Large Boost Spike

DCsleeper · Oct 10, 2006, 05:56 AM

I am running CLB control, ABC around 2-2.5 turns out with a gain setting of 60. Lately with the colder temps I am seeing a large spike in boost under the following conditions. Basically, if I am cruising around 70 and punch it in 5th I get a spike to 25 psi and hit the boost limiter. The same situation occurs if I downshift to 4th and punch it. A normal 3rd gear pull I get a spike to about 23psi and then tapers down to 20 by readline.

What could cause this boost spike? Any ideas of how to correct this issue. I am not seeing any knock but it sucks to slam into the boost limiter and have the car fall on its face.

Thanks,
DcSleeper

nirvevo · Oct 10, 2006, 08:20 PM

Quote:

Originally Posted by DCsleeper

I am running CLB control, ABC around 2-2.5 turns out with a gain setting of 60. Lately with the colder temps I am seeing a large spike in boost under the following conditions. Basically, if I am cruising around 70 and punch it in 5th I get a spike to 25 psi and hit the boost limiter. The same situation occurs if I downshift to 4th and punch it. A normal 3rd gear pull I get a spike to about 23psi and then tapers down to 20 by readline.

What could cause this boost spike? Any ideas of how to correct this issue. I am not seeing any knock but it sucks to slam into the boost limiter and have the car fall on its face.

Thanks,
DcSleeper

I don't think that the following comment is the whole problem - but I'll be it's a contributing factor - the dreaded ABC - it took me a while and a few bad days at the track to finally look at it. I put on a Hallman - ..... bing ....Boost spikes gone.

I don't know if that thing gets dirty , worn out, or just sucks out of the box.

At first, I wouldn't listen to a few different shops around town that turned their noses up at it. I thought, TurboXS wouldn't send it out if it wasn't atleast usable. I might have been wrong about that.

Most if not all MBC's have to be adjusted with colder weather (or if the barometric pressure goes up.) The electronic ones have the ability to self govern themselves when the barometric pressure changes and the density of the air is affected.

Good Luck (Hallmans are cheap at JSC Speed - you can usually get one for around 70 or 80 - or get an add on remote cable and control it from the cabin for about 130 - according to the guy that makes the Hallman, the regular Pro model is fine the the Evo)

DCsleeper · Oct 15, 2006, 04:49 PM

Update...

turned the boost down to hold approximatly 21psi. I hit full boost around 3200 rpms and can hold static till about 5500 then tapers off to 19 by redline....this is in a forth gear pull up an onramp ....good thing it is fairly long

From what I have read 21psi is max for the ABC and stock bcs setup. Oviously if you try to exceed this you have the problems that I had earlier. Probably in the near future I will install either the Perrin EBCS or Jack's GM setup.

Now if I can just get back some of the power I lost.... Now that I have the boost and fuel in line I think that I maybe able to gain some hp in the timing...probably will have to wait till next week.

At least it is running safely now.