Just had my VR6 golf on the rollers and it only made 107.5 bhp at the wheels!! Why is this? Would installing a new cold air feed cure it??
All depends on the rollers, but sounds very low!! If so, a cold air hose isnt going to make any noticeable difference [:^(] Could be a bit more serious...Did the RR operator not think it was down??
Audiman is just taking the p*ss Its my car that was low :-), the operator said it was because i used Optimax and my standard chip and this takes longer to burn hence the timing wrong . The advice was to go back to non supermarket normal unleaded. I must admit i never notice any performance improvment when using it in this car . I need to check some of the basics on it as i have not had it very long, plugs, leads maf ETC .. Only fault it shows is the occasional lambda fault i have only changed the oil since running it :-)
I have just filled mine up with regular unleaded for the first time. I thought it might have been the optimax making it run lean. I have only driven it about a mile since but i'll let you know if it makes any difference.
errrm how does a higher octane fuel take longer to burn? In the VW handbook it gives a higher bhp figure when using 98 RON fuel instead of 95. Im confused
Higher octane fuel will not pre-ignite as much so i guess thats the just the other way of describing it. The other VR on the rollers was told to only used Optimax as his with chip pinked a bit at 4k but pulled through it Mine made 157 at the flywheel so its only 16bhp down on a standard car, i shall check all the basics first then start to worry. The battery was off for some time on saturday so the ECU had to learn all the setting for idle and stuff but seemed ok once i got the the rollers
The octaine raiting is higher - longer ringed petro chemicals are less explosive than straight / cross chained as they contain less hydrogen. they burn for longer and hotter like coal as opposed to light fuels (eg butane)
What does the ecu do if the battery is removed for any lengh of time? Self/re diagnosis? Factory reset?
Audiman have a look at this thread - my VR6 was similarly low on power and it turned out to be the cat (cant be whats wrong with 1990's mota though as his has a decat). http://www.clubgti.com/forum/forum_posts.asp?TID=480&PN=1
The difference between optimax and normal unleaded isnt going to be so great that you'll see power losses like that. I'd say 2-3 horse difference MAX. Something else is up with your engine mate.
On duff's VR it is a fuelling prob, caused by the sh!t mapping created by VW. There is more to fuel octane ratings. You have RON and MON. Esso 97 RON has a higher MON rating than Optimax. If the VR is re-mapped to allow it to use the Optimax more eff. than the power will be way up there. It may also be a dirty MAF.
Interesting info on that other thread, i do have a cat bypass for the car , not fitted yet so i can try that, But i reckon i shall do all the basics first, new Fuel filter plugs check the leads etc maf , coil pack check. The car feels flat low down but pulls very well top end between 6000-6500 is very sweet and noisy , Just feels crap at 2k-3k and feels like its missing a bit. It can`t be that bad it does 32-31 mpg at 80-90mph every weekday.
Sorry m8, had to post the results, but some interesting comments on reasons why power may be on the low side. I think fuel filter, plugs and MAF wash are a good starting point. ECU checked for faults but none found.
