Car down on power, no changes made.

SS_Firehawk

So back in May before ZDayZ, I had my car tuned. List of mods are...

F.I. CBE & RTP's
Z1 ceramic coated headers and CAI
Ported upper manifold, lower manifold, and throttlebodies
72 row oil cooler
Ecutek tune

She put down 332/270, but power was down everywhere under 7000rpm compared to my previous tune.

Last year with stock headers, nothing ported , and full AAM exhaust/ RTP's, with an Uprev tune, she made 327/270

Since my tune in May, my car makes an odd squealing noise between 3.5 and 4k, only under load. I can maintain an rpm in that range and it will continue squealing. It gets worse as the engine warms up.

My butt Dyno was telling me power was down. So I went to Proven power to get on their Dyno and verify. The first pull was 295/237. That's the lowest I've ever dyno'd with this car. The next pull was 305/239, again that was still low, especially the torque. After letting it cool for 15 minutes, we ran one more and was able to eek out 312/245.

This was a different Dyno, but still a Dynojet, it was also about 8-10 degrees warmer, which understandably reduces power. But this is beyond normal correction, weather or different dynojet Dyno. The tune looks a tad richer than before, but nothing terrible. Even then, I've never seen this many bolt ons and tune on a car and perform worse over time.

I'm trying to get some time with Martin so he can data log the car and check the tune. My 1/4 traps are about 1mph slower than what I was making stock. Elmo also handed me my *** when we were both tuned the same night, by the same tuner, and dyno. I was up 10hp and he stomped me with a slipping clutch and short shifting at 7k. I'll update this with some Dyno pictures soon.

Any ideas as to why my power is rubbish would be welcome.

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BGTV8

Could be lots of things

Down on torque means the engine is not getting enough fuel, air or ignition.

Fuel
Tank of bad fuel, injector issue, fuel pressure issue

Air
Filter issue
Part blocked zorst (or cat)

Ignition
Timing sensor fault - crank/cam angle position sensor but would have to be marginal or the ECU would fault

This will turn into a journey down the rat-hole quickly so check the obvious stuff first

SS_Firehawk

I can say that my filters are still very clean. I can visibly see a very small amount of dirt in the filters, but still very clean. I also don't run cats, and I'm not throwing any codes. I fuel exclusively at Shell. I made sure tondyno with a full tank to make sure the pump wouldn't be working too hard.

Hopefully it's something stupid. I had a couple buddies say that maybe it's a vacuum leak, but I haven't seen or heard anything today it's that either. The squealing.. No one knows. That ***** mystery. Either way, even on a bad day, this car should be able to make over 330. He'll, it should make more. But I guess one problem at a time.

I have new Z1 oversized filters coming in tomorrow. I ordered a new F.I. crash bar, and undertray. I'm hoping this improves airflow as well. I'm just confused and frustrated

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cwrenny

Have you checked the condition of your MAF sensors? do they need to be cleaned.. a vacuum leak wont give you a rich tune but bad MAFs could be reading higher making the car think there's more air than there actually is.. squealing noise could be belt or the harmonics of the engine itself in the exhaust... I know my exhaust makes a similar sound to the Decel hiss around that RPM, however I'm running FI RTP with 200 cell ultra high flow cats welded into them.

Other than what BGTV8 also mentioned I'm not too sure what else it could be..

SouthArk370Z

If the squeal is not coming from a belt, it's may be a vacuum leak. Or possibly an exhaust leak. You need to get a better idea of where it's coming from.

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SS_Firehawk

Yeah, I thought maybe the belt too, but it's under load. I need to put it on a Dyno that can load it and see if it can be reproduced

The MAFs we're clean when I had them out a few months back. I don't get any surging or stutter. Damn car is just lethargic

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SS_Firehawk

Shout out to Jayhovah for letting me borrow his Ecutek cable

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Jayhovah

Woop Woop!

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jchammond

FireHawk;
Did you recently change your tire sizes/specs ?

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SS_Firehawk

Tires are 285 square. The rubber weighs about 3lbs less in the rear. The wheels are 30lbs each compared to stock Nismo weights. They're fully forged, but they still have a lot of heft unfortunately.

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jchammond

I thought I remembered you swapping wheels/tire's.
As I know this greatly affects real feel & timed acceleration; I'm unsure what difference it has on Dyno WHP and/or tuning.
As I know that my wheel/tire changes were drastically changed compared to yours.
My front's increased by 10# each & 14# each on rear= 1sec. 0-120 loss.

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SS_Firehawk

Yeah...
Fronts gained 10lbs. Tires were the same weight. My lugs are significantly lighter, but it's centralized mass and it's minimal.
My rears are 6lbs heavier. New tires weigh 27lbs compared to 31lbs in the stock rears. So it's strictly from the wheels.

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jchammond

You're basically a push on any changes from a dyno; as the outer more mass from the tire's you cut, made up for the wheels.
You did lose some acceleration from the beef up front; but a Dyno wouldn't know that.
That squeal sounds like it may be your culprit.

__________________
MazWorx built long block | FI-TT-100 Stage 2.75 | IPT built 7A/T

http://www.the370z.com/members-370z-...s-musings.html

cwrenny

There is a chance that the sound could be an exhaust leak... If you have a leak before your 02 sensor that would also cause your car to run richer. The 02 would be reading slightly lower numbers because of the leak and the car ECU would add more fuel to try and compensate. I'd try to get some time on a hoist and see if you can find any exhaust leaks.. if you still have stock manifolds this is going to be difficult because of the heat shields.

SS_Firehawk

I had the car checked for exhaust leaks. They tightened everything just in case. I'll go through and check the intake side again. I'm going to do some data logging in the next day or two and see what I find.

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