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]

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]

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

[greenfoam]

Also means go to the petrol station twice as often

[Jordo2]

acceleration enrichment

how do i go about that with efi? im old and have lived in carby land 2 long.

[Jordo2]

i hav just noticed a fuel leak from the little 90 degree rubber hose that comes off the back of the fuel tank. its leaking enough to run a wet strip on the bottom of the tank that leads to a single drop clinging to the tank. would this b enough to interrupt the fuel delivery under pwr?

[rob drag racer]

how do i go about that with efi? im old and have lived in carby land 2 long.

you just need a good remap im sure delcowizzid or greenfoam can fill you in

[greenfoam]

Not really a VN should be able to run to 100 in under 8 seconds stock on the stock tune if everythings as it should be. My old series 1 used to go 7.2 0-60 mph on the stock tune, 7.1 on the SV3800 tune and 6.9 was the most I was ever able to get out of it. They all vary a bit sure but you can't make magic out of them they just aren't that kind of motor. It's being laying int he front yard for years now but I had a little hoon in it on a permit last year and it's stuffed now, wont go faster than 7.5 , you have no idea how slow that feels compared to 5.5

[Jordo2]

Not really a VN should be able to run to 100 in under 8 seconds stock on the stock tune if everythings as it should be. My old series 1 used to go 7.2 0-60 mph on the stock tune, 7.1 on the SV3800 tune and 6.9 was the most I was ever able to get out of it. They all vary a bit sure but you can't make magic out of them they just aren't that kind of motor. It's being laying int he front yard for years now but I had a little hoon in it on a permit last year and it's stuffed now, wont go faster than 7.5 , you have no idea how slow that feels compared to 5.5

yeh, pity tho, i think im gunna need sum of that magic u speak of to work this out , mines got no nads. and wow, 5.5! wot do i need to do to get that pwr? Also, could a gearbox issue rob me of this sort of pwr? not that i kno i have one, but the driveline did come out of a rear ended car?

[rob drag racer]

my vp runs under 8 and sure without major mods it aint going anywhere to fast but its fun getting there lol

[rob drag racer]

yeh, pity tho, i think im gunna need sum of that magic u speak of to work this out , mines got no nads. and wow, 5.5! wot do i need to do to get that pwr? Also, could a gearbox issue rob me of this sort of pwr? not that i kno i have one, but the driveline did come out of a rear ended car?

if the box is slipping sure you lose a bit of rear wheel power and look at some diff gears atleast then you will be puting the power down better and to get a 5.5 you need a v8

[Jordo2]

my vp runs under 8 and sure without major mods it aint going anywhere to fast but its fun getting there lol

yeh figured as much, at least i wasnt imagining things.

[Jordo2]

if the box is slipping sure you lose a bit of rear wheel power and look at some diff gears atleast then you will be puting the power down better and to get a 5.5 you need a v8

well i load tested the box and it didnt feel like it slipped at all but i guess that method is a pretty sketchy,unless the box is slipping real bad. as 4 diff gears, i may do that later but id like to sort this first. with the fuel reg, can i use a s1 type to test/use? and can i use the s1 injectors? im not sure if they flow any differently?

[rob drag racer]

well i load tested the box and it didnt feel like it slipped at all but i guess that method is a pretty sketchy,unless the box is slipping real bad. as 4 diff gears, i may do that later but id like to sort this first. with the fuel reg, can i use a s1 type to test/use? and can i use the s1 injectors? im not sure if they flow any differently?

ive used s1 vn injectors ect before in a s1 vp which is the same as a s2 vn and didn't see any difference or loss in power

[greenfoam]

Is the car a Calais by any chance?

Here's a old video of mine on the old style gtech
http://www.youtube.com/watch?v=BwiHG6CCq2U

[Jordo2]

Is the car a Calais by any chance?

Here's a old video of mine on the old style gtech
YouTube - VN V6 0-100 (7.16 seconds to 60mph on gtech)

the engine and driveline are out of a calais. the car is exec.

[greenfoam]

Ok, just wondering if it was heavier than your mates thats all. What weight are you entering in the gtech? I used to guess mine at 3350lbs for the power run and at 3350 it used to make 133 rwhp or you could enter 3350 in yours and compare it directly. Even if I had the weight wrong you should be able to figure something out from that to compare with (mine was all stock apart from cai and tune) still had a 2 ton capable two bar on it and was a Lexcen GL (Berlina)

[rob drag racer]

i still recon a good tune\remap and diff gears could make a difference !

mind you the diff gears wont change the power just be able to get there quicker lol