I need a good scope screen shot of the cam and crank sensor waveforms for a 1996 3.9 v6 Dodge Dakota.
Somebody installed the wrong flex-plate; a v8 rather than a v6.
In order to avoid replacing the flex-plate, I have created a circuit to convert the v8 flex-plate pattern to the v6 flex-plate pattern using a phase-locked loop and ic counters.
I need to see the correct waveforms to verify relative timing and correct pattern for my conversion circuit.
Thanks

 

You can't. The designs are 100% different. The V8 pattern is one 5 degree hole every 45 degrees. The V6 pattern is two 5 degree holes, 1 degree apart but i'm not sure if it is 3 sets or 6 sets. You're better off changing flexplates. I've tried electronically emulating both the V6 and V8 signal and neither worked.

 

Thanks for your reply.
My circuit is working (sort of); the truck now idles at 2800rpm!
The hole pattern (according to Pioneer flexplate FRA537) is 3 equally spaced sets of 3 holes spaced as follows:
2 holes 8.5 deg apart then one hole 47.3 deg after the previous. The holes are about 4.25 deg wide.
So there area total of 9 holes, 3 doubles and 3 singles
My circuit is a pll with a X9 freq multiplier feeding a pattern counter.
The phase of the pattern is programmable in 5 deg increments by jamming the desired phase into the pattern counter at the cam sensor transitions.

So I still need the good scope waveforms to insure my circuit is not causing the racing idle.

Thanks again!

 

I would say to start moving your algorithm in small amounts forward and aft. More than likely you've messed with the fuel sync and need to slide your algorithm around to compensate. Best way to check would be to find somebody with a Snap-On OBDII live data scanner and get fuel sync to between -5 degrees and +5 degrees.

You've gotten much more involved than I did. I gave up and modified the transmission unwillingly but for a more universal result in my case. I never decoupled and examined the V6 flexplate in depth; I'm doing a V8/GM trans swap and was in the middle of a giant mess.

 

Thanks for the reply.

My next plan is to find someone in my areas (Wilmington NC or Akron Ohio) who would be willing to let me put my scope on their nice running 1996 3.9 l V6 .
These real cam and crank reference waveforms will be very helpful for evaluation of my conversion circuit.

Any volunteers ???

 

You'd be better off obtaining a shop/shade tree mechanic with a Snap-On tool and moving your algorithm

 

I requested the scope waveforms from JustAnswer.com and they sent me the waveform from a 1999 Dakota V6. It enabled me to determine the correct phasing.
The truck is now up and running good.
Thanks for your help!!