Flat Spot

gerzod · Post by **gerzod** » Mon Jul 26, 2010 10:28 am

any luck finding out what was causing your flat spot spike?

Also, does anyone know if there is a way i can test the knock sensor?
after some more research it seems that this is a likely cause. I am quite confident it is related to one of the engines
control systems as the flat spot is always exactly in the same rev range.

if not would a mechanic be able to test it?

steptoe · Post by **steptoe** » Mon Jul 26, 2010 2:02 pm

anyone with a factory manual will be able to tell you if there is a knock sensor test in it and likely to be able to help. The L series EA82T has a a test procedure in its manuals

sven '2' · Post by **sven '2'** » Mon Jul 26, 2010 7:08 pm

gerzod wrote:
if not would a mechanic be able to test it?

22 posts later and you are back at at posts 2 & 3...

gerzod · Post by **gerzod** » Mon Jul 26, 2010 7:52 pm

I am just trying to learn mate. I have some basic tools and if i can do it myself then i would rather learn how. I would prefer to be able to do these things myself, but if it requires some special tool (such as some specific diagnostics reader that costs $500) i would rather take it to a mechanic. Also, many mechanics will not test these things, they will just replace something, see if it fixes the problem and if not then keep playing the guessing game (albeit with more educated guesses than mine), and if i will be paying for that kind of stuff i would rather be doing the troubleshooting myself and learn.

I found a legacy manual online but its missing the section on testing the knock sensor, does anyone know where i can find that info?

steptoe · Post by **steptoe** » Mon Jul 26, 2010 10:58 pm

well said, and it is the reason so many of us are in here. And HOWZAT ! As I put thumb to manual it sticks right on knock sensor testing or EA82 mpfi . It is a case of finding a test connector, measuring a voltage at idle, then apply a sharp knock to the block near the sensor, noting a voltage change, and noting a timing change. I can only assume same sort of process applies to the EJ system. Looks easy enough so long as you have correct instruction and sequence flow chart to refer to - which is why you asked in the first place.

I know someone who may be able to help....