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Which temp sensor are you using, the stock one or one of the faster GM or VW units?
I use the stock sensor. I could never convince myself that faster response was a good thing. The stock sensor is pretty much locked to the air-box temperature, which heats up at the rate of the engine. I reckon it is more likely you will get a jolt of cooler air than hotter so a delay is actually preferable.
Example, sitting in traffic, you suddenly are able to floor it. At first, you may get a dump of hot air, but the air-temp sensor is already quite hot. Even as the incoming air becomes cooler, the rest of the intake and engine are still hot so the advance shouldn't be raised for a while.
You should know full well that you cannot put this sort of comment out there.
LOL!
Yeah... so I can't locate my endoscope. Was going to try and grab pics of Piston #5 before tomorrow's track day, but I guess that's out for now.
I found the original EZF chip, but after Ken's input, I may decide to leave his in. I think it's just a matter of monitoring things for a while and UOA to see if there are signs of bearing wear or other adverse symptoms.
Did anybody post boroscoping #5 cylinder bore for evidence of scoring? -just a idea, to be safe,especially if you have if you are showing metal deposits on spark plug. I bought a '88 944 that had been brought in with a rod knock and the metal particles had worked there way into #2 cyl. ruining the block, I hope not in your case.
as an unfortunate expert in blowing up engines in race 928's here is my thoughts
Knock is deadly.....your AFR looks pretty decent, but it is possible that single cylinder might lean out? Maybe a clogged injector, who knows?
I would NOT run a performance street tune chip in a race car....NO WAY...the risk is far too high for the small HP gain.....Honestly I don't like the stock spark curve of the Euro S LH engines.... My old krankenwagen runs a euro S LH dual dizzy now and typically blows an engine every race now.
What octane fuel do you run? If I ever race 928's again I will ALWAYS use 100 octane...sure its pricey but engines cost MORE
Also cut the filter and inspect after every event. Once again filters are cheap...
The strength of the 928 platform on track isn't HP....its balance...it handles well, has good brakes and torque to get off corners.... typically I would pull other racers right off the corner, then hold even once they got into their HP range...
The good news is you caught it before it turned into this
An update from this past weekend. I had a track day on Friday. Car seemed very happy as I set a new personal best. Ran with Ken's chip after the above discussion - and given temps were much more reasonable. Wasn't able to locate my endoscope, so no pics of Cyl #5 (yet).
After the track day, I took a sample of oil and I "think" I saw a couple flakes, but I cannot tell for sure. I tried looking on black paper which was inconclusive, and then on black plastic - which is where I thought I saw something. Unfortunately with the Accusump, the filters do not lend themselves to cutting open and inspecting. I wanted to try running without the Accusump, and run a normal filter but that's a PITA. So my plan is to now drain this oil, take the Accusump out of the loop, use an OE filter, drive and re-inspect. If it appears to be clear we'll call it good and move on. If not... well I really don't want to be a pessimist.
Totally forgot to inspect plugs as I was dealing with some family stuff this weekend too, but will look at those possibly this next weekend. I still want to dive into the injectors too as this is the only thing that makes sense for why #5 might be knocking and others seem okay.
So we'll keep this thread open for now and I'll keep updating as I gather more info.
Sorry I haven't updated this for a while. I was in Rome with the Wifey for some R&R and pasta.
So the latest is I took and oil sample and there was clearly still a few flakes here and there - nothing like before. I'm pretty sure this is residual, but it was very concerning that the filter in the Accusump housing had not caught these. So just before I left for italy, I did an oil change (again) and this time I placed an OE filter in there to hopefully clear things out. I need to drive the car some to circulate the oil and hopefully get rid of any remaining copper flakes. If I still see copper flakes after this, I will likely have to pull the pan again - or maybe the entire motor for a much deeper analysis.
I changed the oil again, this time to Mobil 1 as it;s 1/2 the price of Amsoil and I just can't afford the throw $100 bills into the drain. Anywho... I did a single track day on the 8th of September and hit a personal best. It was an awesome day. The car seems very happy.
After that day at the track, I took a sample of oil and looked at it in the sunlight. I saw 1 flake of copper, so I was breathing a sigh of relief.
But to be extra sure, I sent a sample into BlackStone Labs. Everything looks normal, except Lead which was slightly elevated by 1 point, which the lab hypothesized may still be residual from teh spun bearing. Nothing to be worried about. No indication of fuel or antifreeze contamination.
Here's the initial report. I'll start posting these in my main Coke Car thread. But for now, I think this issue is resolved. Good thing too... Heading to Mid-Ohio tomorrow for the weeknd!
That sounds good, AO. I did the same sunlight check 300 miles after my rod bearing change and the difference was like night and day. Just 150 miles on the old bearings and I could see already see about 10 flecks. 300 miles after the change I could just barely see one near microscopic fleck with my reading glasses on.
08-09-2017, 04:38 PM
