Topic: Turbochargers

[st.chevrolet]

the moment that valve starts to open you'll drop boost and will close back
one issue is how you control it

assuming you find a way with some fast switching electromagnetic valves that would open/close in sequence (not mechanically actuated as that would not work) second issue is how do you control the fuel delivery for anything over 0 pressure.
let me explain this last one (i'll simplify the numbers):
your stock map reads 0 absolute pressure to 14.7 absolute pressure (no vacuum, wide open throttle) - the voltage output is 0v to 5v (at idle you'll have something like 1.6 or close to that) - your fuel delivery is based on that range
once you do this mod and let's say you're at 6 psi max boost for a total of 20.7 psi absolute pressure - how do you compensate for the extra air between 14.7 psi and 20.7 psi - you will need more fuel and will not be a set value but progressive as the boost increases
what you need to do is to shift your map output so it will give you 1.6v at idle and 5v at 20.7psi

in reality the stock 1 bar map outputs something like 4.7v at wot

you can do it with a 2 bar map and a volt mod for the map input, but you'll also need a voltage limiter on the output of the MAP so it won't go over 5v or it will set a fault code in your PCM and possibly stop functioning until you reset the computer

the other alternative is to keep the 1 bar map and use an FMU (you'll have to determine the ratio you need)

your stock 1 bar map will only read 1 bar so potentially you can have it in the same spot as the stock one without this bypass valve you are trying to do - i had it that way and it did not damage mine but i can't guarantee you that it won't happen to yours

but regardless, your computer will most likely throw codes if you with one of these options, you will not be able to tune it properly and instead of getting 30% increase in power once you're at full boost you'll get like 10% or best case scenario if you manage to tune it for that specific range your mpg will hurt badly - for the amount of money, time and research you will put into getting it to work you'll be better of buying a piggyback from the start. As i understand this is your DD, if you mistune it you'll risk damaging the engine - if it was a drag racer then you would mostly be worried to get it right in a specific rpm range and mostly at wot which makes it lot easier, in your case you need to make sure it will function properly at all ranges. Your PCM needs to have the fuel trims in a reasonable range or it will never be able to compensate, that's what the fuel delivery table is for.

But, if you decide to go with something other than the programmable piggyback let us know your progress - i'll be interested in finding out how it goes.

X2

[st.chevrolet]

Vodkaman  I have been advised by others who have tried it, that the OBDII TJ's work well with just mechanical fuel management. ie: the Hesco # HESTJFMU  TJ Fuel Management System  (www.hesco.us) along with injectors from a 5.0 Mustang or Ford truck. I realize you are looking for the perfect answer and not finding it, however Air Sierra's setup works well, his peak boost is only 6psi and his stock computer handles it fine with NO check engine lights. My setup works well also (2.5L) its my DD an I get no check engine lights. I use the SS PSC-1 and also water/methanol, works great with my OBDI system. You should probably follow Air Sierra's build along with whatever additional options you chose to use ie: Split Second FTC-1 or HESTJFMU along with larger injectors.

[sharpxmen]

Nothing new under the sun. The valve is suggested  already exist: http://www.synapseengineering.com/
Ml 003 Missing link - is the one for TJ.
It's not because I refuse a piggy back, it's in addition, to avoid Check Engine light at boost.

if you get a piggyback and you properly size your injectors you will not get a check engine light. Your stock MAP will be replaced by the piggyback system.

i looked at that link you posted, which valve are you referring to on their site, SB001?

[sharpxmen]

i looked at that link you posted, which valve are you referring to on their site, SB001?

nevermind, you did mention it ML003

if you use a piggyback you don't need it - you can limit the voltage output in the MAP output table.
if you go with an FMU or voltage mod + 2bar or the long shot of keeping the stock MAP then you can make use of it

if you use it with the piggyback then it won't work or to be more specific there's no point in getting the piggyback as this valve will cancel any benefits you would get from the piggyback in boost (won't read anything over atmospheric pressure).


EDIT: whichever way you twist it, cheapest way is the Split Second PSC1 + properly sized injectors. Not sure how much this ML003 costs though, maybe you're onto something or might be that i don't see the whole picture (not sure of your final plan) so maybe you should clarify the final layout (it will keep me from guessing).

[Vodkaman]

I've just heard that the boost can physically destroy stock Map, which will result in Check Engine light on.

[sharpxmen]

I've just heard that the boost can physically destroy stock Map, which will result in Check Engine light on.

you won't be using the stock map, it gets removed when using the PSC1 or FTC1

[Vodkaman]

Yes, I was mistaken. It is a Split Second which is installed in between stock Map and PCM. Correct?

[sharpxmen]

Yes, I was mistaken. It is a Split Second which is installed in between stock Map and PCM. Correct?

you replace the stock MAP output going to the PCM with the SS PSC1 or FTC1, whichever you chose to go with

Also, according to Sean (St. Chevrolet) you might get away without a split second unit (check his last post in this thread)

[Vodkaman]

Well, Hesco & SS are at the same price, so I prefer SS, because of computer control. Air Sierras thread is closed, at least he does not answer. There are big questions to his setup, because according to you, stock Map is not  able to suffer the boost. So his setup works, but how, nobody knows.

[sharpxmen]

Well, Hesco & SS are at the same price, so I prefer SS, because of computer control. Air Sierras thread is closed, at least he does not answer. There are big questions to his setup, because according to you, stock Map is not  able to suffer the boost. So his setup works, but how, nobody knows.

he might have an FMU or he might just had his tuned for the full boost and he drives conservatively most of the time. an FMU would help in this case (stock MAP)

EDIT: Split Second PSC1 is $285 if i remember correctly, Hesco FMU with the Fuel Pump on it is something like $600

[st.chevrolet]

Sharpxmen
SplitSecond has some new products and the price for PSC-1-002 has dropped to $239.00, I paid $265.00 when I bought mine.The FTC1-019B is   $499.00.That Hesco TJ FMU looks pretty easy for a DIY build. Air Sierra's setup worked fine with the stock ECM as long as he limited boost to 6psi, its all in his thread.

[sharpxmen]

Sharpxmen
SplitSecond has some new products and the price for PSC-1-002 has dropped to $239.00, I paid $265.00 when I bought mine.The FTC1-019B is   $499.00.That Hesco TJ FMU looks pretty easy to build. Air Sierra's setup worked fine with the stock ECM as long as he limited boost to 6psi, its all in his thread.

that's even better then ($239).

I guess what i am wondering with air sierra's setup is what would his AFR be if he's cruising at 2 or 3 psi of boost down the hwy - since in that case he would pretty much get the same amount of fuel (theoretically) as at 6 psi - not sure if you get what i mean. If you drive mostly w/o boost and only go up there once in a while when needed it might do the job. Maybe is something specific to 2.4L OBD2 PCM that i'm missing.

yeah, you can make the hesco setup but still need to buy a high press pump and an fmu - my guess it will be more than $239 though (damn, that's pretty good) so why not just use what's known to be working (but for sure he should email sales at splitsecond first to make sure that the unit works with the 2.4L PCM).

[st.chevrolet]

that's even better then ($239).

I guess what i am wondering with air sierra's setup is what would his AFR be if he's cruising at 2 or 3 psi of boost down the hwy - since in that case he would pretty much get the same amount of fuel (theoretically) as at 6 psi - not sure if you get what i mean. If you drive mostly w/o boost and only go up there once in a while when needed it might do the job. Maybe is something specific to 2.4L OBD2 PCM that i'm missing.

yeah, you can make the hesco setup but still need to buy a high press pump and an fmu - my guess it will be more than $239 though (damn, that's pretty good) so why not just use what's known to be working (but for sure he should email sales at splitsecond first to make sure that the unit works with the 2.4L PCM).

In his thread Air Sierra mention's he has an onboard engine analyzer and that the AFR is perfect through out the entire rpm range as far as rich/lean conditions. He also mentions trying different injectors but going back to the stock injectors.

[enginethatcould]

I bought the manual about a month ago for $7.50 US, and for anyone wanting to turbo the 2.5L YJ this is a perfect step by step on how to do it. If you follow the guide it shouldn't cost you allot somewhere in the area of $350. I have been accumulating all the parts I need to do it, all I have left is to buy injectors and to date I have spent $270.
For anyone wanting to turbo there Jeep and knows little about turbos this is the best help you can get especially for $7.50
I give this guide a high rating, but I did change a few things from the way the guide said to do it, but only because I am a bit of a perfectionist and didn't mind spending the extra bit of money.

Is this book still out there? If so where can I find it?

[jfrabat]

Is this book still out there? If so where can I find it?

There was a PDF on eBay at one time that was a guide to turboing a YJ, but, IMHO was worthless...  I did get Corky Bell's Maximum Boost, which is a much better guide.  It's not only a guide, but explains the why's and how's...