Half Boost?

Guys, got a question. I've got an 05 5MT LGT, intake, uppipe, downpipe, pulley, Stage 2 Cobb tune. I know I should change my tune away from the stock Cobb one but I've got the old AP and can't update this one and don't wanna spend the money on a new one. Anyways. Car's been working fine, bout 85k on it, no major defects. Driving it a few days ago and it just doesn't seem to have the punch that it had the day before, and always had. To me, doesn't feel like the turbo's spinning up all the way. So I hook up the ol' AP and read boost, max in 3rd and 4th gear (not enough room to spin up 5th) was 8.3 lbs. WTH?! Not getting any codes, not running rough, nothing new to report except for that it doesn't want to gimme full boost. Now I haven't tried anything on my end like re-flashing the ECU or anything like that but I don't know why it would just BAM change overnight like that. Except for eating up clutches, the cars been a dream up until a few days ago. Still runs just fine and will get me from A - B as needed, just not as quickly as I wanted. Any help you guys can give will be greatly appreciated. Thanks a lot.

I'd love to tell you what my IAM is, if I knew wth hell it was or how to get it.

Ignition Advance Multiplier. It's a parameter you can log with the Cobb AP.

I have the OLD AP, serial connection to the computer. I don't think it does any data logging.

Let's say that did get dropped to 0. What would be the cause and how do I fix it?

It's not so simple, there could be a number of reasons why your iam drops. That's kind of like asking what the cure for the common cold is. The problem may also not necessarily by with your IAM anyways, its just the easiest thing to check on (with a newer AP anyway).

 

It might be worth it to look into getting a newer AP, or taking your car to a tuner. Logging is important for tuning of any kind in keeping your engine healthy.

Ok. As I am 100% broke right now, literally, is there any way I can diagnose anything and fix what may be wrong, with what I do have. Maybe perhaps some software I can get on my laptop and get a cable to hook up and log the data?

VAG-COM cable from Ebay <$20. Romraider edit/log software for free. There are stickies...

It really can be 1000 different things unless you can datalog it. It can be something as simple as you popped a vaccum line off your ebc or as far as cracked ringlands in my case My car ran perfectly fine minus the occasional loss of boost.

So I was able to get a hold of a OBD2 - USB cable that a buddy of mine had and loaded up RomRaider. Got nuthin. Couldn't even connect to the ECU. Does anyone know if this is purely because of the cheap cable he had, or because I could have been doing something wrong? Only real option I had was to choose between COM3 or COM17 to connect with, and neither worked.

did you install the drivers for the cable?

Yeah, I let windows install the drivers for it, which I'm reading might not have been good and I should have used ecuflash's packaged drivers to install it. Know anything about that?

yea install the packaged drivers or download the FTI cdm ones

Update: I disconnected the battery and reconnected it again. Full boost. I know that this is just a bandaid and didn't fix the underlying problem. I'm still going to get the logger up and running cuz there has been some other tuning problems. Thanks for all your guys help so far!

Let the car relearn the fuel trims and pull an LV. If the fuel trims are all small values, preferably negative, you should be okay from a hardware perspective. I'd then ditch the crappy OTS Cobb map and spend the $150 or so on an e-tune from a reputable tuner. Up to you if you want to do that via the VAG-COM cable or the AP.

Check your waste gate arm bushing... at 85K-ish, mine (orginal VF40) WG arm bushing borked during a cross-country trip and I had exactly the same symptoms you list above.

 

Just look at where the WG arm comes out of the turbo and if the bushing is sitting outside the turbo housing, pushing the actuator arm away from the turbo (approximately 1/4"-1/2"), then your WG is sitting half-way across the port and there's no way it'll hold boost like that. Luckily I was carrying a nearly-new VF46 with me and changed it out in an Atlanta (left from San Diego) and dyno checked/returned it for the new 46, then life was good again.

Honestly, just unplug your negative terminal off your batter and see if it goes away Sometimes it could be something in your tune that throws it off.

Check your waste gate arm bushing... at 85K-ish, mine (orginal VF40) WG arm bushing borked during a cross-country trip and I had exactly the same symptoms you list above.

I think that since he gets back to his target boost pressure after a reset it's not mechanical, but that he was at low IAM (for whatever reason) and the boost control system was disabled.

Did the same thing after reset and finally found the WG arm. We were baffled.

Did the same thing after reset and finally found the WG arm. We were baffled.

Hmm. Interesting. Well, doesn't take but 10 minutes to take a look see.

So I've been trying and trying to get anything out of my ecu onto the laptop, can't get anything. As far as I can tell, the laptop is communicating with the cable just fine, it's showing up everywhere it should in windows, but the cable isn't able to pull anything from the ecu itself, can't connect. I've used different drivers and everything. Could this just be that it's a cheap POS cable from China (which it is) that can't communicate with the ecu, or is there sumthin else I'm not seeing?

And the feedback on the WG arm bushing is?

Bumping so I stay relevant. I keep forgetting to go out and look at my turbo but as soon as I do, I'll let everyone know.