Constantly hitting boost cutoff! frustrating..
my car was fine all summer, if ever i hit boost cutoff i would need to just turn down my MBC.
now that its winter nomatter how low it goes i always seem to hit it. i took off my MBC completly and it was fine ( it was also slow as hell) i only hit it in 4th and 5th gear after pinning the gas for around 4-5 seconds. i watch my boost guage at it hits around 9psi now ( its turned down) and for some reason i still hit it but the boost gauge never seems to actually go anywhere near 14psi when it cuts. i was thinking a. my boost gauge cannot detect the spike for some reason b. it might not be the cutoff but a leak instead ( but it cuts for a second then is fine for another 4-5seconds) c. a cheap boost controller what do you think? thanks! |
TCV maybe?
|
Maybe you are misfiring?
|
I've had oil soaked air box to turbo hoses collapse and feel just like a boost cut switch. Boost fine to a certain point; go past that point and boom...nothing.
|
Originally Posted by tech
(Post 256405)
Maybe you are misfiring?
ive changed the sparkplugs as well as the wires and cap/rotor before winter so hopefully all that stuff is good. what next?
Originally Posted by swiftjustice44
(Post 256411)
I've had oil soaked air box to turbo hoses collapse and feel just like a boost cut switch. Boost fine to a certain point; go past that point and boom...nothing.
thanks |
I just did all silicone lines a couple weeks ago, and believe me you will NOT regret that. my turbo holds boost better and boosts faster. it feels like i got a new turbo.
|
Did you buy good parts? Like the good Bosch cap and rotor?
Which wires did you get? How much boost are you running? What did you gap the spark plugs to? |
Originally Posted by tech
(Post 256519)
Did you buy good parts? Like the good Bosch cap and rotor?
Which wires did you get? How much boost are you running? What did you gap the spark plugs to? but its like -6 to -15 degrees celcuis dont know if that changes anything!? maybe weakens the intercooler hose rubbers? |
It doesn't matter how much boost you're running, plugs should still be gapped accordingly. .028. I would check them. Also, are you running a cheap MBC? That's probably not helping any.
And -15C is only like 5F. It's kind of hard to troubleshoot boosting issues when your boosting in that cold of temperature. Being that cold is going to **** with a lot of things. You just have to imagine how dense the air is at those temps. My friend has a stage III+ S70 and boosts completely normal, however, in really cold temps, he gets misfires, spikes, etc, and it's because it's so cold out. |
Originally Posted by gilber33
(Post 256573)
It doesn't matter how much boost you're running, plugs should still be gapped accordingly. .028. I would check them. Also, are you running a cheap MBC? That's probably not helping any.
And -15C is only like 5F. It's kind of hard to troubleshoot boosting issues when your boosting in that cold of temperature. Being that cold is going to **** with a lot of things. You just have to imagine how dense the air is at those temps. My friend has a stage III+ S70 and boosts completely normal, however, in really cold temps, he gets misfires, spikes, etc, and it's because it's so cold out. |
Originally Posted by matt01
(Post 256610)
so maybe its best to run no MBC in winter..
|
Originally Posted by gilber33
(Post 256618)
Nah, it's fine. Just turn it down maybe. Or don't do WOT runs all the time.
|
matt01.......get a tune and you wont have to worry about it ever again.
|
Originally Posted by boxpin
(Post 256635)
matt01.......get a tune and you wont have to worry about it ever again.
|
Then he is not hitting fuel cut off and it something else. IPD removes fuel cut off from all their tunes.
|
Originally Posted by boxpin
(Post 256646)
Then he is not hitting fuel cut off and it something else. IPD removes fuel cut off from all their tunes.
Put in the BCS and see if it's still happening. If it is, it will help you narrow down where to start looking. Wait, he said he took off his MBC and put the BCS back on and it was fine, why is this still going? lol. put the bcs back on, get a better MBC, and put it back on when it's not -150 degrees outside. |
matt01, maybe you could explain what the cut off feels like.
I have felt both, the fuel cut off is an abrupt stall. The entire engine shuts off for a sec then runs again. A misfire is more of a jolt or popping noise/feel. Fuel cut off is obvious but misfires are scary and you think damaged something cuz its not a pretty sound. |
Originally Posted by boxpin
(Post 256649)
matt01, maybe you could explain what the cut off feels like.
I have felt both, the fuel cut off is an abrupt stall. The entire engine shuts off for a sec then runs again. A misfire is more of a jolt or popping noise/feel. Fuel cut off is obvious but misfires are scary and you think damaged something cuz its not a pretty sound. WOT its fine for a few seconds, all of a sudden my boost goes from 10 down to about 2 with like a noise like the engine suddenly stopped, not sure what the RPM gauge reads at this point, i normally look at the boost. it stays "down" for maybe half a second but i seem to lose so much momentum in that time. then the boost builds back up right away and im good to go for another few seconds if i keep my foot in it.. with no MBC it would never "cutoff" but i was only reaching about 7 psi max at that point.. x2 on getting a tune.. im looking for a good used one stage one for 4.4 manual.. |
Originally Posted by matt01
(Post 256690)
its hard to explain really..
with no MBC it would never "cutoff" but i was only reaching about 7 psi max at that point.. |
Originally Posted by gilber33
(Post 256698)
That's because that's stock boost and you're not boosting high enough to hit cutoff. I bet you're misfiring and it sounds like your running a cheap MBC and that isn't helping. Also, check your gap. We asked before what your plugs were gaped to and you didn't know. You should know what they're gaped to and they should be .028, and then play with the gap from there depending on how the car is running.
but the gap is worth looking into.. ill check that. if i buy volvo plugs are they pre-gapped.. right now i have bosch or something.. |
All times are GMT -5. The time now is 03:31 PM. |
© 2024 MH Sub I, LLC dba Internet Brands