Carpokes Porsche Forum

Ok - Got her to start!

But she knocks REALLY bad so I know things are not correct. I need to start by verifying my timing. I am going to do that by resetting the ignition table to fixed and checking against the timing light to make sure I have the trigger wheel angle set correctly.

My question is this for you turbo guys with the IGN, AFR and VE tables. How did you guys set your RPM across the x-axis and the Load (y-axis)? I know that I need to go above 100 on the load side because of the turbo factor above 100kpA.

So - making progress but do not want to damage anything so trying to play it VERY safe and careful.

Thanks in advance as always!

-scott

BTW - here is the first start video...

Congratulations! When you say Knock, do you mean pre-ignition/pinging (as opposed rod knock, etc.)? How did you conclude it was knocking? It didn't sound that bad to me, but almost sounded like it has an exhaust leak or that something is open to the crankcase. What engine management are you using? If helpful, here's how I added timing marks to the front cover of my motor, back when I was creating a logger for ignition timing.... I had to use a timing light to confirm my readings, and quickly discovered there are no timing light marks.

Hmmmm

That’s a great question and I am not sure what knock it would be…I assume double checking the timing with it in fixed and with a light would rule out the pre ignition knock?

The cat back part of the exhaust is not mounted so that is the reason for the loudness.

I have a knocksense module and the light is pretty much on solid (but I have not run the engine long enough to try to sort that yet - it has a trim adjustment to it).

I am using microsquirt.

Open to any and all suggestions. I am thrilled that it started but know there is a lot to do.

KnocksenseMS is designed to detect ignition knock (aka pinging/pre-ignition).

Are you using the factory speed and ref sensors or a separate trigger wheel? Definitely worth checking the base idle timing with a timing light just to make sure the system has the TDC offset correct. Assuming you are ok there, and have a single-digit ignition advance at idle, my hunch is that the Knocksense may need to be adjusted, and that the motor isn't really knocking. I'm not a Knocksense user, but understand the knock-detection signature/filter can be set to best match the motor it is running on, and that there is a sensitivity adjustment the user needs to make when installing. Where did you get it and did the seller know it was intended for a 951? Did you run through the sensitivity set up?

The motor sounds like it's running a little fast, but hitting on all cylinders and running well. I think you are further along than you might think!!

Thanks Tom -

I hope you are right and it is great to have someone that knows more what to listen for and observe helping me dissect everything!

It is idling at about 2000 rpm, so that needs some work as well. I may just be too paranoid about the knocking. I will start with the timing check with a light and report back. I have not messed with the Knocksense adjustment yet as I have not left the engine running long enough to try!

You have to tell the folks whaat type of car and displacement you have when you order the KS unit, so they know it was for a 951 and the correct CC's - this engine is bone stock other than the ECU and related items.

Congratulations on getting it started!

I will start by telling you that whatever you think you are hearing in that video is NOT detonation/knock/pinging as it as pretty much impossible for such a thing to occur at idle or low load---it only happens when the engine is heavily loaded via throttle opening while driving.

Our own @chris white has for years featured a link on his website to an article that is the best treatise about abnormal combustion (detonation and preignition) that I have come across:

http://944enhancement.com/html/knock_ping.html

Which MS are you running? Let me know if you need any help with your config, I've just spent a few weeks getting mine going. Make sure you have no vacuum leaks, MAP should be in the low 30s before you do any tuning, I got screwed over by a leaky heater valve that only showed up after a week of road tuning when we turned the heat on!

Thanks guys -

Bergerac - I am running micro squirt. I'll reply later today with all the details, but 36-1 crank mounted trigger wheel, LS coil packs, Ford mustang injectors. Completely stock engine otherwise. I am reevaluating my tables now in addition to verifying my timing, so I appreciate any help you can share.

CDA951 - so, do you think it is ok at this point to let the engine idle as is and adjust the Knocksense module sensitivity to take the light out at this stage?

Thanks again -

-Scott

Drscottsmith wrote: Tue Sep 26, 2023 5:41 am Thanks guys -

Bergerac - I am running micro squirt. I'll reply later today with all the details, but 36-1 crank mounted trigger wheel, LS coil packs, Ford mustang injectors. Completely stock engine otherwise. I am reevaluating my tables now in addition to verifying my timing, so I appreciate any help you can share.

CDA951 - so, do you think it is ok at this point to let the engine idle as is and adjust the Knocksense module sensitivity to take the light out at this stage?

Thanks again -

-Scott

Yes, you should dial back the sensitivity if the unit is indicating knock at idle---even if there is an actual disconcerting knocking noise going on (which should of course should be investigated), it is NOT spark knock, which only occurs under heavy load and causes the engine block to resonate at a particular frequency.

I have not personally set up a knock detection system from scratch, but from what I have seen the only good way is to have a professional tuner do this on a load bearing dyno by slowly advancing ignition timing with the engine under load (but not much boost) until knock is heard (using headphones) and tuning the system to that frequency. Then dial back the ignition timing curve to allow a margin of safety.

Before any of this, you should use a timing light to verify that actual ignition timing is what the MicroSquirt controller is showing. You can either make timing marks on the front cover like @Tom did, or you can use the OT mark on the flywheel if it is visible.

There is probably a way to "lock" the ignition timing setting in the ECU software for use while verifying timing, other MS users can tell you how to do it if you cannot find it in the initial setup instructions.

Ok - some updates for today.

#1 - Finally got the timing adjusted at idle. It is a little jumpy but not awful. Idle is still way too high (2000 rpm). Idle screw on thrttle body is all the way in. ICV is disconnected physically and turned off in the software.

#2 - I have a pretty good oil leak at the front of the engine - have to investigate that - guess it is a not seated seal

#3 - knock light is off now for the most part so feel better about that (I did not do anything to it).

#3 - Next step before anything else is to get the oil leak fixed and idle speed down to normal.