Hello, recently purchased an LR3 with lean code. Went through the normal troubleshooting. Discovered my MAF at idle is a little high 6ish g/s around 800rmp.

But in my quest looking for an air leak, I noticed my lean code and high trim would happen only after engine was warmed up. So I decided to cap some vacuum lines and see if I could pinpoint the issue. One correlation I found was as my scan tool told me the EVAP was opening my engine on both banks was increasing short term trim... More so on B1. So I decided to cap the EVAP line at the throttle body.

This immediately lowered my short term fuel trims and brought down my long-term trims from around 15 to 8ish. My question is, how long can I run like this and what damage will it do. At the moment after a few test drives I am not seeing any check engine light. I also used a vacuum cap to plug the EVAP line. Thoughts?

 

The EVAP is really a passive system. As you prob know, just for pulling gas fumes from the tank and subsequently burning them in combustion. So in theory, there should be no issues performance or economy wise and nothing should get hurt. But if you ever plan to play with the Rover in deeper water, it may be a good idea to check for leaks since a leak to EVAP means a leak in the fuel tank system. Water could get in. The most obvious location for a leak is the fuel filler cap.

 

Thanks. I did about 2 hours of driving today. Still got a lean code so I ordered a new MAF sensor as well. I'll check the fuel cap again and see what I see.

 

Could easily be the intake pipes, they develop cracks.

 

i vote intake duct also. caping off the evap line may give you a low evap flow code... so your just swapping one check engine light code for another..

 

Yes, I did get an EVAP code but my thought is there are probably multiple things happening at the same time so I am trying to isolate systems as much as possible. I noticed the EVAP code only triggers at startup so I can always disconnect after to check fuel trims levels.

I also have a cheap smoke tester from Amazon to test the intake. My first observation was a leak in the EGR housing. I sealed that but am still not ruling anything out.

My main observation is that lean codes are being triggered when moving from 1800rpm ish to idle mostly by quickly letting off the throttle. There is no engine hesitation but I noticed the fuel trims shoot way up to 19 on Long-term. Maybe because the EGR is closing too slowly. I can also see a direct correlation in the EVAP % increase and fuel trims when it is hooked up. Honestly there are not obvious vacuum leaks in the engine bay using WD40 to search pretty extensively. Also new resonator from previous owner.

 

if its only bank 1 i would be focusing on anything that has to do with just that bank. not both. so anything that goes to the main part of the intake is prolly not the concern.

 

EGR valve leaks by design. I know... makes no sense, but look it up and there are videos.

 

True. An overall vacuum leak will not impact just one bank.

 

The sagga continues. I install new MAF sensor and noticed a higher G/s reading overall compared to the old one. It had one strange thing that looked to be soldered, not sure if that is good or bad, I'll try to attach a photo. I then did a hard reset and have allowed the computer to relearn. After a little driving, my lean code came back but I noticed a potential clue. My command TAC was jumping all over the place. Bouncing from 5% to 24% at idle. I plan to clean my throttle body next and see if it makes a difference. Any know if this is normal fluxuation and the potential cause? Thanks in advance for your advice.
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