Lost the amount of boost / power ????

[CX7nCali]

Hmm, my CX-7 seems to have lost it's power. You can feel the turbo at 2500rpm, but only slightly. It no longer really kicks in like it did. It's been like that for a week or so, and I just turned 1,000 miles.

It's not "bad", but I can definitely feel the difference.

Anyone experience this?

All 3 tanks of 91 octane gas averaged 18 mpg with 80 percent highway driving.

And there seems to be a lot of black (unburned?) soot in the tailpipes.

I wanted to get some feedback before I take it in.

 

[G-Papi]

Nobody's reported that problem yet to my knowledge. The sooty tailpipes seem to be a characteristic of the car, but loss of turno boost is something new.

If you (as you say) are burning 91 octane, then this shouldn't happen.

Take it in, and keep us posted on what they find.

 

[Brian MP5T]

It could be climate diferences. Some turbo ECUs will adjust boost depending on air density (Temp and Barometric Pressure)

 

[cruzdreamer]

Mine seems a little less but I was figuring I am just getting used to the car and that maybe so. I drive reasonable and get 20.5 city so far.

 

[xavier]

Id say, if you havent already, take it in and have them flash the tcm/pcm. I think it made a small difference on mine.

 

[jmhumr]

I've noticed a decrease in "pep" and I'm at about 1200 miles now. It seems to be very inconsistent. There are times when I wonder if the turbo fails to kick in because I feel no surge at all. But then there are other times when it kicks in just like the day I bought it. At first I thought it was a weather or warmup related issue, but unfortunately I haven't noticed a correlation. It seems to have a mind of it's own. I'm definitely gonna have my dealer take a look.

 

[G-Papi]

You guys are definitely not going to like this suggestion.

I've noticed a decrease in "pep" and I'm at about 1200 miles now. It seems to be very inconsistent. There are times when I wonder if the turbo fails to kick in because I feel no surge at all. But then there are other times when it kicks in just like the day I bought it. At first I thought it was a weather or warmup related issue, but unfortunately I haven't noticed a correlation. It seems to have a mind of it's own. I'm definitely gonna have my dealer take a look.

A few threads back, I suggested that my car sometimes fails to revert to first gear after a complete stop. This happens most often when in the sport manual shift mode. It will actually start off in second gear, and since the shift indicator lights are so far removed from what I'm actually doing, it took me a while to notice what was actually going on. When starting in second gear, the CX-7 begins its roll like a freight train because (naturally) of the longer time it will take to reach the 2500 rpm threshold for the turbo.

A TCM reflash has not been developed to address this problem, and the failure to revert all the way back to first is a random occurance, with no apparent pattern, other than that it happens most often to me in the manual mode. I've developed a habit now of just giving the shift lever a complimentary tap while I'm at a stop, just to be sure it's in 1st, without having to look at the indicator.

 

[cruzdreamer]

I sometimes feel like you jmhumr.....sometimes I feel it's kicking in and other times I wonder if it did....never having a turbo before I am not sure...like I said...maybe I am used to it? I will mention it at my next dealer visit.

 

[Brian MP5T]

Most FI cars are like that.. It feels better some days..

 

[CX7nCali]

There's definitely something wrong.

My guesses:

1) Turbo not working properly
2) Transmission not locking up
3) Rings didn't seat, therefore loss of compression

I have a bad feeling it's number 3.

I'm hoping it's number 1.

The tranny does have some shifting issues, like staying in 3rd at 10mph, but they are separate from the lack of boost at 2500 rpm. Although, it's possible the engine and turbo are working fine, and the transmission isn't engaging properly.

I'll try to take it in Tue or Wed.

 

[Brian MP5T]

On modern engines, it's highly unlikely that the rings would not seat..

They are basically seated directly from the factory..

 

[xavier]

I havent had a power loss but the dang detonation has got me worried!!!

 

[Brian MP5T]

^^^ It should, and you should all report it to your dealer... Mazda will have to look into the problem and modify the ECU MAP.

 

[xavier]

Im going to have to make another trip back out to my dealer. I was driving 65 in 6th gear yesterday and pressed the gas just enough to downshift to 5th to pass someone...rpms were barely at 3000 rpms and it started knocking again.

 

[Brian MP5T]

Is it loud or faint??

 

[G-Papi]

The knock to which he refers (if it's like mine) is a deep throated rattle that can be felt in the seat of the pants. I know spark knock - and that's defitely what it is. It's usually accompanied by a heavy cloud of grey smoke from the exhaust pipes.

 

[G-Papi]

btw this is off-topic of the original post in this thread.

 

[starwars]

The gear stays in 2nd gear : Second gear fixed mode

Hi, in owner's manual page 5-14: Second gear mode is the reason why you stopped and the gear is fixed in 2nd. Hope it helps.

--Arthur

 

[xavier]

Is it loud or faint??

It was pretty loud. Sounds like marble madness in the bottom of the block.(ughdance)

 

[Brian MP5T]

It was pretty loud. Sounds like marble madness in the bottom of the block.(ughdance)

Def Detonation then..

Just wanted to verify...