P2118 Reduced performance

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Buffalo76

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Hello all this is my first post and I am very desperate for some advice. I have a LR4 that just turned 112,000 miles on the odometer. I recently noticed a surging idle and followed by a code of a P0174. So I decided that the intake gasket and throttle body gasket were due for a refresh. The job went well and in under an hour I had it al back together. I took the time to also clean the throttle body. After putting it all back together I went and started it. It was rough at first and the idle high. I figured that some sensors needed to be re aligned. With-in 10 min I received a new code of P2118 for the throttle body along with reduced perofrmance.
So I did my research and understood that I may have lost the TB values and needed to reset the values using a GAP tool. I went out and purchased my tool from Lucky8 LLC and out of the box was very impressed with capabilities. I did a full system reset and reprogrammed the ecu with a hard start. Upon the first start up idle was again high and the reduced performance was still on.
I am new to the gap tool and I am wondering what I am doing wrong. I am at my wits end and am about to get a new throttle body just incase I broke mine during cleaning.

Any insight or advice would be greatly appreciated at this time.
 

jlach993

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Did you manually move the throttle plate with your fingers? I heard that messes them up. I'm hoping that's not the case with yours man. I would start simple and let the truck sit overnight with the negative cable off. It should work itself out in the morning. I've done that countless times for various issues and it has worked.
 

jlglr4

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Not sure if you saw this thread - post 41: https://www.landroverworld.org/threads/engine-revs-high-upon-start-up.40662/page-5.

Maybe also check your PCV valve if you haven’t done that in a while. It’s probably the single most common cause of the lean code, and so easy to do (though I’d have the new one ready as that cap that’s on it usually breaks, so you need to replace it after taking it off). Might also check your MAF sensor values to make sure the MAFs are both working, maybe spray them with some maf cleaner. Also check to make sure all those electrical connections are good with the mafs and the throttle body. I seem to remember seeing a post on time on a broken wire to a throttle body, so you might inspect that harness carefully.

I haven’t heard of the lean condition causing the throttle body issue, seems more likely that a throttle body problem would cause the lean code. But these things above are so easy to do that it‘s worth just doing it to rule them out.
 

Buffalo76

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All fixed, it took several tries from the Gap tool to reset the values. Once the values were reset it would idle but high like a vacuum leak. After determining that the TB,gas pedal and ecu were all talking and reading equal values. I preformed a soft reboot on the ecu. My idle went from 1100 to a normal 850. No engine codes and its a happy beast. I am looking forward to reseting the values on my transfer case and transmission later this week to tighten things up. A complete remap via GAP is in the near future.
 

ryanjl

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I'd be wary about resetting values on the transmission or transfer case unless you've done work on both.
 

Buffalo76

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Ok so everything was fixed and sure enough the P0174 has returned after a few hundred miles of driving. I am at a loss as to what else to look for. I am going to try the pcv valves and see if that is the hail Mary to save my ass. Has anyone else had this happen to them of the code returning after several weeks of driving?
 

ryanjl

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You may have already seen this, but this 10-year old post on another forum seems to have a decent troubleshooting procedure:

 

jlglr4

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After PCV refresh, also check the breather hose connections: back of the PCV to the throttle body and the drivers side back of the valve cover to the air intake plenum (this one connects underneath the plenum and can slip off if it wasn’t put on correctly).

Other lean code causes that come to mind would be MAFs, a leak anywhere in the break-assist vacuum pump and lines, faulty purge valve (drivers side right along valve cover), clogged fuel injector, failing fuel pump (either low pressure or high pressure).
 

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