Need a bit of help diagnosing

[FunkyBuddha]

I've had the AFC in for about 3 weeks now. I'm running the stock supermap that I downloaded off this site.

Mods: Ion FMIC, Greddy RS bov, Turbo XS MBC, Prosport boost gauge, AEM UEGO wideband, Injen Intake

Problem:

I've been seeing 8 to 10psi the past 3 weeks with all these mods installed. The MBC is set to its lowest setting.

2 days ago, the car started to slow down. It won't boost past 6psi now. I feel like the car bogs at around 5500rpm.

VAC value on boost gauge is ok (18 to 20Hg)

Wastegate is ok (tested the blow through method)

No stuttering or rough idles

I don't hear any boost leaks (not anything audible anyways)

Been running the supermap for the AFC

Wideband values look to be normal.

I have not datalogged on the AFC yet.

I have not reset ECU

Current problems with the car: turbo leaking oil

[sandspeed]

Everything sounds like its good except your vacuum at idle. It should be at 21hg to 22hg. Check your vacuum connections from the wastegate to the mbc and then from the mbc to the vacuum source. Perhaps the mbc is broken?

[bonospeed]

when my turbo started burning oil my bov (also a greddy rs) was not opening properly, which caused compressor surge eventually destroying the turbo

[FunkyBuddha]

Everything sounds like its good except your vacuum at idle. It should be at 21hg to 22hg. Check your vacuum connections from the wastegate to the mbc and then from the mbc to the vacuum source. Perhaps the mbc is broken?


Isn't vac pressure also affected by the altitude of my location? I'm not sure..but a lot of turbo cars here run around those numbers since we're about 4000 feet above sea level.

[bonospeed]

after replacing my turbo my vac reads 19 with no leaks (pressure tested to 15psi) and thats in denver at 5300ft

[geomatics_tech]

Isn't vac pressure also affected by the altitude of my location? I'm not sure..but a lot of turbo cars here run around those numbers since we're about 4000 feet above sea level.

I see -9.4 to -9.9 psi (19.3 to 20.15hg) at idle on my profec in Calgary, I was concerned initially but my idle is good and have no stalling issues.

[bonospeed]

if you adjust your mbc can you boost over 6.5? also have you done compression tests on the engine??

[FunkyBuddha]

if you adjust your mbc can you boost over 6.5? also have you done compression tests on the engine??


The compression tests were all excellent. above 190 for every cylinder.
I'll double check my vac and boost lines tonight and then turn my mbc up one notch to see if I can.

What does heat and engine temps do to the amount of pressure in the turbo system?

[bonospeed]

your boost pressure will read the same 6 psi is 6psi but if the car overheats gaskets can melt oil lines can fry etc. is the car running especially hot?

[FunkyBuddha]

Ya the car's running a bit hot actually. More than before but again, the weather out here is about 20 - 22 degrees C*

The temp gauge in the car looks normal.

I don't get rough idles.

I tried fooling around w/ the MBC last night and it wasn't making a difference.

I replaced a couple of vac lines since they were kind of old.

THis morning I would be able to hit 8psi but it was a struggle. It didn't have the same pull. There was a slight hiccup around 5000 rpm and then it would pull again. This was done in 2nd gear.

When I shift to 3rd and 4th, it's harder to boost above 7psi and drops to 6psi at around 5000rpm.

This heat issue...what can I check? I hear the fans turn on and they run.

Question for people: Do your strut tower bars get hot? Like you can't place your hand on it for more than 10 seconds?

[FunkyBuddha]

And..

what are the symptoms of a leaky exhaust manifold gasket?

what are the symptoms of a bad turbo? (i know mine's leaking oil) I haven't checked shaft play yet.

[livelyjay]

I was just doing to say it sounds like you might have an exhaust leak. A leaky exhaust manifold gasket will yield carbon deposits on your engine where the leak is.

[Noel]

are you sure the wga is fine? that sounds very simliar to what happened to myself however my situation was alittle more extreme where I was boosting almost nothing and my car wouldnt even idle.

as for the cut at 5500 rmp that is the maps fault. Mine does that aswell you need to go in and finely tune your map at that rmp/boost level. I, myself have not done this yet and my mods are very similiar to yours and im currently running the "winter FMIC map"

check the vac lines or your cupplers thats really all I can suggest at this point in time based on what you told me and my personal experiences.

[FunkyBuddha]

If the WGA is not fine..wouldn't I be spiking? If the WGA is not fine, it will just flap around. Now I wonder if it's possible for a WG to stick close/open? What would the effects be for these 2 scenarios?

Idle is good. Running supermap. It was running pretty darn good w/o hesitation.

I've also reset the ECU...twice since last night.

[HondaNoMore]

Wg sticking closed you would over boost and stuck open I don't think you would boost at all

[Noel]

wga diaphram wont hold vac, so flap will remain open effecting how much or fast the turbines spin, the faster more exhaust running through the turbines the most boostage and vise versa

could be your ( if its a stock wga ) is just old and worn out, mine crapped the bed at like 60k..had to get a new one and shes good to go thanks to my forge one.

I may be mistaken however that sounds much like the problems I was having with my old wga

I pumped her up to 8-10 psi after always running 6-7 and the thats when it threw the towel in. I found that when I did my blow test if you can get ANY air in the tube shes either on its way out or broken

[FunkyBuddha]

I pumped her up to 8-10 psi after always running 6-7 and the thats when it threw the towel in. I found that when I did my blow test if you can get ANY air in the tube shes either on its way out or broken


Ya...no....I can't blow any air in. At all.

[Noel]

hmm...interesting


1 - wga
2 - vac lines
3 - couples/piping
4 - fmic core hole? leak?


other than those man im out of luck unless anyone else will pipe in with some help im sure it'll be appreciated

[FunkyBuddha]

Ya for sure.

I went under the car last night. Checked the pipes for play, checked for holes, leaks nothing. I replaced a few vac lines that were old and dirty.
Car seemed to be better but still not boosting as it should be..

We'll see what anybody else can say

[yashooa]

Mine did this with a bad WGA it would not respond to a boost controller at all.
It would run high or very low and spooled like crap.
This was on the stock stuff at about 80k miles or so.
I bought the ATP 6PSI model for 60 bucks.
I only pull about 18-21 of Vac in Texas with my setup and it runs fine.
I have bigger cams, lower compression and a host of other things that will change my car from another car I am far from worried.

[FunkyBuddha]

Okay..went out w/ my brother and did a few runs while datalogging w/ the AFC.

1. I never went past 5psi on the 8 runs that I did.

2. I hit 6.7 once and that was the highlight of my night

3. Most were 3rd gear but a few were from 2nd gear and a couple were shifting from 1, 2, & 3

4. Car is running a bit too hot (now that I've been paying attention

5. MBC does not affect car.

[mgerst1]

heatsoak? IC may not be working or radiator may not be working properly. check your coolant line, radiator tank (is it full of liquid), thermostat

[yashooa]

Okay..went out w/ my brother and did a few runs while datalogging w/ the AFC.

1. I never went past 5psi on the 8 runs that I did.

2. I hit 6.7 once and that was the highlight of my night

3. Most were 3rd gear but a few were from 2nd gear and a couple were shifting from 1, 2, & 3

4. Car is running a bit too hot (now that I've been paying attention

5. MBC does not affect car.

Man, that MBC thing is just like mine was with a bad WGA.
It is cheap to buy and easy to install if you have someone to help.
You can change it out on the car without removing the manifold.
We used a small box-end wrench and a long flat head screw driver...like 12 inches or so.
One guy placed the screw driver head against the actuator arm nut and then leaned forward as the guy on the bottom took another driver and popped off the e-clip.
Then we took the nuts off that hold the WGA on.
We installed it in reverse order.

[Noel]

w0rd

and its not that easy haha, well it is, it just takes alot of patience its annoying to get your hands up there especially when they are club hands like mine

[FunkyBuddha]

Ya..i'm kinda sure it's my WGA now. I can't boost past 2psi last night and today. Fuuuuuuuuuuuuuuuuuuuuuuuuuuck

[Noel]

any updated?

[FunkyBuddha]

Ya..ordered a new wastegate..so waiting for that.

Had to put in a new thermostat so I got a Mazdaspeed low temp one. I think the overheating was causing me not to hit my designated boost level.

Also got a newer turbo but that's not getting here till August.

Car's runnin 6psi now...and it pulls good.

[solo.]

I bet you have a nice crack in your exhaust manifold.
If not, check your boost solenoids for broken nipples and tighten all clamps on the car.

[FunkyBuddha]

I bet you have a nice crack in your exhaust manifold.
If not, check your boost solenoids for broken nipples and tighten all clamps on the car.


Will do. But with a crack..I'd be seeing some erratic boost behavior won't I?