Low boost, running out of ideas...

[tempaccount]

I decided to start a new thread as my issue doesn't seem to pertain to the bypass.

Background:
I live in Denver 5,200 feet above sea level
2005 Elise
10,xxx miles
BWR SC 1,500 miles on the install

Problem:
Max boost @ 8,200rpm ~5 (I've previously seen 7psi)

Here's what I've done so far:
Replaced the Supercharger belt / and tried a shorter belt

Replaced Belt Tensioner

Compression test 175 across all cylinders (loss at 5000 feet of altitude= .8617)

Removed SC to inspect bypass valve / the valve operates and seals properly

Upon removal found transmission mount bolt had sheared. Replaced transmission mounting bolt with grade 8 bolt

Replaced intake manifold gasket

Swapped ECU with CharlieX tuned ECU

Conclusion:
I've run out of ideas as to what it may be...

The car achieves 5 psi easily, be tween 4500 and 5000rpm. At cam changeover it drops and then creeps back to right around 5 psi.

One passenger did mention while driving with me that during one run I let the car bounce off the limiter and they said they said they saw 6.5-7psi briefly. I can't understand why the pressure would increase on the limiter but it may have?

I'm grabbing at straws at this point.

The car is mostly used at the track, perhaps a hard downshift may have "stretched" a valve??? (Wouldn't the compression test have shown it)

Maybe I have a really dirty air filter or some kind of blockage in the air box (maybe I should try a run with the airbox removed).

What am I missing?

[apk919]

Originally Posted by tempaccount

I decided to start a new thread as my issue doesn't seem to pertain to the bypass.

Background:
I live in Denver 5,200 feet above sea level
2005 Elise
10,xxx miles
BWR SC 1,500 miles on the install

Problem:
Max boost @ 8,200rpm ~5 (I've previously seen 7psi)

Here's what I've done so far:
Replaced the Supercharger belt / and tried a shorter belt

Replaced Belt Tensioner

Compression test 175 across all cylinders (loss at 5000 feet of altitude= .8617)

Removed SC to inspect bypass valve / the valve operates and seals properly

Upon removal found transmission mount bolt had sheared. Replaced transmission mounting bolt with grade 8 bolt

Replaced intake manifold gasket

Swapped ECU with CharlieX tuned ECU

Conclusion:
I've run out of ideas as to what it may be...

The car achieves 5 psi easily, be tween 4500 and 5000rpm. At cam changeover it drops and then creeps back to right around 5 psi.

One passenger did mention while driving with me that during one run I let the car bounce off the limiter and they said they said they saw 6.5-7psi briefly. I can't understand why the pressure would increase on the limiter but it may have?

I'm grabbing at straws at this point.

The car is mostly used at the track, perhaps a hard downshift may have "stretched" a valve??? (Wouldn't the compression test have shown it)

Maybe I have a really dirty air filter or some kind of blockage in the air box (maybe I should try a run with the airbox removed).

What am I missing?

1) Check your air filter...

2) Do you have access to a OBD-II scanner with live data? If so, what flow are you getting through your MAF at full load?

[tempaccount]

Originally Posted by apk919

1) Check your air filter...

2) Do you have access to a OBD-II scanner with live data? If so, what flow are you getting through your MAF at full load?

I don't have access to an OBD-II scanner. Do you (or anyone here) have a recommendation for a inexpensive scanner that would work for this purpose?

Does anyone make a smaller pulley for the BWR SC, I'm tempted to just try to spin it a little faster and see what happens.

[apk919]

Originally Posted by tempaccount

I don't have access to an OBD-II scanner. Do you (or anyone here) have a recommendation for a inexpensive scanner that would work for this purpose?

Does anyone make a smaller pulley for the BWR SC, I'm tempted to just try to spin it a little faster and see what happens.

I have a number of OBD-II scanners...

This one from Sears can read and reset diagnostic codes, as well as display real time OBD-II data: Craftsman CanOBD2&1 Scan Tool Kit with PC Software & Optional RepairSolutions®



There may be cheaper ones out there that provide the same functionality...

[Dragon]

Have you tried anouther boost gauge by any chance?
Have you looked for cracks in the manifold?
Have you checked to insure your throttle body opens all the way?
Have you checked the fuel injector seals?

Air box or Filter restriction as you mentioned is also a possible problem...

I haven't seen your other thread, so I'm starting out with no prior knowledge of what you've done to date hence all the questions...

[Jermaine@VF]

What time of year did you check the boost previously? Was it at the same altitude?

[tempaccount]

Originally Posted by Dragon

Have you tried anouther boost gauge by any chance?
Have you looked for cracks in the manifold?
Have you checked to insure your throttle body opens all the way?
Have you checked the fuel injector seals?

Air box or Filter restriction as you mentioned is also a possible problem...

I haven't seen your other thread, so I'm starting out with no prior knowledge of what you've done to date hence all the questions...

I've tried multiple gauges
The manifold looked to be in good shape
I did investigate the throttle cable was fully opening the throttle body

I did not check the injector seals. I will try that.

[tempaccount]

Originally Posted by Jermaine@VF

What time of year did you check the boost previously? Was it at the same altitude?

The altitude is unchanged.

The time of year/outside temperature is something I've been thinking about...

The previous reading was done on a cool (50 deg) spring evening. The latest readings have been captured on warm (80 deg) summer afternoons. I would assume the heat would lower the efficiency of the blower but could 30-40 degrees of ambient air temperature make a 2psi difference?

[fzust]

Originally Posted by tempaccount

The altitude is unchanged.

The time of year/outside temperature is something I've been thinking about...

The previous reading was done on a cool (50 deg) spring evening. The latest readings have been captured on warm (80 deg) summer afternoons. I would assume the heat would lower the efficiency of the blower but could 30-40 degrees of ambient air temperature make a 2psi difference?

I had a Turbo M3 that would run 10psi on cold mornings and 7.5-8 when it was hot. It had a wastegate that was too restrictive. That said, since you are positive displacement, I think maybe not. I know I asked before, but did you verify the bypass valve actuator does not have a leak? If the vacuum is not enough to overcome the leak you could be partially bypassing the blower.

[tommyc]

Just an idea to see if all the vaccuum lines on the air box are ok, plug the line going to the servo on the air box which should send all vaccuum to to only the bypass valve. this will cause the flap on the bottom of the airbox to stay open but it will rule out bypass valve disorder from air leak in the lines on the airbox. the line to plg is the orange silicone one.

[Demonized]

Originally Posted by tempaccount

I don't have access to an OBD-II scanner. Do you (or anyone here) have a recommendation for a inexpensive scanner that would work for this purpose?

Does anyone make a smaller pulley for the BWR SC, I'm tempted to just try to spin it a little faster and see what happens.

I have an OBDII reader that will show lb/min airflow over the MAF.

CAN OBDII Code Reader AL309 from etoolcart.com cost me $85 shipped.

If your Elise isn't in pieces you could drive it up here and we could check it out, I'm just south of Denver.. You're in CS if I recall correctly?

[tempaccount]

Originally Posted by Demonized

I have an OBDII reader that will show lb/min airflow over the MAF.

CAN OBDII Code Reader AL309 from etoolcart.com cost me $85 shipped.

If your Elise isn't in pieces you could drive it up here and we could check it out, I'm just south of Denver.. You're in CS if I recall correctly?

Thanks for the offer. I'm actually in Boulder. The car is mostly put back together aside from the belly pan and engine cover.

My wife's out of town this weekend and I'm watching the 1 year old so it would be difficult to get down to South Denver.

[scottyb]

Check for a boost pressure gauge line for a leak. I had one in the line running to my boost pressure gauge and had similar results that went away after I fixed the leak.

[turbophil]

Don't get so hung up on what your gauge says. Dyno it. If the power is fine, then boost is also fine...

If it's low on power and low on boost, etc- it's mechnical- Plan and simple. You may drain the oil on the blower and see if it looks like black sludge. If so, perhaps the shaft coupler is destroying itself. This has happened to others... That's a stretch though...

Again, dyno it is your best bet...

TP

[scottyb]

Originally Posted by turbophil

Don't get so hung up on what your gauge says. Dyno it. If the power is fine, then boost is also fine...

If it's low on power and low on boost, etc- it's mechnical- Plan and simple. You may drain the oil on the blower and see if it looks like black sludge. If so, perhaps the shaft coupler is destroying itself. This has happened to others... That's a stretch though...

Again, dyno it is your best bet...

TP

Well Phil, when we did the BW Vs Katana Dyno shoot out, I was pulling 220hp with a nice boost leak in my line to my gauge. It wasn't till the line complete disconnected that I realized that I had a leak and was leaving a nice chunk of Hp off the table.

[turbophil]

I'm not trying to be overly doubtful of you, but it would be one heck of a vacuum leak to bleed off enough air to impact whp... Again, it's just hard to diagnose without before and after dynos...

Later,

TP

[scottyb]

The leak was small enough to slow up the building of pressure and caused a nice drop during the cam change. It was really apparent if your were on the throttle for a bit, built up pressure despite the leak, and then lifted off the throttle. The engine kind of bucked. At first we thought it was a stuck blow off valve or an issue with the tune. All that disappeared after the leak was fixed.

[tempaccount]

Originally Posted by scottyb

Check for a boost pressure gauge line for a leak. I had one in the line running to my boost pressure gauge and had similar results that went away after I fixed the leak.

The boost gauge sender is threaded directly into the intake manifold so there shouldn't be any leaks.

[tempaccount]

Originally Posted by turbophil

Don't get so hung up on what your gauge says. Dyno it. If the power is fine, then boost is also fine...

If it's low on power and low on boost, etc- it's mechnical- Plan and simple. You may drain the oil on the blower and see if it looks like black sludge. If so, perhaps the shaft coupler is destroying itself. This has happened to others... That's a stretch though...

Again, dyno it is your best bet...

TP

A dyno is likely in my future but I did have the car recently at the natural dyno, the dragstrip.

The car did a 14.6 at 95mph (consistent 3 passes) which seems to me to indicate a loss in performance? I don't have any other baselines for BWR/Katana cars 1/4 mile times at 5,000feet but I was anticipating more...

[Demonized]

Did you have your car on the dyno since the ~173whp run?