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Need help from V manual trans owners

2K views 16 replies 10 participants last post by  thebigjimsho 
#1 ·
Posted a thread a few days ago about questions on boost rpm but haven't gotten much response. I have a 2009 6 speed manual with 15k miles. Have only owned if for about 2 months but I have a question I'm hoping another manual V owner might be able to help with. The boost gauge on my car does not seem to move much under moderate or even heavy throttle. Boost seems to kick in and register on the gauge at 4 sometimes 5k rpms. By then it's almost time to shift and it starts over again. My concern is this, I drove a 2011 automatic with about the same mileage on Monday. Under moderate throttle you could feel and hear the boost (and see the gauge move) at 2k rpms and up. I don't know if there should be a difference between a manual an automatic like that or if I am have a problem with my car. I know I am getting boost because you can feel it and eventually see the gauge move but there is very little supercharger whine and it just seems the boost should be kicking in at a much lower rpm and increasing with throttle pressure. Dont think its a gauge issue because it does move. Any info would be greatly appreciated.
 
#4 ·
thebigjimsho said:
I think I mentioned to find someone who can scan OBD-II. This will tell you if you are making boost.

If you have an iPhone or Android you can do it yourself with a Bluetooth dongle.
If there were a problem that would register with the OBD-II, wouldn't I get a check engine light for a trouble code. I haven't had it scanned but I also don't have any lights on stating that there is a code.
 
#9 ·
Nutz said:
I've seen this happen here when owners were experiencing low boost from poor gas, west coast residents if I remember correctly. Try running out the tank and getting high test from another completely different reputable fuel supplier. Good luck.
I'll give that a try. Haven't driven it much so I am only on my second tank of gas since I bought it. I'm on the east coast and filled up with Sunoco 94 octane. At about a 1/4 tank now so I will eventually run that down and try somewhere else. Thanks for the advice

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Cadillac Cust Svc said:
Hi Mikes2009V,

If you continue to have concerns, although I see some great posts from community members above, your dealership would be able to perform a full diagnosis on your V, to attempt to track down the cause of these issues. Please keep us updated on your situation!

Best,

Katie
Cadillac Customer Service
Thanks Katie. I want to see what kind of feedback I get here but the car is certified thru GM with 100k warranty so a trip to the dealer to have is scanned may be the next step.
 
#15 ·
When I no-lift it actually seems smoother...but it does chew up a lot of tire, so I only allow myself once a week, and only w/the summer tires on warm days.

Back to the OP's question: Going 65ish in 6th roll onto the gas like you need to pass someone in a hurry...you should see some activity on the boost gauge.
 
#16 ·
"No LIFT SHIFT" Shuts the throttle blade a bit which in turn does lower applied boost.. Our blowers are not like turbos, They are RPM dependant. When you let off the gas at say 6000 rpms, the blower is still able to make the same amount of boost as the rotors are still turning the same speed.

The only difference is, that there is a bypass valve inside that will bypass the intercooler core and put that boosted air back into the non pressure side of the intake.

As for boost also, the octane of fuel you run will not change the amount of boost your car makes. "Well This could be different as there is a safety in the ecm software that will turn on the boost bypass override if it sees a massive misfire event. However a light would be turned on the dash if that was the case and we are talking about 8+ degrees of knock and a whole cly missing."

One VERY easy way to see if you have the boost you are supposed to have is simple. Just go get a boost gauge at the parts store and put it on the car and drive it to see where it is.

If you dont have the boost you are supposed to have, you have a few options.
Fix the boost bypass valve adjustment and make sure it is set correctly.
Clean the air filter/replace.
Put on a new supercharger belt...

Again, it is rpm dependant, so if it isnt making boost, it is simple to find out why..
 
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