NefMoto

Hi, I've been having irritating issues for the past 3 weeks that I haven't been able to solve.

Specs: 1.8T AYP K03s, Forge DV Yellow spring, N75F, High flow tip, KN Cone intake, Stage 1

I've been fixing issues since 3 weeks and still the low boost issues and low power persists. Changed N75 to F version and Map sensor (this made the car actually boost but it was still cutting. Changed fuel pump, fixed a boost cut problem. Fixed a cut boost hose, no better results. Now noticed a exhaust leak at manifold changed to a perfect used manifold and tested turbo. Wastegate cracks at 0.5bar. Boost leak test is ok.

The problem persists. Just did some logs today. Basically the car doesn't boost even past 0.5bar on 1st and 2nd gears. After 3rd gear it somewhat boosts to 0.8bar. This is with N75 ON and the n75 readings fluctuate around 70% WGDC and max out at 80.4% to redline on every gear. I took off the hose that goes from WG to N75. Car now boosts fine and follows requested! But the power is lower...

I basically did a better 0-402m time with 0.6bar and n75 connected, than with 1bar constantly and wastegate hose off.

Logs basically show WGDC from 65% to 80.4% maxed out. Timing retard is 0. Narrowband voltages are weird. 0.84v idle, 0.78 from 3-4k rpm then in random points it goes down to 0.4v and even lower. MAF is 159g/s at 6k rpm. Those readings are not bad. But the car isn't making power, I can feel it.

What in the world is happening? Bad n75, I've been changing two? Should I change to a 1mb wideband ecu, because the only thing that left here is the management system in this 512KB ECU. I should get an AEM AFR gauge and make sure I have fuel, then move on with solving the boost issue, even if it takes switching to a wideband ecu.

I have no idea why you didn't bother posting logs of the two runs you "feel" have different power.

Forgot laptop at work. Will post tomorrow. Currently just trying to understand what could be causing this. There is no leaks in the system been tested couple times... just can't understand how its not boosting at all, or the solenoid wgdc is wrong and its not working. I actually got lower than wg pressure boost when I tested it on 1st and 2nd gears with n75 connected. Top hose off and it hits 1.1bars max.

Will update tomorrow.

If you remove the wastegate line and only make 16psi you have a hardware fault.  Leak/dead turbo.

dont waste your time. others have told him this as well and he refuses to believe, however obvious it may be.

I am not even sure why I am chipping in... but to me it sounds: cut off WG and limited boost regardless, if not turbo failure / leak, then the ECU cutting throttle because of unable to maintain requested boost (hence my guess the feeling of lower power). And then, man, tuning anything and no AFR? And trying to judge things out of narrow band voltages...

I am sure because I've literally sent the turbo for testing flow tested and they adjusted wastegate and it cracks at 7psi like stock. They told me install the turbo its not a turbo issue. Installed new manifold new gaskets everything is tight no leaks. Boost tested AGAIN today it holds the pressure well.

I am suspecting throttle being closed due to fuel issue, maybe the fuel pump I changed was also bad.

Current narrowband voltages on a full throttle go from 0.8v to 0.7v then at random points it hits closed-loop and goes down to 0.5v and back up to 0.78v. Do I have a fuel issue? Because its supposed to be 0.9v to be rich. Getting an aem wideband soon.

I've been saying like numerous times the turbo has been 100% tested, no cracks, new manifold, all installed properly. Boost leak test been done numerous times successfully, also no exhaust leaks.

I noticed when I took the wastegate line off and would hit 1 bar, the car would be slower than with it ON and only 0.6bar. Even though I was hitting 162g/s. The only conclusion here is Motronic closing the throttle after low lambda readings. Will be replacing o2 sensor and get a new fuel pump I guess.

Goes lean, or goes closed loop? These are two different things. I think it would be the other way round - throttle cuts in because of boost problems, kills load, ECU goes closed loop and drops the fuel to 1.0 lambda.

Anyhow, this is pointless academic discussion without proper logs.

Will be posting soon I lost my usb where I stored them at. Its going lean, narrowband voltages are like 0.78v then just dip to 0.5v sometimes which is super lean... It should be around 0.87-0.90v at full throttle.

Have you logged at all?  If that throttle is not closing and it's not making more than a bar with no WG line, you have a hardware issue.  Absolutely no doubt about it.

I will log TPS, its the only thing I haven't logged. I logged basically N75 Wgdc its at 80.4% capped, sometimes dips to 50% (with n75 on) and boost is very limited (only peaking 1 bar at high gears low rpm then dieing off). With n75 hose off its following requested (max 1bar) and its funny, but its making less power like that. No limp mode, just gotta find the reason Motronic is dropping boost. For lambda, as I said, its fluctuating too much.

Before this issue the boost would hit 1 bar then n75 would release to 50% and go to 0.5bar immediately. Changed fuel pump. Now the boost isn't being released by the n75 like it would, its just dropping, if its anywhere above 3.5k RPM.

Let me find that usb and get the logs uploaded. P.s. just did another boost leak test no boost leaks, also retorqued the manifold nuts they were all ok. Turbo also was ok. Compression ok. So there is either Fuel issues here or this 512kb ecu is being an idiot.

Going out right now will log Throttle position and do a log with n75 plugged off to see if the boost holds wg pressure (0.5bar last time I tested with hand pump). Catch u guys in a bit will be posting logs as soon as I can.

Here are the logs. Throttle body pos. sensor is at 87% and pedal sensor pos. sensor 1 is staying at 50% for some odd reason. Lambda is dropping close to 0volts at the exact same areas where I have the boost dropping. Now is the boost drops causing lambda to drop, or low lambda  (low fuel) is causing the boost to go safe? Here are the two logs where u can see this.

I labeled the variables correctly.