MicroSquirt.com read only forum (Jan.15,2018)

Remember, not all engines will be happy at 12:1 AFR. Richer = cooler = less chance for detonation.

In addition, you should remove or lock open the TVIS system. It is super restrictive and will remove one variable from your equation. Not to mention the stock AFM is most likley pinned wide open, still thinking that you are running 11 lbs on a stock sized turbo and outputting timing values accordingly.

Ditch the stock ECU and airflow meter and control spark with the MS. Done.

As far as detecting knock, bolt some copper tubing to the head or block and attach some heater hose connected to a can (det can) this will allow you to hear past all of the mechanical noises and listen to what is going on inside the chamber. Also check the plugs after EVERY pull.

nfn15037 wrote:Remember, not all engines will be happy at 12:1 AFR. Richer = cooler = less chance for detonation.

True, but i have it on decent authority that this is pretty safe on this engine and i have no other bad signs yet.

In addition, you should remove or lock open the TVIS system. It is super restrictive and will remove one variable from your equation. Not to mention the stock AFM is most likley pinned wide open, still thinking that you are running 11 lbs on a stock sized turbo and outputting timing values accordingly.

The TVIS is open past 3800Kish rpm anyway, so theres little point in locking it open as you just lose low end torque. Ideally you'd remove it yes but its not meant to be THAT restrictive until big flows?

Ditch the stock ECU and airflow meter and control spark with the MS. Done.
As far as detecting knock, bolt some copper tubing to the head or block and attach some heater hose connected to a can (det can) this will allow you to hear past all of the mechanical noises and listen to what is going on inside the chamber. Also check the plugs after EVERY pull.

I plan to do this very soon. I'll be doing the det can thing ASAP but i cant check the plugs after every pull - that would be insane - its not so simple on the 3sgte - 2 intercooler mount bolts, 3 IC guard bolts, remove cover, undo 3 hose clamps, remove IC with a struggle, allow 3 hours before engine is touchably cool then reverse to re-fit. It'd be one run a day at that rate! Its literally a 45 minute job and damage to clamps etc ever time. I've checked them fairly regularly. I'm running cooler grade plugs too for safety. Never seen any bad signs as yet (fingers crossed lol).

J

On my 4age I have my TVIS set to open at 4400.
It makes the idle noticably smoother and the boost comes in maybe 15% faster with the TVIS closed.
Not surprising with the ovesized large port head.

I also noticed I had to advance ignition noticably after TVIS opened.
A sign that mixing still is less effective at the transition RPM?

See maps on my success story page.

[ps. it takes me less than 60 seconds to remove my intercooler ]

I've just thought, I can access one of the plugs without removing it. But its not good to keep pulling plugs from an alu head. I could do the IC removal faster but its such a complete nut-ache and its slowly damaging all the hose clips and the connector hoses. Plus it is physically impossible to touch with heat for quite some time.

J

I have a 165 AllTrac, so feel your dilemma. However, the spark plugs are a very good indicator of timing, and they will show visible signs of detonation long before the untrained ear will. After, all the plug is IN there! Use antiseize and be careful with the threads, but you must get a look at the plugs. You could be here asking all these questions and listening to this noise for a few days and in that time you could spin a rod bearing or blow a head gasket if it really is detonation! I know people that calibrate engine magement systems for a living, and pulling the plugs is common practice.

The reason I suggested locking the TVIS open is to rule that thing out of the equation. If the noise goes away, obviously it is something with the TVIS. If not, cross it off the list and continue on the troubleshooting flowchart.

OK, cheers for the ideas. As you say I should stop being lazy really. Ive had this noise for a while and never noticed spatter on the plugs, even on cyl3. Its just louder than ever now. I have had a couple of other CT20b-on-185 drivers claim to have the same noise and im fairly sure i didnt get it with the CT26 so that throws another spanner in there - is it just the intake noise of the CT20 at high boost?? :s

I'll try pulling the vac hose and plugging it for the tvis which should hold it open for a test run.

J