Monaro 6.0 VXR running rough

[shunter V8]

Hi I have been having a problem with the ro at first it seemed when it was cold it was running very erratically when you put your foot on the gas it was spluttering until the revs picked up then it was fine, once warmed up all seemed good. Today it did the same but I have noticed if you are in a higher gear (even 2nd) and below 2k rpm when you accelerate it stammers and splutters until you get above 2k then it's fine. I was advised to run the tank almost dry of fuel as the car does not do a big mileage so it could be spent fuel but I have done this with no joy. Any suggestions would be greatly appreciated.

Edited by shunter V8 on Sunday 10th April 21:44

[SturdyHSV]

Low rpm puts the highest load on the ignition system. Does it idle rough / unevenly?

Change of plugs might help, check any grounds you can find, I have a spare coil pack you could swap through the 8 positions to see if that clears it up

I'm based around Northampton if you want a second eye over stuff

[shunter V8]

Thanks for your help and yes it does idle a bit rough compared with what it did as it was silky smooth, that's good advice on the ignition system I didn't know that so it could be that is the culprit. I am on the Isle of man so unfortunately not near you but I really appreciate the offer.

[SturdyHSV]

Definitely check the various grounds and things, there's a few on the cylinder heads front and back, maybe tidy up the battery negative terminal etc.

I have a spare coil pack I could post to you, if it's noticeable at idle then it's a simple swap to work through swapping the new coilpack to each spot to see if it improves etc.

Could also just try unplugging each coilpack in turn, see if one of them makes no difference to the idle which could indicate which one is bad, these engines run surprisingly well on 7 cylinders.

If you want to replace the spark plugs for the sake of it, rockauto seem cheapest (amazingly) to ship from the states, just a cheap set of copper plugs will do the trick to test.

[shunter V8]

That's fantastic thanks for your kind offer, I will check grounds and change plugs first and take it from there. I will let you know how I get on.

[shunter V8]

Can anyone confirm the proper plug for this engine i have found NGK IZTR5B11 under VXR8 with the LS2 fitted, i would presume the Ro would use the same plug. Sturdy you are spot on with Rock Auto less than half the price i could get that plug in the UK. Thanks.

[SturdyHSV]

I bought a load of NGK 2238s, £1.17 each No expense spent there!

https://www.rockauto.com/en/moreinfo.php?pk=33143&...

Can use the 05 Pontiac GTO as well for various parts

https://www.rockauto.com/en/catalog/pontiac,2005,g...

[shunter V8]

Oh yes that's more like it not that i am saying i am tight of course. I will get some of them ordered up, its no big deal even if that's not the fault at that price. Many thanks for your help Sturdy.

[SturdyHSV]

shunter V8 said:

Oh yes that's more like it not that i am saying i am tight of course. I will get some of them ordered up, its no big deal even if that's not the fault at that price. Many thanks for your help Sturdy.

I don't see the point of buying fancy iridium plugs that'll last 100,000 miles or whatever it is when you'd probably change them as part of a service every few years anyway

[Panamax]

Do these cars not have a diagnostic port? With that American engine they surely must.

I'm no fan of changing random parts if there's a clear route to finding what's wrong.

[shunter V8]

I totally agree with you Sturdy my car has only done 35k miles from new and has had the plugs changed at least once in the twelve years I have had it, I managed to borrow a tool today called a spark view that clamps on to the HT lead and gives a reading all cylinders were a similar reading a steady 10kv rising to just below 15kv so I presume that is saying the coil packs are ok I am not so sure its checking the plugs I will ask the chap I borrowed it off. No faults have come up on the dash so even though there is a diagnostic socket would I be correct in saying that nothing would be recorded or do they not work that way.

[Lincsls1]

Don't problems with MAF sensors cause poor running issues?

[vxr2010]

hello , hope all is well on the IOM , i would do all the basics as above , plugs leads etc , often if you are doing the plugs the leads often break any way , was it the ls2 that had the throttle body issue , worth giving the TB a clean see if any thing improves , is your air filter clogged

[SturdyHSV]

I have an LS2 TB going if it turns out you need one

I had a grounding issue and got similar symptoms, it's a cheap thing to investigate at least.

[shunter V8]

That's great to know I will investigate further when the weather improves it's awful here. Yes all good on the island thanks looking forward to TT.

[fred bloggs]

shunter V8 said:

I totally agree with you Sturdy my car has only done 35k miles from new and has had the plugs changed at least once in the twelve years I have had it, I managed to borrow a tool today called a spark view that clamps on to the HT lead and gives a reading all cylinders were a similar reading a steady 10kv rising to just below 15kv so I presume that is saying the coil packs are ok I am not so sure its checking the plugs I will ask the chap I borrowed it off. No faults have come up on the dash so even though there is a diagnostic socket would I be correct in saying that nothing would be recorded or do they not work that way.

If you still have original plug leads, they tend to split where they join the plug cap. Your test wouldn't pick this up, if this is the case.

[shunter V8]

Thanks and that's a very good point as I know they have not been changed in twelve years and very much doubt they were done before that.

[bonesxu1]

Looking forward to TT but not the influx of international Covid!
Hi Stuart, you should give my mate Jock a shout to have a look at it. I can send you his number if you like, he is in Unionmills.

[throwyourbike]

vxr2010 said:

hello , hope all is well on the IOM , i would do all the basics as above , plugs leads etc , often if you are doing the plugs the leads often break any way , was it the ls2 that had the throttle body issue , worth giving the TB a clean see if any thing improves , is your air filter clogged

Yeah the LS2 can have throttle body issues but in my experience the car just goes into limp mode rather than run rough.

[shunter V8]

That's funny I was just talking about you yesterday as someone said that mine was the only HSV on the island, Union Mills is perfect for me, is he down in Corletts yard., please send his number on to me in case I need it, I wanted to check a few things today but have landed an absolute stinker of a cold.