View Full Version : rattling after VCM and tune
I noticed that my AFM ute rattles but just for a split sec after they've done tune and replaced otrcai with VCM. This is happening when car is changing from 4cyl to 8cyl basically when I accelerate.
Any ideas guys, should I take it back?
Wonky
16-10-2011, 01:42 PM
Rattles as in detonates? If so definitely take it back ASAP!!
macca33
16-10-2011, 01:58 PM
I'd say that it is engine knock - by the description. It may be a throttle tip-in thing, or the way the AFM is set up in the tune. Either way, as Wonky says, take it back, take the tuner for a run in it and reproduce the problem.
Are you using the same fuel that it was tuned on now, ie same RON rating?
cheers
Rattles as in detonates? If so definitely take it back ASAP!!
Hi Wonky, yes, as soon as I accelerate and car changes from 4 to 8cyl I can hear that rattle sound but for no more than half a sec...
I'd say that it is engine knock - by the description. It may be a throttle tip-in thing, or the way the AFM is set up in the tune. Either way, as Wonky says, take it back, take the tuner for a run in it and reproduce the problem.
Are you using the same fuel that it was tuned on now, ie same RON rating?
cheers
I was using V-Power back than but atm I am using normal unleaded...
macca33
16-10-2011, 02:18 PM
Well, that is clearly the problem mate. If it was tuned on 98RON fuel, running it on 91RON is going to break your engine.....
ssv402
16-10-2011, 02:21 PM
I was using V-Power back than but atm I am using normal unleaded...
As Macca said, that is your entire problem there. Add a bottle of (NULON) octane booster to the tank to get you by, dont drive hard, and never use anything less than V power again! You can destroy your engine using normal unleaded in your application.
HEKYEH
16-10-2011, 02:26 PM
I was using V-Power back than but atm I am using normal unleaded...
Wow....stunned for words really....
:fewl:
Uncle Tone
16-10-2011, 02:32 PM
Wow....stunned for words really....
:fewl:
Yeah, definitely not smart.....but then he may not have known.
Plenty
16-10-2011, 04:14 PM
Could have been just an assumption from tuner that the client knew to keep using 98RON.
On country trips it is sometimes unavoidable, i sometimes need to use 91RON and have had no such issues.
SirNemesis
16-10-2011, 04:16 PM
Could have been just an assumption from tuner that the client knew to keep using 98RON.
On country trips it is sometimes unavoidable, i sometimes need to use 91RON and have had no such issues.
You tune the car on the fuel you are going to use long term. Not much point tuning it for 98RON and then driving 91RON. If you are in a situation where you would be using 91RON, thats the fuel you should have had in the tank when it went it to get tuned.
swingtan
16-10-2011, 04:39 PM
Alright, I'll buck the trend here....
There is nothing particularly wrong with tuning for 98, but dropping bak to another fuel if 98 is not available. However, correct use of the timing tables and fine tuning of the octane scaler are neccesary. My car is tuned on 98 and it gets that nearly exclusively. However, every year we go on holidays to an area where 98 is simply not availble, so 95 goes in. Not only that but I tow a pretty heavy trailer on this trip. The log data shows a significant increase in knock retard, but I can hear no audible knock.
Just contact the tuner and let them know what's going on. They should be able to fix it up.
Simon
**** I didn't now all that stuff...so I should put in V power as soon as I can or wait till the tank is empty?
What if the noise is still there?
DCV1NU
16-10-2011, 05:25 PM
Just take it back to your tuner asap & let them know, personally i'd put 98ron in asap aswell.
v8dude78
16-10-2011, 05:45 PM
As ssv402 said grab a bottle of NULON Octane Booster.
Put some in and next fill up, Fill up with 98 ron fuel :)
As Macca said, that is your entire problem there. Add a bottle of (NULON) octane booster to the tank to get you by, dont drive hard, and never use anything less than V power again! You can destroy your engine using normal unleaded in your application.
HEKYEH
16-10-2011, 05:49 PM
Doesn't have to be Shell V Power. There are heaps of threads on Shell vs BP vs Caltex etc etc....
Just use 98RON...
I'd be filling up on good fuel ASAP...
Talk to the guys at VCM & get it tweaked. Meanwhile, drive cautiously.
Paleface
16-10-2011, 06:26 PM
Hi Urko, one more thing, if you're using 91 ron to save money, don't bother. You'll get much further on a tank of 98 than you would on a tank of 91, enough to offset the price difference.
That's been my experience anyway in both my car and the wife's car.
Thanks guys for everything, I really appreciate it...
Just bought octane booster today and it seemed to help a little bit. The rattle is still there but not as much as before ( its 90% better)
Didnt know that I am going to have issues because different fuel. I am ringing the shop tomorrow to see what they are going to say.
Hope I haven't done any damage so far.
Cheers
vessloveit
17-10-2011, 05:36 PM
With the right tune you should be able to use 91 RON, my VE was tuned whilst running 98 RON, I have tried the E10 95 RON and logs have shown some knock retard but there is no audible knocking, have since changed back to BP Ultimate and no knock retard.
kangavxss
17-10-2011, 09:17 PM
Alright, I'll buck the trend here....
There is nothing particularly wrong with tuning for 98, but dropping bak to another fuel if 98 is not available. However, correct use of the timing tables and fine tuning of the octane scaler are neccesary. My car is tuned on 98 and it gets that nearly exclusively. However, every year we go on holidays to an area where 98 is simply not availble, so 95 goes in. Not only that but I tow a pretty heavy trailer on this trip. The log data shows a significant increase in knock retard, but I can hear no audible knock.
Just contact the tuner and let them know what's going on. They should be able to fix it up.
Simon
Take some bottles of octane boost with you on ur trip if 98 isnt available...
My car was tuned with EFI-Live and has 2 timing tables the pcm has to choose from if it detects a lower octane fuel used. It is always handy to carry a bottle of Octane booster as Swingtan suggested just to be on the safe side.
swingtan
18-10-2011, 07:31 AM
Take some bottles of octane boost with you on ur trip if 98 isnt available...
Why? If the tune is set up correctly, there is no danger of running a lower octane fuel. If I'm on holidays and towing a trailer, I'm not really going to be looking for the additional power that 98 will give me, well, maybe for overtaking but that's not going to happen a lot where we go for holidays.
Another point about octane boost is OK, but I probably wouldn't want to run it too often. Apart from the cost involved, it can leave deposits in the combustion chamber and on the plugs if too much or the wrong type is used. I'd rather just have a good tune that caters for lower octane fuel.
FWIW, On the last trip I did to Adelaide, I filled up with 95 in Bordertown. I logged virtually no change in detected knock on the 95/98 mix, though that was just the car, no trailer. People should remember that the knock sensors are a "last ditch effort" to control the combustion process. If it's knocking, you are already way past the best timing point. Actually, if you tuned so you "just" eliminated knock on 91/95, you'd probably be close to optimal timing on 98. I haven't tested it, but it's probably not too far off.
Simon
Take some bottles of octane boost with you on ur trip if 98 isnt available...
Oops , my bad ,sorry for the misquote Simon. Totally agree with your post.
I just put 98 RON fuel in my car and the rattle is gone...it sucks that I cant use 95 octane fuel. So I could really damege my engine bacause of that?
I dont want to sound like a broken record, but call VCM and they will change the low-octane table to respond appropriately and/or do whatever else is needed to ensure you are safe.
You started the thread asking for advice ... it is probably time to consider accepting it.
:teach:
HRT 8
20-10-2011, 09:00 PM
I dont want to sound like a broken record, but call VCM and they will change the low-octane table to respond appropriately and/or do whatever else is needed to ensure you are safe.
You started the thread asking for advice ... it is probably time to consider accepting it.
:teach:
Ken, you can lead a horse to water!!
hotls8
20-10-2011, 09:09 PM
I just put 98 RON fuel in my car and the rattle is gone...it sucks that I cant use 95 octane fuel. So I could really damege my engine bacause of that?
My car was tuned for 98 and i run 95 in it all the time cause im a cheap ass and it has'nt damaged my engine there was one time when i had to use 91 and my car hated it but i switch between 98/95 all the time depending on prices
johnv
21-10-2011, 02:39 PM
I just put 98 RON fuel in my car and the rattle is gone...it sucks that I cant use 95 octane fuel. So I could really damege my engine bacause of that?
if you want to use 95 all the time, have it tuned on 95.
Ken, you can lead a horse to water!!
yea yea...but you can't make it drink
I am taking my car to shop next week and they will fix it
Cheers
GTS Coupe
21-10-2011, 09:21 PM
FWIW, it has been proven mutiple times that commercially available octane boosters increase octane at most 0.5 RON. So putting some in with 91 will give you 91.5. Run it if you want, but don't go thinking it is a magic bullet, just run the stuff you need to in the first place.
Sheridan
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