Missing/stumbling

[razzle308]

Hi All.
I have a Missing/stumbling at various points of driving.
Sometimes under acceleration sometimes cruising. Seems to happen more on inclines.
The computer shows no codes even after cleared and the missfire happens.
It not a small missfire...the car really stumbles.
New 02 coils checked.
New sparks.
New fuel filter.

Interesting thing though. I did a test and found it doesnt do it on cruise control. In fact if i enable cruise while it's stumbling it stops it.

Any ideas?

 

[Freddy1333]

Driving home from Perth on Friday (420km trip) my VZ V6 developed an intermittent miss under load and at idle. It was ok at 110kph on the flat but would miss going up hill. On Saturday I replaced the Denso Iridium plugs with AC Delco Platinum plugs. The Denso set had done 110,000km so was a bit surprised that one was starting to fail. The Delco set are good for 160,000km it says on the packet.

I also replaced the inline fuel filter. I gave the old one a shake, which had done 45,000km and let the contents drain out.

EDIT: I spoke tooo soon.

I took it for a thrash on Saturday after the above work but today just cruising around the intermittent misfire is back!!!

Ideas please.

 

[razzle308]

Driving home from Perth on Friday (420km trip) my VZ V6 developed an intermittent miss under load and at idle. It was ok at 110kph on the flat but would miss going up hill. On Saturday I replaced the Denso Iridium plugs with AC Delco Platinum plugs. The Denso set had done 110,000km so was a bit surprised that one was starting to fail. The Delco set are good for 160,000km it says on the packet.

I also replaced the inline fuel filter. I gave the old one a shake, which had done 45,000km and let the contents drain out.

View attachment 260228View attachment 260228

EDIT: I spoke tooo soon.

I took it for a thrash on Saturday after the above work but today just cruising around the intermittent misfire is back!!!

Ideas please.

How does this help?

 

[vc commodore]

Leads get replaced as well? Or just plugs....

If just the plugs, replace the leads as well

 

[the_boozer]

Leads get replaced as well? Or just plugs....

its vz coil on plug no leads. The last vz I saw my mate scratching his head over turned out to be the ecu.

 

[DRAGON7]

Try cleaning the MAF and throttle body area. Fixed my Ecotec issues without changing any parts.

 

[rambunctious]

A bottle of injector cleaner is cheap and sometimes works wonders.

 

[Ginger Beer]

As stated in another thread, get your injectors sonic cleaned and tested

They "may" be the issue

At 100k km your injectors are well overdue for a service and possibly repair or replace

Injectors don't last forever, they are a serviceable part that requires periodical maintenance

The seals breakdown, they get carbon build up over time, and occasionally oxidise as well, whist the filters get 99% of the particles out of the fuel, that 1% that gets past the filters can cause issues over time

My recommendation to everyone is to get them cleaned every 50k km, cost is minimal in the big picture, get a few quotes, pull your injectors and drop them off

1 hour at the most to pull them, a day at the most to get the shop to clean and service, then 1 hour to replace, don't forget to lube the O ring with a little fresh engine oil before installing (don't forget the lube, there's always time for lube......LOL)

https://www.injectorrx.com/fuel-injector-cleaning-and-flow-testing-service/fuel-injector-symptoms/

 

[DRAGON7]

A bottle of injector cleaner is cheap and sometimes works wonders.

Yeah, I tried that first. But cleaning the MAF with brake or maf cleaner worked for me.

 

[Ginger Beer]

Yeah, I tried that first. But cleaning the MAF with brake or maf cleaner worked for me.

I've found bottled injector cleaner that you poor in your fuel tank starts cleaning in the tank first, sending everything though your fuel filters which can start blocking them, if you use it, use it prior to changing your fuel filter, then, change your fuel filters after it has run through