flash968

i'm not throwing any complicated arguments anywhere - i'm just making sure nobody thinks for a minute that comparing charts from one car to another from different dynos on different days is of ANY use whatsoever in diagnostics - it is a very common mistake made all too often - even the A/F thing can be skewed - placement and condition can afect the outcome - we had a set of runs we had to dump for exactly that reason

sparky - when you do the g-tech thing, have you accounted for wheels and such in the weight entry? - on the 400m thing, how are you insuring that you are both driving the same? - from a dead start, .5 sec can easily be bad launch - do a 3rd gear run from 50mph and see how it does

i agree that a leakdown test will be far more of a useful tool in determing the condition of your engine

sparky

Scott - good to see you're alive and kicking hard ;-) yeah, Classic Adelaide was a hoot - eat your heart out! (For those who don't know - CA is 4 days of tarmac rallying with 300 other cars over closed public roads throughout Adelaide hills with no speed limits - definitely 968 territory!)

Have added leak down test to the must-do list, stay tuned.

But no suggestions yet on cause of my unusual AFR profile? (14:1 until 4000 rpm, then suddenly 12:1 ??) I can't imagine this caused by a leaky combustion chamber?

RajDatta

Sparky, those number are not eyebrow raising. They are definitely within threshold for a NA 968. I would not worry too much about your AFR.
Raj

Lemming

Sparky,

I thought my AF numbers were strange as well. I have an adjustable pressure regulator sitting in the garage and plan to put that on the next time I'm heading to the dyno. I'd like to see it closer to 12.8 from 3.5K and up.

sparky

I was just reading up on the role of the two Hall sensors, one on flywheel the other on camshafts. Apparently if the camshaft one stops working the DME know this and protects things by retarding the ignition around 6 degrees.

Just a wild theory for now, but wondering if a hall sensor fault is behind my low engine power? How does one check if Hall sensor is working? I could easily disconnect it (from camshaft housing) to see if car runs any worse. If not, then its probably faulty?

Is there a Hall sensor check measurement I can do with my trusty multimeter?

Sparky

Lemming

I believe that there is a write-up on Clarks Garage.

968perf

Lemming hoping you are still around this is a rather old thread. On your track car, did you get a race chip to control optimal air fuel mix using mass flow or did you more simple unplug your O2. How much did it impact your fuel economy? Not really a concern on the track but more driving to/from. Just deleted my cat and the O2 sensor is confusing the ECU. what's even more baffling is that the power loss is on the high end, 5500 rpm.