Rob_B 0 Posted May 19, 2005 my boost is bleeding off 4 psi at the top of the rev range in 4th and 5th gears, any ideas chaps? had the timing belt changed and the timing needed setting up again, could this be the problem? cheers, Rob Quote Share this post Link to post Share on other sites
andycowuk 0 Posted May 19, 2005 retard you ignition a degree or two, your car must be pinking more than the ECU can adjust for, so as a safety boost gets vented through the isv. What is the RPM that the boost is vented at? Quote Share this post Link to post Share on other sites
Rob_B 0 Posted May 19, 2005 i would say at about 5k if i then back it off in 4th gear it will boost right up to 13 again but it wont do this in 5th the timing was set to 6 degrees before top dead centre which i believe is correct. Quote Share this post Link to post Share on other sites
andycowuk 0 Posted May 19, 2005 the isv will also bleed boost if you hit .8 bar (11.603019 pounds per square inch) Quote Share this post Link to post Share on other sites
Rob_B 0 Posted May 19, 2005 is that not standard boost level? Quote Share this post Link to post Share on other sites
andycowuk 0 Posted May 19, 2005 std boost is typically around .7bar (I only get .65 on std pulley although i have p&p head/charger) Something must be affecting your isv that it is holding slightly more boost before bleeding........ Quote Share this post Link to post Share on other sites
Rob_B 0 Posted May 19, 2005 so if the isv bleeds off the boost at 0.8 bar, then putting a smaller pulley on wont do much as the boost will still bleed off at 0.8 bar? Quote Share this post Link to post Share on other sites
andycowuk 0 Posted May 19, 2005 yeah. A guy on the forum sandy had a dyno plot that was done a while ago, but it showd the boost fly up to .8 by about 3.5 - 4k rpm, then it just sat level till the red line...... i wonder if he has it in his members gallery..... Quote Share this post Link to post Share on other sites
swfblade 0 Posted May 19, 2005 surely the ISV is controlled by the ECU?!? and an uprated ECU will bleed at much higher boost?! How come I can get up to 15psi otherwise?!? Quote Share this post Link to post Share on other sites
W3RKD 0 Posted May 20, 2005 the map sensor bleeds at around 15-16psi which is just over 1 bar. there are some good posts on here about how the map sensor works too. Rob-b i would agree with andrew and say that you are running to advanced on your ign timing. how was the timing set ? blue cts off and @ 2-2500rpm ? Quote Share this post Link to post Share on other sites
Rob_B 0 Posted May 20, 2005 yeah the timing was set between 2 and 2500 rpm with the blue water temp sensor off.mite just check the timing again tomorrow. this isnt a belt slip issue is it or just leaking boost? i couldnt really understand it as its only happening in 4th and 5th gears!!! Quote Share this post Link to post Share on other sites
