Okay, since the 3.1 has been running like crap, missing, occasionally backfiring when cold, etc, I decided to check the timing last week (yes, I now have a timing light, and yes, I know how to use it). When I first looked at the timing (some idiot had marked the balancer incorrectly and was using the wrong line.. I use the widest line which is the TDC line, correct? ) it was off the scale by about 3/4 to a full inch. Now, I stopped the engine, loosened the dist clamp bolt, and restarted the engine to set the timing at 10* BTDC as is shown on the VECI label. The engine ran like crap again, so I set it at 12* BTDC, which it seems to like the best. I shut down the engine, tightened the bolt, and restarted the engine to check the setting. Now, I KNOW the dist had not moved (the bolt was too tight for the dist to move on its own, and I know for damn sure I had not turned it) but the timing had jumped back up to where it was before.

I've set the timing three times now with the same result, the last time leaving the engine running while tightening the bolt. You can hear the engine pick up in RPM (it's not supposed to be over 1k, but it is when idle and HOT) when the timing changes. Yes, I did have the bypass connector (I think thats what its called.. the one with the tan wire you are supposed to disconnect, anyways) disconnected, and had not plugged it back in all of the times I set it. Could this be the pickup coil going floozy or is it the ign module itself?

BTW, what exactly is the timing spec for the 3.1? Is it the same 10* BTDC as for the 2.8?

 

Hello Maverick H1l,

According to the spec's in the service manual. The timing on the 3.1L V6 is supposed to be 10 degrees BTDC at 675 RPM's.

 

yes, the 3.1 calls for 10* from the factory. you did unplug the little plug over by the blower fan, right? if you don't do that while setting timing, it will do wierd things. just set it where the engine seems to run best, you can hear it smooth out when it likes the idle timing that you put it at.

 

Try bringing the #1 cyl up to tdc of compression, and make sure that the widest mark on the balancer lines up with the 0 degree mark on the timing tab. Maybe the balancer's slipped... if you bring #1 up to TDC compression and it doesn't line up with the 0 degree mark, scribe a new line on the outside ring of the balancer, and use that to set timing. (Then replace the balancer soon.)

I don't think a bad pickup coil or module would cause the timing to re-set itself from 12 degrees back to 10 degrees. I'd be more apt to suggest a worn out timing chain.

Have you tried setting the base timing with the engine cold? There were some times where I set timing with the motor cold, went for a drive (to heat it up), came home and checked the timing, and it was a hair off of 10 degrees advanced- so I don't think engine hot/warm makes too much a difference on our cars for base timing.

Have you ever worked on the dist before (pulling it out of the motor)? I wonder... if the previous guy used the wrong mark, maybe he also strung the wires wrong on the cap! The timing might be 180 degrees out of sync. (Your #1 is at TDC, and should be sparking at #1, but it's really sparking on #4.) Try this; when you've got #1 at TDC to check the balancer, pull the dist cap off but leave the wires on. Hold the cap near the distributor so you can get an idea of which terminal the rotor is pointing at. The rotor should be pointing between the #1 cap terminal and #2 cap terminal.

A little bit of "fun" info; I tried 12 degrees advanced a few times on my car- and it didn't run any better. That's why I've always stayed at 10 degrees. Granted, I have a 2.8... but I've wondered why other guys' motors love 12 degrees, but for me, it's no different.

 

I personally have done nothing to the 3.1 other than run it and find out why its running like crap and so damn noisy. My father paid our local mechanic friend to put the engine in and explicitly told me NOT to touch the engine.

I doubt that the balancer would jump in excess of ten degrees every minute or so... especially with the engine OFF...