M104-AMG

iTrader: (8)

I have this funny feeling that either I have a failing secondary turbo, or something is wrong with the turbo-controls or the doors, although visually they all check out, and I have 10-8-10 boost pattern.

In short, it doesn't seem to pull as quickly as it use to between 80-120 mph (in 3rd gear), although all the boost patterns look normal.

Any areas to check first ?

:-) neil

16-in. of vaccuum @ idle
Apexi PFC, tuned by Steve Kan
880cc injectors all around
HKS DP
hi-flow metallic cat; Magnaflow resonator; Trust SP muffler
SR Motorsports SMIC
Spec '99 airbox cover
Stock airbox

mad_7tist

it has been super hot and humid here lately.... time it. then do a run at night. my butt has gotten used to it also. i think my car is slow too

Ledfoot

iTrader: (1)

...maybe fuel filter clogged...better check A/F before you continue.

dgeesaman

iTrader: (7)

Are your AFRs still where they should be? It seems like maybe something is causing the car to run rich - like a thermosensor issue or something.

Dave

M104-AMG

iTrader: (8)

Can I check the AFR's with a PFC, or do I need an aftermarket/wideband O2-sensor ?

I had the wiring for the intake (UIM) air-temperature sensor go bad, but I did fix it. Perhaps the actual sensor is bad . . .

Neil

Mahjik

iTrader: (1)

When I've seen something like that, it's either been:

1. weather related
2. slipping clutch (as it will begin fail in the upper gears first)

yuichiror

iTrader: (1)

I'm pretty sure you'll have to have a wideband and gauge to read the AFR's.

M104-AMG

iTrader: (8)

It's definitely hotter and more humid, and I did tell Steve to tune it conservitively.

It's a fairly new clutch with less than 5,000 miles on it, and no drag race starts.

It's been about 5,000 miles on the fuel-filter. Time to change ?

I do have a Supra TT fuel-pump installed.

:-) neil

Mahjik

iTrader: (1)

Clutches are only good for a certain amount of torque. If you are pushing more torque than the clutch can take, then it won't take long to start slipping. How much power are you pushing and what clutch are you using?

5000? Don't need to change it.

M104-AMG

iTrader: (8)

She was dyno'd at 275HP to the rear, but I don't remember the torque.

I'm using a Pettit Rallye/Heavy Duty clutch. I honestly don't believe it's slipping, because it will still chirp the tires during a 1st to 2nd gear upchange at WOT, and not slip.

:-) neil

Narfle

iTrader: (16)

The true rotary test is the idle. If it idles with all the idle advance pulled out and pulls acceptable and steady vacuum and doesnt shake rattle and roll you have good compression.

If you have a crazy port it could show symptoms of broken but then youd be really sure it wasnt broken when you stepped on the gas. But that is one crazy port.

Mahjik

iTrader: (1)

I don't necessarily believe it's your clutch either.

But just FYI, if your clutch is failing, you'll notice it in the upper gears first (4th and 5th). By the time it gets to 1st and 2nd, the clutch is about to completely give up the ghost (unless you just have a complete failure and friction material rips off the disc).

When my clutch started slipping, I would notice on the highway that the car just wasn't moving when I accelerated hard (typically in 4th gear at that time). The boost and RPM's were screaming; it just couldn't get the power to the wheels. Under light acceleration, it wasn't noticeable.

M104-AMG

iTrader: (8)

Nothing ported on her.

Wouldn't the torque multiplication be the greatest in 1st and 2nd gear, and hence wouldn't it slip/fail on these gears first ?

I'll drop the inspection cover on the bellhousing and take a look . . .

:-) neil

Mahjik

iTrader: (1)

Damon had a good post on it:
https://www.rx7club.com/showpost.php...85&postcount=6

I don't necessarily think it's your clutch. It's a possibility but at 275rwhp the stock clutch should be ok.

DamonB

If boost is fine and you only notice a difference at high speed I bet it's track temperature you're noticing; the air is less dense and therefore power drops. The higher gears will show the biggest difference in acceleration when it's hot out.

...and for crying out loud people the fuel filter can't cause problems like this. If there were a fuel delivery problem it would be noticed anytime the injectors are at a high duty cycle; this is irrelevant of speed.

64,000 mile fuel filter

pluto

check and change your plugs, they're only good for around 3-4k miles before you started to feel a degradation in performance.

tphan

^^^X2. Slipped a little during street tune session with S. Kan. Now I can't not mashed the gas in 4th w/o rpm goes to the limit.

M104-AMG

iTrader: (8)

Thanks Steve. I'll do that.

How about sending me my original PFC map, plus the tune you did, as promised.

Thanks,
Neil

M104-AMG

iTrader: (8)

It happens even in the morning. . .

:-) neil

M104-AMG

iTrader: (8)

Thanks Steve. I'll do that.

How about sending me my original PFC map, plus the tune you did, as promised.

Thanks,
Neil

pluto

I get swamped at work so I never really had time to reply most emails. email again if you haven't done so and I'll forward you your map...

Steve

M104-AMG

iTrader: (8)

I just sent you an email at your gothamracing account.

Thanks,
:-) neil

M104-AMG

iTrader: (8)

FWIW, melted metallic cat had caused the restriction.

Running just a resonated mid-pipe, so all is well.

:-) neil

adam c

iTrader: (2)

What brand cat was it, and how many miles before it failed?

axr6

An other question;

Did you have the air pump piped into the metallic cat?

Albert