Rb20 Wierd Boost Issue

[BrianEng]

This is my first time with a FI car...now I have an AVCR running just the pressure sensor right now to see how its boosting, and I also have an RSM to see my revs...

The car drives fine until it see about 0.1-0.2 bar, and kind of bogs out, so much so I have to shift gears. I know its not a MAF issue cause the car has gone over 2500RPM, maybe close to 3700RPM, and the problem happens at a host of RPMs depending on the gear and such eh. Being in a higher gear like 5th, it seems to build boost more smoothly...

I tightened the wastegate actuator arm because a buddy of mine said that might be causin the issues, didn't help the problem much tho eh lol....

I checked for leaks but cannot seem to hear anything checking out all the lines and i couldnt hear and leaking air.

My throttle hasn't even seen past about 35 percent because it usually bogs down too if I floor it and build the boost faster. It feels wierd, kinda like its loosing its guts and cant seem to want to move, but Im too afraid to give it and see what happens because I have no clue eh lol...

Anyways, I hope someone might have some insight into whats goin on!

Ciao

[chrissso]

Sounds like you may have a boost leak. Check all of you intercooler plumbing for loose clamps and plumbing that has blown apart.

[BrianEng]

Ill double check it, but I cant see/hear any leaks, and I'm almost 100% sure i double checked all the piping for the IC, ill take a look agian to be sure, but I noticed on the way home from work it buckles when you hold it at the point and almost looses boost complete and drops back to mmHg

[IFRYCE]

also try your fuel pressure. Sounds similar to what happened with my car

when it happens, do you have to back off and slowly reapply the accelerator? this is similar to what happened to me and when i did happen, i just slowly held the accelerator on slightly and revved the guts out of it and then it seemed to run fine again.

Again, try your fuel pump/fuel pressure

Cheers

Ben

[Jolinator]

ive had this before when i left one of my ic hoseclamps looose, it was tight enough that under vacume it wouldnt leak but once it saw some positive pressure it was leaking like all crap, in my case i could really hear it, once it started to get on song there was a metalic sucking noise,

go over it with a fine tooth comb from afm to throttle body, checking all your clamps are tight, no split hoses etc,

[BrianEng]

I just noticed something else eh. I hooked up the safc and saw the voltage with ignition on was fluctuating between 0.35-0.4v, but in the pdf thing I have it says it should be at around 0.5v....

Now I had an extra harness that had a maf clip because mine was cliped for some reason on the harness....Unfortunately, I have two....yes two....soldered connections between the maf and the ecu, ontopp of the safc being there too....

I have it set up as 1 In 1 Out as per the instructions in the DIY/FAQ section, with 6 and Up, and it hasnt changed.

I tried cleaning the afm pins and thats when it raised to around 0.4ish, but at around 2500 where it should be 1.5 I think, i get like 1.6v, and AFL doesnt seem to go over 40%ish...

Retightened all the couplers and lines just to be safe, now it'll go to about 0.3bar sometimes, it varies so much, and the wastegate arm is still stiff...

Fuel is provided by a walbro 255lph, and I dont see any clean spots under the car as its covered in rust proofing gunk...

I did replace the plugs, NGK BCPR6 -11 still running trying to get to stock boost ...

I cant think of anything else, maybe I need some dyno time with a wideband to get more info?

[RANDY]

Brian.. FYI, 0mmHg would be neutral/no boost pressure... half on the scale basically.

So.. do you ever get it over the horizontal halfway mark? 0.3bar you measured... do you have an aftermarket guage?

Is it at certain revs that it cuts out badly? It kinda sounds like a faulty AFM... unless you're just not getting power, but the revs are smooth. In which case it sounds like the boost controller is open and forcing the wastegate open as soon as the wastegate's spring pressure is matched.

The stock RB20 wastegate opens at 10psi, so if yours is stock, then I doubt that would be it. Need more info on your aftermarket bits and mods I think!

[BrianEng]

No mods yet, just AVC-R that doesnt even have the solenoid attached to the WG, just the pressure sensor to tell me how much boost...

This is, it happens, or feels less bad when the car is cold, when its hot, its more likely to happen...Car revs smoothly until it reaches the bogging point, the kinda cuts out making boost and then im back in vacuum...

[RANDY]

oh =-o

Like a big amount of missing or something? What kind of revs are you at when this happens? Could be a coil or spark plug problem...

[BrianEng]

Revs seem to vary...but I havent been able to rev over 3200ish while driving, but at idle I can rev it up till black smoke blows out the back lol, I changed the plugs already, but ill recheck them again tonite

[BrianEng]

Sorry guys, Ive been really busy lately with work and everything, I finally pulled apart the intercooler and piping and redid it...that solved the boost problem...inturn creating another one...

I seem tohave melted the white wire going to the alternator, and frying the fuse with it, the 75A big guy lol...

I fixed the wire, albeit a bit crunchy for the first 4-5cm so i clipped it and attached a new O ring at the end. Thinking it was connected at the wrong spot, I moved it to the other bolt, at 3 O'clock looking at the back of it from 12 o'clock position where it melted.... put another fuse in, attach the battery, fireworks, fuse blown again....now before I go buy a fuse or five.....Id like to know where abouts the white and ground wire should be connected to...

Currently the black is on the bottom most of the two bolts at 6 oclock

Muchly appreciated

Brian