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Pinging 4.0 with Hesco Harmonic CPS

Swaping 258 to 4.0, 4.0 parts to 258 etc!
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Neuner
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Pinging 4.0 with Hesco Harmonic CPS

Post by Neuner » February 7th, 2018, 12:20 pm

Did a swap a number of years ago and has been running great EXCEPT for a relentless pinging.

Used a Hesco bracket and harmonic balancer for my CPS. I used some spacers on the CPS bracket to artificially retard the timing and I've bumped to 91 octane instead of 87 which had helped. I still get some pinging when over 60 and against wind but not nearly as bad as before. Originally was getting around 19-19.5 MPG but after the changes I'm now at 17 MPG.

I've recently been reading about the Cam Shaft Sensor and it's control of the injector timing. Trying to figure out if I need to cut the tabs and adjust this somehow as well? If so, how do you go about it?
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SkylinesSuck
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Re: Pinging 4.0 with Hesco Harmonic CPS

Post by SkylinesSuck » February 7th, 2018, 4:54 pm

Stock 4.0? What vehicle/ECU?

Neuner
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Re: Pinging 4.0 with Hesco Harmonic CPS

Post by Neuner » February 11th, 2018, 6:27 am

Not sure why I'm not getting notices.

It is from a '98 Grand Cherokee, OBDII. Yes, stock. OEM PCM from a manual XJ of the same year.
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SkylinesSuck
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Re: Pinging 4.0 with Hesco Harmonic CPS

Post by SkylinesSuck » February 11th, 2018, 10:07 am

And you are certain it's pinging and not some other similar noise?

Neuner
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Re: Pinging 4.0 with Hesco Harmonic CPS

Post by Neuner » February 12th, 2018, 10:37 am

Yes.
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SkylinesSuck
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Re: Pinging 4.0 with Hesco Harmonic CPS

Post by SkylinesSuck » February 12th, 2018, 6:54 pm

It would be worth it in my mind to verify the base timing with a gun and check the advance via an OBD2 reader and something like Torque (Android app). But if the engine had never been opened up (head not cut, stock gasket, etc.) I would just be guessing.

When you swapped it, did you remove and reinstall the dizzy? I did mine 1 tooth off before and it ran fine idling and free revving but when you put any load on it at all (like driving out of the driveway) it would ping it's ass off.

Neuner
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Re: Pinging 4.0 with Hesco Harmonic CPS

Post by Neuner » February 13th, 2018, 5:19 am

I did nothing to the distributor. Only thing custom on it is the CPS. The CPS is the only thing that I've manipulated. I've used washers and extended screws to artificially retard the timing. It runs, accelerates and idles great so I really don't want to mess with it any further. Pinging is for the most part now gone as long as I use 91 octane. MPG's have decreased and it appears I smell unburnt gas more. This is what has me thinking the injectors are off and the cam shaft position sensor may need adjustment somehow? I just am wondering if I was getting better MPGs because of the too-far-advance timing and what I'm experiencing now is where it should be. It's the gas smell that has me wondering though.

How'd you set it one tooth off and in what direction, advance or retard?
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SkylinesSuck
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Re: Pinging 4.0 with Hesco Harmonic CPS

Post by SkylinesSuck » February 13th, 2018, 6:53 am

I'm still trying to figure out how you are retarding the motor with washers on the crank position sensor. Are you moving it back away from the fly wheel or counter clockwise?

I would get a timing gun and verify the base timing, along with seeing what the computer is advancing it via an OBDII reader.

I had to replace my dizzy with a junk yard unit at one point. I just had the rotor turned a little too far and installed the whole unit one tooth off (rotor was pointed too far clockwise) but the housing was in it's normal, correct position. That made it super pingy until I figured it out and fixed it.

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