i have a stock ROW large port 3.0 in my 79SC. i have an X-faktory ITB kit with ms3x and a base map in my basement. once i get my car sealed, i'll be working on the EFI conversion. i'll try to get my maps up asap and then update as i tune it in...but it's going to be a while.

Sounds good.. my engine is a 3.0 carrera engine, which I believe would have the same ports as yours. However we are using different intake setups.. mine is from RHD here in Australia.... I copied Jaysons ignition and VE tables to my tune, and the car ran quite well.. however was still quite rich. I am slowly finding time to get my throttle linkage setup properly (wasnt seeing 100% throttle movement) and running logs and going through and changing.

Then car started to run on 5 cylinders when cold and as it got warm, ran fine; suspect fouled plugs.. need to pull them and inspect/clean before going further.

Rarely, I get a loud backfire through one of the intakes.. it is rare and difficult to emulate.. not sure what to do with that.
Also occasionally if I am travelling at speed, and shut the throttle, the car will emit a MASSIVE bang out the exhaust.. in my rearview mirror, I can see a large cloud of smoke!! I wonder how much longer my muffler will survive!

Mike, it sounds like most of your problems come back to being way too rich.
Do you have a wideband?
Also, if you’re dumping enough fuel to backfire out the muffler like that, the packing in the muffler won’t be long for this world.

You need to get all 6 throttles synchronized dead on at idle with a carb sync tool. Start by getting all 1-3 sync'd and then 4-6 sync'd and then work on getting the two banks sync'd together. This took me hours to do and I still have 1 cyl that doesn't quite open with the others. But doing any light throttle (1-5%) tuning will be off until you get the throttles all sync'd up.

I wonder if cyl 5 is maybe not opening as much as the others so not enough air is getting to it for combustion?

pops thru the intake are due to a lean condition. You VE map probably isn't lean, but your wall wetting or accel enrichment could be. If you are using Jayson's wall wetting on your ITB setup, don't expect it to work. He runs a common plenum manifold with a single throttle body. ITBs allow a whole lot more air in when you open them 2% than a single throttle plate feeding 6 cylinders will at 2%.
Here is my wall wetting table on my ITB setup. It revs up super quickly and cleanly on my car but might need some fine tuning for your setup:
http://forums.pelicanparts.com/uploa...1528981771.png

Do you have your decel fuel cut setup yet? That will make a huge difference in off throttle conditions and in MPG too.

ok. update.. I got my car dyno tuned with the stock engine and exhaust.. nice and clean, and produced just under 200hp at the wheels..

Then I got the itch for headers and muffler.. and before you know it, I have just rebuilt my motor again using CP 10.2:1 pistons and a Webcam 464/465 grind. Headers are from GT racing (georges european headers) and muffler is a M&K GT3 2in/2out... Off for a tune next week, but would like to know if anyone else has similar compression and cams that can give me something to get half close...

If you are on the throttle and abruptly let up and then get a huge flame or bang out of the exhaust, you probably have the fuel in the lower pressure/vacuum areas set too rich, m2cents.

If you are decelerating and you get little pops but not a huge bang, that is probably closer to where you want to be.

Then, if your software allows it, you should be able to turn off ignition and/or fuel (can;t remember which it is) below a certain level, for example 40kpa. If you do that, the popping will stop as soon as you hit whatever threshold you set (like 40kpa).

This should help control you decel popping and you can adjust that threshold to suit your engine. Set a level for ignition to resume as well as momentary enrichment at resumption, and that should get you to a good landing spot at idle.

I also throw more timing in the cells below idle range, so if the rpm's drop on decel, the timing increase will juice the rpm's back into the cells where the idle is expected and tuned for.

Hope this is useful. I only read half the thread but seemed like you were trying to sort out decel popping, which is something I had to do in the past.

Bumping this back up, also adding my NA VE table at the request of Jim:

http://forums.pelicanparts.com/uploa...1565105465.jpg

Emery I love my flames:D

LOL yeah baby! flames and decel are the best :)

2.7l
 

I've had this tune for about 3 months and it's working really well. 77 911S, 2.7L, JE 9.5:1, 40mm PMO's, stock cams.

IGN:
http://forums.pelicanparts.com/uploa...1565651455.jpg
VE:
http://forums.pelicanparts.com/uploa...1565651544.jpg
DYNO:
http://forums.pelicanparts.com/uploa...1565651576.jpg

I'm new to this, so find it interesting to see the different scaling for rpm and tps brealpoints (did I use that term correctly?)

Also, I notice that my car takes a while to fire up when starting.. if I turn the key for a few seconds, then stop.. then try again.. it starts reasonably well.
But if I just keep trying to start without the pause, it takes a long time to fire up....

Any suggestions?

On mine, it likes a quick blip of the throttle when starting cool.

Sounds like it is waiting for fuel pressure to build up. I think it's bleeding fuel back into the tank while turned off instead of leaving the system pressurized.
Check your check-valve at the pump.

mike, what do you have for your crankingVE, crankingIGN and crankinglambda? These will be on the "starting" tab in AEM's out of the box layouts I believe. Maybe just take a screenshot of that tab and upload.

I have the exact same issue. No problem whatsoever when reasonably warm already, only cold starts. I have tuned the 'start' functions in AEM's software ad-nauseam with no change. I have the fuel pump prime the system with pressure for a few seconds before firing so I know it's not that.

That's a great little engine, on stock cams no less! A solid 2.7RS MFI motor makes those numbers at the wheels on a dynojet.

Are you running a knock sensor? Just wondering how you got to your final WOT ignition timing numbers as they are very close to mine. Trial and error on the dyno? I'm running twin plug with a bit more compression @ 10.5:1, 2.8L EFI ITB motor.

Yeah, the HP numbers seemed a bit high to me as well. What was discussed with the tuner was setting the timing using MBT with a knock sensor installed, however, I wasn't there when this was performed, but they are a good shop. He spent quite a bit of time trying to flatten out the torque curve to no avail, not sure why yet.

Having a shop that knows to do it via MBT and proper sensors is fab. Again, fabulous little motor. Throw a DC40 cam in and I'm sure you'll see another 12-15bhp at the wheels, or don't!

If you're using a magnetic crank ref, might try measuring output and check/adjust the noise floor.

My Bosch ref sensor puts out 0.9V-1.1-ish peaks at cranking speeds (roughly 200 RPM). The MoTeC default "ignore anything below this" setting was 0.3V (and the helpfile says "half to 2/3rds of peak value").

I increased it to 0.4V and it seems to achieve sync (and thus fire injectors and coil packs) much faster - I believe it's firing up as soon as it sees the 2nd or 3rd cam sync pulse. Before it'd take a good 3-4 seconds turning over before it would get sync and catch.

I set the value lower, out of curiosity; ECU thought it was spinning over on the starter at around 5K. Just reading noise...

That's great info. Will look into that with AEM software. Using Motec Hall sensors for both crank and cam.