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[ifly87]

I am tuning a ls, we are running like 10-11psi on it since for some reason I cannot get the boost cut to raise above 11.2 psi. Even still it seems like it is hitting the boost cut sometimes and this is really pissing us off. Its got a stock map sensor in it, how do I raise the boost cut up without changing to a 2.5-3bar and re-tuning it? Everytime I change the boost cut from 11.2 it just pops right back in the box.

[900s]

Isn't the stock map only good to about that much positive manifold pressure? That'd probably explain why it keeps popping back into the boost cut box.

[ApexSilver06MR]

run a 3 bar and be done

[Joseph Davis]

MAP sensors are cheap, engines are not.  Quit fucking around and removing safety features, upgrade the goddamn MAP so you can have more boost and keep the safety feature..

[ifly87]

Its not my car and he only wants the boost he's running now (10-11psi no more), so he doesnt understand why he needs a new sensor. It gets choppy every now and then, and we've already gapped the plugs down and even put in a msd blaster coil thinking it was ignition. I just want to be able to put the boost cut up to like 12-13psi. not trying to cheat the sensor or anything, i'm still keeping boost within the stock sensors limits. It just must be spiking briefly to hit the cut or somthing.

[88dx]

If he dosent want to buy a Map sensor just remove the boost cut and the Vac line to the wastegate 

[ifly87]

I just want to be able to raise the boost cut a few psi, even just to tell me for sure that its the boost cut that its hitting not somthing with the ignition.

[sewell94]

Its not posssible to have a 13psi boost cut with a stock map. The map sensor is how the engine reads boost and activates a boost cut. If the sensor doesn't read that high then the ecu can't activate the boost cut.   Either get rid of the boost cut or get a higher reading map.  OR You could lower the boost slightly.

[ifly87]

I understand how it works, I would be fine getting rid of the boost cut altogether, but like i'm saying it wont let me, I dont know why but if I try putting anything but 11.2 in the box it changes it back.

How are you supposed to "lower the boost a few psi"?? the boost is where this guy wants it, he just doesnt want his shit geeking out at full boost.

[sewell94]

I didnt say to lower the boost a few psi, i said slightly, just enough not to hit the boost cut. Hes not going to notice .5lb of boost. If anything it'll be faster from not hitting the cut. The guy is going to have to make a decison, lower the boost,  buy  a map sensor, or live with having a car that hits boost cut. 

[bigwig]

Dude, forget what you want.  On a stock map sensor, the highest the boost cut can be is somewhere in the world of 10-11psi.

I'll change the variables, but leave the conditions the same.  Say you have an oven that you want to be 500*.  Your thermometer only reads up to 450*.  The oven has the capabilities to hit 500*.  How the hell is the oven going to cut off at 500* if the thermometer reads only up to 450*?  It can't.  You need a new thermometer or to cook at 450* or less.

Switch thermometer with map sensor, and degrees with psi and it's the same damn scenario.

[Joseph Davis]

Its not my car and he only wants the boost he's running now (10-11psi no more), so he doesnt understand why he needs a new sensor.

It OBVIOUSLY doesn't work running up against the limit of the stock sensor... WHY would he EVER need an upgraded one?? 


MAP sensors are not fucking expensive, and all you're doing by trying to save this guy 59 cents is take a hit in your wallet because you certainly aren't charging for your time in order to make him happy with shit he has no intention of spending $15 on - to change the oil, or anything else for that matter. Fuck him, and fuck you for trying to make a fool like that happy.

[bigwig]

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MPX4250AP-ND

Buy 2 so you don't have to pay the surcharge.  Charge the kid $35 for the sensor.  You get a free map sensor and he gets a safer car.

I personally suggest the 2.5bar sensor because it is easier to solder, bigger/less fragile, and 2.5bar is typically enough for anyone.  Honestly, if I were to do a 3,4, or 5 bar of the Motorola sensor, I'd buy Xenocron's board.  The 3-5 bar sensors are SMALL.  There is a picture floating around PGMFI from YEARS ago where I took a picture of a 2.5 bar, 3.0bar, and a quarter.  The small casing is annoying enough where the extra $20 for the board would probably be worth it to me.

[Joseph Davis]

I had a more difficult time soldering sensors to Blundell's board (that is sold as xenocron's) than I did soldering directly to the sensor.  I'm 100% sure glue would have fixed that, but with how hard they are to align quickly I'd make sure the superglue and board (and room) is cold so it doesn't set up as quick, or just use another kind of glue and wait 4-14 hours before soldering.

[bigwig]

Ive never touched the board and I only call it a Xenocron board because he is the one who exclusively sells it.  I ASSumed that the board would make life easier because fixing those wires to those little legs on the sensors seemed like a huge hassle.

I wish Motorola would have just sold the higher pressure sensors in the same casing as the 2.5bar.  That would be ideal.

[Joseph Davis]

Xeno makes it very lucrative for those of us who want to design gear, and offers to provide startup cash if we have a working prototype.  Further, the sort of people who want to build stuff don't want to play salesman.  It's not a bad situation.

[ifly87]

Yeah I understand how it works, I just didnt want the boost cut on there. I just straight up told him i'm not helping him unless he goes with a bigger sensor.

[Tim]

it won't let you raise the boost cut above 11.2 because your right most column is 11.2

How do you know what your car is actually running when your that close to your map limits?

I had an unknown spring running stock map and freelog and when I switched to ectune with a 2.5 it confirmed my suspicions that my boost gage was horribly off.

[ryan89crx]

I had an unknown spring running stock map and freelog and when I switched to ectune with a 2.5 it confirmed my suspicions that my boost gage was horribly off.

I have only had one boost gauge read close to correct ever. Seems like they are ALWAYS incorrect.

[bigwig]

I had an unknown spring running stock map and freelog and when I switched to ectune with a 2.5 it confirmed my suspicions that my boost gage was horribly off.

I have only had one boost gauge read close to correct ever. Seems like they are ALWAYS incorrect.

Gauge pressure and map pressure are not the same.  Not to mention, the pressure shown in Crome is wrong.  Whoever did the algebra did it dead wrong.  It's not HUGELY off, but it is off.

[lilpooh21186]

drop that knowlage bigwig there's ablsolute and guage pressure fuck guage pressure tune your Vehical KPA style Or millibar

[Joseph Davis]

I had an unknown spring running stock map and freelog and when I switched to ectune with a 2.5 it confirmed my suspicions that my boost gage was horribly off.

I have only had one boost gauge read close to correct ever. Seems like they are ALWAYS incorrect.

Gauge pressure and map pressure are not the same.  Not to mention, the pressure shown in Crome is wrong.  Whoever did the algebra did it dead wrong.  It's not HUGELY off, but it is off.

You base this off of what?

[bigwig]

I had an unknown spring running stock map and freelog and when I switched to ectune with a 2.5 it confirmed my suspicions that my boost gage was horribly off.

I have only had one boost gauge read close to correct ever. Seems like they are ALWAYS incorrect.

Gauge pressure and map pressure are not the same.  Not to mention, the pressure shown in Crome is wrong.  Whoever did the algebra did it dead wrong.  It's not HUGELY off, but it is off.

You base this off of what?

http://forum.pgmfi.org/viewtopic.php?f=35&t=9240
 

[ifly87]

While datalogging, crome is telling me boost is in the upper 10's, and i'm sure its spiking maybe very little but enough to make it hit that cut. Its ok I'm not worried about it anymore.

[DmC]

While datalogging, crome is telling me boost is in the upper 10's, and i'm sure its spiking maybe very little but enough to make it hit that cut. Its ok I'm not worried about it anymore.

funny ive tuned more then a few cars with extra features added for launch control only and never touched the boost cut setting, but ran a few psi past the stock map and never had it actually cut fuel. Look though your logs and stuff I don't think boost cut is your problem.
broke dick pukes can't afford my time anymore. life is good.

[ryan89crx]

While datalogging, crome is telling me boost is in the upper 10's, and i'm sure its spiking maybe very little but enough to make it hit that cut. Its ok I'm not worried about it anymore.

funny ive tuned more then a few cars with extra features added for launch control only and never touched the boost cut setting, but ran a few psi past the stock map and never had it actually cut fuel. Look though your logs and stuff I don't think boost cut is your problem.
broke dick pukes can't afford my time anymore. life is good.

On the older versions of Crome that was possible, but IIRC the Gold roms have the boost cut set automatically, and there is no way to turn it off.

[bigwig]

While datalogging, crome is telling me boost is in the upper 10's, and i'm sure its spiking maybe very little but enough to make it hit that cut. Its ok I'm not worried about it anymore.

funny ive tuned more then a few cars with extra features added for launch control only and never touched the boost cut setting, but ran a few psi past the stock map and never had it actually cut fuel. Look though your logs and stuff I don't think boost cut is your problem.
broke dick pukes can't afford my time anymore. life is good.

On the older versions of Crome that was possible, but IIRC the Gold roms have the boost cut set automatically, and there is no way to turn it off.

If you guys want to fix this issue do the following.

1) Make a BIN file with the cut set to 10psi.
2) Make a BIN file with the cut set to 7psi.
3) Download a hex editor.
4) Compare the two files using the Hex editor.
5) Change the 1 different location to 255(essentially moving the boost cut out of the sensors range)

That SHOULD work, but I won't make a complete promise.

[ryan89crx]

I've never felt the need to boost above the map sensor limit, but thanks for the heads up.

[HiProfile]

I understand how it works, I would be fine getting rid of the boost cut altogether, but like i'm saying it wont let me, I dont know why but if I try putting anything but 11.2 in the box it changes it back.
 

It's probably a new idiot feature. Why would John Cui want to give you the tools to blow up an engine and come back and blame him for it?

The best way to sidestep this is to use a "map clamp" or whatever Dodge guys use. It uses a diode to keep the MAP output just below your boost cut level (voltage) so you can crank it up. BAD idea though, if it's not your car. At 11psi it will be rich and have too little timing, and if it creeps over 13psi, it will be lean with too much timing.



I tuned someone's car for 10.9psi, which he beat senseless for weeks, I made him sign away for no boost cut. Not a WEEK after selling it, the new retarded owner upped the boost and blew the motor. That is what I see happening. At some point he will try for more, or there will be an unseasonably cold day and boost will creep - then BOOM! And he'll blame you. I don't care if it's your dad's twin brother, nobody has respect for anyone now when it involves money vs their stupidity.

[ryan89crx]

Not a WEEK after selling it, the new retarded owner upped the boost and blew the motor. That is what I see happening

Happens ALL THE TIME. Either when he sells the car or the owner decides that it will be fine to up the boost because his buddies told him it was ok.