Discovery 3 2.7 TDV6 misfire - no compression on one cylinder...but why??

JAS Land Rovers here again with another Picoscope related video...here we diagnose a Discovery 3 with no compression on one cylinder...but which cylinder...and why?!

[@Sundayorie]

Thanks for the very informative video. I am watching it 5yrs after it was released but it still has very practical content and a wonderful well thought-out approach to that misfire problem. I actually came across the video as I was researching on the problems with the Lion 2.7 diesel since I am working on one that has a permanent misfire on cylinder {guess which?} yes cyl 2 just like yours . The only difference is that this one I am dealing with had interestingly lower compression on cylinder 2 compared to the other cylinders. Majority were at 380psi while the cylinder 2 was at 320psi a whole 60 psi difference. We have not as yet got to the point of removing the body so we can access the engine properly and carry out a proper inspection of the affected cylinder but to me it already is a sign of a mechanical issue causing our misfire due to low compression relative to all the rest. I can see a cylinder head job coming up one way or the other. Your approach was very good. Some in the garage where I was called to check on the car were really arguing about the timing being off etc but the mere fact that it has no delayed start at all but only the permanent misfire together with the low compression read out from cylinder 2 I now have some added confidence to give them my final submission in writing that they should remove the head on that side and do the needful. By the way what is the nominally accepted compression reading for this particular engine since I did not come across any technical manual to give me that data? Thanks for the very educative video. I have subscribed and will be following you closely on your journey to proper workmanship. All the best

[@gmak1n785]

Another great video, I work as a technical manager at a retailer and it is fantastic to see such a highly skilled independent garage working with the Land Rover product. Keep up the good work !

[@joehodgy]

Thanks Glenn!! You guys like to keep us busy...long may it continue! hehe

[@gndichu]

Thank you for sharing this great video and I am super impressed with the way you were able to do a compression test using just a diagnostic machine

[@harrywilson4311]

Great video, fantastic diagnostics for a first time fix. Keep them coming👍

[@joehodgy]

Thanks for the feedback! Great to hear 😊

[@DavidJohnson-kk5jw]

Where did you clamp the amp clamp to get your reading? We've done a few relative compression tests but unable to get on any of the main battery upper engine bay wiring on the 2.7 we've got in?

[@shaunsautorepairs5410]

Thats awesome..ive just found your channel and subscribed... I just wanted to know could you do this without taking the body off.

[@joehodgy]

Heya - yes the heads can be removed without taking the body off...but...body off makes *everything* easier...and easier to get right :)

[@VaderWhoop]

The fact a small broken valve spring requires all the time, equipment and expense to remove the body to get at the head; is horrific! An otherwise simple job on many other vehicles, is a heavy equipment time labour intensive task on a land rover, costing thousands rather than hundreds. It's easy to see why people sell non runners for next to nothing.

[@COM70]

I’m really happy to have found this channel as I have been really really frustrated with both main dealer service as well as specialist “engine diagnostics” garages in the past. They have ended up costing me thousands of euro and actually caused extra damage to my vehicles. I carry out all my own mechanical work and am very interested in learning about automotive electronics. I used to be a sound engineer and so I’m somewhat familiar with digital electronics and I was wondering if you could advise me if (www.picotech.com/oscilloscope/2000/picoscope-2000-overview) this might be a good starter scope and if so what is a good working band with to order it in(options are selectable on the page) thanks a mill if you get time to answer this, don’t worry if you don’t.

[@joehodgy]

Hey Cathal and thanks for the comment! We use the four channel version of this scope - www.picoauto.com/products//automotive-oscilloscope-kit/overview - I'm not sure how the 2000 compares but I'm sure you'll work it out :)