Hi guys....Looking for some advice on possible causes of the problem my 8 is having. My 8 has been running fine boosted with the Greddy kit on about 6-7 psi with AP via MM tune for more than a year now. But just recently, it started bogging on WOT and won't hold boost as well. It almost sounds like when your BOV is loose and won't hold boost. Which is why its the first thing I tried to check, tightening it step by step, to the point of compressor surge. But problem never went away.

The car idles and drives fine as long as I don't boost or press gas too hard. It can even climb up to higher rpms (like 7k) no problem as long as I lightly press on gas.

I recently replaced spark plugs and checked the coils (BHR). One of the coil wires, closest to the firewall, broke, so i tried to be creative and reconnected it using copperwires. I THINK its fine now seeing as the car has no idling problems.

Another thing I had in mind was that it could be a boost leak, so I tried to do a tester but only had a bike pump available to me. I attached the tester to the turbo outlet pipe and covered the pipe by the TB, put all my weight on the bike pump and got to the point where I couldn't press down on it anymore, so I asked some1 else to hold the pressure for me while I listen for hissing noises and heard none. I may have done this half as*ed tho..lol.

I also changed most of the couplers with new ones since I had the stock ones that came with the kit.

A few things to note:
The battery is really old and has discharged a few times. But I have no problems starting her up. Also, while I was putting on the new couplers, I decided to check the turbine thats next to the inlet pipe for shaft play and there was none, it actually felt the same as when it was new.

I plan on taking it to a shop after one last boost leak test, but before that, I'd really appreciate some inputs or ideas from u guys. I'd rather use the $ for school and do it myself than being lazy and giving away money for something I could do myself. Thanks!

 

Sounds like a boost leak . Your test seems ok but maybe its in the manifold .

Can you do a log at idle cruise and wot - that may tell us what's up .

Log AFR , MAF , load , LTFT , timing . rpm , TPS

 

Here ya go:

 

Good work with the logs .

*LTFT at idle is over -14% . A negative trim at idle indicates air leaking out of the system if anything so that rules out a leak post throttle body as that would generate a +ve trim from unmetered air being sucked in.
*Any hint of load and it goes rich
*Afrs seems to float around at cruise a lot

Have you checked the connection of the turbo outlet pipe to the turbo ?
I have found that a vac. cleaner on blow jammed into the intake and a soapy spray bottle works well to find a leak .

 

No I haven't yet. I'll check that asap n let u know...tnx!

 

A negative trim means there is less air going into the system than the MAF is metering. It doesn't rule out an open.
Furthermore, any leak - before or after the TB - would potentially produce a positive FT.

You mean any hint of open loop.

He didn't log STFT, so we don't know if the cruise log was in open loop or not.
I can assure you he is not (through experience), but your observation on this is not well founded.

His MAF is over-reporting. This can be any one of many things.

 

Did you just contradict yourself there ? ... heh .
I wasn't sure if a leak close to the turbo would produce a positive or a negative trim because it may be possible to have a slight positive pressure straight after the turbo .


nit picker

So - you just came in here to give ME a hard time . No attempt to actually help the guy out ...wonderful .

 

He didn't ask for my help.

The datalogs you asked for do not contain enough information.

If Ron needs me, he knows where to find me.

He never got past the second iteration of the MMCCS. That calibration isn't even remotely close to a complete work, so it is difficult to say where it sits.

 

Wonder why ....

You really think logging STFT will magically unravel this issue ?

Maybe you should re-read his first post .

 

Unfortunately, I couldn't get the data logs in time and went past the 6month deadline. I didn't really have the $ to extend your services so I figured I'd just take it easy on driving and boost only on my weekly "redline maintenance."

Actually, I'd appreciate whatever help you can give on this issue. I didn't bother asking because I figured you'd be too busy with everyone else's tune...and you probably still are..lol But like I said, any help you can give will be greatly appreciated.

 

https://www.rx8club.com/mazdamaniac-183/attention-current-mazdamaniac-custom-calibration-customers-212845/

Jump right in.

Actually, yes. It always does.

 

[QUOTE=MazdaManiac;3993943
Actually, yes. It always does.[/QUOTE]

how exactly ?

 

Short answer - it shows exactly when the engine moves in and out of closed-loop.

 

True - but how does that help in this instance ?

 

You're kidding, right?

 

/\ no

 

So, you've been doing all this tuning now without understanding the OL/CL transition and the relationship of the STFT as a flag for the transition?

How the hell do you know what to adjust in a part-throttle situation (MAF, fuel table or injector scaling)?
How about fuel table adjustments in transition (from partial to full load)?
How were you setting up your load maximum curve?!?!

You don't know anything about where the PCM is without seeing where it stops using STFT. Even the exit load tables are useless without understanding this little piece of data.

It points to EVERYTHING.

Ron's car is falling on its face somewhere, but you don't know where without STFT.

 

OK, for instance:

Look at his "cruise" log from 45 to 50 seconds. Is he in OL or CL?
What is the transition? What MAF value is screwed up for the translation into load?

How about his "WOT" log? He never actually goes into WOT (or even sweeps the RPM range), so we are guessing what the PCM is doing at any point in that log.

 

Well I do know when the transition is but still fail to see why you make such a big deal about it .
You practically only need breath on the throttle to go into OL - so you hardly need to see the stft logged to know if you are in OL or not . As you mentioned earlier -experience would tell you - you don't actually need to see it.

The ecu moves into OL at very low throttle/loads and then you are into OL maps . What are you talking about ?


Why do you need to know? I'd really like to know what it is that you are tuning that I'm not .

Yet again you have made this into a "I'm clever and you are not" answer and explained absolutely nothing .
Well done !

 

Incorrect.

Also incorrect.

I have neither the time or inclination to repeat the same goddamn stuff over and over again.
You know where to get all this information.

 

I'll clue you in -

The logs that are posted here are useless.
However, logs presented using the guidelines in my calibration service instructions would make it absolutely possible to solve this issue.

 

Translation : stop arguing with me , you might make me look bad .

 

Ok, so I tried to find boost leaks and actually found 2 small ones. I Fixed them and test drove but it barely made any difference. Although I can actually hold my bogging now in boost fluctuating from 3-6 psi. It only went up to 5psi then went 0-2 before. This leads me to believe that I am either plagued with boost leaks im not seeing, or it has nothing to do with it.

The leaks I found were on the wastegate signal tube and the lower bolt of the inlet pipe which I threadlocked. I retested to make sure the leaks were fixed and there was none.

I'll take you up on your offer MM and will be logging on the 14th of June. But while I'm waiting. Is there anything else I should check or should I just wait till I submit you the logs?

PS. I appreciate both of your help on this problem. Its a bit hard to concentrate on school when you have the urge to try n fix your car. Its been a bit frustrating..lol