Stalling with new BOV
Thread Starter
Instructor
Joined: Oct 2014
Posts: 236
Likes: 7
From: Abingdon Virginia
Stalling with new BOV
I have my bothers car while he is serving over seas. I wanted to surprise him with a BIG BUBBA turbo smart valve on his car to give it a more aggressive sound. The car had a vulture motorsports sleeper valve (http://www.ebay.com/itm/New-SLEEPER-Black-ADJUSTABLE-50mm-Blow-Off-Valve-BOV-ADAPTOR-/121444022130?pt=LH_DefaultDomain_15&hash=item1c46a0b772&vxp=mtr)
Car ran and idled great. I installed the new valve and liked that it was open at idle to take pressure off the head unit unlike the other bov which had some surge. I drove the car around and the car stalls sometimes when I come to a stop. The rpm drops low to around 500 then goes back up to the commanded idle most of the time but stalls other times. I pressure checked the system and adjusted the BIG BUBBA from all the way open to all the way closed. Same problems.
I took it off reinstalled old BOV and no more stalling.
Anyone out there have any ideas on what may be the problem? I have HPTUNERS but I am not as good with it as my Bro is.
Thanks
Car ran and idled great. I installed the new valve and liked that it was open at idle to take pressure off the head unit unlike the other bov which had some surge. I drove the car around and the car stalls sometimes when I come to a stop. The rpm drops low to around 500 then goes back up to the commanded idle most of the time but stalls other times. I pressure checked the system and adjusted the BIG BUBBA from all the way open to all the way closed. Same problems.
I took it off reinstalled old BOV and no more stalling.
Anyone out there have any ideas on what may be the problem? I have HPTUNERS but I am not as good with it as my Bro is.
Thanks
Burning Brakes
Joined: Dec 2003
Posts: 1,243
Likes: 5
From: Loveland CO
where is the BOV located... Before or after the MAF? did the old one recirculate into the intake or just blow off into the engine bay?
Look to see if its leaking.. there are a few adjusments you may need to do to it to keep it closed at idle. some come with stiffer springs, shims or adjustment screws.. this one looks like it has an adjustment screw, loosen the nut, screw the threads in to tension the spring, tighten the nut and test. if you are too tight it wont let out all the pressure, if you are too lose it will be open at idle and not work correctly as you are seeing. sounds like its leaking unmetered air into the motor and making your fuel mixture all screwy. I assume the BOV is after the MAF (between maf and TB)? also you dont want it to be open at idle, it is also letting in unfiltered air. Only time the BOV should be open is when you are between shifts while in boost... Blow OFF valve not In.. relieves pressure from throttle plate creating back pressure on the Blower, when in boost.
S
Look to see if its leaking.. there are a few adjusments you may need to do to it to keep it closed at idle. some come with stiffer springs, shims or adjustment screws.. this one looks like it has an adjustment screw, loosen the nut, screw the threads in to tension the spring, tighten the nut and test. if you are too tight it wont let out all the pressure, if you are too lose it will be open at idle and not work correctly as you are seeing. sounds like its leaking unmetered air into the motor and making your fuel mixture all screwy. I assume the BOV is after the MAF (between maf and TB)? also you dont want it to be open at idle, it is also letting in unfiltered air. Only time the BOV should be open is when you are between shifts while in boost... Blow OFF valve not In.. relieves pressure from throttle plate creating back pressure on the Blower, when in boost.
S
Last edited by RedZMonte; Mar 5, 2015 at 11:46 AM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
That was my VERY FIRST thought. You are somehow getting un-metered air into the engine intake. Check the pluming between the MAF and TB. Check for loose/damaged/missing vacuum lined on the manifold. Check the PCV fittings.
If unmetered air gets into the engine those are the symptoms you will see. The PCM tries to close off the Throttle plate to compensate for that extra air and when it does the engine stalls.
Thread Starter
Instructor
Joined: Oct 2014
Posts: 236
Likes: 7
From: Abingdon Virginia
That was my VERY FIRST thought. You are somehow getting un-metered air into the engine intake. Check the pluming between the MAF and TB. Check for loose/damaged/missing vacuum lined on the manifold. Check the PCV fittings.
If unmetered air gets into the engine those are the symptoms you will see. The PCM tries to close off the Throttle plate to compensate for that extra air and when it does the engine stalls.
This car is speed density 2-bar, no maf. There is only one line to the intake manifold. No leaks. I pressure tested the system already. The Big Bubba lets air out at idle to take pressure off the head unit where the vulture sleeper does not. My STFT are +/- 1% at idle.
The stalling is predominantly when Im in gear and slow down to a stop, however it does flare downward on RPMs on warm start up and quickly recovers to target idle, never stalls on cold start.
When I swap the old BOV back on the car the problem does not exist.
Thread Starter
Instructor
Joined: Oct 2014
Posts: 236
Likes: 7
From: Abingdon Virginia
where is the BOV located... Before or after the MAF? did the old one recirculate into the intake or just blow off into the engine bay?
Look to see if its leaking.. there are a few adjusments you may need to do to it to keep it closed at idle. some come with stiffer springs, shims or adjustment screws.. this one looks like it has an adjustment screw, loosen the nut, screw the threads in to tension the spring, tighten the nut and test. if you are too tight it wont let out all the pressure, if you are too lose it will be open at idle and not work correctly as you are seeing. sounds like its leaking unmetered air into the motor and making your fuel mixture all screwy. I assume the BOV is after the MAF (between maf and TB)? also you dont want it to be open at idle, it is also letting in unfiltered air. Only time the BOV should be open is when you are between shifts while in boost... Blow OFF valve not In.. relieves pressure from throttle plate creating back pressure on the Blower, when in boost.
S
Look to see if its leaking.. there are a few adjusments you may need to do to it to keep it closed at idle. some come with stiffer springs, shims or adjustment screws.. this one looks like it has an adjustment screw, loosen the nut, screw the threads in to tension the spring, tighten the nut and test. if you are too tight it wont let out all the pressure, if you are too lose it will be open at idle and not work correctly as you are seeing. sounds like its leaking unmetered air into the motor and making your fuel mixture all screwy. I assume the BOV is after the MAF (between maf and TB)? also you dont want it to be open at idle, it is also letting in unfiltered air. Only time the BOV should be open is when you are between shifts while in boost... Blow OFF valve not In.. relieves pressure from throttle plate creating back pressure on the Blower, when in boost.
S
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The PCM was tuned with the old BOV and what ever it was doing to the air in front of the TB,, the new valve isnt.
It may need that part of the tune adjusted. The idle and decell can be tricky to tune.
Bill
It may need that part of the tune adjusted. The idle and decell can be tricky to tune.
Bill
Thread Starter
Instructor
Joined: Oct 2014
Posts: 236
Likes: 7
From: Abingdon Virginia
Thanks Bill for responding, appreciate your input.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski