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Discussion Starter #1
Finally got my z16xe engine back together and running ( pressure was off as wife borrowed daughters car that she didn’t really need at the time but now wants back! ). Ended up replacing rings,rod bolts, water and oil pump as well as having the head skimmed with a couple of new valves and all 16 lapped in.
Oil and filter and plugs were also changed.
Engine fired up quickly and gained oil pressure soon after, top end rattled a bit for few minutes then settled down nicely.
Problem now is the engine revs ok ish but is lumpy on idle and on the road is very juddery and will cut out at junctions if the revs aren’t kept up.
Once up to a decent speed it pulls nicely with the odd judder.
Revving when stationary the engine will take a while to return to idle speed and when on the road the engine will overrun when changing gear and is generally difficult to drive.

Other clues are that I was a bit heavy handed removing the throttle body electrical connector and pulled the socket out of the body by 2 or 3mm. The car ran more or less as above but fault codes came up as P0170 Fuel Trim System Rich which makes sense as it did sound like it was hunting at idle.
I changed the throttle body with a second hand one and it seemed a bit better and no fault codes came up once I had cleared them but it still drives crap with the same symptoms.
Another possible mistake was I could not get the 4 injectors on the rail to seat properly onto the tapered top of the injector ports. Individually the injectors would seat properly but not when fitted to the rail. Pretty sure the rail wasn’t bent when it was disassembled. There is about a 3mm “ish “ shiny bit of the injectors above the tapered seat.
The last possible mistake I can think of is that I flushed out the hose connections on the rocker cover but it has had about 6 weeks to dry.
Before I cluelessly start changing parts just wondered if anyone had any ideas?

I have a opcom that I bought from a member of this forum and can access data but not great at interpreting it.

Any help will be much appreciated ! 🙏

Sorry did start this story on another post a while ago but couldn’t figure out how to add it.

Thanks and sorry for the long post!
 

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If you can record some live data at idle with the car upto temp and also a quick drive and upload it I'm sure we can have a look for you. You will need to zip the files up to upload to here.

Have you checked compression. Sounds like a vac leak to me. Go around and spray and vac pipes and around the inlet manifold with water while it's running and listen for it sucking in.
 

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Many thanks, will do this now. Did record some live data last night and it came out as .csv files which my computer turned into excel files. I’ll do both live data tests, test for air leaks and post them. Cheers
I
 

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Many thanks, will do this now. Did record some live data last night and it came out as .csv files which my computer turned into excel files. I’ll do both live data tests, test for air leaks and post them. Cheers
I
Hi, could only manage a few of the tests today. Will do the rest tomorrow.

Compression was good at 225-230 lbs/square inch for all 4 cylinders.
had a quick check of the hoses but have yet to do the water spray.

Had the injectors out again as they were not seated by about 4-5mm.
There seems no way they will as the metal bracket will not go down any further stopping the injectors pushing home. I will attach photos. I don't know if this is causing air to be sucked in and it may be a red herring. I just think the 2 tapered parts of the injectors should sit on the tapered parts of the injector bore.

I upload some idle data as well

Many thanks
 

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Discussion Starter #6
Hi, could only manage a few of the tests today. Will do the rest tomorrow.

Compression was good at 225-230 lbs/square inch for all 4 cylinders.
had a quick check of the hoses but have yet to do the water spray.

Had the injectors out again as they were not seated by about 4-5mm.
There seems no way they will as the metal bracket will not go down any further stopping the injectors pushing home. I will attach photos. I don't know if this is causing air to be sucked in and it may be a red herring. I just think the 2 tapered parts of the injectors should sit on the tapered parts of the injector bore.

I upload some idle data as well

Many thanks
 

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As long as the o rings sit into the sleeve on the manifold it should seal fine. Did you clean the seats up and fit new o rings.
 

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Discussion Starter #9
Hi, the tapered seats were clean ish but the injector tapers or bevels are about 4mm away from mating. The bores of the injectors were clean. I confess I chanced it on the o rings as they looked good and weren’t brittle. I was going to replace them and as the 3 local Vauxhall main dealers had to order them in from Germany ( 5-10 days ) I came to the conclusion nobody bothered.
I will upload the idle data when I suss it out. I have created a zip file but it wont let me upload it for some reason.

Many thanks
 

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The .csv you sent just shows ignition on data, try doing it again but have the engine running before you hit Record.
 
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