Tephra, can you make a mod to fix the VIII's p0300 issue?
I have an 03 with the ACT Prolight flywheel and the knock tables are untouched. I have 33000 miles on my car and have never had the P0300 code. There was a thread a while back about Shep traced it to the 4-5 synchro. I bought my car used and the synchro TSB was done. 22000 miles on it since I bought it and not a problem with the P0300.
Once on a really bad flash in the beginning. So bad the car wouldn't even run right.
And again when I nipped a wall sliding sideways on ice. Well, shortly after. As I tried to crank the car over it wouldn't fire sputtered, then ran. I got multiple CEL's on that one. Including CAS and VSS and just a random handful of CEL's. All cleared and never came back.
I've put 12,000 miles on the car since August. And not a single P0300 other than those two.
The only code I get is P0137. Which with the patch - I don't get that anymore either.
Timing has been changed all over, its been tuned rich, lean, everywhere in between... car has 272's... vta bov... no problems with P0300's.
Which makes me wonder if it isn't more related to the clutch / FW.
i get that code at random times i've had my VIII about 2 years. its had all kinds of tunes i have a built tranny from TRE and ACT super clutch set up lol stock fw plus a handful of other mods. i just changed my rom to the 14 from the 0008 for the v5.1 patch and i get the code when i go WOT and beating on it. but it doesnt seem to hurt performance just annoying light. usually it will go away by itself. really weird....but my car does weirder stuff so i dont worry about it too much. lol
Its definitely not triggered by the front O2 sensor, its far to simple of a device to even NOTICE a misfire that intermittent. Knock sensor is the most likely cause. A misfire will register in a different frequency range than detonation so its possible there are tables specifically made for these different frequency ranges.
Maybe someone can log the knock voltage and pull off one spark plug wire to intentionally cause a misfire and see if there is anything obvious happening with the knock sensors readings?
Think about what a misfire is and what it affects. One thing is a misfire could cause the load to dip or spike. Losing 25% of the power potential surely affects the readings of multiple sensors.
A bad or clogged fuel injector could totally be a cause. Not enough gas in the combustion chamber won't ignite, causing a misfire (lean misfire). Even a faulty or leaking EGR valve can cause misfires.
Maybe someone can log the knock voltage and pull off one spark plug wire to intentionally cause a misfire and see if there is anything obvious happening with the knock sensors readings?
Think about what a misfire is and what it affects. One thing is a misfire could cause the load to dip or spike. Losing 25% of the power potential surely affects the readings of multiple sensors.
A bad or clogged fuel injector could totally be a cause. Not enough gas in the combustion chamber won't ignite, causing a misfire (lean misfire). Even a faulty or leaking EGR valve can cause misfires.
Last edited by Jack_of_Trades; Apr 10, 2008 at 04:10 AM.
I get this code from time to time in my stock 03. I dont use any ECU flashing (never have). It comes on in high load high rpm on my car. 6k rpm at full (albeit stock) boost. It is possibly that it is in that situation at partial throttle (letting off a tad) that this happens. Usually it comes on if I pull out to pass someone real fast.
Its definitely not triggered by the front O2 sensor, its far to simple of a device to even NOTICE a misfire that intermittent. Knock sensor is the most likely cause. A misfire will register in a different frequency range than detonation so its possible there are tables specifically made for these different frequency ranges.
From what I have read there seems to be several causes of this code. For me, I have to believe that it is due to a vibration caused by the trans. The reason I know this is I have tried everything else over the past 3 years to get rid of the annoying code (new injectors, ignition amplifier, reflashed ECU, and new exhaust hangers to prevent the exhaust from hitting anything).
I really wish that someone good with disassembling code would just find the p0300 error code and disable it. This is the only code I ever throw and it is incredibly annoying. For me, only occurs in low/med load conditions about 3500 rpms in 5th gear no boost (about 75 mph cruising).
Correct you are. The main change from the older series ROM 94170008 and series 94170014 was a change to one of the knock filter tables. I think it was the first or second table. Would have to go back and compare to be sure. When I had the flash performed by mitsubishi years ago the frequency of the error dramatically dropped. Later I flashed my ECU with the latest ROM in the series 94170015 to see if it would cure the problem for good. Unfortunatly it did not, but again lowered the frequency of occurance. Between 94170014 and 94170015 I was not able to see any changes in the tables currenlty viewable in ECUFlash.
From what I have read there seems to be several causes of this code. For me, I have to believe that it is due to a vibration caused by the trans. The reason I know this is I have tried everything else over the past 3 years to get rid of the annoying code (new injectors, ignition amplifier, reflashed ECU, and new exhaust hangers to prevent the exhaust from hitting anything).
I really wish that someone good with disassembling code would just find the p0300 error code and disable it. This is the only code I ever throw and it is incredibly annoying. For me, only occurs in low/med load conditions about 3500 rpms in 5th gear no boost (about 75 mph cruising).
From what I have read there seems to be several causes of this code. For me, I have to believe that it is due to a vibration caused by the trans. The reason I know this is I have tried everything else over the past 3 years to get rid of the annoying code (new injectors, ignition amplifier, reflashed ECU, and new exhaust hangers to prevent the exhaust from hitting anything).
I really wish that someone good with disassembling code would just find the p0300 error code and disable it. This is the only code I ever throw and it is incredibly annoying. For me, only occurs in low/med load conditions about 3500 rpms in 5th gear no boost (about 75 mph cruising).
So, I am one of those people who would pay its weight in gold to get rid of this gremlin. Everyone is saying to wait for the ecuflash to come out that will convert the ecu to an aem, but i dont know if i can weight that long.
Interesting
Originally Posted by The Internet
One of the best techniques for detecting misfires has been to monitor engine crankshaft acceleration, as described in commonly owned U.S. patents 5,044,194; 5,044,195; 5,056,360; 5,095,742; 5,109,695; and 5,117,681. In these systems, the time to rotate through an angular interval associated with each engine cylinder is measured. Acceleration is calculated based on the time intervals and the acceleration values are processed to determine a power losss value associated with each cylinder. Power loss values are compared with a threshold to detect misfires.
Parameters for successful operation of these misfire detectors are quite demanding. For example, it is desirable to detect a misfire rate of about one or two percent since this rate can adversely affect emission levels. In addition, the identity of the misfiring cylinder associated with each individual misfire must be determined and stored to facilitate later servicing of an engine to correct the condition leading to the misfires. Typically, such diagnostic strategies must have very low false alarm rates, especially when detectors are deployed in large numbers of vehicles.
Parameters for successful operation of these misfire detectors are quite demanding. For example, it is desirable to detect a misfire rate of about one or two percent since this rate can adversely affect emission levels. In addition, the identity of the misfiring cylinder associated with each individual misfire must be determined and stored to facilitate later servicing of an engine to correct the condition leading to the misfires. Typically, such diagnostic strategies must have very low false alarm rates, especially when detectors are deployed in large numbers of vehicles.
Here's the actual patent information for the detection system that Mitsubishi uses:
http://www.freepatentsonline.com/EP0744608.html
http://www.freepatentsonline.com/EP0744608.html
I think the thing to get from the tech description is the harmonic imbalances. A lightened flywheel could definitely create an imbalance that could be detected and considered "misfire" by the ECU. Also, the range of crank angle acceleration detection could be different in early ECU roms, i.e. they could be more sensitive. I don't know if any of the disassemblers have come across the routine for it or not, but if they find it, I'm sure the "sensitivity" could be adjusted until the code stopped coming up.
Well, Mitsu has said its a tranny noise issue since day one. It definitely fits the bill. If we could alter the amount of consecutive faults it would need before it gets triggered, that'd help.
I dont get the code during any kind of driving it always comes on at idle or stop and go. It doesnot affect performance at all. I dont really care but I still check it every time so its not something else. 
Man to be able to disable that code for good would be sweet.
Never had it untill the clutch either
on the 15 rom too didnt make a difference. Still get it every couple days. Oh well check it out and keep boosting FTW
Man to be able to disable that code for good would be sweet.Never had it untill the clutch either
on the 15 rom too didnt make a difference. Still get it every couple days. Oh well check it out and keep boosting FTW