Well, where do I begin?

The problem seems to be inconsistent. My problem is under full throttle. As it approaches 58k rpms the whine of the sc starts to get softer and the power seems to pulse.

Possibilities???

Perhaps a lean condition?

Not enough fuel?

Do you think that a bigger stronger fuel pump would fix this?


These problems seem to be occuring in the cooler climates. Would denser air be a contributing factor to this?

Would larger injections help?


Problem doesn't seem to be there when there is a warmer climate.

Any ideas?

 

Not sure since I have a Vortech but I have heard that Stillen is a monster out of the hole and in the low to mid RPM range... It dies out in the mid upper and higher RPM's though... Sounds like it might be normal for the Stillen.

 

I don't know. It didn't use to do this. Its not that it is dying off, but rather a surge feeling and the whining of the sc seems to do a "waawaawaawaa" noise.

 

Hmmm.... Belt slipage?

 

Never seen this problem from the Stillen.... (and I have seen alot from them) I have alot of experience with this Stillen and your explanation is the first I have heard of.... sory

 

Possibly

 

Can't be belt slippage. I'm not hearing any and I don't notice any of the issues in first gear, only in 2nd and up.

Maybe detonation or extreme leaning out causing timing to retard to the max and loss of power? Is that possible?

 

I saw where a 350z guy lined up some marks on his pulley and belt with white out or something to see if his belt was slipping.

 

OK -

First - lining up your belt with white out really wont work - as the ratio is not even for the line to be on the same spot again, and having to turn the engine slowly to get them close to even tell will be VERY difficult.

A slipping belt is not usually something you will hear. A great way to know if the belt is slipping, without a dyno graph that it, is to feel the inside of the pulleys with a finger - if it comes out with black rubber dust on it, you've got a slipping and burning belt - so it should be replaced and adjusted accordingly.

It sounds to me, like you have a timing issue - likely combined with a lean run. Take a look at the auxiliary pump, if you have one, and make sure it is clean and has a good ground. Sometimes a bad connection mixed with higher RPM's will give you that lean type of condition when it isn't pumping properly.

You could also have a vacuum leak, forcing it lean as well and making it surge at higher RPM's.

If you are only noticing it in 1st gear - verify your VDC switch is off - you could be breaking loose and it's interfering.

Lastly - get it tuned and checked. With the weather changing, and depending on when you had it tuned last, if you did at all, that could be it. FI cars need a couple tunes a year in changing climates. With any piggy back, you should be able to save MAPS and configurations so you can reload them...I for one, have a summer and now a Fall tune to load for the proper weather conditions, and can do so in less than 5 minutes. When it gets really cold, it'll be tuned again, and I'll be covered year 'round.

Rick

 

Interesting that you would mention timing retard. I am currently having that issue, at least looking at my dyno graph, it looks as if my timing is retarding at mid-range (4200 to 4800). I am currently running the stg IV kit and my numbers are pretty disappointing to say the least. A couple of things were suggested to me, one was to try higher octane fuel and see if the problem still persist. The other issue maybe might be a sensitive knock sensor (I have an 03 year car). But in your case, i would definitely get a dyno with the A/F and see what is happening to your car. The stg IV i have on my car just did not feel strong at all, and a dyno graph sure enough showed my car losing power at mid-range. I would start there and try solving your issues from there.
Good Luck!!

 

A good wideband A/F meter will answer alot of questions. It'll tell you if you're running lean and the ecu is retarding timing because it's hearing knock. A boost gauge will tell you if the belt is slipping. You guys gotta get some gauges, you can learn alot about what the car is doing.

 

it sounds like a slipping belt thats just not squealing.mine runs a lot better in the cool weather.it actually pulls much harder in the upper rpm band.
maybe see if the coolant pump for the intercooler is still working.im sorry i cant help anymore then this.

 

Spray some 3M 90 adhesive on the belt while it's running and then take it for a run - if you boost better and the problem goes away, then tighten the belt as well...that'll rule that out for about $3.

Rick

 

Thanks. I just took it for a drive and sure enough I heard the belt squeal up in that range. Its kinda funny because I listened for it yesterday and didn't hear it. I'll go tighten it up and let ya know what happens. Where can I pick up that adhesive? Autozone? Thanks everyone.

 

I don't know if Autozone will have it, but I think I got mine at Lowes....

Rick