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Vauxhall Astra 1.9 DTH 2008 - Slight misfire - Fixed #

Posted by Paul Mooney on April 10, 2017, 8:20 am

Year of Manufacture *: 2008
Engine Size and Code *: 1.9 dth

Hi guys. Just joined the forums recently. Cant believe the wealth of information and helpfulness of people after spending an evening reading alot of posts.

This is actually my own car, bought it originally with a worn clutch and flywheel, thinking it was the main cause of the issue Im about to explain.

The car will idle at steady revs, with what seems like a slight misfire. But if I try to move of from a standing start The revs flucuate up and down on there own, the engine starts to hunt(like a petrol drawing air). When you get upto speed and driving on the roads theres no issue and crucially no fault codes.

Ive carried out a leak off test and all injectors are evenly matched.

Ive carried out a parameter test when the fault occurs, the fuel pressure remains steady, but the injection amount jumps from 8mm to 0mm and back up.

The slight misfire baffles me, because if I disconnect either of the 4 injectors theres an audible decrease in engine revs. And it shakes alot more. So I dont think its an injector issue.

Also noted is that If I disconnect either of the 4 injectors and try to move of to recreate the fault, theres no problem except for the obvious misfire.

The fuel rail has been swapped out as well as the pressure regulator valve on the HP pump with known good parts.

Next step is to test the injectors, but im doubtful they are the issue.

Thanks Paul

Re: Vauxhall Astra

Posted by Tony Ludford <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5539' width='330' height='300' border=0 style='border:none;'> on April 10, 2017, 1:29 pm, in reply to "Vauxhall Astra"
Tony Ludford

What is the inlet manifold like (dirty)?
What is the egr valve doing and map sensor readings?
Has it got inlet manifold flaps? They're prone to breaking up I believe.

Just a few things for you to think about.

Re: Vauxhall Astra

Posted by Peter Keverne <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2835' width='330' height='300' border=0 style='border:none;'> on April 10, 2017, 6:25 pm, in reply to "Vauxhall Astra"
Peter Keverne

Hi Paul
What tool are you using to read this?

peter

Re: Vauxhall Astra

Posted by Paul Mooney on April 10, 2017, 7:10 pm, in reply to "Re: Vauxhall Astra"
Edited by board administrator April 13, 2017, 11:01 am

I have used snap-on Verus and also my botch kts 570. Neither throw up a fault code... I have heard tho the Vauxhall machine brings up codes that other machines don't.

It has already had an egr valve. I have blanked it as well. I have also disconnected all air system pipe work and the fault is still there. So it's definately diesel related.

Thanks Paul

Re: Vauxhall Astra

Posted by Peter Keverne <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2835' width='330' height='300' border=0 style='border:none;'> on April 10, 2017, 7:49 pm, in reply to "Re: Vauxhall Astra"
Peter Keverne

Hi Paul
Not much help, but i was going to suggest getting it on another machine,perhaps a scope on the injectors before pulling them, i can confirm that vauxcom does do exactly as you say, so perhaps might be the way forward?

peter

Re: Vauxhall Astra

Posted by Paul Mooney <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat4025' width='330' height='300' border=0 style='border:none;'> on April 10, 2017, 10:41 pm, in reply to "Re: Vauxhall Astra"
Paul Mooney

Done, purchased a vauxcom machine this evening. Will be put to good use on other vehicles as well.

I actually checked this evening and I had a fault for camshaft position sensor.

Ive read somewhere before, people having issues with cam and crank timing being slightly out causing random running faults. This car has 77k and hasnt had its belt replaced yet. Might do that tomorrow see if it turns anything up.

Re: Vauxhall Astra

Posted by Ian Slattery <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1196' width='330' height='300' border=0 style='border:none;'> on April 11, 2017, 7:58 pm, in reply to "Re: Vauxhall Astra"
Ian Slattery

Hi Paul

When doing the belt check the keyway on the crank.

Regards Ian.

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #

Posted by Paul Mooney on April 18, 2017, 12:40 pm, in reply to "Vauxhall Astra 1.9 DTH 2008 - Slight misfire #"
Edited by board administrator April 20, 2017, 8:37 am

OK have an update on this.

I noticed by chance the fault occurs even when I was in neutral and rolling down a hill. It was speed related rather than load related.

So I disconnected the abs pump and low and behold the fault went away. Car drives perfect. So I connected back up and did a parameter check, the brake pressure sensor was jumping from 0 to 650 bar which Is well outside the maximum limit. This must be altering the engine timing and map thinking the car is braking. Next step is an abs pump or repair to brake pressure sensor.

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #

Posted by Paul Mooney <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat4025' width='330' height='300' border=0 style='border:none;'> on April 18, 2017, 4:27 pm, in reply to "Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #"
Paul Mooney

OK, so when the abs pump is disconnected the fault occurs for about 10 seconds by itself, without the car moving. When I checked engine parameters the speedo reading had defaulted to 2 km/h. After ten seconds the car runs fine and drives fine So this fault seems to be speed related. How can a speed reading totally change the engine running characteristics.

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #

Posted by Ian Baxter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1560' width='330' height='300' border=0 style='border:none;'> on April 18, 2017, 6:57 pm, in reply to "Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #"

Has it got ESP? (Electronic Stability Programme), or similar traction control system fitted ?

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #

Posted by PAUL MOONEY <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat4025' width='330' height='300' border=0 style='border:none;'> on April 19, 2017, 8:28 am, in reply to "Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #"
Paul Mooney

Yes it had esp. But I don't see any anomalies with the abs readings...

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #

Posted by Ian Baxter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1560' width='330' height='300' border=0 style='border:none;'> on April 19, 2017, 1:25 pm, in reply to "Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #"

Hello Paul,

"How can a speed reading totally change the engine running characteristics."

ESP systems are interlinked via CAN etc to the engine ECU to help control the vehicle is certain conditions.

(Simplest explanation),,,,,So you may have your foot to the floor on the accelerator, the car starts to skid and the ESP system will take over and cut the engine speed or feather the brakes and engine and transmission. You're not in charge the computers are

.

This is why an ESP fault may not be an ESP fault but an engine fault. If the engine isn't working properly the ESP cannot carry out its function properly. So will stop working.

I hope I've not confused thing too much

Ian

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #

Posted by Shaun Wilson <iframe src='https://members.boardhost.com/ukautotalk8/info/user=shaunwilson' width='330' height='300' border=0 style='border:none;'> on April 20, 2017, 8:11 am, in reply to "Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #"

Hi Paul

The most common cause of a misfire on the Z19DTH is the wiring to injector 3, although the symptoms you describe (apart from the misfire) don't really point to that as wiggling the injector plug usually causes it to correct itself for a while and it sounds like you have had them disassembled. Vauxhall do a kit to repair the injector wiring as the plug becomes corroded internally and needs replacing, so a common enough problem, might be worth another look?

Shaun

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire #

Posted by Paul Mooney <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat4025' width='330' height='300' border=0 style='border:none;'> on May 7, 2017, 10:42 pm, in reply to "Vauxhall Astra 1.9 DTH 2008 - Slight misfire #"

No further forward. Did a scope test on the Injectors and crank and cam correlation. All seems normal.

I've attached a video. Basically I have the abs pump disconnected now. So the speedo reading to ecu is default 2kmh. Means I can get the fault to occur without moving. As soon as I start the car now the fault occurs for 5 secs then goes to normal and drives perfect until ignition is cycled.

But I've found now is that with an injector disconnected the fault doesn't occur. So with engine running when I disconnected any of the Injectors and then reconnected the fault would occur again for 5 seconds everytime.

I've run out of ideas bar changing the ecu.

[img]

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Link: https://youtu.be/qRSjEuIrC1E

Fixed #

Posted by Paul Mooney on May 13, 2017, 3:26 pm, in reply to "Vauxhall Astra 1.9 DTH 2008 - Slight misfire #"
Edited by board administrator May 18, 2017, 2:54 pm

Changed entire ecu kit. Problem solved. Must have been an issue between speed relation to the fuel maps. Not sure, but it wasnt detectable by diagnosis.

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire # FIXED

Posted by Tony Ludford <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5539' width='330' height='300' border=0 style='border:none;'> on May 14, 2017, 6:55 pm, in reply to "Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire # FIXED"
Tony Ludford

I wonder if that would have been fixed with an ecu update?

Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire # FIXED

Posted by PAUL MOONEY <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat4025' width='330' height='300' border=0 style='border:none;'> on May 15, 2017, 1:42 pm, in reply to "Re: Vauxhall Astra 1.9 DTH 2008 - Slight misfire # FIXED"
Paul Mooney

I don't think so, I believe it was a hardware issue. Now thats going good the slight misfire is also gone and its running alot smoother.

Software shouldn't change, so don't think a software update would fix the problem.

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