Bbtr

Hi,

Is it possible someone might be able to shed some light on data i pulled of my ecu please?

Out of pure curiosity I bought a lead and used the btssm on my stock jdm sti bugeye. Ive owned the car for about 1 year now with 72k miles on it. Up until this point the only issues I had was it was on original spark plugs which was causing it to hesitate. The gaps on them were seriously like 2mm! And also im pretty sure it was original fuel filter. That was changed at least 6months ago. I have never heard it pinging at any point until now.

I've always run it on 99 shell or tesco, but to my disgust these were my LV parameters. I know jap cars are meant to be run on 100oct but in stock trim I would have thought uk 99 would be OK. As I said the car was running fine I just wanted btssm for gauges.

I reset the ecu and took the car for a quick spin. On a WOT 4th gear pull there was slight auditable pinging at about 6k rpm now(obviously as the lv tables had been reset). Ok ill give it one more try so i did it again but got a knock warning as shown below. The LV table then updated to -3.8 in that top end of the load table(previously very high at -8 as seen in the attacment).

The flkc dropped to -2.1 or something aswell

the injector duty cycle is quite high for the knock condition and 30deg timing at 6krpm seems excessive.is this normal for an STI?

Has anyone had this bad of an LV table on a stock jdm ecu?

If a fuel pump was on its way out would this not show up as a lean A/fr.
I did a quick log of the afm and it consistantly increases its measurement with boost which leads me to suggest the afm is OK.

my Iam score is still 16 so from what im reading the ecu is generally healthy?

Any help appreciated. Sorry for the long post

1509joe

iTrader: (2)

Something not right there should be something similar to this.

Bbtr

Thanks
Yours jdm on stock tune?

Also how do you get the LV table to show a greater rpm range? Mine only goes yo 5600rpm?

Good to know, I don't really want to tune it happy to keep it stock. I guess if yours is stock I'm looking at a mechanical issue rather than the stock jdm ecu tune being to aggressive.

Guess ill start with the cheap things first such as fresh fuel and injector cleaner, MAF cleaner check,check for boost leaks etc.

It must be an ongoing issue that the ecu has learned as the first LV was taken was when I was sitting in the driveway. Previous to resetting the ecu i had never reset the ecu or even disconnected the battery so it must've been like this for a while.

thanks again,

Michael

1509joe

iTrader: (2)

No has been mapped, As for the rev limit don't really know is yours a wrx or sti? Apparently the stock tune is aggressive and the yellow areas in my graphs are due to it being twin scroll which are noisy in that area or so I'm told. There is no boost or revs in that area. Hope that helps.

Bbtr

Mine is an STI. Also a spec S bugeye but can't find any info on what a spec S is other than it came with no stereo and a stainless exhaust.everything else on the surface seems to be a standard jdm sti with front lsd. Even the ecu in it is a 6s i think.

Thanks for your help mate.

If u get a chance im curious to see how much timing yours has at around 6krpm and boost targets seeing as its been tuned.

I dunno if its something I should be worried about or not.
Ignorance is bliss. Kinda wish I never plugged in tbh. Its one of those things that will play in my head now.

When I purchased it from Hurst cars who are meant to be reputable max said it had been map checked for UK 99 and was OK.

I've done a few more 4th gear pulls up to 6krpm(I run out of road and licence if any faster)the LV value seems to have now increased from 0 to -5 with some new fuel after an ecu reset. I Can't hear any auditable pinging now and pulls smooth and doesn't throw a knock warning.

Thanks again.

1509joe

iTrader: (2)

Couldn't be a 6S ecu that was a v3/4 STI get the carpet up and see cause that would possibly explain a whole lot. As for timing I'm now on Syvecs so cant help you there.

Bbtr

Sorry don't know why I was thinking 6s its a v8 ecu.

1509joe

iTrader: (2)

So you've a v8 ecu in a v7 bugeye ?
Or has it V8 stamped on the ecu ?

Bbtr

V8 stamped on the ecu. It is completely stock as far as I am aware.

1509joe

iTrader: (2)

I am lead to believe that the stock ecu does not or can't pull timing after 6k I will enquire about that for you.

bludgod

iTrader: (3)

going by the ltv air corrections I'd initially consider a boost leak test or at least having the afr checked properly with a wideband as the factory o2 readings arent reliable on boost - also for logging a pull you want to actually log the pull and post it up dont just rely on the ltv saved corrections as they dont always tell the full story.

if there isnt a boost leak it could also be a dodgy maf or o2 sensor giving the ECU poor readings to work with - or it could be something else entirely there just isnt enough data to form a conclusion here.

Bbtr

Bbtr

Its crazy the info you can log its very interesting!

Wouldn't a boost leak show up in the form of waste gate duty cycles being all over the place and not meeting boost targets? They seem very linear from the wot pull in the quick photo i took of the log

The ecu fkc is pulling-3.5 deg timing on everything over any rpm where it is on boost which suggests things aren't happy?

Also the MAf readings seem to very linear in respect it increasing with rpm. Does a failing MAF still read linearly?



This may be unrelated

At around 4krpm i have now noticed a slight miss which is very similar to when the spark plugs needed doing. This is seen in the data log at around 4krpm just as it comes on full boost you can see the MAf increase its value then at 4093rpm it dips slightly then picks up again.

Is it good assumption that 4k rpm is around max peak toqrue thus max cyclinder pressure where for a split second the spark plug isn't firing therefore the engine isnt drawing in air and making power which shows as a slight dip on Grams air per sec on the MAF?

Could this suggest that the coil packs are on their way out. Probably because this import had original plugs with 115000kms kn it the coil where working over time to generate a spark across a huge gap and have broken down down?

Thanks again

MrRtm

I'd check nothings loose pal, I got some horrible readings a few months back, turned out a coil pack was loose, tightened it up, no more horrible readings.

​​​

bludgod

iTrader: (3)

we will have to take your word for it seeing as you've only shown a screenshot of the log and not the actual log itself.


If you want to test for a boost leak, do it mechanically as that's how you can be sure, otherwise your just guessing based on some information and some assumptions. Test and be sure. Remember these cars will make a fair bit more than the standard boost level when mapped so it's no surprise you can be leaking some pressure and the turbo can still make target boost.

Or it's always been like that and you've never noticed before - hard to say without more information.

Yes on total failure the readings will be flat and terrible, on its way to failure it will just read a little less as you get up the scale so the top end of the revs it becomes lean and causes knock. Or possibly the MAF readings aren't accurate because there is a leak somewhere - test and be sure.


Check you've not got a loose wire or something else mechanically out of place though. If you can log per cylinder info (not sure if its available in BTSSM or not) then you could possibly identify one cylinder more troubled than the others - then switch the coilpacks around and see if the problem follows the coil rather than the cylinder. But you can't go purely on the log data you need to get the bonnet up and have a root around and do some physical checks.

Bbtr

"Yes on total failure the readings will be flat and terrible, on its way to failure it will just read a little less as you get up the scale so the top end of the revs it becomes lean and causes knock. Or possibly the MAF readings aren't accurate because there is a leak somewhere - test and be sure."

Should this not show up as a leaner AFR? But yes that makes sense if it was reading lower. This might be why the original learned fuel values was adding fuel.

Thanks again for suggestions.

bludgod

iTrader: (3)

yes - on a wideband o2 sensor it would show as leaner than it's mapped for - you can't trust the front o2 sensor for tuning decisions though it's only good for closed loop/low load operations.

Bbtr

Hi,

I replaced the coil packs and I no longer have a miss. The new ones had a resistance of 1000ohms where as my old ones didn't wven register an ohm reading on my crappy multimeter. It genuinely feels faster as it has added more timjng on boost now. Especially off boost it seems more responsive.

This has cleaned up.the LV table alot compared tk where it was. However it is still pulling a bit of timing on the top wnd of the lv scale -3.5 deg flkc

should airflow increase in linear fashion with rpm ? My MAF readings are all over the place still at high rpm. I have cleaned the MAF and it didn't make a difference. All hose Clamps are tight and I've inspected all joins etc for splits all OK.

here is a screen shot of the log table the MAF readings column K is maf reading and L is rpm. This is a WOT 4th gear pull.


Thanks again,

Michael

Bbtr

Just a follow for anyone with similar issues.
Tightened and triple checked all connections intercooler etc. Btssm was showing between -9 and 10 psi when wewrm

The miss I had at around full boost 4krpm was fixed with coil packs. This showed up in the logs as a drop in maf g/s when the miss occurred. This also had my ignition LV Chartt all over the place.

I disconnected the fuel return line under the bonnet and ran the car for 30 secs with the fuel pressure reg disconnected so the pump was pumping against 43.5psi (verified with fuel pressure gauge after the fuel filter which is what the manual suggests to check the fuel pressure reg is working correctly ) and filled a container with fuel. There was only about 900mls of fuel in 30secs so in 1min it would flow 1.8ltrs at 43.5psi. All of the info I've been reading is that a jdm sti pump does 145l/h at
43psi divide this by 60= it should be able to flow 2.4ltrs a min which is more than what the theoretical 2.2ltrs min 550cc injectors can flow.
Now I know I did this with the car running at idle so if you take into account injector duty cyclr is approx 2% at idle 2% of 2200cc is 40mls of fuel that the engine is using maybe slightly more as the fuel pr3ssure at the rail is higher because I had the fpr reading atmosphere. So max it was doing as an educated punt was around 1ltr in 30secs so 2lts/min.
I was working on the maths of 4x550cc/min injectors=2200cc at 100% duty cycle. My logs were showing duty cycles of 96%. 96%x2200=2.1ltrs the engine requires to be happy. My pump was only supplying 1.8ltrs at 43.5psi. Even if the ecu is only putting 12v dc to the pump instead of 14vdc ( it think it may have some control of pump speed as there is a fuel pump control box in the boot lining going of walbro pump flow charts vs voltage there is roughly an 11% decrease in flow at 12vdc vs 14vdc.
Basically my theory was that the top end of my LV scale at 5krpm and 5600k rpm under full load the fuel pump was just on the cusp of supplying enough fuel.

From my logs I also determined that it seemed to want to pull more timing when it was cold as there was more Grams/s being registered on the maf. More air requires more fuel right.

Long story short I replaced my fuel pump with a walbro 255. I have done multiple 4th gear pulls even up long hills and there has been no knock events or no timing being pulled. The scary thing is who knows how long its been like this.

To recap problem fixed with coil packs and fuel pump.

1509joe

iTrader: (2)

I always run a fuel pressure gauge has saved engines many times. Generally change pumps every two years aswell.

Bbtr

I'll def be checking it more.

pressure wasn't the issue it was flow.

1509joe

iTrader: (2)

When you run out of flow you loose pressure.

Bbtr

To fair I never did run the car with the fuel pressure gauge taped to the window like I was going to do. It was a ghetto fuel pressure gauge made up from various fittings from work i took the safer driveway option.

1509joe

iTrader: (2)

We monitor fuel pressure with the syvecs all the time