Ecotec le5 Turbo 2.4 Build (Page 19/28)
4thfiero FEB 24, 12:08 AM
It wasn't the shop that choose the 2 bar map, it was alpha fab who supplied the engine.
wftb FEB 24, 08:48 AM
I do not know about the turbo cars or the newer NA direct injected motors but all other ecotecs use a 1 bar MAP sensor .Using a stock ECM with HP tuners , this is not a problem .Once you hit 1 bar , your spark retard and power enrich tables will be maxed out and going above 1 bar does not further affect those parameters .At that point , I am relying on the wastegate to keep boost down where the engine can handle it .A 2 bar MAP gives more adjustability for sure but just not necessary for my setup .As far as the cold starting goes , this car is dealing with pretty extreme low temps right now and the aftermarket ECM might not have any sort of cold start tables? The other thing is the huge injectors on the car .I have not been on the ecotec forum for quite a while but back then tuning with 80 lb injectors was very difficult for the guys trying for 600 hp. I think the 92 lb injectors are way overboard in this case .I have a set of 44 lb injectors sitting in a box for when I want to shoot for 400 HP . And other peoples experience has shown these injectors will be more than adequate .
4thfiero FEB 24, 08:53 AM
Yeah, the car runs great except for that first start in the morning on a -30 day...using 60lb injectors. Im taking her back to the shop this Friday for them to tune the cold starting again. They are going to have it for 2 days. Hopefully she will be good!
Will FEB 24, 08:30 PM
The stock engine uses a MAF, right?

The Alfa Fab setup is a retuned stock computer, AIUI... which means that they screwed up the cold start enrichment by messing with something they shouldn't have.

The injector size has nothing to do with it. The cold start enrichment is proportional, so if it calls for 10% more fuel, it gets 10% more fuel, whether that's coming from a 15# injector or a 60# injector.

[This message has been edited by Will (edited 02-24-2015).]

wftb FEB 24, 10:34 PM

quote
Originally posted by Will:

The stock engine uses a MAF, right?

The Alfa Fab setup is a retuned stock computer, AIUI... which means that they screwed up the cold start enrichment by messing with something they shouldn't have.

The injector size has nothing to do with it. The cold start enrichment is proportional, so if it calls for 10% more fuel, it gets 10% more fuel, whether that's coming from a 15# injector or a 60# injector.


As long as the injector constant is changed to suit the larger injectors .Pretty sure the stock engine only uses a MAP sensor , not a MAF .
dobey FEB 24, 10:57 PM

quote
Originally posted by wftb:
]As long as the injector constant is changed to suit the larger injectors .Pretty sure the stock engine only uses a MAP sensor , not a MAF .



AFAICT, stock uses a card MAF located at the exit of the air box. The Alpha Fab standalone LE5 harness also includes the 5-pin connector for the MAF/IAT sensor, it seems: http://www.alphafabindustri...-road-engine-harness

Their Polaris Slingshot Turbo Ecotec 2.4L LE5 engine kit also includes a MAF sensor.

If a MAF sensor was not installed in this build, it seems like that was incorrect.
wftb FEB 24, 11:07 PM
My information is kind of dated I will admit . But it usually is an either/or thing anyways : you have a MAF or a MAP but not both .

[This message has been edited by wftb (edited 02-24-2015).]

4thfiero FEB 24, 11:34 PM
Well either way, its a 2 bar map.
jediperk FEB 25, 02:51 AM
Some of the new cars that have forced induction are using both. Personally, I prefer tuning with a MAF. I know from experience though that GM likes the MAP sensor for the turbo ecotec's and you have to upgrade to the 2 bar for high boost applications. For the original OP: when tuning from scratch you always build the "non-sexy" normal driving and start up tables first. WOT tables should be the last thing done. At least that is how I was taught. I'm not saying to throw the shop that did your install under the bus, but if it were me I might let them know in a diplomatic way that it's a good idea to do it right the first time to maintain the good customer relationships that lead to the best kind of advertising: word of mouth. Thanks again for sharing your turbo ecotec build and as soon as the weather clears more pics please.
dobey FEB 25, 09:12 AM

quote
Originally posted by wftb:

My information is kind of dated I will admit . But it usually is an either/or thing anyways : you have a MAF or a MAP but not both .




In the 80s and early 90s, that was true. I can't think of many GM production vehicles made in the last 10-15 years that didn't have both. With modern OBD-II ECMs, it's possible to use both for more efficiency, as there is much more processing power and data storage space in the ECM.