Crankshaft Position Sensor Mod (aka Timing Advance Mod)
Written by Josh Blackshire
As far as I know, I am the first one doing this with pictures. Does that make me special?
Not really, but those of you wishing to do this might appreciate it. I, for one, was totally
lost when I did this mod because I couldn’t find a single picture and since I had no clue
what in the world I was actually looking for, it was quite difficult for me.
Here’s how to do the timing advance mod…this should add around 3-4 degrees timing I
1.) Begin by purchasing a new crankshaft position sensor from your local auto part store.
I choose to use new sensors for the simple reason that if I screw up, I can always put it
back together with my stock stuff. If you choose to modify your old one, then when you
remove the old one, refer back to this section.
2.) Slot the holes 3/8” to the right as pictured. On mine, I couldn’t go 3/8” so I just went
until I cut the chunk out. There is still plenty of bracket for the bolts to hold onto.
3.) Once you’ve got the sensor modified, you’re almost ready to install the new sensor.
Some people can reach the sensor from underneath the vehicle; others can go in from
overtop. I chose the much easier way—through the inner fender. Of course, when you
remove the inner fender, you’re going to need new plastic fasteners to reattach it. I got
some from the GM dealer my friend works at…for me they were $.65 each, but that was
at dealer cost. He says they retail for a lot more…around $2.50/each. These are the clips
I got…they are removable (though when removing them to take pictures for this how-to,
I did break one). My 98 Dakota required 12 of them.
4.) Loosen the lug nuts on your tire, jack up the truck (Disclaimer: Remember to use a
jack stand in case the jack would fall) and fully remove the tire. Now cut the heads off
all the fasters in the inner fender until it comes off and set it aside. If you already have
removable fasteners, then definitely save some $$$ and remove them properly.
5.) Now that the inner fender is off, take a look in the back left of the opening. You’ll
see the crankshaft position sensor. Remove the 2 bolts holding it on, and then pull the
sensor out of the hole. Be careful when unscrewing the bolts as that heat shield to the left
of your hand is quite sharp.
6.) Remove the rubber grommet inside the hole as well (not pictured in the hole due to
the fact I took the pictures a week after doing the mod). If you do not remove the rubber
grommet, you won’t be able to slide the sensor over.
7.) Disconnect the stock sensor. This is kind of a pain in the butt to find. The connector
is on the right side of the distributor looking in from the front. It’s directly behind the #5
injector. If you look back there, there are two connectors. One goes to the O2 sensor and
on my truck it’s gray. The remaining one goes to the crankshaft position sensor.
8.) Once the stock sensor is fully removed, install the modified sensor (or go back to step
2 and modify the stock one if that’s what you’re choosing to do). My friend and I first
bolted the sensor back on. Bolt it loosely, then slide the sensor over as far as the bell
housing will allow toward the oil filter…if you slotted it correctly, that will be the only
way you can slide it. Tighten the bolts back down and reconnect the sensor. This is
where it gets a little interesting. When you removed the old sensor, you probably
realized just how interesting connecting the new sensor would be. Here’s what we did...it
only cost us a coat hanger and about 2 minutes of “fishing”. First we bent the coat
hanger into a long hook. I then ran it down to my friend who was waiting in the wheel
well. He attached the connector to the hanger and then I carefully pulled it up to the
connector and connected it.
9.) Once that’s done, reset the PCM so you can make sure your engine will still run. To
reset the PCM disconnect the neg. battery cable, turn key to start position and hold for 30
seconds, reconnect cable, start engine and let idle for around 30 seconds without touching
the gas, shut it off, restart and let idle again, shut it off, restart and let idle, give it gas, or
whatever you wish to do (just don’t drive it since you only have 3 wheels on it at the
10.) Reinstall the inner fender with the new clips. Put the tire back on, remove the jack
stand and lower the truck. Don’t forget to tighten your lug nuts all the way. Once that’s
done, take her for a spin. If all went well, you should notice a bit more power on the
butt-dyno. I personally noticed better acceleration and I can squeak my tires off the line
now whereas before I couldn’t even get a chirp.
Free for Distribution.