Porsche Enthusiasts Club Forum

Red Baron you want your mechanic to give you a price to roughly do your headgasket, ask him how much for a careful job, i would

Just spent some time pottering around an industrial estate with a laptop tweaking my commuting map! Getting the low revs and crawling traffic speeds running much more consistently on the AFM gauge and leaning out in the cruise areas I use so they between 13 and 14.5 and nice an smooth so I can cruise in a queue burning less fuel. Been mostly concentrating on the injection map to do this.

More work to be done but I need to recruit the girl to drive around so I play with the laptop - particularly when we start to get onto the limited boost I am allowing on the commuting map.

What boost will you be running and what AFR ratio is ideal ? i am in the 11.5 / 12 at 18 psi

On this map - not much. Maybe 0.5bar max? certainly once on boost I will be looking to run it richer than at cruise to ensure enough fuel for burning and keeping the temps down.

The AFR for a cruise when all is steady i am aiming for somewhere between 13.5 and 14.7 getting richer as soon as the load is increased.

High 13's is where I am when cruising, though I was considering taking some fuel out to run closer to 14.7, I thought under 14 was a little rich ?.

Was seeing between high 13s and into the 14s a lot whilst sitting in the traffic crawling along this morning. I need to look at the injector corrections based on the air temp to make sure whens its cooler it runs puts a bit more fuel in but not to much!

The ECU has a CANbus output with lots of handy things such as Throttle Position and injector corrections, air temp and the like so a little project has started to put together a little micro-controller to read this and drive a small LCD screen for some real time outputs. Handy so its running rich I can mentally note the speed site where the issue is and the temp and investigate.

And of course mostly it seems a fun little project to play with!

When I hear about engine management that can make thousands of adjustments per second I wonder who or what programmed that in ?.

People who paid better attention at school than me!! The work that barks 944 does is really interesting, I don't know how he knows where to begin with modifying the DME.

Not what I did but somebody else rearranged my bumper for me.

That was kind of them! Did you get their details for a claim?

Yeah they stopped and were very nice about it. Notuch damage done thankfully.

I've straightened the bumper irons and now just need the fibreglass repaired and repainted and I know a few guys that can help. Once I have a better idea on cost I'll contact the guy who hit me. Not too fussed as I'm not too precious about the car, just want it straight again but no rush.

That's a bonus then, there are some decent people about

I've been thinking more about this issue. In my mind when idling there shouldn't have been any exhaust gases leaking from the flange on the waste gate pipe as the gate should be closed and the pipe empty? Also, with the exhaust gases rushing down the exhaust pipe and past where the waste gate pipe joins the exhaust pipe, surely this would create a venturi, pulling anything out of the waste gate pipe, rather than blowing exhaust fumes up this pipe?

No other issues with the car but makes me wonder if the waste gate is sticking open?

Opinions appreciated

Cheers
Andy

....checked the waste gate pipe under the car whilst the engine was warming up. The pipe was cold which is a good sign but I'm still confused!

At low rpms the pulses slow down in the turbo with the peaks and troughs damping out, so you end up with a constant pressure slightly above ambient and not enough gas velocity to cause a venturi effect where the wastegate exit joins the exhaust. So even though the wastegate will be closed, if there is an exit route between the wastegate and the exhaust anywhere, the gasses will begin to flow, allbeit at slow speeds and slow pressure from that gasket as well as the tailpipe.