Any real bennys in advancing the timing??
12-16-2011, 10:32 PM
#1
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Year: 1999
Model: Cherokee
Engine: 4.0
Any real bennys in advancing the timing??
On my 99. Is their any real gains. Is it safe with 140+k on the clock. Except for a header, its the only thing I haven't done yet. I do have a distributor. Thanks. Oh and I wanna do a safe advance. Not trying to blow her up.
12-17-2011, 04:50 AM
#2
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
The timing is not controlled by the distributor, but by the PCM. Moving it would not work.
12-17-2011, 09:33 AM
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Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by cruiser54
The timing is not controlled by the distributor, but by the PCM. Moving it would not work.
12-17-2011, 09:34 AM
#5
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Only way I know of to advance the timing is to modinfy the CPSs position.
12-17-2011, 02:20 PM
#7
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Year: 1999
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Engine: 4.0
True. But if I go that far I might as well buy a performance cam,lifters,timing set,and a water pump. But an option nonetheless. I guess ill just leave it be for now. I'm not ready to crack into the motor yet. Thanks guys.
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12-17-2011, 02:54 PM
#8
Yes, Using an aftermarket power programmer will change timing advance, and fuel delivery parameters. I don't believe any of them allow you to change to your own values. you have to use their preset ones. Usually only a couple levels of tune.
12-17-2011, 03:02 PM
#9
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Year: 1999
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Is a programmer really worth doin on a stock motor with just an exhaust system. It made a nice difference on my stang when I had it.
12-17-2011, 06:01 PM
#11
They work really nice on the stang, especially when you add headers, and a better exhaust.
12-17-2011, 06:09 PM
#12
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you cannot adjust anything with the timing on the 4.0L engine. Period. End of story.
No reflash, no chips, no indexing, nothing. The PCM controls and adjusts all aspects of the spark and fuel timing using signals from the CPS and the CKPS, along with the other sensors.
No reflash, no chips, no indexing, nothing. The PCM controls and adjusts all aspects of the spark and fuel timing using signals from the CPS and the CKPS, along with the other sensors.
12-17-2011, 06:35 PM
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Then the only option is to fool the PCM. So it has to be done mechanically degree the cam, put resistors in on certain sensors, get sensors that read differently.....
12-17-2011, 06:47 PM
#14
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Ive heard of using the CPS to adjust timing, cutting slots in it so it can move over farther, etc.
Theres also rumor floating around t hat there is a "high altitude" CPS that is advanced.
Theres also rumor floating around t hat there is a "high altitude" CPS that is advanced.
12-17-2011, 06:51 PM
#15
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good luck with that...
If you're doing it to match modifications like forced induction, an adjustable MAP sensor is the solution on these engines. Other than that if you engine is running like crap, fix the issue causing it.
The CPS functions using pulses, not variable resistance, so you can't modify it.
The lifters are hydraulic, not mechanical, so degreeing the cam will not do what you want.