vn s2 lack of power.

[Jordo2]

gday all, my s2 3.8 is down about 25-30rwhp. i have done/checked the following, compression all good,changed ecu twice,new throt bod,tps,iac,knock sensor operational(as eng lite comes on wen plug is removed).New 02 sensor, new leads,platinum plugs,replaced coil packs,oil pressure sender, map sensor on firewall. The car has tune length extractors, 2.5 system, cai, KnN, 70mm throt bod, corvette servo in trans and 2500 stall. yet i only get bout 98rwhp?? A mates vn has shift kit,cai, 2.5 exhaust, standard vn exhaust manifold, and has thrashed the pants off it and he got 124rwhp and his 0-100 time is 7.2sec and mine is 8.3sec??. Realistically i should b getting around the 130+rwhp with the sml mods i have. To my knowledge, In bog stock trim they usually get between 118 and 125rwhp. the engine and driveline have done 74000km since new, but the car they came out of got rear ended if that makes any difference. The car also idles poorly. dont know if this is related or not. i am completely stumped. can anyone help? cheers.

 

[Morton]

You may have fuel delivery issues - fuel pressure reg or injectors. You could also be running slightly different factory tunes, that would contribute a few hp - maybe not up high though.

Did you both get tested at the same dyno on the same day?

 

[delcowizzid]

ditch the platinum plugs and the large throttlebody i bet you get a lot back

 

[rob drag racer]

ditch the platinum plugs and the large throttlebody i bet you get a lot back

agreed the large tb wont do anything for you at all and the platinum plugs don't make a difference either

look at getting a more aggressive tune and check to see your injectors fuel filter and fuel pump are all in good running order

 

[delcowizzid]

the throttlebody will make more power but with it on a stock tune it seems to make them too lean im tuning a vr with a large throttle body now and it seems way down on takeoff at full throttle giving it some more AE tomorrow too see if it helps it at all off the line raising the fuel helped up top lots just need to do the take off

 

[centy]

look for a vacume leak, ie cracked hose and test the dfi module.
Injector service would be a good choice to.

 

[Bz Kn33z]

7.2 is quick for a VN, but as said above sounds like its fuel related ditch the plugs get some other ones, try swapping computers over and see how it runs agains his vn. and if there is a difference well there are some possible things to change on yours.

 

[Jordo2]

vn s2 lack of pwr

thanx all 4 the help, so far ive taken the lge throt bod off and put the standard plugs bak in, and noticed a drop in throttle respopnse and a bit of tourque, but seemed to gain 2 rwhp. however that may have been the cold air last nite or just a better take off, will check fuel delivery next. i have got a chip that only runs 98ron, and that pushed it up to 116rwhp up from bout 100. by the way im using a gtech pro RR. i have found them to be very accurate in the real on road environment, but only when callibrated very well. anyway i also put this chip into my mates vn and it got 129rwhp up from bout 120 with 7.1sec 0-100, best i did woz bout 8.3sec. for the people that dont trust gtech, rest assured that even if the pwr figure woz wrong, the difference between both cars figures would b accurate. im starting to wonder if my car is normal, and his is cammed? as he didnt own it wen the rebuild woz done on it. has anyone else out there gtech't a standard vn? or one with extractors and exhaust? any rwhp or 0-100 figures would be very helpfull. cheers.

 

[Jordo2]

vn s2 lack of pwr

the throttlebody will make more power but with it on a stock tune it seems to make them too lean im tuning a vr with a large throttle body now and it seems way down on takeoff at full throttle giving it some more AE tomorrow too see if it helps it at all off the line raising the fuel helped up top lots just need to do the take off

gday, i havent tried to raise the fuel yet, and please excuse my retardedness, but wot does AE mean?

 

[delcowizzid]

acceleration enrichment