Very Rough Idle after Timing Chain Replacement?

[Joe B]

All -

Long time reader.....first time poster here.

We have a 2012 LR4 HSE with 141K miles and recently had the timing chain done by a local, reputable, European specialty shop. After the repair, I have noticed that immediately after cold start, there is an extremely rough idle when putting the car into reverse or drive. This generally only happens on cold start or after the vehicle has been sitting for a few hours. If warm, the idle is not as bad. After cold start though, the vehicle will initially idle about 1200 RPM and then drop down to 600. When I put the car in reverse, it feels like it is going to quit and it idles extremely rough. A similar issue happens when putting the vehicle in drive, but it is worse in reverse. Also, when sitting at a stoplight or coming to a 4-way stop, when accelerating, there is a slight stutter and it is not smooth acceleration. This definitely did not happen before the timing chain was redone.

I am wondering whether this is a symptom of the timing chain not being installed correctly, or just an idle adjustment? Thank you for your help.

 

[jlglr4]

I think it certainly could be timing, but could be other things as well, like a sensor that didn’t get connected back up, or a vacuum leak from a tube or air intake connection that didn’t get put back correctly, or maybe one of the variable valve timing units not working correctly. I would let the shop know right away. Then, if you have a scanner, check for codes and check your fuel trims (if your scanner can do this). Also, check your air intake to make sure they put everything back together correctly - check the PCV breather tubes to make sure they’re attached. Particularly the drivers side tube which attaches under the air intake plenum gets forgotten sometimes.

 

[djkaosone]

If you have the gap iid tool, I'd suggest clearing the adaptation values. Over time, your truck learned and compensated for timing and when it was fixed the timing is now "off" according to the learned values.

Just clear the adaptation values, drive it like you stole it for a few days and it'll relearn new values.

 

[Joe B]

Thanks for the reply and for the guidance. We took the car into the shop this morning to have them check it. They confirmed that they did clear all the adaptation values after the timing chain replacement. He said that it was giving an error code this morning that the fuel mixture was too rich. They were checking the MAF sensor and oxygen sensors to see if this was the problem. The tech at the shop thinks that what likely happened is that when they were doing the time timing chain replacement they may have damaged one of the injectors. He explained that the injectors require a special tool for removal when doing the timing chain. He thinks it is possible that one of the injectors was damaged when they were removing it, which is resulting in the mixture error and the stutter when you first start the engine during cold start. They were going to let the engine cool and check again this afternoon. This seems logical to me, but welcome thoughts.

 

[djkaosone]

If you have the gap iid tool and the scv6, I belive you can check individual injector flow rates. That'll be a quick easy way to see if 1 or many of them are off. I'd hold them accountable for it.

 

[ktm525]

Injectors are pulled for a timing chain replacement?

 

[jlglr4]

I think you have to pull injectors to get the valve covers off.

 

[ktm525]

I didn't realize they had to come off too.

 

[greiswig]

I think you have to pull injectors to get the valve covers off.

Wow. You start to wonder if the J/LR engineers purposely built these to be difficult to maintain. "My brother-in-law is a service tech...gotta keep my sister wealthy!"

 

[Nechaken]

I want to say I've seen, somewhere out there on youtube is a video of someone who flexed the valve cover enough to remove the front timing cover without pulling the injectors and valve covers.