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https://yabb.autonerdz.com/cgi/yabb2//YaBB.pl General Public Area >> PicoScope >> Cylinder ID with WPS500 https://yabb.autonerdz.com/cgi/yabb2//YaBB.pl?num=1280222826 Message started by SMG on Jul 27^th, 2010 at 1:27am

Title: Cylinder ID with WPS500
Post by SMG on Jul 27^th, 2010 at 1:27am

Hi

I have only had the WPS500 for a short while and I am still fumbling along.

This car is a 1995 V8 Landrover firing order 1-8-4-3-6-5-7-2

The trace taken was at 3000rpm, WPS in the exhaust, trigger on No1

I know it has a miss but cant work out what cylinder it is.

https://yabb.autonerdz.com/cgi/yabb2//YaBB.pl?action=downloadfile;file=Miss_at_3000_rpm.psdata (99 KB | )

Title: Re: Cylinder ID with WPS500
Post by Mick on Jul 27^th, 2010 at 8:39am

s4cs4c wrote on Jul 27^th, 2010 at 1:27am:

One of our members here called Brandon has made some great videos on this subject here is the link

http://www.autonerdz.com/cgi/yabb2/YaBB.pl?num=1274065904

To answer your question you need to go back 3 firing events to identify which cylinder is bad.

I really like the video he has with the piece of paper flapping on the tail pipe this really works.

Mick

Title: Re: Cylinder ID with WPS500
Post by SMG on Jul 27^th, 2010 at 1:50pm

Hi

Many thanks for that. I think I am getting the idea.
However, I would like to run it past you guys just to see if I am catching on!

Before I go any further, the car has complete new ignition system, plugs, leads, cap, arm, coil. Fitted by the garage to try and find the miss. There are no fault codes logged.

The poor cylinder appears to be No7. I have done a running compression test with the WPS500 on all cylinders and have noticed one slight difference on No7 as shown in the attached files.

Can anyone explain to the difference to me and if it would result in a possible miss?

Regards

Simon

https://yabb.autonerdz.com/cgi/yabb2//YaBB.pl?action=downloadfile;file=1995_Disco_WPS_comression_on_No7_Cyl__3000_rpm_poss_faulty.psdata (100 KB | )

V8_Landrover_No_7_miss_with_reference.jpg (94 KB | )

Title: Re: Cylinder ID with WPS500
Post by Brad H on Jul 27^th, 2010 at 4:20pm

Hi Simon,

Can you provide a psdata file of the problem cylinder @ cranking speed?
I find this the best to view valve events.

Brad

Title: Re: Cylinder ID with WPS500
Post by autosparky on Jul 28^th, 2010 at 12:26am

Here’s what I think, exhaust timing is late at 172ºdeg, but if your other cylinder patterns are ok then it has to be the lifter fault or spring, the other weird part is the 360 deg after compression about 40ms, it should have a flat pattern but yours is sloping curve, I reckon the exhaust is staying open. Going by the history of these engines I’ve had quite a few sticking valves in the guides due to lack of lubrication