I may be overboosting

V8Huntr · 07-07-2008, 11:12 AM

Well I was on the highway last night and went to move around some guy doing about 45mph. Well I dropped into 5th and went WOT. I noticed out of the corner of my eye that my boost gauge read 22lbs! Well I thought I may have just misread it.

After I left my girlfriends house I got onto the highway. There weren't any other cars on the road with me so I shifted into 5th and mashed the gas again. The boost gauge rose steadily to 22lbs again and held there. There was no spike and settle, nor was it creeping.

I then dropped into 4th and went WOT and the boost was normal with a spike of 20 which settled back down to 18-19lbs. I shifted right into 5th and kept WOT and it was normal with the same spike of 20 which settled back down to 18-19lbs.

It only seems to overboost in 5th gear when going WOT from low speed and low rpm. It does not do it in any other gear because I have tested every gear individually under these conditions.

Mods are:
Cobb AP V1 - Stage 2 OTS Map
Helix CATTED DP
HKS HiPower Catback
AEM cold air intake
NGK 1 Step colder plugs
Prosport electronic boost gauge

I know for a fact that it is not due to the intake because I have been stage 2 for 40K miles and it has been on the whole time. I have had the intake tested for its affects on AFR and it didn't have any ill effects because my AFRs were dead on.

My only thought is that the boost gauge is going bad because it's a Prosport Boost gauge and I'm not sure how accurate it really is. I'm going to clear the ECU tonight when I get home and try this all again in a few days after the ECU has had time to learn.

Anyone have any other suggestions as to what may be causing this??

bluedemon_II · 07-07-2008, 12:53 PM

You are going into WOT in 5th gear from 3,000 rpm or so right? Because if it is like that then your solenoid cant keep up with the pressure spike and it will boost up higher than its supposed to until the solenoid gets to a point in a upper rpm that its able to regulate it. My Auto meter gauge reads the same psi when I mash the accelerator at the same conditions that you do, I'm supposed to be running 21.5- 22 psi and if I do this it will go up to 23.5 or so but i run a MBC but it seams that my boostcontroler cant hang up in them psi. I'm changing to an other mbc "hallman" or an gm solenoid.

ninjaboy76 · 07-07-2008, 01:08 PM

Try verifying your boost readings with the Cobb AP. Most boost gauges aren't accurate. It sounds like you are boost more than what a stage two map is suppose to in every gear. You should only be boosting around 18 psi. You may have to try a LWG map to correct the problem. I had to run a LWG map on my 04.

***520*** · 07-07-2008, 01:15 PM

ap only reads to 18.5 right? Maybe v2 is different?
+1 on the LWG map or maybe porting your WG?

ninjaboy76 · 07-07-2008, 01:20 PM

Yes AP only reads up to 18.5 psi, but if he is seeing this then he knows he's overboosting.

07-07-2008, 11:12 AM	#1
V8Huntr Spec C Club Car: 04' WRB STi Fav Mod: TBE Location: Allentown, PA Posts: 1,643 Join Date: Sep 2006 Trader Rating: (0)	I may be overboosting Well I was on the highway last night and went to move around some guy doing about 45mph. Well I dropped into 5th and went WOT. I noticed out of the corner of my eye that my boost gauge read 22lbs! Well I thought I may have just misread it. After I left my girlfriends house I got onto the highway. There weren't any other cars on the road with me so I shifted into 5th and mashed the gas again. The boost gauge rose steadily to 22lbs again and held there. There was no spike and settle, nor was it creeping. I then dropped into 4th and went WOT and the boost was normal with a spike of 20 which settled back down to 18-19lbs. I shifted right into 5th and kept WOT and it was normal with the same spike of 20 which settled back down to 18-19lbs. It only seems to overboost in 5th gear when going WOT from low speed and low rpm. It does not do it in any other gear because I have tested every gear individually under these conditions. Mods are: Cobb AP V1 - Stage 2 OTS Map Helix CATTED DP HKS HiPower Catback AEM cold air intake NGK 1 Step colder plugs Prosport electronic boost gauge I know for a fact that it is not due to the intake because I have been stage 2 for 40K miles and it has been on the whole time. I have had the intake tested for its affects on AFR and it didn't have any ill effects because my AFRs were dead on. My only thought is that the boost gauge is going bad because it's a Prosport Boost gauge and I'm not sure how accurate it really is. I'm going to clear the ECU tonight when I get home and try this all again in a few days after the ECU has had time to learn. Anyone have any other suggestions as to what may be causing this?? This ad is not endorsed by this member. Please register or login to hide this ad.

07-07-2008, 12:53 PM	#2
bluedemon_II Grassroots STI Racer Car: 04 Sti Wrb on Silver Location: Hatillo, Puerto Rico Posts: 501 Join Date: Jul 2007 Trader Rating: (0)	Re: I may be overboosting You are going into WOT in 5th gear from 3,000 rpm or so right? Because if it is like that then your solenoid cant keep up with the pressure spike and it will boost up higher than its supposed to until the solenoid gets to a point in a upper rpm that its able to regulate it. My Auto meter gauge reads the same psi when I mash the accelerator at the same conditions that you do, I'm supposed to be running 21.5- 22 psi and if I do this it will go up to 23.5 or so but i run a MBC but it seams that my boostcontroler cant hang up in them psi. I'm changing to an other mbc "hallman" or an gm solenoid.

07-07-2008, 01:08 PM	#3
ninjaboy76 Spec C Club Car: 08 CBR1000RR Fav Mod: None Location: Kansas Posts: 2,434 Join Date: Jun 2004 Trader Rating: (6)	Re: I may be overboosting Try verifying your boost readings with the Cobb AP. Most boost gauges aren't accurate. It sounds like you are boost more than what a stage two map is suppose to in every gear. You should only be boosting around 18 psi. You may have to try a LWG map to correct the problem. I had to run a LWG map on my 04.

07-07-2008, 01:15 PM	#4
*520* STi > EVO... Wait what??? Car: 03 EVO Fav Mod: stock :( Location: Michigan / Saint Louis Posts: 12,397 Join Date: Oct 2005 Trader Rating: (1)	Re: I may be overboosting ap only reads to 18.5 right? Maybe v2 is different? +1 on the LWG map or maybe porting your WG?

07-07-2008, 01:20 PM	#5
ninjaboy76 Spec C Club Car: 08 CBR1000RR Fav Mod: None Location: Kansas Posts: 2,434 Join Date: Jun 2004 Trader Rating: (6)	Re: I may be overboosting Yes AP only reads up to 18.5 psi, but if he is seeing this then he knows he's overboosting. This ad is not endorsed by this member. Please register or login to hide this ad.