaust leaks before or near the HO2S(s)

 

[dgalvin66]

Just4fun: The last part of that is exactly why I am thinking that the exhaust leaks getting fixed may help to fix these 2 DTC's (fingers crossed). The list I have reffers both 1131 & 1151 back to 1130 which is basicaly what you posted I think. Very good info. If this does not fix it then I need to look at a few other things in that post.

I just got back from Autozone, I had them pull the codes. The scantool they used pulled alot more than mine did.
In addition to the P1131 & P1151 they also got B1155, B1230, B1233, B1158 & B1229 which they told me are all ABS (BRAKES) but when I look them up I get different info but unfortunatly I can not find much on them other than this:
B1155 Ford Subwoofer No.1 Short to Battery
B1230 Ford Driver Safety belt Retractor Low or High Resistance on Squib
B1233 Ford Glass Break Sensor Failure
B1158 Ford Subwoofer No.2 Open
B1229 Ford Fuel Temperature Sensor B Circuit Low Input
The last one concerns me the most and I can not find any info on any of these any place I search. I would greatly appreciate any help with these you can provide.

 

[JUST4FUN]

those are body codes ill look into the last one

 

[ZombieSoldier]

A lot of times a lean code is caused by one of 2 Things. A cylinder misfire and or a vacuum leak.

 

[rburch]

MAF will cause a lean condition also!

 

[ZombieSoldier]

You are right, but I was putting out 2 causes that weren't mentioned. 1 is pretty easy an cheap, check vacuum lines. The second, well it requires a bit more to narrow down.

 

[rburch]

A place to check for vacuum leaks is between the battery and the fire wall. Thats where the main vacuum connection is and there is a tee there with a rubber hose that degrades after time.

Be gentle with the hard vacuum lines because they can be brittle and break!

 

[dgalvin66]

Ok I had all the exhaust leaks fixed, muffler and the 2 cats on pass side replaced on Monday, cleared the codes and drove it about 45 miles. The CEL did not come back on. I checked for any codes and the P1131 & P1151 were there again. I checked again for any vacuum leaks and could not find any. I had already fixed any that were found at the start of this mess.

So Tues I replaced the MAF & IAC (had cleaned both already but the IAC did not really clean up well). When I was putting the air cleaner back onto the TB I took a closer look at the elbow feeding the plastic line to the drivers side valve cover and it had some cracks in it but not all the way thru, so I checked the elbow on the other end of the line at the valve cover and it was the same. Went to several auto parts storees and could not find any replacement elbows so I just bought 3 feet of PCV line and cut to length and replaced the elbows and the plastice molded line (I think it is just a fresh air feed), finished putting it all together and now it idles almost like a new truck. I put about 50 miles on it tonight and it ran great, checked for any codes and there were none to report.
So maybe tomorrow afternoon or Thur I will take it in and have the emmision inspection done and hopefully it will pass and I can get it registered. Then the real fun starts....

Thanks for all of the help and advice. I will have olot more questions for all of you.

 

[ExpeditionLova]

hope ur truck is aight you helped me out i had the p1151 code to

 

[ExpeditionLova]

i kno this is old but could u show me pics of the elbow your
speaking of pleaseeeeeeeee