• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Camshaft position sensor ?

RCP Phx

NAXJA Forum User
Location
Phoenix,Az
On a 2000 does it really do anything? I'm assuming the initial timing, the advance curve, and the total timing are all controlled by the ECU.
 
The crankshaft position sensor gives the ECU the information about where in the revolution the crankshaft is at. The camshaft position sensor tells the ECU where in the four strokes the engine/cam is at. In other words. The #1 cylinder does not fire at TDC on every rotation, but every other rotation.

Once that is established, the ECU can easily keep track of it for the duration the engine is on. On a Renix, if the cam sensor is not working, it randomly picks one and tries it. If it starts, all is fine. If it does not, you try again until it starts.
 
On the 2000-01's the coil rail does fire every revolution!
 
OK the coil may fire the plug, but the same synchronization occurs for the injector pulses.
 
I realize that, but what would happen if I changed it say +/- 5* ? Would The ECU automatically compensate? I'm looking to test more timing?
 
It would affect injector timing, not ignition timing.

You'd want to move the crank position sensor.
 
It would affect injector timing, not ignition timing.

You'd want to move the crank position sensor.

That's correct.

Valve timing, ignition timing, injector timing, all are completely independent.

I just had this argument with the so-called mods on another site, regarding advancing valve timing and ignition timing..........one has nothing to do with the other, advancing valve timing does not advance ignition timing. Actually, what you are doing is retarding injector timing by 2 degrees in relationship to valve timing....if you are doing anything at all.

This is the lock-box that AMC/Chrysler locked you in.

Everyone loves to talk performance..........if you cannot adjust your timing parameters, no performance, and that's where everyone is stuck.
Jeep people cannot get this through there thick heads.


You want a solution? Here-

I have a high-end machine shop making a one-off part for me now, I've seen what they do with a water-jet, gears, mind blowing precision.

Have the tone ring machined off a new flywheel. Have a machine shop cut you a new tone ring. Just as you can remove and replace a starter ring gear, you can do the same with the tone ring.
Flywheel and tone ring will need to be degreed and marked.
With the engine on an engine dyno, begin the long process of timing the ring.
First one will cost you about $10K.

Then spend another $$$$$ finding someone to develop a programmable ECU, or a remap or flashed ECU.

Until then.........you guys nibble round the edges. And even then, the 4.0 has it's own mechanical constraints.
 
Well, that's a theory.

It's a lot easier to move the CPS on it's mounts. Or on a late model adjust timing in the ECU.


Both of which are regularly done.
 
The iginition timing tables can be changed in anything from 91 and newer, and if I really cared enough about the renix, I could probably make it happen for those guys as well. But it's easier to just get the renix high altitude CPS and call it good.
 
As usual your on Pluto while the rest of us reside on Earth!

There would be no reason to do all that when a adjustment for the crank sensor could be made for pocket change.
You can only change the valve timing with offset gears( I already have that).
The ECU still "mapped" regarding the readings that it gets from the sensors.
Those maps can easily be changed "ALOT" cheaper thru Chris T or Flyan Ryan.
 
As usual your on Pluto while the rest of us reside on Earth!

There would be no reason to do all that when a adjustment for the crank sensor could be made for pocket change.
You can only change the valve timing with offset gears( I already have that).
The ECU still "mapped" regarding the readings that it gets from the sensors.
Those maps can easily be changed "ALOT" cheaper thru Chris T or Flyan Ryan.

F'ing bullshit.

What's a lot?

1 degree with CPS??


This discussion has taken place over the years by many, look back on the stroker sites, many have tried to fool the ECU to advance timing.

And if it were so easy, you'd just do it........instead you are asking how to do it.


Again, thick heads.
 
+/- 5* by CPS. Or you can break the tab and rotate the distributor.

AMC actually sold CPS's that were advanced 5* as an option.
 
So can I assume correctly that with exception of being able to "tweak" a few components, that the "proper" adjustment of different parameters (such as widening the ign timing curve) can only be done thru the ECU?
 
So can I assume correctly that with exception of being able to "tweak" a few components, that the "proper" adjustment of different parameters (such as widening the ign timing curve) can only be done thru the ECU?

Yep.

And once you accept this fact..................


I'm only posting here because, and not argue specifics, I read and read and read all the stroker's posts, just how badass and soforth.


Then right back to the same questions- how do I get more.

You guys are never satisfied, ever. 4.0s leave you wanting.

Well, for all your money and effort......you are half way to a SBC...........lol


That's where I'm going with mine......I got off the merry-go-round long ago.
 
Jeep Driver, you have no idea what you're talking about. If I wanted I can set my timing to ANY number I want, usually +6 degrees is what the motor wants on decent fuel, but I can advance or retard the timing by any number of degrees.
 
Jeep Driver, you have no idea what you're talking about. If I wanted I can set my timing to ANY number I want, usually +6 degrees is what the motor wants on decent fuel, but I can advance or retard the timing by any number of degrees.

Interesting.

So, you have complete control over the timing curve?

So, if you went supercharged and you needed 18 degrees at idle, 26 degrees at part throttle/cruise, and 32 degrees at full throttle........you can control that?

Maybe you'd like to share your secret?
 
OK folks, if you want to change the ignition timing reference, thus shifting the whole timing curve, you can spend a few bucks and get the remote mounting kit for the CPS from Hesco. It replaces the harmonic balancer and adds a CPS bracket. With that you can make large changes in the position/timing of the CPS.

On a Renix, you can advance the timing roughly 3 degrees with a high altitude CPS.

I've been running a stroker for almost 20 years now. I run a custom cam, bored throttle body, high altitude CPS, and an adjustable MAP sensor mod, with upgraded injectors, and a Clifford dual tuned header (no longer in production). I wouldn't do any of this without a WEGO gauge (wide band O2). I have seen way too many strokers self destruct due to running too lean or too rich. I have close to 250K on my stroker.

The real key to power and longevity is to get the quench height adjusted correctly. I am running a high static compression ratio, but still get by with regular pump gas with no ping.

If you are contemplating boosting a 4.0L, I recommend talking to Boostwerks.
 
There are multiple timing and fuel tables, the main timing table is engine load over rpm, with modifier tables for TPS and AIT. So yes, your jeep can be tuned to run 32 degrees of timing at WOT and full boost and put your pistons in the oil pan.

As for how the modifications are made, let's say there are many thousands of hours of work and many thousands of dollars in equipment invested in order to be able to make the changes. Even if I told you exact what you change, the cost of the equipment and the lack of availability makes it virtually impossible for someone else to be able to do what I do.
 
Back
Top