Have an impreza sti spec d 2006, starting having hesitation problems a few weeks ago, cleaned the MAF as I saw this writen in the service hsitory from a few years ago so thought I'd try it and seemed to stop for a bit, but was still doing it sometimes but only slightly.

Now it's back and a lot worse, it now jerks and hesitates starting around the 2k rpm mark and carries on up through the rev range.

Decided to buy an obd2 cable and get some software to do a log, this was just going from idle to full throttle while static, I can also do some logs while driving if needed, have uploaded it here, hopefully it works ok, it's just an excel csv file

Mega File Upload - Matlog1.csv

Not sure if there is enough info in the file to tell anything? would really appreciate if anyone who knows what their looking at could give it a look over please? thanks.


Also here is a log when driving the car, showing a bit more the the previous log file

https://www.dropbox.com/s/c53f6yqs6i...log3a.csv?dl=0

 

Replaced spark plugs today, seems much better, still a slight hesitation, but now driveable

Will change fuel filter next

 

Had the same with MY11 Saloon, when I had it remapped hesitation gone. I was told by a respected mapper that an ECU reset can do the trick.

 

Just been out for a drive, seems to have gone back to how it was again, weird as when I first put the new plugs in and drove it, it seemed really good, only slight hesitation.

I have the software to reset the ecu so may try that and report back.

 

is the ecu rom image the latest Subaru have for it ?
only there have been updates that yours may have missed.

 

No probably isn't the latest rom, but seems weird why it was working fine and now not.

 

Mine was intermittent as well

 

I've uploaded the log to dropbox as I think this will work better, if anyone can take a look and maybe help me please?

https://www.dropbox.com/s/c53f6yqs6i...log3a.csv?dl=0

 

Hi, I did an ECU reset and it's running well now, thank you.

Hopefully it stays ok, wil report back if any changes.

 

The problem has returned

I have created a better log using different software which is a lot easier to look at, if anyone could take a look please? it would be greatly appreciated

https://www.dropbox.com/s/c15xu3exv8...8m01s.csv?dl=0

 

Is it forged?

 

No all standard

 

Can you get your LTV (Long term values) from the ECU? See what the IAM is set at (ignition advance multiplier) as it gives an indication of how happy the ECU is.

 

I shall try that and post up another log, may I ask what are long term values? sorry very new to this, thank for replying and helping me

 

They're what the ECU 'learns' as you drive and it applies to the fuel map. If you use romraider you'll get a screenshot of fuelling, IAM and knock correction.

My LTV screenshots can be seen in this thread https://www.scoobynet.com/engine-man...uld-i-log.html

 

Hi, I have used romraider this time and I think I've managed to log the IAM, there was a 1 byte and 4 byte option, not sure what the difference is so I did both

https://www.dropbox.com/s/4wt3fycsas...05558.csv?dl=0

Also I noticed on another log I did, I was getting a misfire count going up, on cylinder 4

 

If you press F6 when youre connected to the ECU it'll bring up the LTV in a little picky that you can save and attach here. Its a bit easier than logging it all the time

 

That log looks a lot like mine before my rebuild.

I'd get it checked by a specialist as it looks to me like there's a lot of knock correction going on off boost. I'd also suggest seeing if bludgod will take a look at the logs as he and others were really good at deciphering mine

Does it crank evenly when it starts or does it sound like its missing occasionally?

 

Just done another log today, getting a high misfire count on cylinder 4 and some on #2

https://www.dropbox.com/s/n77i1an6zo...33810.csv?dl=0

 

I would advise you to stop driving your car, by the looks of things your ringlands have gone completely or are on the way out so the more you drive the worse it will get. If you've caught it early you might get away with dropping a set of pistons in but it depends how much damage there has been to the bores.

Normally what happens is when they crack the intake charge is diluted with oil from behind the piston so you end up with knock readings all over the table as you have now.

I would recommend an immediate trip to a garage for a compression test - have you been drinking much oil at the minute?

If the oil consumption isn't high then I'd still get the compression check done as you can eyeball the spark plugs at the same time.

 

Ouch !

 

Hi, I was using some oil, approx 1litre per 1000miles, I changed the oil and filter and did another 1000miles but it hardly went down after the change, not sure why that is. I changed the plugs, the old plugs looked quite clean.

Also did a compression test, it was approx 160psi on all 4 cylinders.

I hope it's not a ringland crack, but if it is, it is damn!

Thank you for taking the time to reply and check out the logs!!

 

Carry out a cylinder leakdown test. you'll find one of them is leaking into the crankcase.
Looks like your about to have to rebuild it