99 Cherokee idle oscillation
03-21-2011, 05:28 PM
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Year: 99
Model: Cherokee
Engine: 4.0L
99 Cherokee idle oscillation
@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; } 99 Cherokee Sport 4x, stock, Calif. emission.
Engine slightly missing at normal driving speed and Idle. Power seems OK and close to normal gas millage. Check engine light reports throttle pos sensor. Reset check engine light to verify failure. Failure doesn't return.
Four weeks later engine idles rough and then smooth again intermittently, never dies. Feel slight intermittent roughness during driving as well. Checked the normal tune up routine. Plugs light brown but slightly pitted ground electrode, everything else looks good. New plugs installed. Removed & cleaned TP sensor, thinking back to check light report. Idle now has a noticeable oscillation based about 900rpm and varying+/- 100rpm continuously every couple seconds. Doesn't stop oscillating. Weird. Can't feel it at driving speeds. Power seems OK.
Any Ideas?
Muddy
Engine slightly missing at normal driving speed and Idle. Power seems OK and close to normal gas millage. Check engine light reports throttle pos sensor. Reset check engine light to verify failure. Failure doesn't return.
Four weeks later engine idles rough and then smooth again intermittently, never dies. Feel slight intermittent roughness during driving as well. Checked the normal tune up routine. Plugs light brown but slightly pitted ground electrode, everything else looks good. New plugs installed. Removed & cleaned TP sensor, thinking back to check light report. Idle now has a noticeable oscillation based about 900rpm and varying+/- 100rpm continuously every couple seconds. Doesn't stop oscillating. Weird. Can't feel it at driving speeds. Power seems OK.
Any Ideas?
Muddy
03-21-2011, 07:24 PM
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You can test the TPS, Also check/clean/replace if needed the IAC, also look for any vacuum leaks. Have scanned again it may be storing codes even with no CEL.
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