high rev on startup of new 4.7
12-14-2011, 01:44 PM
#1
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Year: 2000
Model: Cherokee
Engine: 4.7L I6
high rev on startup of new 4.7
got it to start finally.
it starts and immediatly redlines.
is there some kind of timing poblem? i dont understand what my cam positioning sensor is doing. if i put it inline with block like it usually is then no start but when its cocked sideways it rough starts and pegs the tach
it starts and immediatly redlines.
is there some kind of timing poblem? i dont understand what my cam positioning sensor is doing. if i put it inline with block like it usually is then no start but when its cocked sideways it rough starts and pegs the tach
12-14-2011, 03:02 PM
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Year: 2000
Model: Cherokee
Engine: 4.7L I6
ok so what im gatering is that its an electrical connection problem, or something sensor wise, thats telling the pcm to make it go WOT.
could i have my 02 sensors wired wrong? or would that even make it do that?
could i have my 02 sensors wired wrong? or would that even make it do that?
12-14-2011, 03:09 PM
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Year: 2000
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vaccume leak wouldnt make it red line like i was holding the throttle WFO while starting lol but thanks for tryin...
its gotta be somethin stupid that is messed up. i have no ideas.
its gotta be somethin stupid that is messed up. i have no ideas.
12-14-2011, 03:13 PM
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Year: 1995
Model: Cherokee
Engine: 4.0 HO
Uh yea a really bad vacuum leak will make it redline at start-up b/c it completely bypasses the IAC. Is your intake seated correctly?
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12-14-2011, 03:26 PM
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Year: 1995
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No, carb/throttle body clean is safe, brake cleaner is bad. Can check with a feeler gauge or visual with mirror and light. What intake and header are you running on it? I had this issue with APN header on 99+ intake
12-14-2011, 03:28 PM
#9
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Year: 2000
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stock and stock. cleaned em good before i installed em. i got a good gasket set but the intake/exhaust gasket was a soft one. is this my prob?
12-14-2011, 03:34 PM
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Year: 1996
Model: Cherokee
Engine: 4.0 HO
Originally Posted by TheJerm
No, carb/throttle body clean is safe, brake cleaner is bad
12-14-2011, 03:37 PM
#14
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Year: 2000
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ive heard that brake cleaner ruins em... dont know why. thats why i used carb cleaner. figured it was ok, guess i was correct.
i guess im gonna take my intake off and put it back on... unless i can get some other input soon. i wouldnt think thats the reason though, if i do all that work and it still happens ima be pissed lol
i guess im gonna take my intake off and put it back on... unless i can get some other input soon. i wouldnt think thats the reason though, if i do all that work and it still happens ima be pissed lol
12-14-2011, 03:37 PM
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Year: 1996
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Originally Posted by TheJerm
Brake cleaner degrades plastics and rubbers, also can etch the metal if its finely machined softer metal