terzo engine issue
Discussion
Hi all. Im a bit new to subaru's and have an issue with a terzo which is on a 1998 on an R, Some times there is a drop off in power and a misfire. which is intermittant. The engine has been quite modified and am unsure of what.The car belongs to the father in law and took it to a mate who had a diagnostic tool and came up as the knock sensor. Im a mechanic myself and would possibly put this fault down to it having the misfire now and then. Are there and common issues with misfires on these turbo engines so I have a bit of a heads up before I have a good look at the weekend?
Any help would be great
Any help would be great
If the knock sensor was loose and the ECU registered knock from the sensor rattling around the ECU might pull sufficient timing to make the IAM (Initial Advanced Multiplier) of the base timing low enough to create some misfiring issues without putting the ECU into any kind of limp mode.
If the knock sensor stopped working altogether i don't think it would cause a misfire or put the ECU into limp mode although i could be wrong.
My first port of call with an intermittent misfire would be electrical issue so spark plugs, HT leads and then coil.
If that proved no joy then i might be inclined to look at the MAF sensor which i would do as a matter of course anyway and give it a good clean out). When Subaru MAF sensors go wrong they don't tend to throw a check engine light but end up reading less and less airflow as time goes by so your fueling runs leaner and leaner the longer it's faulty, misfiring badly especially when the ECU is running in open loop mode, and then you'll start to get misfiring quite badly on engine loading and general loss of power.
If the car is very modified it may be that it's been chipped and it's just not liking the calibrations on the chip x-amount of time after it was installed or nothing has been done to the ECU at all and it's now showing signs of struggling to run correctly with those mods.
You can now have a full custom real-time remap using the ESL Solution which is a daughterboard fitted to your ECU. This allows all the calibrations on your ECU to be changed via a laptop and cable so it runs like factory but makes best use of your mods.
ETA: If you have a wideband handy like an Innovate LC-1 i'd be inclined to check fueling just to make sure it's not running lean when pressing on.
If the knock sensor stopped working altogether i don't think it would cause a misfire or put the ECU into limp mode although i could be wrong.
My first port of call with an intermittent misfire would be electrical issue so spark plugs, HT leads and then coil.
If that proved no joy then i might be inclined to look at the MAF sensor which i would do as a matter of course anyway and give it a good clean out). When Subaru MAF sensors go wrong they don't tend to throw a check engine light but end up reading less and less airflow as time goes by so your fueling runs leaner and leaner the longer it's faulty, misfiring badly especially when the ECU is running in open loop mode, and then you'll start to get misfiring quite badly on engine loading and general loss of power.
If the car is very modified it may be that it's been chipped and it's just not liking the calibrations on the chip x-amount of time after it was installed or nothing has been done to the ECU at all and it's now showing signs of struggling to run correctly with those mods.
You can now have a full custom real-time remap using the ESL Solution which is a daughterboard fitted to your ECU. This allows all the calibrations on your ECU to be changed via a laptop and cable so it runs like factory but makes best use of your mods.
ETA: If you have a wideband handy like an Innovate LC-1 i'd be inclined to check fueling just to make sure it's not running lean when pressing on.
Edited by ScoobieWRX on Friday 20th January 23:30
Gassing Station | Subaru | Top of Page | What's New | My Stuff