rbahr

There is knock control on the NA car. As such there is a signal line going to the ECU which could be monitored. Not sure if you are equipped for that.

rbahr

Any news on this?

garage5

Update... yes.

Solution... no.

I ran some higher octane fuel through the car a mix of 110 leaded and 93 unleaded the ratio made it close to 104 mix.

I only had one knock to where she pulled timing at 7800 rpms. Ideas? Ill post the chart below.

garage5

What do you guys thing... whats causing the car to only enjoy higher octane.

rbahr

Generally:

• Heat
• Timing
• Compression
• Lean mixture

garage5

75 degree weather
Motor is in timing as far *porsche spec*
Compression is a lil low but uniform across the board, no more than 8 psi between highest and lowest cylinders.
Leak down are all under 10% leak down

rbahr

Engine load?

996FLT6

Maybe your ecu box is going zonkers. If leak/compression looks good I look at that next. I've seen that on 6cupcars. Mike

garage5

You know I thought about that from the beginning. I suppose there is no way to confirm its going bonkers.

garage5

I had engine load on the first data log I posted when I started the thread. Here is the full log from data I logged the other night from the graph two or three posts up.

Charles@dundonmotorsports

In your initial log posted the A/F lambda trims are off bank to bank about 5%. B1 is removing fuel while b2 is adding fuel. This may be the place to check first. I would also compare maf sensor readings with another GT3 known to be good and running correct.

It is possible it is pulling timing for safety if the fuel trims are not within spec and or if the MAF measured vs spec are not within a certain range of each other.

Fueling off bank to bank could be
-air leak in the rxhaust
-plugged cat
-damaged exhaust or failing muffler
-cam timing is out of spec. One bank retarded more than the other.
-injectors plugged slightly on one bank.

garage5

Ok this is the type of diagnosis I needed to hear.

No exhaust leaks
No cats anymore
No injector issues (all 6 have been removed and flow tested)

Damage to exhaust or failing muffler *maybe*

Cam timing out of spec, I have suspected this for a while, is this possible to be checked via durametric?

Charles@dundonmotorsports

I believe you can check cam timing with the durametric. On the PIWIS it is listed as camshaft deviation. That is the base spec +/- from 0.

I would also also recommend swapping pre cat o2 sensors bank to bank and recheck your logs

garage5

I swapped the 02s with no change. I even put the old 02s back in with no change.

Its not the mufflers.... I had some old 996 pipes, I put them on with no change.

I am left with Cam timing... will check that shortly.

garage5

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Cam timing:
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bank 1: BBC