Bad Flash? Knock?

[tephra]

Hi Guys,

I am quickly coming to the conclusion that random cruise knock is caused by a "bad" flash.

Anyone have an experience with this?

ie sometimes you do a flash and you get 0 knock, then other times you do a flash and get 15 KS randomly when driving...

Cheers
D.

[palmerblock]

Only way this would be possible is if your battery voltage was lower than desired during a flash?

Define a bad flash please....

I've had the random part throttle knock b4 at low rpm but haven't seen it in a while and I haven't changed anything in that area....I have done recent flashes thou tuning for new parts...

Originally Posted by tephra

Hi Guys,

I am quickly coming to the conclusion that random cruise knock is caused by a "bad" flash.

Anyone have an experience with this?

ie sometimes you do a flash and you get 0 knock, then other times you do a flash and get 15 KS randomly when driving...

Cheers
D.

[tipoytm]

Hi teph, I'm also experiencing some of these random knocks myself... it would be around 3-6 knocksums at 60-80% load (fuel), between 1250-1500 RPM. My car is completely stock using NJ's generic 91oct ROM (slightly tweaked). Since this is in closed loop and the timing at that range is stock, I can't blame it on the tune. I've tried lowering the timing by a degree in that troublespot and it has helped a lot, but still sometimes i see the occasional knocks. I would say averagely, 2 out of 5 days of driving (dd to work)... I would see it once.

I don't think the flash has anything to do with it, since flashing the ECU is ultimately in binary (like all digital hardware) and there are builtin safeguards (ie. checksum) to make sure data is intact upon flashing. I know for sure since I've been flashing the ECU close to 40 times (started from Gunzo's and a lot of tweaks up to this point)... this troublespot has always showed up in the logs occasionally no matter what generic/tweaked tune I put in.

[LAX]

Originally Posted by tipoytm

Hi teph, I'm also experiencing some of these random knocks myself... it would be around 3-6 knocksums at 60-80% load (fuel), between 1250-1500 RPM. My car is completely stock using NJ's generic 91oct ROM (slightly tweaked). Since this is in closed loop and the timing at that range is stock, I can't blame it on the tune. I've tried lowering the timing by a degree in that troublespot and it has helped a lot, but still sometimes i see the occasional knocks. I would say averagely, 2 out of 5 days of driving (dd to work)... I would see it once.

I don't think the flash has anything to do with it, since flashing the ECU is ultimately in binary (like all digital hardware) and there are builtin safeguards (ie. checksum) to make sure data is intact upon flashing. I know for sure since I've been flashing the ECU close to 40 times (started from Gunzo's and a lot of tweaks up to this point)... this troublespot has always showed up in the logs occasionally no matter what generic/tweaked tune I put in.

I have the same exact thing. 60-80 load at part throttle and low rpm (1000-2000 rpm's), I get occasional knocks. Sometimes it will happen all the time. I've tried smoothing the timing a bit and it's still there. Tried switching back to stock map and it's still there (on a 100% stock car). So..I don't think that knock is anything to worry about.

Going back to tephra's concerns, I don't see how a bad flash could cause knock unless the maps actually got screwed up when getting written. One way to double check is to re-read the ROM from the ECU and see if the timing and fuel maps etc all look ok. If the actual procedural code were messed up, then I don't think the car would run at all. I've flashed over 40 times and haven't seen any random knock like that aside from the low load/rpm knock coming from a stop.

[tipoytm]

^ Good to know someone else is experiencing this on a stock X.. and you even tested it out with the factory tune/ROM. I agree, a good way would be to test and compare the ROM by using the built-in ECUflash "compare to ECU" function also. Is Tephra getting the knocks in high-boost or WOT?

[2Fst4U]

Did you guys check your fuel pump relay? Been several accounts of it failing and causing car to run lean and then knock. Anticipate a recall to hit eventually, but the current fix is to replace with a new green relay from Mitsu if you don't want to wait for your motor to get harshed. Just something to maybe look at.
Here is some more info.

http://www.***************/forums/sh...ad.php?t=18887

Edit: Well that's interesting it won't accept the link. Anyway maybe research that.

[tipoytm]

^ no problem, most of us who hangout here in the tuning forums are aware of the fuel pump relay issue. We don't think it's the cause though, I'm almost sure Tephra has tried that out already.

[tephra]

I have no doubt that the ROM on the ECU is ok.

I am talking about something more sinister.