Car wont boost over 10psi

DrBelmore · 11-25-2010, 07:35 PM

Hi I have a 02 bugeye hybrid with vf39, grimmspeed ebcs, and all supporting mods. I have been boosting 19psi at 11.4:1 AFR with no problems. Then all of a sudden one day I was getting on the freeway and I hit on it and it stuttered for a second and then kept going (19psi). Well I get off the freeway and boosted it in first, right when the boost was getting over 10psi the pressure started going all crazy like 13psi, 17, 15, 18, 14, 19. And my AFR's went down to 10:1. Also the motor started stuttering and was kind of shaking (and it was back firing from going so rich). Then I let off and the car drove fine as long as I dont go over 10psi. I tried the same thing in second gear and it did the same exact thing. I did a 20psi boost leak test and heard no leaks. I took off the TMIC tightened all the clamps, checked all the couplers/gaskets and found nothing.

What do you guys think it could be?

Thanks
Eric

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quazimoto · 11-26-2010, 08:55 AM

If your using the factory boost control system sounds like the motor detonated pretty bad and the ECU dropped boost and timing. Post a datalog.

DrBelmore · 11-26-2010, 11:39 AM

Quote:

Originally Posted by quazimoto

If your using the factory boost control system sounds like the motor detonated pretty bad and the ECU dropped boost and timing. Post a datalog.

Oh sorry I should of added that but I am on the Grimmspeed boost solenoid.

quazimoto · 11-26-2010, 06:23 PM

Doesn't mater. The ECU is still controlling the boost. Post a datalog or find out what the IAM is.

gotsugg · 11-26-2010, 10:52 PM

If 10psi is all it will boost, it sounds like you are running spring pressure at your IWG. Could be an issue with you EBC. That doesn't explain the shaking and rich AFRs though.

quazimoto · 11-27-2010, 09:51 AM

Or the engine is knocking repeatedly and the ECU has decided to run wastegate boost.

DrBelmore · 12-03-2010, 10:37 AM

Well I don't have a computer right now that I can datalog but I am still having the same problem. When I slowly give the motor boost, right when I start getting around 8 psi I start hearing tons of fluttering almost like it's the wastegate but it sounds louder then the wastegate. But when I check for boost leaks I cant hear anything leaking.

DrBelmore · 12-03-2010, 04:43 PM

Anyone have any ideas?

GrimmSpeed · 12-03-2010, 05:37 PM

Hey, I do not think our valve is operating incorrectly BUT we just had this same scenario happen, check your wiring connections to the valve, while they are tough if it has been yanked around at all they can break loose. Double check these wires and report back!

Will

DrBelmore · 12-03-2010, 06:22 PM

Quote:

Originally Posted by GrimmSpeed

Hey, I do not think our valve is operating incorrectly BUT we just had this same scenario happen, check your wiring connections to the valve, while they are tough if it has been yanked around at all they can break loose. Double check these wires and report back!

Will

Sounds good. I will check it in the morning. Thanks

Eric

steagalarus · 02-22-2024, 03:22 PM

Did you fix the issue?
Can't go above 15psi boost when I was previously able to get to 22-23.
21 WRX

Mulder · 02-22-2024, 04:55 PM

OP hasn't been on this site in almost 10 years.

steagalarus · 04-02-2024, 03:50 PM

Sadness, I really need to fix my problem

Zackvbra · 04-18-2024, 06:00 PM

Quote:

Originally Posted by steagalarus

Sadness, I really need to fix my problem

Check wastegate duty under boost. If you have an issue with your wastegate it could just be making whatever the mechanical boost limit for the turbo is.

steagalarus · 06-11-2024, 04:35 PM

it was a bad one way check valve for my iag aos
once it was replaced the oil and smoke spewing stopped

11-25-2010, 07:35 PM	#1
DrBelmore Scooby Newbie Member#: 254057 Join Date: Aug 2010 Chapter/Region: MWSOC Location: Milwaukee, WI Vehicle: 2002 WRX	Car wont boost over 10psi Hi I have a 02 bugeye hybrid with vf39, grimmspeed ebcs, and all supporting mods. I have been boosting 19psi at 11.4:1 AFR with no problems. Then all of a sudden one day I was getting on the freeway and I hit on it and it stuttered for a second and then kept going (19psi). Well I get off the freeway and boosted it in first, right when the boost was getting over 10psi the pressure started going all crazy like 13psi, 17, 15, 18, 14, 19. And my AFR's went down to 10:1. Also the motor started stuttering and was kind of shaking (and it was back firing from going so rich). Then I let off and the car drove fine as long as I dont go over 10psi. I tried the same thing in second gear and it did the same exact thing. I did a 20psi boost leak test and heard no leaks. I took off the TMIC tightened all the clamps, checked all the couplers/gaskets and found nothing. What do you guys think it could be? Thanks Eric * Registered users of the site do not see these ads. Last edited by DrBelmore; 12-03-2010 at 04:48 PM.

12-03-2010, 10:37 AM	#7
DrBelmore Scooby Newbie Member#: 254057 Join Date: Aug 2010 Chapter/Region: MWSOC Location: Milwaukee, WI Vehicle: 2002 WRX	Well I don't have a computer right now that I can datalog but I am still having the same problem. When I slowly give the motor boost, right when I start getting around 8 psi I start hearing tons of fluttering almost like it's the wastegate but it sounds louder then the wastegate. But when I check for boost leaks I cant hear anything leaking. Last edited by DrBelmore; 12-03-2010 at 04:34 PM.

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11-26-2010, 08:55 AM	#2
quazimoto Scooby Guru Member#: 70395 Join Date: Sep 2004 Chapter/Region: MAIC Location: Da-boonies,Va	If your using the factory boost control system sounds like the motor detonated pretty bad and the ECU dropped boost and timing. Post a datalog.

11-26-2010, 06:23 PM	#4
quazimoto Scooby Guru Member#: 70395 Join Date: Sep 2004 Chapter/Region: MAIC Location: Da-boonies,Va	Doesn't mater. The ECU is still controlling the boost. Post a datalog or find out what the IAM is.

11-26-2010, 10:52 PM	#5
gotsugg Scooby Specialist Member#: 204014 Join Date: Feb 2009 Chapter/Region: South East Location: Little Rock Vehicle: 02 02 WRB Bugeye GTX3582 front mount turbo	If 10psi is all it will boost, it sounds like you are running spring pressure at your IWG. Could be an issue with you EBC. That doesn't explain the shaking and rich AFRs though.

11-27-2010, 09:51 AM	#6
quazimoto Scooby Guru Member#: 70395 Join Date: Sep 2004 Chapter/Region: MAIC Location: Da-boonies,Va	Or the engine is knocking repeatedly and the ECU has decided to run wastegate boost.

12-03-2010, 04:43 PM	#8
DrBelmore Scooby Newbie Member#: 254057 Join Date: Aug 2010 Chapter/Region: MWSOC Location: Milwaukee, WI Vehicle: 2002 WRX	Anyone have any ideas?

12-03-2010, 05:37 PM	#9
GrimmSpeed NASIOC Vendor Member#: 136396 Join Date: Jan 2007 Chapter/Region: MWSOC Location: Export PA Vehicle: 2020 STI, 2022 WRX	Hey, I do not think our valve is operating incorrectly BUT we just had this same scenario happen, check your wiring connections to the valve, while they are tough if it has been yanked around at all they can break loose. Double check these wires and report back! Will

02-22-2024, 03:22 PM	#11
steagalarus Scooby Newbie Member#: 535693 Join Date: Oct 2023 Vehicle: 2021 WRX (sti trans)	Did you fix the issue? Can't go above 15psi boost when I was previously able to get to 22-23. 21 WRX

02-22-2024, 04:55 PM	#12
Mulder Trust no one Moderator Member#: 11170 Join Date: Oct 2001 Chapter/Region: Tri-State Location: NYC Vehicle: 13 Mini MT 15 WRX/11 CRZ	OP hasn't been on this site in almost 10 years.

04-02-2024, 03:50 PM	#13
steagalarus Scooby Newbie Member#: 535693 Join Date: Oct 2023 Vehicle: 2021 WRX (sti trans)	Sadness, I really need to fix my problem

06-11-2024, 04:35 PM	#15
steagalarus Scooby Newbie Member#: 535693 Join Date: Oct 2023 Vehicle: 2021 WRX (sti trans)	it was a bad one way check valve for my iag aos once it was replaced the oil and smoke spewing stopped