Mazdaspeed3 Boost not building up

[Wingzero54]

When I first got the car I fell in love with the feel of the boost really building up when you came up on 3000rpm, and the car taking off. I've only had it for a few weeks, and had spark plugs and coils changed, so I don't know if that might effect it, but my boost just isn't building up anymore. The dealership test drove it and swears it's fine and won't run any tests on it, so I'm going to take it to another mechanic, but I don't know what tests to run on it.

The boost just doesn't build anymore. The car has very good acceleration on its own, and it's probably getting a little bit of boost, but it's nowhere near what it was. When you hit 3000rpm there's very little change in the acceleration, it picks up but it by no means hits hard acceleration like it used to. The dealership says if there was anything wrong with the car at all the check engine light would flash on, but the only thing I've seen recently is a tire pressure warning. My brother says it may be a leak in the boost line, but I'm thinking it may be something with the turbocharger, because I don't hear it at all anymore either.

 

[b e z]

Do you have anything to monitor with either a gauage or dash hawk?

 

[Wingzero54]

I do not have any sort of monitor. I am starting to think that I should get a boost guage or something of the like though.

 

[Kain]

Without something to read PSI, it's all conjecture.

 

[WillD]

Boost gauge is never a bad thing to have. It will tell you for sure if you are actually have a problem or not as Kain says. That's what I'd do first before I go chasing my tail looking for a problem that may or may not be there.

 

[b e z]

I would go with a dash hawk and not just a boost gauge, I mean if it is what you can afford then something is better than nothing. At least the dash hawk will let you know more than just boost.

 

[MSMS3]

For OP's question a mechanical boost gauge would be a good beginning. Dash Hawk or other monitoring/scan tool is a good step up from that. But unless he wants to have a DH or scan tool connected all the time, having an inexpensive mechanical gauge (less than $50) is a good investment and something he can look at any time, without having to have something plugged into the OBD II port. It's not an either/or. I monitor with a more sophisticated method than Dash Hawk (ScanXL Pro professional software and a laptop), but still always look first to see what my permanently installed mechanical boost gauge is showing, if I have any questions about boost level.

Also, OP may just be getting used to the feel of onset of boost. It's normal when moving from a normally aspirated car to a car with relatively high boost at relatively low rpm to experience that "wow" factor when boost comes on. Over time you become used to it, even though nothing has changed under the hood.

 

[b e z]

Hooking up a gauge is harder than just plugging something into the obd II port as well. I know it was a pain to hook up my boost gauge, granted i did it in the winter with no garage.You also may have to worry about reliability with the gauge you purchased, as did I. So thats why i feel it is easiest to just get something like a dash hawk. It also isnt my choice or decision so im just throwing my opinion out there.

 

[Wingzero54]

Thanks for all the input. To MSMS3, I have thought about maybe I'm getting used to it, so I'm having my brother, who happens to be a mechanic with a lot of work into his cars, take it out for a drive when he gets a chance. He's driven it once when I first got it, and has ridden in some other turbocharged cars, so he would have a much better idea than myself.

I will look into gauges and dash hawks to see what would work best for me.

 

[meicalnissyen]

Also, OP may just becoming used to the feel of onset of boost. It's normal when moving from a normally aspirated car to a car with relatively high boost at relatively low rpm to experience that "wow" factor when boost comes on. Over time you become used to it, even though nothing has changed under the hood.

^^^^

Yup

 

[Wingzero54]

The way I would describe it, is when I first drove it and hit the gas, I was pushed back in my seat, even at 3,000 rpm in 3rd gear. Now I'm hard pressed to get pushed back in my seat in 4th gear on the highway at 5,000 rpm. And I wouldn't say getting used to the car would change whether I get pushed back in my seat or not.

 

[rsvinylgraphics]

I have an Aeroforce Interceptor gauge for sale if you are interested. http://www.mazdas247.com/forum/showthread.php?123803930-Aeroforce-Interceptor-Scan-Gauge

 

[Wingzero54]

I would love to, but just don't have the money.

 

[MSMS3]

Maybe you do have a change in performance, OP. But please bear in mind that your sense of "push back" is purely subjective and is not a very good way to determine whether you have a change in power output.

The sense of "push back" is also dependent on a lot things and one of them is gearing. 4th gear is a lot taller than 3rd. Gear ratios higher than 1:1 multiply torque. That's why a car accelerates hardest in the lowest gears and less so as you go up through the gears. So, you can't compare "push back" in 4th with the same sensation in 3rd.

Also, atmospheric conditions play a role in how turbocharged engines make power. Ambient temps and barometric pressure play a major role. And, of course, there is the issue of heat soak from under hood temp build up. This affects both the ability of your top mount intercooler to bring the boost air temps back down, and can affect your air charge temp going to the turbo if you have a short ram intake. These engines are extremely sensitive to the intake air temp charge and the ability of the intercooler to bring the boosted air temp back down. There are a lot of variables at play in the ultimate temperature of the air entering the engine, and therefore, your power level.

Further, "push back" in 4th gear at 5,000 rpm is going to be less than the same feeling down in third at lower rpm, not only because of the gearing changes, but because at 5,000 rpm, you are already up on boost when you go WOT. At lower rpm, you have to spool up the turbo and this will cause a more abrupt onset of boost.

Short answer: Get or borrow a boost gauge to see what your car is doing.

It's complex. You need to monitor boost level at least, to know if you really are producing less boost under load.

 

[mpsowner]

@Wingzero54 hey dude im having the same problem as you have discride here and im so stumped because im trying to save moneyt at the moment i was wondering if you ever found out what the problem is

cheers