Car runs better 3/4 than WOT what gives??

[SteveR6]

For some reason my car runs way better if I only hit it 3/4 of the way instead of putting it on the floor. Anyone have any idea why this would be?

 

[Mitchel63]

It's probably jsut your imagination.

Could be knocking under WOT though....that would make it slow.

 

[SRTthis]

my truck feels the same way. but its really not....

 

[nightspeed87]

maybe it really needs a tune it might be floading with too much gas under wot opposed to 3/4. Could have some a/f ratio problems maybe.

 

[zachakagoat]

My guess is you may have a bad boost leak causing the engine to lean out or you are running too much boost causing alot of knock and causing the engine to pull timing. Do a boost leak test first and let us know.

 

[DarkSwatCobra]

My guess is you may have a bad boost leak causing the engine to lean out or you are running too much boost causing alot of knock and causing the engine to pull timing. Do a boost leak test first and let us know.

thats worth a shot...

 

[olmytsi]

This is usually caused by the richer a/f ratio the ecu gives you when you are on the high airflow map ( >2.1 grams / rev).

 

[chicagoavenger]

For some reason my car runs way better if I only hit it 3/4 of the way instead of putting it on the floor. Anyone have any idea why this would be?

Do you have a logger? If not get one and see what's really going on

 

[slipstream808]

Plus there is less timing at WOT.

Try 3/4 throttle and WOT at 4.5k RPMs and see how that feels.

 

[95TalonOwner]

It wouldn't hurt to put a new fuel filter in as well. It might be so dirty and old that it can't flow enough fuel at WOT and that is messing everything up.

 

[SteveR6]

Well I'm currently in the market for a datalogger, I turned the boost back down to 10PSI because I thought of it pulling timing at WOT and don't want to risk it without knowing for sure (I was running 14) I have a new fuel filter but haven't gotten time to put it in as I just put in a new turbo. As for the boost leak test I know I need to do that but time has been tight lately, I have the parts to make it just can't seem to find the time to do it. Maybe I'll do it later this evening, if not it will be the weekend. I was just picking peoples brains to find out the possible causes.

 

[zachakagoat]

14psi shouldnt be a problem on a stock GST so that won't be a deal. It all has to do with your boost leak test. If you ahve time to turn it down you have time to make a tester

 

[PieEyedPiper]

I experience the same thing. But I think a perfectly working car would feel liek this anyhow.

Why?
Because the power output of our cars scales up with load/spool etc even with a static throttle position. So even when you do not necesarily intend to go fast or unleash a mess load of horses, your turbo spools regardless and your engine produces more power.

it's not so much "slower" at WOT, but much quicker than you'd expect at 3/4.
At least thats my theory.

 

[MyBeatGSX]

^The explaination is along those lines.

Most cars that make no power up high feel like this. At your current power level, 3/4 throttle is already flowing as much air as you're going to get, so WOT isn't going to make any more power. The throttle is no longer the restricting point after its open 3/4. Its like people that put 75mm TB's on their stock D16 Hondas and wonder why there's no difference between 1/2 and WOT. This is all true of an NA car but even more so of a turbo car because the turbo will force air past the TB whether its open all the way or not, its how you can get full boost at 1/2 throttle with ease. So I wouldn't say its "slower" at WOT, just not any faster.

 

[nightspeed87]

hmm...makes sense, i think he should gone and change the fuel filter get the whole fuel injection system cleaned and ( not sure if he has a KnN filter or anything ) but get a tune up and then postback.

 

[SteveR6]

I have fresh NGKBPR7ES's in the car and an Apex power filter. I'm heading down to make the tester and do the boost leak test now I'll hopefully have time to post back up in acouple hours before work.

 

[SteveR6]

ok, for some reason I can't get more than 5 psi to build up. I think the valve stem was leaking on my tester, I rubber cemented it in there and I'll try again tomorrow. If that doens't do it I'd say I have a hell of a boost leak somewhere. Should air be coming out of the valve cover breather, I noticed it was and capped it and still couldn't build boost, also disconnected and plugged the J pipe MBC hook up.

 

[SteveR6]

If air does leak out of the valve cover breather hose, how the hell do you ever build boost? I'm confused, it's probably simple but sometimes I can't see simple things.