: SLS 2000 Northstar

03-24-10, 12:52 AM
Hi : Please help some more.
IChanged Crankshaft Position Sensors as code suggested which removed bad occasional miss. Ran great for 2 days, now misfiring really badly, code P0300 now setting at times, lots of help from forum and suggestions i.e checked wiring have even checked continuity back to PCM Box all ok. So I reinstalled old sensors and it is now missing all the time like with the new ones. I guess that elimintes the possibility of the new sensors being faulty.
It must be a coinicidence that I have a new problem. RPM appears to surge and sounds like it is running on 7 cyls.
I live in New Zealand, car has done only 30,000 K's . Thought it would be way to early for Spark Plug failure !!

03-24-10, 08:23 AM
my guess is look at the injectors. get the car hooked up to a BETTER| scanner to tell which cyl is missfiring ( your code reader on the DIC will not shot show exactly which cyl is missfiring) and then look at the fuel injector.
being that old with such low KM, it might have used alot of old varnished fuel thus bunging up the injector.
check it out.
if its not that. its the coil casette. that means but a new one and install.

03-24-10, 11:25 AM
Have you checked for a leaky plenum? That's the rubber coupler between the TB and the manifold.

03-24-10, 03:50 PM
Thanks to those members that replied, I will check those things out and post the result.

03-28-10, 12:31 AM
Well would you believe it, in the end it was a faulty spark plug and done less than 30,000 K's must have died of old age.
New set on the way from the USA. They are just too expensive to buy in this country.

03-28-10, 01:11 AM
I really respect you for running what must be quite a rare car over there.