Porsche 928 GT ProMAX ECU upgrade

"OK sounds like fun. We could have a non bootable 928 if we are not careful" I said worriedly.

"No theres detailed instructions - it doesnt look too scary. Have you got an anti static wrist strap? Im going to Dyno test it before and after so you can post the results on the site" Said Mark.

Brilliant. I thought.

The full story, before and after dyno results, interpretation and detailed pictures follow.

ProMAX GT Chip Set box

ProMAX GT Chips

Nice to see a Red GT on the drive again

Battery disconnected and made safe from accidental connection

Point of no return approaches

Its out. Absolutely no going back

Anti Static Wrist Strap used to be really really careful not to cause a 500 quid bill

ProMAX instructions are good. Nice and detailed

Its hard to get these connectors apart but they do come eventually

ProMAX Chip in place, correctly oriented

2nd Chip is easier says the documentation

My anti static expertise was legendary at Sun (I was always frying computers)

ProMAX chip fitted and ready for reassembly

Phew. It took us a while but we were checking and double checking to make sure we got it completely right.

Once we had put it back in the car and re-connected the battery Mark was ready to start. He turned the ignition to position 2. All the dash lit up as per normal. He fired the starter. Perfect start and idle normal.

Then he drove off to the Dyno place for round 2.

Dyno printouts - double click to get better quality Adobe pdfs

Observations about the Dyno Runs

• First dyno run showed power to be circa 297 BHP - about 10% down on what it should be. Need Bosch Hammer diagnostic unit to see if there are my faults that indicate the root cause of this. We carried on regardless as the test would still give us some comparative results
• Dyno guy thought that dip in torque at around 2000rpm post chip upgrade could actually be due to the car getting unsettled on the rollers (which it did) for a short period of time. A queue of people waiting meant that a rerun was not possible at that time. Note even with the dip it is still higher at that point than pre-upgrade.
• The PSD came on for most of the first run.
• The PSD and ABS disabled warnings on the digital dash lit up during the 2nd run. All still works fine (no scary messages during normal driving anyway)
• The fan at the front (not visible) was fairly small and probably only really adequate for minis. Even with it on I could barely feel a draught in front of the radiator.
• A quick "seat of the pants test" on the A3 shows that the car does seem to rev higher in each gear resulting in a higher top speed per gear (circa 100 in 3rd) Whilst high speed runs up to 159mph for the purposes of testing are obviously now perfectly legal, I wasn't prepared to risk going any faster than 100mph.:-)
• The RMB sounds even less Castle Coombe approved than it did before.