stock boost restriction?

[FLYSKY]

i guess only GTR got somethin like this, i've also gotta GTS-t TypeM and never seen anythin like this on the RB20

[gtrjerry73]

Flysky I would say definitely 1 bar maybe more I don't know what the actuators will limit the system to though but with the lines basically blocked right off it could be less than factory? I'm just speculating though on that point lol sorry when your under boost does your factory gauge (assuming it's still ther of course) go half way or right to the top? Should go pretty well right to the top at one Barr.

[jdm_fantasy]

Yup apparently .75-1bar which is just under 15psi? And ya when i do my build I will get a good boost controller and get rid if it altogether obviously but until then (after this summer for sure) I will pray to the car gods that my exhaust wheels stay in one piece less then 80k so shouldn't have a problem if your going to do this and your all factory still I recommend checking all your piping. Right after I raised my boost (via the restrictor) a couple of my clamps came loose after a quick pull. Just a thought

lmao i think a clamp came loose for me to after raising the boost up....went on the highway and was boosting 1 bar....get off after some nice pulls and .7-.8 : / still need to get out there and check....car runs fine just not hittin 1 bar with the restrictor removed lol

[gtrjerry73]

Ya actually I noticed today my car is doing this as well but I know that it's only when I have been on the highway and got the temps up a bit. when the engine is cooler it boosts to 1 bar no problem like at night if it's not warm it almost never does it. Not sure exactly what it could be but I definitely think heat related.

[jdm_fantasy]

weird isnt it? lol yea mine will sometimes make it up to .9 but barely....even when everything is within normal operating temps. Still gotta check the poping....havent had a chance yet, but think im gonna through in some new plugs while im at it since its been 4 yrs lol

[gtrjerry73]

Lol wow ya I just did mine but didn't seem ti fix it could it be the solenoid ? Anyone else had this problem?

[jdm_fantasy]

oh really? hmmm could be the solenoid, i did some checking and could also be the bovs leaking (they are set up to bleed off abit already)....
One person said to do a compression test....pull off intake and hook up an air compressor running only 6psi....if it cant hold it then theres a boost leak. hopfully someone will chime in on this!

[gtrjerry73]

The factory ecu has knock sensors correct? I have a feeling it might just be some bad fuel that is causing boost cut. I fueled up at a gas station by my place but it's a no name place and it wouldnt hit full boost all the way to Calgary. Then filled up at an esso for the way back and it ran perfect, Even got better mileage. I didn't think about it until I filled up at the station by my place again today and it started happening again. Does this make sense? Or do you think I'm way off base?

[Skym]

Leak on entry to MAF = make ECU hit boost cut (load cut). Especially if podfilter clamps onto adaptor that bolts onto MAF's.

Knocks sensors on R32 make ECU dump in more fuel and pull ignition timing to match (for lower octane gas).

[gtrjerry73]

Ah ok. Well I'm all stock (intake included) and just cleaned my mafs and tightened everything a few days ago but I put v power in it and sure enough it hasn't cut boost since... Now I'm confused cause it was definitely running a little rich when it was cutting boost but problem went away after putting octane booster in with "no name gas station fuel" could be another annoying gremlin... Could the screen on one of the Mafs being a bit tattered cause the readings to be off? Are they that sensitive?

[Skym]

Knock sensors might engage safety revlimiter at around 5000rpm (I think only happens when knock sensors have failed). But there are other revlimiters that are non adjustable or I probably don't know about (not displayed in tuning software) that can engage when ECU detects knock.

Would need to get hold of Nissan Consult / ECU documentation / patent? info (I think it's in Japanese language) which shows all the revlimiters, tables, maps, etc the ECU has and what the programming code looks like for those features. Very few have this info. But it's supposedly available if you search the web.

One way to confirm the cause, would be get someone with Nistune tuning software, consult cable, laptop and do a run while datalogging MAF voltage, knock count and if it hits load cut limit (MAF) or rises (knock count) before problem occurs.

Did you use CRC MAF cleaner? Don't use carb cleaner, as it could damage sensor in MAF.

On a GTR in Australia (magazine article) they removed the gauze screens and retuned ECU (PowerFC?, Z32 AFM's??). Gained 8awhp. I guess it shows how restrictive the gauze screens are and why there's a hp increase when switching to MAP setup (with tune to suit) where MAF"s are removed. I think the gauze screens do a few things like straighten out airflow, protect hotwire sensor.

[jdm_fantasy]

Nice info sky....thats interesting how the gained hp from removing the screens. Ive still yet to find out why im only hit .8 bar with the restrictor removed, havent had the time to start diggin. I know my mafs and pod filters are nice and tight....just not sure on the intercooler piping. It had hks hard piping with regular hose clamps instead of t-bolt style. Dont have any other issues with drivablity either....just low boost.

[Skym]

I've read about in the past (years ago) with GTR owners having similar low boost level problems. They traced back to plumbing internal wastegate actuator vacuum hoses the wrong way when installing a aftermarket boost controller.

Maybe compare the internal wastegate actuator vacuum hose plumbing on car against vacuum hose plumbing diagrams in R32 engine manual?

Also the stock boost restrictor shouldn't be removed unless your running a aftermarket boost controller. Boost restrictor helps stock boost control solenoid control boost level. I know of one person (Nistune? forum) that has experimented with different boost restrictor sizes and adjusting boost level via stock ECU.

Also podfilters should help boost level to rise by 0.1bar or so (1bar = 14.5psi). 12psi might be correct considering it still has stock airbox, aftermarket exhaust (from dumppipes? or frontpipe?)? But I would eliminate internal wastegate actuator plumbing first and then look at restrictions like intake, exhaust.

[jdm_fantasy]

I havent played with the wastegate lines yet as i dont have an aftermarket boost controller yet. So thinking those should be fine as there were no issues before hand. I'll be installing one in the coming months though...i better make sure I put the lines right. I know I shouldnt have pulled the restrictor, read up on everything but thought i'd see what happened....might get new turbos outta it lol Interesting about trying different sized restrictors....have the link by chance?

[Dragon Humper]

Also the stock boost restrictor shouldn't be removed unless your running a aftermarket boost controller. Boost restrictor helps stock boost control solenoid control boost level. I know of one person (Nistune? forum) that has experimented with different boost restrictor sizes and adjusting boost level via stock ECU.

Also podfilters should help boost level to rise by 0.1bar or so (1bar = 14.5psi). 12psi might be correct considering it still has stock airbox, aftermarket exhaust (from dumppipes? or frontpipe?)? But I would eliminate internal wastegate actuator plumbing first and then look at restrictions like intake, exhaust.

It must have been really late when you wrote this (noon here, 4am there?) because that is not really very good info there Skym.

There is absolutely nothing wrong with removing the restrictor and leaving everything else stock, including the factory controller. The ECU is perfectly capable of keeping things safe up to about 16psi (in the case of a short boost spike). The MAFs will supply enough fuel to match the air comming in (untill they max out, which for a mostly stock car won't happen even at 16psi) and the fuel maps tied into the MAP sensor are scaled right up to 1 bar (14.7psi). The MAP reads to a full bar so the fuel map has to match that. If it was a .7bar map (which I don't think exists) then you would have a problem. Rest assured the sensor on the R32-3-4 is a 2bar map (full vacuum to 1bar pressure).

If a boost controller is working properly you should see ZERO change is boost pressure regardless of what you bolt onto the car (exhaust, intake). What does increase is HP because you are now moving more air at a given pressure (.7bar for example) to the point that you can make just as much power at .7bar with boltons as a guy with a mostly stock car and boost pressure set at 1bar (with a much lower EGT I might add). If you are seeing changes in boost pressure with the addition of a bolt on then you are looking at an indication that the wastegate is too small and unable to vent enough exhaust flow to control the boost to your commanded level.




Jon.