2000 Pathy timing question

Jose · May 6th, 2006, 09:06 PM

Hi all,
I have a Pathfinder 2000 3.3L with a spark knocking problem when running on regular fuel. As far as I know this engine (VG33E) should work fine with regular fuel. I suspect that it could be due to a ignition timing problem.

There is a procedure for adjusting timing on this engine with ECU in the diagnostic mode. My question: What use is this ignition timing adjustment if the timing will be dynamically changed by the ECU under normal operation? Any hints on other possible causes of this spark knocking?

Thanks in advance,
Jose

steveavant · May 7th, 2006, 02:20 PM

I don't think it's really a timing problem, I think is more a temp problem, you live in Brazil, your winter there is what? +25 degrees...and humidity 99%?? so summer must be a broiler over there. Try retarding the spark but you might loose a lot of power... I that doesn't work try replacing your spark plugs with cooler ones, your parts store should be able to find them. Hope this helps.

Jose · May 7th, 2006, 06:30 PM

Steve, thanks for the reply.

Well, temp here in my city is around 25 degrees but humidity is typically 50-60%. I already replaced the spark plugs with colder ones and the problem persisted. Also, if I use premium fuel there is no knocking.

lewisnc100 · May 8th, 2006, 07:20 AM

Quote:

Originally Posted by Jose

My question: What use is this ignition timing adjustment if the timing will be dynamically changed by the ECU under normal operation?

Jose,

The ECU will adjust timing based on conditions, but the base timing still needs to be correct for those adjustments to work correctly. Here's the steps to check your timing:

- Air conditioner off
- AT in Neutral
- Start engine and warm up fully, do not exceed 1000rpm
- Open engine hood and run engine at 2000rpm for 2 minutes under no-load
- Perform diagnostic test mode II (no idea if this is required)
- Run engine at 2000rpm for 2 minutes under no-load. Race engine (2000-3000rpm) two or three times under no-load, then run engine at idle speed.
- Turn off engine and disconnect TPS
- Start and race engine (2000-3000rpm) two or three times under no-load, then run at idle speed
- Check ignition timing with a timing light (crank has 5 marks, 0,5,10,15,20) should be 15 +/- 2 BTDC.
- Adjust timing if necessary by turning distributor after loosening securing bolts.
- Turn off engine and reconnect TPS