Choppy idle

[Untyped]

New owner of a well used LR4.

I got a 2011 Canadian market.

All seems good except when it warms up while in park or more noticeable in drive I do get a drop in rpm. Almost every 3 seconds or so. Also just driving on the highway it does seem choppy when bellow 2000 rpm. Nothing crazy but there is definitely something.

No codes, no lights...
Got a new MAF, tried on both sides and makes no difference.

Checked the diaphragm for the PCV , no cracks or damages.

I feel like the issues is fuel related.. here are some parameters from my scanner.

Short trim fuel trim bank 1 seems to wonder well above 10%

Why do each MAF has such a big voltage difference? Regardless if I use the new sensor.

 

[scapistron]

If your fuel trim is positive that indicates that your O2 sensor thinks the motor is running lean.

Check the intake between the MAFs and throttle body for cracks. Fuel system treatment might help if an injector is a little clogged. A slight exhaust leak could also present as a lean condition. Another lower effort long shot would be an intake valve cleaning spray through the intake.

Before you start throwing parts at it I'd also recommend testing the coolant for exhaust gasses. Very doubtful, but a cheap and easy test before unleashing the parts bazooka.

 

[Untyped]

If your fuel trim is positive that indicates that your O2 sensor thinks the motor is running lean.

Check the intake between the MAFs and throttle body for cracks. Fuel system treatment might help if an injector is a little clogged. A slight exhaust leak could also present as a lean condition. Another lower effort long shot would be an intake valve cleaning spray through the intake.

Before you start throwing parts at it I'd also recommend testing the coolant for exhaust gasses. Very doubtful, but a cheap and easy test before unleashing the parts bazooka.

Thanks for the info!!

So based on your first comment you are pointing at the upstream oxygen sensor? I also checked those in the scanner and bank 1 is definitely not doing the right thing... check out the latest video, this with the car warmed up in drive holding the brake... it is not smooth at all.

 

[scapistron]

My decision tree has evolved from emptying the parts bazooka at the problem to doing a combination of things that are low effort and cheap.

Check the intake pipe first. Easiest thing to do and is free. If it has a crack you could fix it for less than a dollars worth of electrical tape.

 

[Untyped]

Cheers. Will look into it and update. I did order a cheapo o2 upstream for now to see that helps as well.

 

[Untyped]

Upstream O2 sensor on bank1 was replaced with a $45 Amazon one(needed to use the old connector since the quality is so poor that it won't fit properly). Butter smooth in the 2km test. So that has to be the culprit.

Refer to this same live data as before but everything is somewhat within parameters now.

 

[scapistron]

(needed to use the old connector since the quality is so poor that it won't fit properly)

Genuine Bosch is only $76 from FCP Euro.

 

[Untyped]

Genuine Bosch is only $76 from FCP Euro.

Hmm. Couldn't find it. Mind sharing a link? But also I am in Canada so shipping can be ridiculous.

 

[scapistron]

Mind sharing a link

Rover Oxygen Sensor - Bosch LR035750

Rover Oxygen Sensor - Bosch LR035750

www.fcpeuro.com

Can also just punch the LR part number into Google.

 

[AGLR4]

I didn't see anyone suggest checking the spark plugs yet. If you haven't taken a look at those, it would be a good diagnostic step. I had a slight rough idle once warm for a few months. No codes were being thrown. My initial thought was clogged injectors, but when I went to replace an injector I noticed the spark plugs were toast. The gap was twice what it should have been. The picture shows the worn out plug on the left. It was pretty obvious that it was the plugs at that point and i'm surprised that it even ran as well as it did since all eight of the plugs were worn the same. No more miss with replacement.