how do i fix the timing/running/idle problem with my jeep?

20

Asked by Sep 03, 2015 at 02:35 AM about the 1998 Jeep Grand Cherokee

Question type: Maintenance & Repair

its a straight 6 with a 4L engine. I got it to the drivable stage but the idle was really rough. thought it was a timing problem so me and my dad messed with the timing manically, he thinks it could now be the computer that's bad. it has a problem on starting up and reads that cylinders  4, 5, and 6 are miss firing. when trying to drive it doesn't want to leave 2,000 rpm and or shift up.

8 Answers

1,335

what year jeep is it? make sure your plug wires are in the right order

1 out of 1 people think this is helpful.
115

AFTER YOU MAKE SURE THE ORDER IS FROM THE RIGHT NUMBER ON DISTRIBUTOR , TO THE RIGHT NUMBER ON PLUGS, IF YOU HAVE EXTRA WIRE, LIKE ONE YOU CAN TAKE OUT ANOTHER JEEP OR EXTRA OR BUY AT JUNK YARD JUST ONE . IF YOU CANT , YOU CAN DIAGNOSE YOURSELF. REPLACE 4 OR 5 OR 6, WITH 1 OR TWO OR 3 . REPLACE ONLY ONE. LIKE TRY REPLACING CYL 3 WIRE OR PLUG (TRY WIRES FIRST SO YOU KNOW.) WITH CYLINDER 1 SPARK PLUG WIRE OR TERMINAL. LIKE THAT IF THE CODES CHANGE TO CYLINDER ONE MISFIRE, YOU WILL KNOW THAT YOUR DAD DAMAGED THE WIRE OR SNAPED THE INSIDE OF THR WIRE PLUG CONECTION TO SPARK PLUG IF ITS NOT WIRE CHECK PLUGS, BUT I THINK YOUR DAD WOULNT DAMAGE 3 WIRES, SO IM THINKING THE ORDER IS WRONG IF NOT THE ORDER CHECK WIRES THEN PLUGS MISFIRE . ALSO THAT SIDE OF THE ENGINE MIGHT HAVE A OIL LEAK INTO 3 SPARK PLUGS SO CHECK FOR OIL ON PLUGS. IF GASKET GOES USUALY COOLANT WILL ALSO MIX WITH OIL, SO CHECK YOUR COOLANT IN RESOURVAR, SINCE IT CIRCULATES , THE OIL WOULD ALSO BE IN RESORVAR, IF YOU CANT SEE, (OIL FLOATS ON WATER) PUT SOME ON FINGERS AND YOU SHOULD FEEL OIL IN ANTIFREEZE SINCE ANTIFREEZE IS LIKE WATER AND HAS NO TASTE, BUT HAS SMELL , AND OIL IS THICK, LIGHT YELLOEW USUALLY OR DARK IN MOST CASES. ITS EASIER TO FEEL. JUST DONT INGEST ANTIFREEZE, IT HAS NO TASTE AND IT WILL KILL YOU

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20

we have already double checked the wires are in the right order. the jeeps years is a 1998 thought id put that in some where sorry.

1 out of 1 people think this is helpful.
20

Hey everyone, it's Dad here. We have a 1998 Jeep ZJ with a recently rebuilt engine and new head. The jeep has about 20 hours of run time on the engine since it was reassembled. The Jeep was running decently just with a drivability issue that annoyed me. It was very rough running at ideal and didn't have the power I would have expected from a fresh 4L. After messing with the mechanical timing a bit, included retracing the firing order, plugs, plug wires, and a R&R on the distributor itself with no significant findings. After this, it is idling better, both in park and in gear BUT it isn't starting nearly as well as it was, and it doesn't want to rap up in RMP, and has now started backfiring when you force the RPM up. When I attach my scanner it is now giving me multiple misfire codes. Ok, thoughts everyone?

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1,335

is the cap and rotor new

20

Cap, rotor, wires, and plugs were all new out of the box at reassembly. However we do see some carbon already on the plugs. Nothing major though.

1,335

i think i would try starting the jeep put it in drive hold your food on the brake give it a little gas as to put it under a load holding the brake with a spray bottle with just water in it spray the plug wires and cap make sure the motor is cold not hot. spray the wires down and see if the miss gets worse or stays the same

1,335

did you find your problem

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