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SUVs Jeep Cherokee and Jeep Grand Cherokee Jeep Cherokee Grand Cherokee Engine and Performance Problems
568 messages, Last post on Dec 01, 2009 at 6:46 PM
You are in the Jeep Cherokee and Jeep Grand Cherokee Forum. Your Hosts are steve_ & tidester
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Replying to: tuggajb (Oct 29, 2009 1:52 pm)
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Replying to: jeep323 (Oct 29, 2009 6:25 pm) |
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This is a 1989 4wd 2.5l 4-cyl auto 2-door Cherokee. Granted that by design it's not very powerful... But in addition it has a really annoying quirk. When under hard throttle acceleration (what other kind is there with a 2.5l four?), motor doesn't seem to be pulling at full power. But when the throttle is backed off halfway or more, the motor actually "surges" and runs stronger at part-throttle than it does at full throttle. Also occurs in normal driving, just not as obvious. Not a misfire, just weak... For various reasons, over a couple of years, have ended up replacing EGR valve, dist. cap & rotor, wires, plugs, fuel filter, tried swapping fuel pumps, swapped to a different throttle body (& checked correct fuel pressure), replaced O2 sensor, catalyst (loose pieces were rattling around inside), replaced water temp and inlet air sensors, swapped ignition module and MAP sensor at one point or another, bought a new (high-altitude) CPS, etc. Last update was to add a "torquer cam" (great results from that). But still it surges. Took it in to Jeep dealer for analysis -- they "tweaked" the TPS setting, then told me their best guess is that this is caused by "a slow computer" (a $500 replacement based on a guess?). I've been in electronics many yrs; generally you either have a good computer or a dead computer -- a "slow" computer would have to violate numerous laws of physics... (the Renix CPU is like the Eagle; not much in the way of retained error codes or diagnostics to look at) Starts & runs (as well as can be expected), gets good mileage, but the non-linear throttle response is crazy. Any ideas, or anyone seen this on another Jeep? Maybe it's generic to the 4-cyl? |
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Replying to: eric784254 (Jul 25, 2009 6:26 am)  aol.com
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Replying to: bertt (Nov 13, 2009 9:19 pm) Let's keep the discussion here so everyone will benefit.  tidester, host SUVs and Smart Shopper |
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Replying to: tidester (Nov 14, 2009 12:24 pm)
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Replying to: bertt (Nov 15, 2009 8:11 am)
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Replying to: steve_ (Nov 15, 2009 8:30 am) |
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Replying to: tidester (Nov 14, 2009 12:24 pm) 1 Inspect M.A.P. Sensor Faulty M.A.P. Sensor. 2 Inspect EGR Valve Improperly Functioning or Faulty EGR Valve 3 Inspect Fuel Injector Dirty or Worn Fuel Injectors. 4 Inspect Idle Air Control Valve Damaged, Loose, or Faulty Idle Air Control Valve. 5 Inspect Idle Speed Actuator Damaged, Loose, or Faulty Idle Speed Actuator. 6 Inspect Throttle Position Sensor Faulty or Incorrectly Connected Throttle Position Sensor. 7 Inspect Fuel Filter Clogged or Dirty Fuel Filter. 8 Inspect PCV Valve Plugged or Damaged PCV Valve. 9 Inspect Carburetor Worn, Faulty or Damaged Carburetor. 10 Inspect Valve Burned, Worn, or Sticking Exhaust Valves. 12 Inspect TimingSet Slipped TimingChain or Worn TimingGear(s). 13 Inspect Fuel Pump Faulty Fuel Pump. 14 Inspect Camshaft Camshaft Lobes Worn. 16 Inspect Point Set Burned, Worn or Incorrectly Set Ignition Points
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Replying to: dvossbrink (Nov 16, 2009 7:39 pm) tidester, host SUVs and Smart Shopper |
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