It's definitely not easy to get to those to do all that needs to be done however, they can sometimes get caked with oil and sludge. I havent heard of a never car having one go bad for a while though.
6
Boost fluctuations and hesitation: APR Stage 1
- Thread starter thatspsychotic
- Start date
It's definitely not easy to get to those to do all that needs to be done however, they can sometimes get caked with oil and sludge. I havent heard of a never car having one go bad for a while though.
hbrown0509
Go Kart Champion
Yeah just just get the turbo muffler removed I remember I had to disconnect a hose of the N75 to get to One of the bolts (I have decently big hands) and getting it back on was a pain.
I feel like dealing with the N75 again would be worth it if it solves the issue. I don’t get any codes at all when the fluctuations and hesitation happens. With all the blow by oil that you find in the charge pipe and DV it wouldn’t be much of a surprise how these can get clogged. I just feel like if it was the wastegate wouldn’t it be throwing codes? Also from when it was logged last it seems to be holding pressure fine.
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What do you peak and hold now?
hbrown0509
Go Kart Champion
Use to be around 18. Not sure anymore as the fluctuations make it hard to measure.
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Stock IC?
hbrown0509
Go Kart Champion
Ok, so approximately double the internal volume of stock, so your WGA which iirc is 4 psi on the ihi is going to have a hard time holding under boost
hbrown0509
Go Kart Champion
Is it because it’s too weak to hold the extra volume?
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Do you hear the WG flutter at peak boost? Sounds like a pressure cooker?
hbrown0509
Go Kart Champion
Then you're probably ok, but if that flapper door is hung up, broken, etc, then you'll have a boost leak that the ECU will attempt to compensate for and you'll get major fluctuations
hbrown0509
Go Kart Champion
Thanks for the info. It only happens in gears 3-6 going from low/mid-WOT. Pretty much 2500-3800 rpms. It just seems that at 32k miles the turbo shouldn’t be crapping out.
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Likely because at those rpms, and gears, the engine load is high, which requires boost almost immediately once you get on the throttle much more.
How about in say 3rd @ 4500-5k?
hbrown0509
Go Kart Champion
That is correct. Similar to what my GIAC dealer says.
Yeah in those RPM ranges it’s fine. I’m guessing because I’m outside the efficiency range of the turbo.
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thatspsychotic
Ready to race!
OP here, cool to see this thread getting traction. I actually do have an update as of very recently.
This problem had persisted for me through V2.4 of the APR tune, and the oscillations started to get pretty bad and overall off-boost performance was pretty crummy. I was getting boost oscillations even going from coast to WOT above 4k RPM, and it seemed to be taking longer than it should to reach peak boost, and would hunt and oscillate on its way there.
Then recently Arin posted in the massive APR Stage 1 V2.0 thread about an example where someone having issues like this was able to fix the issues by thoroughly checking for boost leaks, particularly PCV-related issues.
I said to myself forget this, let me go in and make sure that everything in the engine bay that I've touched has been really torqued down well enough. I'd replaced the PCV plate and had previously cleaned the IAT sensor, so I added about a quarter turn more to every bolt on the PCV plate (stopping short of uncomfortable tightness) and the bolt on the IAT sensor. I also re-checked the spark plug torque, since in the past I had issues with not quite enough torque there, especially after being dumb and re-using the crush washers after checking the plug gaps.
Although I'm really hesitant to believe it, it honestly made a pretty massive difference. Boost oscillations are pretty much gone, and off-boost behavior is way better. I strongly think it was something about how the PCV plate was mounted that the car wasn't happy with, and it was probably affecting how the PCV system operated and possibly allowing boost to go where it shouldn't, or otherwise messing things up.
Check the simple stuff first. I swore up and down that it was the tune and was ready to drop $650 on a Cobb Accessport with a Stratified tune.
Do I think APR's wastegate PID tuning needs refinement? Sure. Could things be made even a bit better by replacing the N75 anyways? Probably. Sometimes boost onset feels a little too muted, and sometimes engine braking isn't strong enough, and sometimes the throttle pedal response isn't perfect at low speeds (tune imperfections). But simply re-torquing everything down seems to have largely addressed my issues. I hate that that's my answer, but that's what it is.
Time will tell if 1.) this was a real fix and 2.) if symptoms will return. But let me tell you this: I was reluctant to have friends drive the car because it felt broken and like there was only a vague suggestion of a relationship between the accelerator pedal and what the car was doing.
I now wouldn't hesitate to hand the keys to my car enthusiast friends and have them hoon it. They'd probably note how the suspension and bushings are getting sloppy after 143k miles, but that's a different problem space.
Do the easy stuff first, and double-check everything you've touched. Err on the high side of torque recommendations.
This problem had persisted for me through V2.4 of the APR tune, and the oscillations started to get pretty bad and overall off-boost performance was pretty crummy. I was getting boost oscillations even going from coast to WOT above 4k RPM, and it seemed to be taking longer than it should to reach peak boost, and would hunt and oscillate on its way there.
Then recently Arin posted in the massive APR Stage 1 V2.0 thread about an example where someone having issues like this was able to fix the issues by thoroughly checking for boost leaks, particularly PCV-related issues.
I said to myself forget this, let me go in and make sure that everything in the engine bay that I've touched has been really torqued down well enough. I'd replaced the PCV plate and had previously cleaned the IAT sensor, so I added about a quarter turn more to every bolt on the PCV plate (stopping short of uncomfortable tightness) and the bolt on the IAT sensor. I also re-checked the spark plug torque, since in the past I had issues with not quite enough torque there, especially after being dumb and re-using the crush washers after checking the plug gaps.
Although I'm really hesitant to believe it, it honestly made a pretty massive difference. Boost oscillations are pretty much gone, and off-boost behavior is way better. I strongly think it was something about how the PCV plate was mounted that the car wasn't happy with, and it was probably affecting how the PCV system operated and possibly allowing boost to go where it shouldn't, or otherwise messing things up.
Check the simple stuff first. I swore up and down that it was the tune and was ready to drop $650 on a Cobb Accessport with a Stratified tune.
Do I think APR's wastegate PID tuning needs refinement? Sure. Could things be made even a bit better by replacing the N75 anyways? Probably. Sometimes boost onset feels a little too muted, and sometimes engine braking isn't strong enough, and sometimes the throttle pedal response isn't perfect at low speeds (tune imperfections). But simply re-torquing everything down seems to have largely addressed my issues. I hate that that's my answer, but that's what it is.
Time will tell if 1.) this was a real fix and 2.) if symptoms will return. But let me tell you this: I was reluctant to have friends drive the car because it felt broken and like there was only a vague suggestion of a relationship between the accelerator pedal and what the car was doing.
I now wouldn't hesitate to hand the keys to my car enthusiast friends and have them hoon it. They'd probably note how the suspension and bushings are getting sloppy after 143k miles, but that's a different problem space.
Do the easy stuff first, and double-check everything you've touched. Err on the high side of torque recommendations.
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