First start Issues; Tach and Idle

[airfix4]

1970 Porsche 911t
2.2L
GSXR 600 ITB's,
MS2 v3.57
Fuel only

I fired up the 911 for the first time this weekend. The IAT and MAT (calibrated thermistors) were hooked up but not installed.

The idle was decent at first (I expected it to be a little high for warm up period), then dropped down to barely running.

There is a significant tach difference (~1000 rpm) between the car and tuner studio. Tuner studio thought it was around 1k and the gauge was hardly registering. This needs to be resolved. I have pertronix installed. Pic attached.

Tach Hookup.jpg

Again, to this point the IAT and MAT were positioned near each other, i.e. no differential.
Then I place the the MAT on the cylinder.

Idle jumped up significantly (3K). I let it burn off the residual oil, cobwebs and who knows what else for a couple minutes before shutting it down. The car has been sitting for 19 months waiting for me to finish this project.

It seems to be running rich. I'm sure I didn't give it enough time to "blow the cobwebs" out of it, but figure baby steps will increase the probability of success.

So I'm gathering my thoughts and welcome input/suggestions. The current tune was written for a 42psi system, I believe. I'm at 49psi. Perhaps lean the entire map 2-3% and run for a bit to let things stabilize??

Tune is also attached.

Hall 1970 911t 2_2L.msq

[airfix4]

I read this in the megamanual, "If your dash tachometer no longer works after sharing when sharing a signal with MegaSquirt® EFI Controller, the most common solution is to add a resistor with a value between 1K and 100K Ohms to the tach input line to MegaSquirt. This is simple and cheap, and there's no switching issues or other complications. Some people use a 100K pot as variable resistor, tune it until it works, then replace it with an equivalent resistor", but my issue is a difference between the car tach and tuner studio. The dash tach seem more accurate, although bounces a lot as it always has.

[kaeman]

if your tach has always bounced a lot then I would suspect it isn't in very good shape, they do wear out.... just like all mechanical and electrical things. the megasquirt is being used fuel only then the signal its getting might not be properly filtered and may require some small adjustments to get a clean signal. the ecu is only going to work as well as the info it receives and processes, you need to mount the sensors correctly and then try running the engine, both temp sensors are use in fueling calcs... quit guessing and just finish the install, then work on starting it, mount all the sensors, make sure all power and grounds are correctly attached as per instructions in the manuals. then fire it up... otherwise you will be chasing your tail trying to fix stuff that's not broken and that's a big pain...good luck.

[airfix4]

Thanks kaeman,

I replaced the tach signal wire with a better shielded wire and fixed the tach surge issue. I also took your advice and finished the install. I was able to get it out of WUE finally and start tuning after a fuel pump replacement. I'm making some progress, but have to set aside significant amount of time to do any tuning, as it takes a while to get 11 quarts of 20w50 oil to temperature. I think someone expierienced would be able to tune well where I currently am, but I will probably have to splurge for an o2 to dial things in.

[kaeman]

yes a wideband o2 will make tuning much easier. you will actually know what your engine is doing. and the ecu will be able to see the changes as they happen.