wcs

iTrader: (2)

You're having problems.
I would start by replacing the coils.

autoxgt

Why do you say that?
I know its due for coils based on what I've read on here but it appeared to be decent for the miles.

wcs

iTrader: (2)

(@brettus)
Right, Sorry Brett my fault your thread is being hijacked.

Ok I'm use to seeing the dyno's in 4th gear not 3rd but anyway ...
If this is a dyno from an Automatic 06 or greater then IMO it is a good dyno, however if this is from a MT meh
I'm guessing its an MT as you said this was done in 3rd gear but I guess this could be done in a Auto as well. You handle is AutoxGT so I'm up in the air on guessing if you have an auto or mt.
I'll stick with MT as its what I'm use to and own.

In the second dyno you posted, see that first dip that is the APV opening up.

The OEM tune has it set for 6250 rpm and your car barely recovers after it opens.
To add to that my limited experience with dyno (I've help organize with MM 3 or 4 dyno days) tells me that a squggle HP line at the top end is typically caused by an ignition problem.

You can buy a HEI Coil tester from eBay cheap cheap ... I would recommend buying one and testing your ignition.

Without seeing a data log of your G/S its hard to diagnose much further but I would be willing to bet your not pulling enough air across that Maf.

Again if it is a 6 port MT (?) you should be reading +210 g/s across the Maf at 8500+rpm

Now you see that second dip that's the VDI opening at 7250 rpm.
You engine recovers rather nicely from that, which is odd as it struggled to recover from the APV opening.

If it was my car I would:
1) Check ignition (HEI tester)
2) Check SSV is function correctly, start with a vacuum hunt, check that ssv actuator is staying open. Use a hand vacuum pump to test this.
3) Check compression

I just find your dyno from strange that it flat-lines right after the APV opens.

What do you think? Am I on crack?

------------edit------------

Thought this was Brettus thread ... ummm he has one .. I will try and find it for you

autoxgt

Thanks for the info. I will have the dealer check the coils and compression along with the ecu to make sure its up to date.
The car is MT. The first pull was done in 4th gear dut there was a spike in the reading so it showed 208whp after the second valve opening.
The two charts I posted were of runs 2 and 3, both in 3rd gear. The 158HP run was pull #2 and the 161HP pull was run #3.
Im new to the rotary/RX-8 stuff so I'm still reading/searching info.
We were running on a mustang dyno with about 15 other random cars so, the dyno tech was playing around with correction factors and such.
Two guys that also ran that day were saying that they were 20+hp low comparred to their last dyno run, so I'm not sure how accurate the final number are.
I did see that it looked like it was "missing" on the top end.
The car is a 2006 GT 6MT by the way.
Thanks for the advice.

wcs

iTrader: (2)

You're welcome
The common belief around here is that Mustang dyno's always give lower numbers.
I'm no expert by any stretch ... RIWWP has thoughts on why dyno's give such various readings.
It's sort of religious around here along with Oil questions so be-careful posting stuff about it or asking as it can get ugly fast!
Just a heads up

A little be more info on the SSV of which I have experience diagnosing.
The ssv is opened by a vacuum actuator which can fail after time. What I have seen is the diaphragm fails so maintain vacuum so it will initially open then slowly closes again and by the time you reach redline it's closed completely.

I don't know if I would go to the dealer just yet, especially if you feel the car is operating ok.
The dealer is going to rape you on coils and if you are any kind of a do-it-yourself'er replacing the coils is simple.

Like I said already testing them is cheap and simple.

Here are some other links that might interest you:
Strongly recommend this one if you haven't read it already
https://www.rx8club.com/new-member-forum-197/new-potential-owners-start-here-202454/

other stuff
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/highest-horsepower-dynos-sc-turbo-nitrous-post-them-here-180037/

https://www.rx8club.com/series-i-major-horsepower-upgrades-93/dyno-comparisons-sc-turbo-115058/

SSV Thread
https://www.rx8club.com/series-i-do-yourself-forum-73/diy-remove-ssv-beta-teaser-video-184663/

RIWWP

iTrader: (2)

^ I don't think my theory really applies for him. The torque instability and drop off in the 2nd half of the range tells me that something is wrong. Ignition is most likely as you said. E-shaft profile and MAF would be the next two to check.

autoxgt

Thanks for the heads up. I'm not saying anything bad about the dyno. I know the arguing that happens there.
I'm just having the dealer do some diagnostics and compression check and such. Trying to build a little relationship with the dealer in case it ends up needing the engine core replacement deal.
I plan on picking up the BHR ignition kit in a few months. I have some work I need to do on the brakes first.
Can I check for vacuum leaks using propane around the diaphragms or is there another way to test them?
I'm diy'er so I will be doing most of the work myself.

RIWWP

iTrader: (2)

Do not use propane. In theory it would work under the same principle, but it's a dangerous gas to use in an engine bay with plenty of heat and electrical sources.

Use a can of carb cleaner instead. Much safer, much easier to control, and will have the same result.

Typically though, vacuum leaks cause more problems the lower the RPM it is, less problems the higher the RPM. The reason is that a vacuum leak inherent means that air is entering the engine that is not passing the MAF sensor, which means that the MAF readings are not accurate (reads low, because you are using the same amount of air anyway). This other air source becomes a much smaller and smaller percentage of the overall airflow as the RPM / load climbs, so the MAF error is reduced and it's closer and closer to the true airflow.

Low compression is another issue that is more pronounced at lower RPM (because our compression increase as RPM does).

Your issues are high RPM stumble and fall off. If it was just fall off steadily, then it would suggest a flow problem with either air in (bad intake design, intake valve problem) or exhaust out (clogged cat). With the stumble added in though, it's showing that something is having trouble keeping up with the RPM, in which case it points to ignition having trouble firing accurately as the RPM increases, or the e-shaft profile starts to skew, or the MAF is dirty, and it has trouble reading high air flow rates consistently.

wcs

iTrader: (2)

You can use propane for general vacuum leaks around the UIM however a leaking SSV actuator would not be discovered this way.

SSV only opens under load and rpm

There is a diaphragm actuator the opens the SSV it is connected to a vacuum accumulator located at the bottom/back of the UIM. It's really close to the Oil Filter, back that way.

So the only way to test the diaphragm is to use a hand vacuum pump and check that it holds vacuum.
Checking the accumulator at the back would likely be done best by taking the UIM apart

edit-------------
But like RIWWP said ...
Check ignition
Clean ESS (reset as well)
Clean Maf

These are really cheap and easy to do

You might have to clean the ESS as well, I actually had a piece of copper wire sticking to mine and it made the car run horrible.

autoxgt

Thanks guys. I will check and fix these things. I knew when I bought the car, that I would need to do a lot of this sort of stuff. I have already read a wright up on cleaning the MAF/intake assembly which I will be doing next weekend.
Am I right to assume that once I check/clean the ESS that I can reset the profile by doing the ECU reset (key on, hit brake paddle ect.)?
I will be changing the plugs when I do the brakes next month and hopefully the BHR ignition kit soon there after.
I will re-dyno it and post new results after the new coils and such are done.
Again, thanks for the input and if I run into any other stuff, I will post in the appropriate area.

maskedferret

iTrader: (1)

New plugs, even.

wcs

iTrader: (2)

Compression

bse50

He has a 4port engine and he doesn't know.

maskedferret

iTrader: (1)

Meh, I know; just checked it yesterday before swapping plugs :

Front: 99, 97, 105 @ 284 -> normalized to 250 : 96.19, 94.25, 102.02
Rear: 101, 104, 104 @ 284 -> normalized to 250 : 98.13, 101.05, 101.05

Just below spec, but just above what I tested at the end of last year.

maskedferret

iTrader: (1)

bse50

We all lose a couple of ports over time

wcs

iTrader: (2)

Did u check the ssv.
Dark brew had similar dyno when his ssv was screwed

maskedferret

iTrader: (1)

No, I haven't; but it's been on my short list of things to do. Not exactly looking forward to dismantling the UIM to get at it. It would make sense, actually; that pronounced dip isn't on this dyno chart like it was on my previous ones. Shouldn't I expect a code to be thrown if there was an issue, though?

Aaron B

Another frustrating trip to the dyno for me



162whp, same as early last month, and same lack of power after 7200rpm. After the last visit I changed the ignition coils, plugs and wires hoping that was the culprit, apparently not.

The runs were logged on my AP and I have the CSV files here:

https://docs.google.com/spreadsheet/...DdKUUs1NFZ0UUE

https://docs.google.com/spreadsheet/...Uhib2dKeS0wTmc

https://docs.google.com/spreadsheet/...m5LdnZQbGhRUkE

https://docs.google.com/spreadsheet/...zdqRTNpY2ctU3c

I noticed that the mass air flow really seems to level off quickly from 7500rpm on, could that possibly be the culprit? Vacuum leak? Sticky valve?

The car is a 2007 with 18,000mi (autocross car). K&N drop in filter, BHR mid with 100cpi cat, RB "race" cat back and running an AP with a MM tune.

Any help diagnosing would be greatly appreciated, I've had the car 2 years, my first rotary, and I really haven't gotten into the workings of it yet because I've been focusing on sorting the suspension.

TIA

-Aaron

wcs

iTrader: (2)

No necessarily.
Jon explains why somewhere, I think in this thread

https://www.rx8club.com/showthread.php?t=184663

You don't have to dismantle the UIM to check if the SSV is sticking. Just move the actuator arm up and down, its easily reached.

You can also test the SSV actuator to make sure its not leaking.
Use a hand vacuum pump and slow apply vacuum until the SSV Opens, make sure actuator maintains vacuum and doesn't leak back down.

Same with the VDI actuator, its in the same area.

Same with you Aaron.
Is it an Auto or MT?

Your max calculated load reading at the torque peak seems low, which would make sense if your not getting enough air.
You g/s values seem low everywhere.

The SSV opens by load typically between 3250 and 4500 and the APV opens at 6250 rpm and VDI opens at 7250 rpm.
The SSV and VDI operate from the same vacuum accumulator, the APV is controlled electrically.
Therefore if one of the actuators where to have a bad leak when the solenoid opened it the vacuum would bleed away for both the SSV and VDI actuators, compounding the air flow problem.
Maybe you have a bad vacuum line or actuator on the SSV or VDI?

If you don't have a CAI check to make sure the VFAD is working correctly.

Pics of LIM and Actuator locations
https://www.rx8club.com/rx-8-discussion-3/possible-vdi-ssv-232316/

Jon talking about SSV cel and tests
https://www.rx8club.com/series-i-trouble-shooting-95/low-power-low-rpms-new-engine-232332/

PhillipM

That thing looks like it's dying at 6500rpms right where the APV should be opening.

wcs

iTrader: (2)

It's hard to diagnose from where we sit, lol
You could be right ...

But I would guess the SSV never really opens ...

You can see the dip at 6250 rpm that is the APV and it does recover and again when the VDI opens at 7250 rpm

Thru the entire rpm range the G/S seems low and he never hits 100% calculated load around the torque peak at 6000-6500 rpm

You don't always see it but sometimes there is also a dip when the SSV opens.

So PhillipM at least we can give Aaron something to look for in the way of Intake Valves not functioning correctly, yes?

Aaron B

Sorry for the missing info. The car is a MT car and the VFAD has been removed, figured even if it didn't make any more power without, it was still a couple pounds off the nose.

Thank you for the info so far, I will start reading into it.

wcs

iTrader: (2)

Check that nipple on the UIM behind the TB on the bottom of the UIM.

It should be plugged.

Make sure the cap hasn't come off or is cracked.

Aaron B

Are you referring to the vacuum nipple for the VFAD system? It should be ok, the system was removed between the two different dyno sessions that apparently had the same problem.

I will double check the vacuum cap, though, I suppose it IS possible that the VFAD system had a leak AND the cap that replaced it is not sealing properly.

Thank you again, guys, for your time in helping with this.

*edit

I guess I don't know for sure that the two sessions had the exact same problem, I only had the one yesterday datalogged, all I have to go off of for the previous session is the dyno readout.