Boost problem. Cuts out around 15-17psi.

blackevolution8 · Apr 25, 2009, 01:48 PM

Here's my issue. Im using a map from my last car with almost the same exact setup. stock turbo, stock head, stock bore block, Tial bov w/ 11psi spring, 280 cams, 1000cc injectors, 3" turboback, AEM speed density.

Here's the differences. Last years stock turbo had the 10.5 hotside and buschur o2 housing. This turbo does not. Also last year I had the 5 bar map sensor. This year is 3.5.

I took the map and only changed the map sensor. Then rewrote the kpa axis and 275kpa max. Never touched anything else. I put it up on the dyno and leaned out cruising speeds. Never touched timing yet. Car was running great. I made a couple of small pulls getting to near 10psi and stopping just to lean out those settings. I got a good 11.2-4 afr. Now I raised my rpm on the dyno and went for a full pull. Im using the buschur boost controller but only made 1 turn to make sure it would make a pound or two over stock.

As soon as I hit 190kpa, it acted like a fuel cut or a coupler blew off. I checked everything. AFR's at 11.3, timing at 5-6 advanced. Little knock. All couplers were tight. I tried it again. Same thing. I removed the buschur mbc and tried an old forge that I had. Same thing. 15-17psi it bucks and cuts out.

Does anyone have any ideas? I used this map last year and only changed the map sensor to 3.5. I ran 26psi last year with no issues. Im stuck and I cant find anything on the AEM that I might have accidently turned on or off.

It doesnt matter where Im at in RPM. I can go 100% Throttle at 2k rpms or ease into 10 psi and then full throttle from there at 5k RPMs. As soon as it his 15-17psi its cuts out.

MZP@TeamD · Apr 25, 2009, 09:27 PM

It could be so many different things from software issue( Boost cut, the way you rescaled the map and.....) or the hardware problem( spark plug gap, boost or vacum leak and......) if you post a log file or cal map we will have a better idea of what the problem could be.

sba · Apr 28, 2009, 10:14 AM

Did you solve the problem?if yes , what was hapening?

Aby@MIL.SPEC · Apr 28, 2009, 07:36 PM

if you change the axis, did you then take the old, lets say 200kpa ignition & fuel row & paste it into the new 200kpa row? if not, you'll have to do that for all load rows.

how can you make the max load 275 when you have a 3.5 bar sensor? i am running a aem 3.5 & the highest load value i can put in the boost cut is 35.12 / 242.14 kPa

the data value that is located within the map isnt going to change when you change the sensor within the wizard, but the load reference point will.

GL

blackevolution8 · Apr 28, 2009, 07:54 PM

3.5 Bar is approximetally 350 kpa. Which should give you around 36psi gauge pressure. Correct me if Im wrong. If thats right, you should easily be able to set your map and read up to 350kpa with a 3.5 map sensor.

I compared the map to the previous and sure enough it had fuel cut at 180kpa. It must have changed when I selected from 5 bar to 3.5 bar. All my load tables were immedietally smaller which had to have lowered my fuel cut.

I shouldnt boost any more than 25psi right now with my mods so my load table is at 274.8kpa. I went into my options and changed my fuel cut to 274.8 and it stayed. Im not sure why yours wont go higher. Mine did. Perhaps something got set wrong somewhere else? Happened to me.

awdboosted · Apr 28, 2009, 08:11 PM

What is your Fuel cut load set at??
Setup/ rev limiters/ Main Rev Limiter/ Option - Main limit

Aby@MIL.SPEC · Apr 28, 2009, 11:47 PM

Quote:

Originally Posted by blackevolution8

3.5 Bar is approximetally 350 kpa. Which should give you around 36psi gauge pressure. Correct me if Im wrong. If thats right, you should easily be able to set your map and read up to 350kpa with a 3.5 map sensor.

I compared the map to the previous and sure enough it had fuel cut at 180kpa. It must have changed when I selected from 5 bar to 3.5 bar. All my load tables were immedietally smaller which had to have lowered my fuel cut.

I shouldnt boost any more than 25psi right now with my mods so my load table is at 274.8kpa. I went into my options and changed my fuel cut to 274.8 and it stayed. Im not sure why yours wont go higher. Mine did. Perhaps something got set wrong somewhere else? Happened to me.

your right, i didnt take into consideration the vacuum aspect, when using kpa vs psi...as the range is -14.x / +35.12...the range of the sensor for viewing load as psi....kpa i guess scales ~25-350 if i were to change my cal file.

ionut_4g63 · May 21, 2009, 04:22 AM

I got the same problem 2...and it turned out to be the o2housing...and a friend had a problem just like this and it was the fuel pump...it was jumping from the case...check it out.

blackevolution8 · May 21, 2009, 04:45 AM

It actually turned out to be my fuel cut. I didnt realize that when I lowered from 5bar to3.5bar that it changed my fuel cut in my options table. Just me learning the system. Raised it back up and now it pulls great.