Hello everybody ,

i am new to the forum and would like to quickly introduce me and my car before asking questions right away

I live in Namibia and drive a 2004 Discovery 2 V8 with the Bosch ecu with Old man emu suspension ARB bullbar and warn Thor winch snorkel and steel rear bumper. Pictures will follow


I have been hunting a missfire and rough running issue for a while now.

a quick list of what i have done so far :

After finding a leak on the intake with propane i replaced the upper and lower intake gaskets

new coil packs

new HT leads

new Champion spark plugs

new Bosch MAF

after all that the misfire got way better she is now idling smooth


what is happing now while i am driving she is very hesitant up to about 2000 to 2300 rpm and then takes off like a rocket but experiencing power surges through the acceleration. it feels like the timing is jumping around and i did confirm that with the Hawkeye . while accelerating the timing is not gradually increasing more jumping around .

before i throw more new sensors and parts at her i wanted to hear if somebody maybe had the issue before.

is it possible that a crankshaft position sensor is on the way out fooling around or do they generally just die ?

and if not what other sensor could have such a big influence on timing.


thank you for your time and help

regards Jonah

 

Hello Jonah. A year ago I had the same problem with random acceleration and power surges on my V8. What fixed the problem was replacing the Crankshaft Position Sensor (not a camshaft position sensor) with a Bosch brand unit #ERR-735.
Hope this helps.

 

In my experience the crankshaft position sensor is either working or not. I could be wrong. However, I would check and replace vacuum lines. I’ve had rough running from vacuum leaks.

 

Be sure to check for coolant inside the combustion chamber as well. The clue would be one or more of your new spark plugs being fouled and or wet.

 

Nope...they can work intermittently. The quality is also a factor. I've bought new ones and the truck just didnt feel right. Swapped it out with a different brand and it works great.

 

CPS failures are normally temperature related, does it drive fine when cold but round when hot, or vice versa?

 

yes and no.
I had a CPS keep killing the engine when the engine got hot but ran fine once it cooled down. I replaced it for a Duralast CPS and that kept giving me the random engine acceleration and power surges but it didn't shut down the engine. I returned the Duralast CPS and bought a Bosch which the engine has been running great for a over a year now.

 

I wanted to add my experience with the correlation between a misfire code and the crankshaft position sensor.

I was getting a misfire code I couldn’t figure out for months. I replaced the crankshaft position sensor about two months ago and the misfire fault hasn’t come back.

I only replaced the CPS when my D2 died while at a stop and wouldn’t start, except for a few times here and there but died again. I thought I had a much more serious issue that had to do with the ticking and low compression in one of the cylinders. Just the CPS throwing that misfirecode and causing her to stumble. This issue prevented me from getting a smog certification completed. I’ve just passed smog (in CA)!

Getting to the CPS was a pain for me, by the way. Maybe someone has a better way about it.

I bought a Bosch CPS for $52 on Amazon - the best price I could find: Bosch Automotive 0261210158 Crankshaft Position Sensor https://www.amazon.com/dp/B0049PK3HM/ref=cm_sw_r_cp_api_i_FVUJDbHYXHRY0

 

Thank you for following up for future members.