Vauxhall Meriva Intermittent Misfire

Cam Code · Post by **Cam Code** » Mon Aug 08, 2016 10:20 pm

First...Hello to all Pico users....Second...please don't shoot me down if I ask or haven't done something that's totally obvious to you, as we all have to start somewhere and I'm right at the beginning as far as Scoping goes

(Can you tell I've been BURNT in forums before).... Anyway on to the problem. Vehicle is a 2008/09 Z14XEP Vauxhall Meriva , Pending codes stored are P0300 P0303 P0304.. occasionally the EML will light and then the codes change from pending to Stored and limp home is set......New (Darts Parts) already installed are as follows MAF/Coolant Temp Sensor/Cam & Crank/Multi COP Pack/Plugs and its just been serviced. So far the work I've done is as follows, Smoke tested with no obvious leak and a compression test (160 psi) on all cylinders with little variation between, I've also removed and checked the whole engine loom (Delphi micro 64) connectors "talk about small" for splayed/corroded terminals etc.
Both pre & post cat sensors appear to be behaving normally but not scoped yet. Personally I believe this is an ignition firing fault caused by a failing ECU unless the new Coil pack is also faulty

. But until I can prove this out

how can I condemn it ? Hence the Pico Scope.

The tests that I have carried out on the ignition system using the scope are....Secondary 4 cylinders.......Primary Driver (Dual) Test.......Primary Driver (Voltage vs Current) vs Secondary. All of these tests were done using Pico's auto settings as I don't have the experience yet

And I'm sure that I.ve made mistakes as certain waveforms are inverted etc so please forgive me in advance.

Regards Paul

victor2k · Post by **victor2k** » Tue Aug 09, 2016 9:17 am

Hello,
What short and long fuel trim(lambda regulation) you can see on your system?Or maybe additive/multiplicative correction of lambda?
What fuel pressure was measured on the rail?
To protect your Pico inputs must use a 1:20 atenuator.Also I think you must scope the voltage/curent signals when the misfire is present.For capture of erratic misfire I use a clamp on the supply of ignition coil pack for 5-10 minutes(in my attached file you can see the missing actuation of injector 1,not attached the full file because of size).
Regards

Cam Code · Post by **Cam Code** » Tue Aug 09, 2016 1:43 pm

victor2k wrote:Hello,
What short and long fuel trim(lambda regulation) you can see on your system?Or maybe additive/multiplicative correction of lambda?

Hi Victor when this engine is cold and before the lambda goes closed loop the misfire is much more prominent....So if anything.... additive/multiplicative correction of lambda makes things better.

What fuel pressure was measured on the rail?

Can't see it myself as car runs fine under load WOT

To protect your Pico inputs must use a 1:20 attenuator

I followed Pico's guided test procedures so I hope I've not damaged my scope

Regards Paul

STC · Post by **STC** » Tue Aug 09, 2016 7:33 pm

First and foremost. Put all the original parts back on the car !! It is too easy to have a car with one fault and then "parts darts add another fault. Even dealer parts can be faulty out of the box and that then just messes with your mental health

Then as per Victor Fuel Pressure & Flow, Fuel Trims - Short & Long

Running Compressions ?

One Amp Clamp on Common Injector wire and the second on Supply or Earth wire to Coil then watch what drops out first.

Didn't these suffer from cam followers working loose ??

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