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Unread 07-15-2010, 01:29 AM   #1
freakinheep89
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1995 ZJ 
 
Join Date: Jan 2010
Location: Mobile, Alabama
Posts: 3,271
ZJ 5.2 strange running conditions??

Alright, i have searched and found similar probs but none quite like this. my 95 ZJ 5.2 has some serious issues.

First off: the idle, it will idle fine when cold most of the time, then idle gets very erratic at op temp. sometimes when i start it on a cold start it will shoot the idle straight to 1400 and hold it there til i put it in gear, at which point it drops to 1000 and idles around at 20mph. sometimes when it warms up it will idle fine, most of the time it doesnt though. never a single misfire at idle.

Second: terrible MPG's, i mean terrible(less than 10 city) I believe the O2 is bad but hasnt thrown a code yet. i know its runnin rich cause of the exhaust smell

Third: sometimes when the erratic idle happens while warm, it seems to have a random misfire under deceleration, i can feel it jerk, give it gas and it goes away. also it sometimes seems really sluggish sometimes when accelerating under load, only at cruising speeds with rpms less than 2600. sometimes when i press the gas the rpms bog down and it slows instead of going faster.

Hardware:New plugs, taylor plug wires, accel coil, cap and rotor, non mopar TPS(problem?), original MAP sensor from '95, not sure of the O2 brand, removed and cleaned TB, IAC(correctly adjusted),no cat(im sorry, i didnt take it off), new muffler.TV cable is adjusted properly, downshifts smoothly, OD engages smoothly, smooth tranny in general.

From what ive read and in my experience this sounds like a combination of a bad O2 sensor, MAP, and maybe TPS.

Really need some insight on this one, its drivin me insane. Thanks in advance

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[SIZE="1"][B]95 ZJ 5.2[/B]- D30/XJ shafts/D35 Yukon alloys,249, 2"BB, 30x9.5"Wildcat EXT,lots of motor mods, rancho shocks & stabilizer.[/SIZE]

[QUOTE=slayercr23;12630497]How would i go about Stroking it?[/QUOTE]
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Unread 07-15-2010, 01:35 AM   #2
ZJ5point2GCL
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The oxygen sensor its self can cause or at least contribute to all those symptoms, i would change that and then see.
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Unread 07-15-2010, 01:44 AM   #3
Virmagicus
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Sounds like a bad O2 sensor.
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Unread 07-15-2010, 06:01 AM   #4
greasefingers
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I am thinking maybe the intake manifold gasket is leaking, but I do not have that engine so wait for others to chime in.
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Unread 07-15-2010, 02:20 PM   #5
freakinheep89
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MAP definitely has a problem, i started it today and it idled at 1400 again, so i unplugged the MAP just to see, the idle did not change, it was as if the MAP was being bypassed by the PCM. several hours later on another cold start, it idled fine, i unplug the MAP and it dies.
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[SIZE="1"][B]95 ZJ 5.2[/B]- D30/XJ shafts/D35 Yukon alloys,249, 2"BB, 30x9.5"Wildcat EXT,lots of motor mods, rancho shocks & stabilizer.[/SIZE]

[QUOTE=slayercr23;12630497]How would i go about Stroking it?[/QUOTE]
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Unread 07-16-2010, 12:19 PM   #6
freakinheep89
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BUMP> gonna try to see how much the jeep dealer wants for a mopar O2s today, Autozone wants 90 for the bosch so ill use that as my price reference.Any new ideas?
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TJ-
[SIZE="1"][B]95 ZJ 5.2[/B]- D30/XJ shafts/D35 Yukon alloys,249, 2"BB, 30x9.5"Wildcat EXT,lots of motor mods, rancho shocks & stabilizer.[/SIZE]

[QUOTE=slayercr23;12630497]How would i go about Stroking it?[/QUOTE]
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Unread 07-16-2010, 12:40 PM   #7
greasefingers
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The dealership by me charged $ 74/ea
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94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new
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Unread 07-16-2010, 02:58 PM   #8
freakinheep89
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i called every dealer around and the cheapest was $91 after tax, picked it up and bout to install as soon as it stops raining, which should be in the next 2-3 days.
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TJ-
[SIZE="1"][B]95 ZJ 5.2[/B]- D30/XJ shafts/D35 Yukon alloys,249, 2"BB, 30x9.5"Wildcat EXT,lots of motor mods, rancho shocks & stabilizer.[/SIZE]

[QUOTE=slayercr23;12630497]How would i go about Stroking it?[/QUOTE]
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Unread 07-16-2010, 03:27 PM   #9
SnowLeopard
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Nevermind. Just reread your post. You already cleaned the IAC.
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Last edited by SnowLeopard; 07-16-2010 at 03:28 PM.. Reason: Nevermind. Redundant.
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Unread 07-21-2010, 01:45 PM   #10
freakinheep89
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BUMP>ok so i figured ou the problem with the map sensor was actually a bad connector, replaced it along with the O2 and reset adaptives and now everythings working good..averaging 19mpg most of my trip was cruising at 55mph.
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TJ-
[SIZE="1"][B]95 ZJ 5.2[/B]- D30/XJ shafts/D35 Yukon alloys,249, 2"BB, 30x9.5"Wildcat EXT,lots of motor mods, rancho shocks & stabilizer.[/SIZE]

[QUOTE=slayercr23;12630497]How would i go about Stroking it?[/QUOTE]
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idles rough , oxygen sensor , tps

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