As Car Idles, It Loses Power (for Lack Of Better Words=/ .. )

[Touge Kyousou]

Heya all,

I think i've come across a weird problem with my car... in that when the car comes to a stop and stays stopped for a minute, the power the engine produces is lower than if i come to stop, then quickly take off again.

So scenario 1 (low power)

Car has been sitting idle for a minute, then i take off mashing the accelerator once the clutch is engaged...doesn't feel fast

Scenario 2 (normal power)

Car has been driving around, comes to a stop then i take off a few seconds later, mashing the accelerator once the clutch is engaged and it feels alot faster than scenario 1.

This isn't all butt dyno btw, i did a dyno run when i got the car serviced last and it came at 131rwkw. Obviously, the car had been sitting on the dyno to warm up etc (like scenario 1). Compare this to a stock V35 350gt that should get around 160 rwkw.

Also, i've got one of those gtech thingos and it consistently gives around 200-210HP from scenario 2 and around 170hp from scenario 1.

It's a V35 skyline 350gt with a y pipe back exhaust, upgraded air intake tube and drop in filter.

Any info/help appreciated, thanks!

[(B1) MR_fanny]

even though you say "clutch is engaged" i may sound stupid in asking if its an auto? could be a gearbox vs electronic computer thingy maybe?

[Touge Kyousou]

even though you say "clutch is engaged" i may sound stupid in asking if its an auto? could be a gearbox vs electronic computer thingy maybe?

The car's a manual.

The way i see it, it's either a heat or main ecu problem... no Check engine light though and it seems it's gonna be a bitch to track the problem *sigh*

[(B1) MR_fanny]

my guess is heat soak related too as its siting there on idle for a while compared to short stop start.

[Touge Kyousou]

Mhmm, definitely sounds like it but for some reason a little heatsoak (the v35's aren't even turbo) manages to take away 30rwkw's wth =/

Very weird... car will most likely go on a dyno next week with a scantool attached, see what the thing is doing. Failing that i might try a radiator flush with a nismo thermostat and see if that helps..

[jeffworld2]

perhaps there is a temp sensor d/c or hanging down somewhere it shouldnt be. only one i can think of would be if the radiators been out the sender on it. dont know anything about 350gt ecus and what effect something like this would have though, but its something to have a quick look for.

maybe air intake temp too? good luck

[Yo-Yo]

how long ago did the problem start?

You mentioned you have some mods, did you purchase the car with them or did you have them installed. eg, Has the problem come up after you modified

maybe an ecu reset if you haven't tried yet?

[Touge Kyousou]

To be honest, i didn't notice the problem until i got the dyno run. The car is quite new to me so for the most part, i've been driving it nicely but as i'm settling into it, i've started giving it more and more and realised the problem this way.

The exhaust was done by the importer when i bought the car - However, i've seen the car up on the hoist and it all looks good. Everything lines up, nothing is loose and the installation doesn't require going anywhere near the exhaust sensors (it's a jap brand y pipe back exhaust). The intake tube is a nissan factory item that i installed myself along with the air filter (trust).

I checked for any disconnected plugs tonight but didn't see any. Checked level of all fluids and that's ok too..

While i was at it, i also gave the air flow meter a good hit of electrical contact cleaner.. not hoping for much though lol.

If i/garage finds the proble, i'll post here for future reference.

Edit - The ecu's been reset before

Edited October 25, 2008 by Touge Kyousou