Thread: Map sensor reading goes from 35kpa to 65kp every 6 seconds?

Recently had my lim removed and supercharger for a lifter replacement. I noticed my boost gauge at idle would jump from 20hgs to 10hgs every 6 seconds. I plugged my hptuners in and ran a scan. Noticed on the map sensor gauge it would go to 35kpa to 65kpa every 6 seconds following my after market boost gauge. I checked all my vac lines, looked good to my knowledge. I checked the diagram also. Also when on the highway when slowing to get of the exit it stays at 10hgs on the boost gauge and 65kpa at the map sensor on my hp tuner. Car idles and drives fine. Do you guys have any ideas what might be going on. Sorry for the long read. TIA.

I beat there is a vac leak at your tb spacer.

scan idle air counts and see what they say

If theres a leak at the spacer, i replaced both gaskets though, should I pull it apart again and use blue gasket sealer on both sides of the gaskets?

ok I scanned the idle steps at idle heat off. Goes between 15 to 18 steps if Im reading it right. Then when I turn the heat on it goes to 25 to 28 steps. The boost gauge stays right at 18hgs. But as soon as I turn the heat or air off the boost gauge moves to 10hgs and back to 20hgs every few seconds. Weird... Thanks for the help so far.

Idle air counts should read in the mid 40's at idle. Sounds like you have a vac leak. Are your LFT's maxing at 16.4 aswell at idle and decel?

get rid of the spacer. it doesnt do anything.

its not supposed to seal 100% you weirdo.

I have the spacer there for my nitrous port. At Idle my lifts are normal. I will scan again right now and look.

this is assuming you have a stock cam. Cams can change Air counts

I have stock cams.

Yeah Id say you have a vac leak. Id take a spray bottle and spray around with a high concentration of soapy water and see what you find.

Ok just scanned again and my LTs are at 13+ at idle and when i rev it goes to 2+ and then back to 11-13LTs Short term fuel is steady at 0.0 to 0.3

But if its a vac leak how would soapy water work, wouldnt it just suck the stuff in instead of making bubbles.

yep probably a leak. It works you will see the bubbles get pulled in, and the water around will bubble up as the waters drawn in

is the vac leak near the throttle body?

Originally Posted by 02grandprix

is the vac leak near the throttle body?

Could be. Could also be at the Blower/Lim. Could be at the EGR tube. Could be vac line itself

No luck, maybe i ll grab some carb cleaner or starter fluid later on today and give that a try, or is there a better way to do it?