Mother

2000 996 w/Custom SC -This is the first Dyno tune on a Mustang dyno so feedback welcome FVD programmers are going to send new map soon and run again. Some questions though.

?. No growth in boost vs RPM stays at about 1.5-2 psi
?. Low HP and Torq dip is it related in the AFR settings range between 4400 to 6300 RPM

What to check?

fast996

did u customize a VF kit?
whats timing like in the middle? also 11.0 a/f seems kinda rich , explaining the dip in power maybe. PS. whats your exhaust setup?

Macster

No growth in boost suggests a leak on the high pressure side of the intake. (Or the SC drive is slipping.) But I suspect a boost leak. If so, this can account for the lower output and the rich AFR since this air has been measured and the DME will fuel accordingly but the boost allows some air to bleed away and the result is the mixture is too rich.

Sincerely,

Macster.

Mother

Yes, it is built from scratch however intake is the same. I did not measure today the timing using my Duramatric, however the programmers said it was not needed if I supplied it via durametric? The exhaust is just maxflo mufflers. I suffer from stalling and get some hunting then stalls and just figured it was mixture since it smells rich on startup at idle and ECU can not compensate.

fast996

thats how ur tuning it? no standalone? just letting the ECU compensate closedloop

Mother

Are you talking about a leak after the throttle body or before? They suggested a leak also, however I was not convinced the boost pressure would not rise more as the boost increased however never reaching 5-7psi target psi if a leak was present ....it just seems steady? They tap the pressure on the vacuum tube on the BOV valve for the measurement. They can do a smoke test.

Mother

Tuning takes place using FVD programmers to make me fuel maps based on the data I send them then I reload the new map and re-test.

Hyper911

belt slipping or vac leak would cause this. Given its a centrifical blower and you are getting 2.5lb immediately I would say boost leak. Belt slippage, unless maybe if it is really loose, would show an increase in boost followed by an early plateau as rpm's rise, and maybe a loss in PSI. What about your blow off/by pass valve could be stuck open and bleeding off boost.

Macster

The leak, if it exists, exists on the high pressure side, the side of the intake system that experiences boost pressure. Where the TB is I do not think makes any difference. Any hose the experiences high pressure, any hose fitting that holds a hose that experiences high pressure is suspect.

It is not unknown for a turbo-charged Porsche to experience a boost leak and these engines are built from the ground up to run with boost, their intakes are designed from day one to contain boost up to 0.7 bar and sometimes higher if the car is driven at higher altitudes.

The smoke test if it does not involve pressure may not turn up the leak if it requires considerable pressure to create.

Sincerely,

Macster.

redridge

did you put a resistor on your maf? With all that extra air coming in you need to lower the signal... try a 220ohm to start.

Mother

Is my check valve in right the white facing rear of eng?

Mother

I think I am using a 480 ohm now and need to check MAF voltages. I just can not remember what voltages I need to look at for it to be correct.

Mother

I was thinking of using soapy water around the joints going from the SC discharge to the throttle body. And hooking up a visual gauge to rule out a bad dyno sensor. The eng was rebuilt 5000 miles ago.

Mother

This belt is on tight and can barley get it over the belt tensioner during installation and is warm to the touch after shutdown like it is not slipping. Regarding the BOV I do need to check any suggestions...

nick49

Is the BOV adjustable? Maybe you can introduce pressure to it from a compressor with a gauge in line and test at which point it opens.

What boost pressure are you supposed to have before it bleeds off?

Do you know the drive pullys are right for the RPM and the boost wanted?

GL getting it sorted.