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scumbag
 
Join Date: Dec 2017
Location: noblesville, IN
Posts: 342
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Quote:
Originally Posted by mikedsilva View Post
Has anyone assembled a stock 3.0 using itbs? Would love to see a fuel and ignition table to suit..
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.
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build thread: http://forums.pelicanparts.com/porsche-911-technical-forum/989493-my-low-budget-dream-car-build.html
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Old 06-13-2018, 11:06 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #21 (permalink)
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Join Date: Jul 2013
Location: Brisbane, Australia.
Posts: 550
Quote:
Originally Posted by chrisbalich View Post
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!
Old 06-13-2018, 12:25 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #22 (permalink)
scumbag
 
Join Date: Dec 2017
Location: noblesville, IN
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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.
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Old 06-13-2018, 06:21 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #23 (permalink)
New-ish 911SC Targa Owner
 
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Join Date: Jun 2015
Location: Richmond VA
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Quote:
Originally Posted by mikedsilva View Post
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.
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.

Quote:
Originally Posted by mikedsilva View Post
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.
I wonder if cyl 5 is maybe not opening as much as the others so not enough air is getting to it for combustion?

Quote:
Originally Posted by mikedsilva View Post
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.
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:


Quote:
Originally Posted by mikedsilva View Post
Also occasionally if I am travelling at speed, and shut the throttle, the car will emit a MASSIVE bang out the exhaust.
Do you have your decel fuel cut setup yet? That will make a huge difference in off throttle conditions and in MPG too.
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Old 06-14-2018, 05:10 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #24 (permalink)
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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...
Old 10-20-2018, 12:07 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #25 (permalink)
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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.
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1988 930 coupe - Silver Metallic
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Old 10-20-2018, 05:45 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #26 (permalink)
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