Has it ever had the egr channels cleaned in the lower inlet manifold. This usually causes these symptoms.

Whats it like with egr unplugged.

 

Thanks Marks152 good suggestion. Yes should've said that I had the inlet manifold off the other year and cleaned out that EGR channel. Did that at the same time as the timing belt but I've not unplugged the egr valve and gone for a drive. It also got the throttle body changed at the same time as the egr channel which I cleaned up.

I should also say I checked spark plugs and gaps and the coil pack is a few years old (genuine dephi). When that went last time it would miss under load and if anything the car is running better than ever once going.

Good shout on the egr valve unplugged test will do that and report back.

Thanks,

 

I can't view the data at the minute but have a look at m32guy's thread

https://www.vauxhallownersnetwork.co.uk/index.php?threads/z16xep-poor-running-when-warm.839453/

It might give you some tips.

 

Thanks, need to re-read that and try and understand how to use this live data. Unplugging the EGR was an interesting test drive as it didn't make any difference but I noticed I get the same slight judder when dipping the clutch. So drive along take foot clean off throttle you get a slight judder rocking sensation I think that's confirmed clutch. It's had the first gear judder since 48k and now on 110k I think the clutch is overdue but don't want to commit to that job until I know the engine is running right.

I gave it a good run then left it idling and it wasn't bad at all but not 100% right at idle. I plugged back in the EGR and went for another run and exactly the same although two interesting points. I noticed a bit of exhaust rattle type noise pulling away from petrol station which I will have to investigate. This shouldn't be making any noise as the sections are not that old so that's perked my interest. I want a good look under the exhaust heat shield and test for any leaks on that manifold. Be nice if I could work out from the live data if the pre and post cat sensors are working to back up any potential exhaust or cat issue.

Second point happened after getting some food leaving car stood for 30mins it was slower to fire up. It's been spot on since the EGR start saga and this was nothing compared to that. Just took a bit longer say it usually fires on 2-3 cranks this was like 4-5, enough you notice and think hmmm that wasn't right. That's got me thinking the crankshaft and camshaft sensor are also original items on this car.

It's like the final hurdle this it's honestly sounding and driving better than ever just not quite right at idle particularly when cold.

Thanks

 

Quick update on this one. Treated it to a new oil cap as the old one was loose probably caused by that diaphragm in the crankcase issue I sorted out. The idle was better but again not perfect so I started looking at the long and short fuel trims. You can see it's adding fuel to make up for excess oxygen so I starting looking on the inlet side and then the exhaust. I'd not checked this sooner because I needed to remove the oxygen sensor to get the heat shield off easily. It was really rusty so I was surprised when it broke free without any real drama. Shop vac taped up the exhaust on blow and soapy water out it's got some leaks on the manifold, the one in the middle is interesting as I can't see a crack yet but it's leaking.

Probably all those years of first gear juddering and worn engine mounts. It's a one piece manifold and cat which is annoying but at least I'm making progress

 

yup. 100% someone needs a new exhaust manifold.

 

Hopefully you found culprit At least it's not the egr channels which you know is a pig of a job

 

@N871BUD Yeah I was convinced there was a crack in that middle bit of the manifold and kept testing it on the car. However I've taken it off the car today and couldn't see a crack or defect despite scraping away at the surface. I taped it all up and tested it again off the car and No bubbles, result! I'm thinking potentially there was a leak on the underside of the manifold gasket that I couldn't quite get any spray on but the air channels up to that gap.

Before I took off the manifold+cat I got the car on stands and gave the whole exhaust a check over. The flexi pipe is sound but the front joint to cat is not, also the middle section is leaking too.

These leaks look really bad due to the time I left it bubbling but a leak is a leak . That center section is a few years old but it was a genuine Vauxhall one and think it was a good make like Bosal. It's leaking at the seams and already showing signs of rust due to the short journeys this car does. The front to middle joint is also leaking and I did use Holts firegum at assembly time. Anyone recommend anything better than that?

The backbox and joints were the only thing 100% leak free lol.

I was expecting some drama with the manifold studs and potentially some snapping removing the nuts. Soaked them yesterday in Plus gas and only 3 backed out the studs too. I decided to remove all the studs anyway to make cleanup easier of the matting faces and so I can replace them with new. The stud extractor paid for itself here as the two nut method was struggling, some of these were well in.

@jayb9998 yeah that's true those EGR channels were a pig of a job. I couldn't determine if my new aftermarket EGR was opening to the correct % in Opcom live data so blanked it off just to rule it out from the investigation. Interestingly it's not thrown an engine code yet which I thought it would. Anyone else fully banked off the EGR on a Z16XEP and got no fault code? It's tempting to leave that in long term to keep the inlet cleaner.

That was this afternoons fun and games and the pictures hopefully brighten up the thread a bit.

 

@N871BUD Yeah I was convinced there was a crack in that middle bit of the manifold and kept testing it on the car. However I've taken it off the car today and couldn't see a crack or defect despite scraping away at the surface. I taped it all up and tested it again off the car and No bubbles, result! I'm thinking potentially there was a leak on the underside of the manifold gasket that I couldn't quite get any spray on but the air channels up to that gap.

Before I took off the manifold+cat I got the car on stands and gave the whole exhaust a check over. The flexi pipe is sound but the front joint to cat is not, also the middle section is leaking too.

These leaks look really bad due to the time I left it bubbling but a leak is a leak . That center section is a few years old but it was a genuine Vauxhall one and think it was a good make like Bosal. It's leaking at the seams and already showing signs of rust due to the short journeys this car does. The front to middle joint is also leaking and I did use Holts firegum at assembly time. Anyone recommend anything better than that?

The backbox and joints were the only thing 100% leak free lol.

I was expecting some drama with the manifold studs and potentially some snapping removing the nuts. Soaked them yesterday in Plus gas and only 3 backed out the studs too. I decided to remove all the studs anyway to make cleanup easier of the matting faces and so I can replace them with new. The stud extractor paid for itself here as the two nut method was struggling, some of these were well in.

@jayb9998 yeah that's true those EGR channels were a pig of a job. I couldn't determine if my new aftermarket EGR was opening to the correct % in Opcom live data so blanked it off just to rule it out from the investigation. Interestingly it's not thrown an engine code yet which I thought it would. Anyone else fully banked off the EGR on a Z16XEP and got no fault code? It's tempting to leave that in long term to keep the inlet cleaner.

That was this afternoons fun and games and the pictures hopefully brighten up the thread a bit.

Don't think you can block it off I know you can't in my engine z16xe1 it may throw up a code once a drive cycle is complete

 

I seem to recall it throws p0171 after a while.

 

Hmmm looks like a big exhaust job there...

Those cast manifolds are a bit of pain to check of the car really, i had on the corsa like that... You could not see anything wrong of the car still bubling on the car or, from cold start the in question section would get slighly wet after cold start for a few seconds...

In your case i guess you could try to sort the under joint as could be caused by that?

 

@jayb9998 & @marks152 surprised me too although only done 60 miles with that blanking EGR blanking plate so like you say time will tell on that one. I spared you all the original EGR and cam cover saga but for your amusement...

The last one would not come out and snapped off right at the base I made a right dogs dinner of drilling it out getting it ever so slightly off center. In the end I wasn't happy so got another thermostat housing from the scrap yard. I tried two there and the heads were all rust free on the bolts and undid no bother. That's where the blanking plate came from too

Had to buy a few new gaskets but was glad this was one of my own. Can you imagine someone wanting an EGR valve changing and you say "yeah easy mate 30mins tops, then that happens lol".

This was swiftly surpassed by the cam cover giving similar issues so I made little wells out of blu-tac and soaked them alubright deoxidizer. Tried plus gas for good measure and then similar welding on nuts and using the stud extractor.

One came out one would not budge and bust the extractor! Drilled it out in the end but bought some drill guides this time to get it spot on. Manged to run a tap down and clean up the thread instead of an insert too which was lucky.

Just waiting on parts now and yeah @N871BUD I'm still a bit skeptical on that manifold however I've tested it twice off the car just to make sure. Had the shop vac on blow up the exhaust end and all the manifold section taped over and sprayed it as the tape whistled and squeaked trying to contain all that air. It's looking good so fingers crossed it was an inaccessible leak on the underside manifold gasket tricking me.

 

Posts like this remind me of the defunct AOC forum, to bad i did not got to save the how to's i made their some would of been useful on this one for astra's and probably save us all of some typing...