volvolove Posted July 1, 2004 Report Share Posted July 1, 2004 Opened my car up on the highway tonight from about 50-90 and found the following. 1) Spiking to 17 lbs - however the BCS quickly brings it back down to 15. 2) Air fuel mixture was reading 1.04 v and holding (which is WICKED rich). Second time I gunned it it came down to around .92- .94 v. I'm hoping that the 1.04v was because of the temperature variance (cool in morning and hot during day) lately and or because I don't floor my car that much. Have any of you guys eliminated boost spike? Link to comment Share on other sites More sharing options...
550 Posted July 1, 2004 Report Share Posted July 1, 2004 I usually get spike inbetween gears, im not so sure you can reduce that, not positive.I know dawes claims there MBC pretty much eleminates spiking, I don't know if that will fit in with your current setup though. Link to comment Share on other sites More sharing options...
jross Posted July 1, 2004 Report Share Posted July 1, 2004 There was a post/thread on here a while ago on how to eliminate spiking... I think it was a technique courtesy of the Saab or Audi guys, but I forget. IIRC, the basic setup was a sort of split section of tubing, with a MBC on one fork of a Y and some sort of valve on the other fork that would vent to atmosphere above a certain pressure.... Link to comment Share on other sites More sharing options...
wills Posted July 1, 2004 Report Share Posted July 1, 2004 If MBC is not in line with BCS then I am not sure the boost spike causes the over rich condition. It is typical with most chip/ECU programers to run to the rich side for safety. Link to comment Share on other sites More sharing options...
Guest DougK Posted July 1, 2004 Report Share Posted July 1, 2004 Opened my car up on the highway tonight from about 50-90 and found the following. 1) Spiking to 17 lbs - however the BCS quickly brings it back down to 15. 2) Air fuel mixture was reading 1.04 v and holding (which is WICKED rich). Second time I gunned it it came down to around .92- .94 v. I'm hoping that the 1.04v was because of the temperature variance (cool in morning and hot during day) lately and or because I don't floor my car that much. Have any of you guys eliminated boost spike?Dont put faith in narrowband 02 readings.I tuned my car to 1.2 volt, blew a headgasket bougth a wideband and found that 1.2v w/ my narrow band at WOT was actually 17:1 AFR. Im dead serious. Link to comment Share on other sites More sharing options...
volvolove Posted July 1, 2004 Author Report Share Posted July 1, 2004 Thanks guys. Does anyone have a link to a boost spike limiting trick thread? And How deadly is spiking to 17 psi for the motor? Link to comment Share on other sites More sharing options...
JHEIII874T5M Posted July 1, 2004 Report Share Posted July 1, 2004 I've run 20 PSI on the 15G with the speedtuning chip and still have high 170's, 180 PSI across all cylinders for compression. Um, I blew a couple exhaust seals I think, though. The Speedtuning chip has you run pretty rich, how do you have the MBC setup? Link to comment Share on other sites More sharing options...
turbobrick Posted July 1, 2004 Report Share Posted July 1, 2004 narrowband a/f gauges are a joke... unless you want to find out too late. Link to comment Share on other sites More sharing options...
JHEIII874T5M Posted July 1, 2004 Report Share Posted July 1, 2004 narrowband a/f gauges are a joke... unless you want to find out too late.yea, but if you want a light show it's cool Link to comment Share on other sites More sharing options...
volvolove Posted July 2, 2004 Author Report Share Posted July 2, 2004 Actually my air fuel ratiometer is just a digital voltage readout, so I don't have to deal with the flickering lights. So all in all a spike to 17 psi for a second isn't to worry about I guess. My MBC is setup inline with the BCS. Link to comment Share on other sites More sharing options...
JHEIII874T5M Posted July 2, 2004 Report Share Posted July 2, 2004 OK, I figured you were inline with the BCS... you will spike that way, and not hold as much boost, a 17 PSI spike is perfectly fine on the speedtuning ECU, glad you got the digi readout lol Link to comment Share on other sites More sharing options...
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