Mitchocalypse

iTrader: (2)

I own a 93 jdm fd. current relevant mods include power fc ( current boost setting is pr .80, sc .75) i have another with pr and sc at .85. This was programmed by rotary performance. Trust intake, efini y pipe + crossover, trust intercooler and piping, still on stock twins.

Like i've mentionned, according to pfc, i should be making .80 cm/kg^2 of boost on this lower boost setting. However, the highest i've seen it get is .65. I thought it was a boost leak (i suppose it still could be) but i had rigged a tester up and hooked a compressor up to a charge pipe right after the crossover tube. I ran it and found a fair sized leak at the elbow to throttle body part. This was odd since it was definitely bolted up tight and the o-ring gasket was still there. Regardless, I made a gasket and placed it back. When running the compressor again, i didn't notice any more leakage from there. So decided to test it out. I gained a little bit more boost. Before it would barely make .6, now i usually get to the .64 i mentionned. However, it seems my secondary will kick in, and when it does, the boost will go down again to .54 ish. The power increase i noticed from fixing that throttle body to elbow leak was quite impressive but there is obviously something wrong.

I for the most part have been following this guide to solve my issue but i'm sort of stuck. let me try to explain.

i can pretty well check most of the things off the primary turbo checklist:

y-pipe: no more couplers= no more cracks (since i have the efini.) meaning i should be okay in this dept.

1" dia. hoses: turbos were working fine before. Can't see this being an issue

inlet: have the trust intake now. Should not be an issue.

To/from IC: Pressure tested and soap bubble tested. Seems fine now.

Air bypass, (BOV) Was working just fine. Didn't touch it.

Now that i look, I haven't checked the charge control valve but it was working fine and i haven't touched it so i can't see that being an issue. Same with the turbo control section. Was working fine before and i didn't lay a finger on that sort of stuff.

The one thing i see that could cause an issue but i doubt it, is the exahust restriction part. I have it tuned for downpipe, straight through midpipe and catback. however, my dp isn't installed yet (its the hks one) but the jdm dp isn't catted anyways so could it really affect things that much? midpipe i have is a resonated one, no cat. rx7.com told me they will flow the same so this should be fine for now. I do have a catback on though.

I don't know if i should move on to the secondary turbo section of this write up or what?
Should i put the dp on then see what happens? (would be on but i just got it last night)

Could there be another issue such as ported wastegates or a bored out boost pill that I don't know about that could cause this grief?

I've been dealing with this for about a solid week now and am just about done dicking around. I thought i would see what you guys have to say and if we still can't get it, just take it to the rotary specialist. Normally i have fun working on cars but this is just annoying to me.

RotoryDreamer

Well running higher than stock boost can cause the solinoids to start sticking/failing so defiantly go through and check them all. My best guess is that the wastegate isn't shutting all the way or the restrictor pill in the line going to it could be missing or the hose ballooned out around it.

Also how many mile are on the turbos? They are known for developing large cracks over time especially if they have ben pushed hard. Could have a crack by the wastegate causing a problem.

Also check around the lower intake for leaks I believe the 93s had paper gaskets the got upgraded to metal from 94 on.


Also do you know if the turbos have ever seen a blown motor? A piece of apex seal going through the turbos can really mess them up.

Mitchocalypse

iTrader: (2)

Okay here's the deal. Turbos were working fine.. too fine before i did some bolt ons + pfc. turbos have about 56k miles on them. Same with engine, which hasn't been blown/rebuilt.

Before i did these mods, the previous owner had a midpipe on it so it was actually OVER boosting. Should mention, i just did these bolt ons last weekend. It hasn't had these problems grow on it, it just started behaving like this after the mods. After said mods, it hasn't seen over stock levels of boost. I would find it very VERY coincidental if it was that last pull (while overboosting) that caused my solenoids to kick the bucket.
I will check everything again. I'm still learning this turbo system so it's a bit overwhelming

I should also mention, nearing higher rpms, the boost decreases a fair bit.

RotoryDreamer

Where are you getting your boost readings from? With a midpipe and no wastegate porting you should be having problems with boost creep up top. Was the pfc tuned by a shop for the car or is it the base tune it came with already loaded on?

Mahjik

iTrader: (1)

What happen or what was changed between when things were working properly and now?

Mitchocalypse

iTrader: (2)

trust intake
efini y-pipe
fmic
mishi rad
ast delete
fuel pump
fuel filter
o2 sensor
water injection
a/c + p/s removal
Power fc

i know some of these are completely irrelevant but whatever.
the previous owner had a resonated midpipe on it as well as an ssqv placed in the stock bov position. The car never came with the stock bypass valve and it was working okay so i never thought twice. If it , makes any difference, this car was boosting to 14 psi before.

Mahjik

iTrader: (1)

I would start by verifying the following given where your recent work has been:

* Wastegate actuator/solenoid
* Charge Control actuator/valve

Mitchocalypse

iTrader: (2)

sorry guys it sounds like i'm being really redundant here. I really am trying to learn this system but it's so complicated. Regarding the above post, You suggested I look at the charge control valve. Looking at the following picture, I don't know what it is pointing to:



From what I am understanding, is this charge control valve is in fact the butterfly valve inside of the pipe that connects the y-pipe with the secondary turbo air out.

But then I go back to this site:
http://www.autosportracetech.com/RX-...leshooting.htm
And it seems to be suggesting that The charge control valve is the charge control actuator? Im so confused right now.
But despite names.. to actually test that it is working properly, would the precedure I would use be the same as on the link?

quoted:

The next thing in the previous post is the wastegate actuator. I just checked the pills tonight. I didn't have a tool to check the exact size of the holes but doing the math, they should have been approx 1.5mm, which that's about where i would estimate. I'm guessing these aren't the problem.

Here is another quote from the site:
So I think I have ruled out pills,
How would I know if the wastegate isn't operating at 95% duty? Should I just do the procedure regardless that the site mentions:
The only other thing mentionned in primary turbo trouble shooting is the precontrol actuator. The only thing that would apply to me is the door slightly ajar (as the wastegate.) I guess if I'm under the car taking off the wastegate rod, i might as well check this one too. The procedure seems almost identical (according to the same site):
Am I on the right track?
The only other thing it suggested is to check or replace the one way check valves. I have no idea where they are but one of those sites has the part number and they're right on the vac line diagram so it shouldn't be a big problem. I hope one of the things up there is the problem.


I should mention also.. I thought it might be a good detail to include that my pfc has 2 boost settings. When turned onto the higher one, my boost does go up a seemingly proportional amount. I can't tie that in with anything i've learned but maybe someone else could.

if you're interested, here are my boost settings on the pfc:


And here is a 2nd gear highway pull just so you can sort of see whats up:
[youtube]FwFKcIVygls[/youtube]

Thanks for the help guys. I really think this could be fixed tomorrow

RotoryDreamer

Is the pfc new or used? I know their are some settings that can affect hitting target boost though idk if you can adjust them with a commander or if you need a datalogit.

Are you getting a proper transition? Even boost on prim and sec. with around a 2ish psi drop during switch over.

If your getting a proper transition but just have lower than target boost I would say either boost leak or the boost control settings on the pfc need to be messed with to get to the target boost level.

Mitchocalypse

iTrader: (2)

Yeah, now that you mention it it seems there's just a lower target boost.
I got the PFC new from rotary performance.

I havd a friend with a fog machine that he said is great for finding leaks. I might have an idea where one is though. I guess I'll start here for today. Thanks!