Loss of low end power

I have an 05 LGT Limited with 48k on it. I've owned the car since about 19k with Accessport st1 93 flash the whole time. For some reason, the last 3 months or so, it seems to have lost it's low end power. It feels like I'm doing a lot more waiting for it to spool up. Accessport says I'm hitting 15.6psi, but it feels like it's a lot later in the rev range. Only other mod is a K&N drop in filter. I'm not sure where to go with this, I've been thinking maybe pull the plugs and check them out, other than that I have no idea. Anyone else experience this? If I punch it above 3k rpm it still goes, but it used to at least have some more guts below that! Any tips would be greatly appreciated.

oil from the filter got on the MAF perhaps?

Possibly the increase of heat and humidity is playing a part...

I got some MAF cleaner and cleaned the sensor, that was my first thought. I guess heat / humidity could play a role, but it's been more of a longer slow progression, so I'm still leaning towards something mechanical. I guess next step would be plugs?

Hi,

have you figured out what the problem was? I have 05 LGT with 87K km (about 50-55K miles) with same issue. I haven't changed plugs and do my own oil changes. I change air filter once a year. Not sure what else I could be missing :S

I have exact same problem, at times i feel like i have to wait before it "kicks in", and other times the car literally jumps.

 

Thanks

Start with a leak in the intercooler. Then next potential issue is the wastegate on the turbo. These turbos have a habit of having the wastegate bushing move, keeping the wastegate in a partial open condition. You'll lose low end power, but overboost on the high end.

thanks for the tips...but none of this is familiar to me :/

after year and half i still have this issue. Obviously it won't fix itself however, it's not any worse than it was a year and half ago.

I haven't checked anything yet as i don't trust mechanics. Anything I can do to check wastegate? Any feedback is appreciated.

Can wastegate damage turbo?

 

obsidiangt>> have you fixed this issue?

Intercooler, check for oily or residue on the passenger side towards the front of the car. Or take it to a mechanic for a smoke test.

 

You can try moving the wastegate actuator. If you have an accessport or can data log, that is the best way to see what is happening. Sometimes you can hear the wastegate rattling, especially when the car is cold on morning startup.

 

I only know this because that was what happen to my car. The same hill I drive up to work required dropping to 4th to get up and I was making only 4 psi at 3000 rpm.

We would suggest a smoke test as a first angle of approach and see where that leads. If you are local give us a call and we can investigate a bit for you. Can be a stuck waste gate etc.

 

Mike

I'm in the same boat here. Just seems to lack the torque it once had. What does a smoke test consist of ?

Smoke test requires the intake hose to be pulled and a smoke generator plugged into it. Any leaks will have smoke billowing out.

X2 on this please post a solution

Intercooler, check for oily or residue on the passenger side towards the front of the car. Or take it to a mechanic for a smoke test.

 

You can try moving the wastegate actuator. If you have an accessport or can data log, that is the best way to see what is happening. Sometimes you can hear the wastegate rattling, especially when the car is cold on morning startup.

 

I only know this because that was what happen to my car. The same hill I drive up to work required dropping to 4th to get up and I was making only 4 psi at 3000 rpm.

 

What did you do to fix this problem?

Smoke test revealed a leak in the intercooler, passenger side towards the front of the car. Replaced the intercooler with an AVO unit. Problem didn't go away. Pulled the turbo and discovered the stuck wastegate.

 

See the picture of my turbo. http://legacygt.com/forums/showpost.php?p=3546780&postcount=11

Scotty, did you have to pull the turbo out in order to fix the wastegate issue?

I had already suspected the wastegate issue when I did the datalog. It was only making 4 psi at 3000 rpm and 16 psi at redline, shouldn't be that low or high. I ended up upgrading the turbo anyways. If you are just trying to fix the wastegate, you will need to pull the turbo.

sorry for the late reply. Thank you for your help!