Thread: 98 4.0 Liter timming
03-15-2012, 09:37 PM #1
98 4.0 Liter timming
Hello all i have a 6cyl 4.0liter i know the pcm is static timing and i cant change it but i got my jeep for my mom who is on dialices due to kidneys failing.
My obd2 said a lot of bla bla..
what i put in new.
Plugs wires ign coil distrib cap rotor and cam sensor.
Crank case sensor. i hallowed the cat since it was cloged.
I put in mas air flow thing and the little rubber hose was good.
There are on more codes.. the jeep idles ok
but has a random stall.
I was told to use the obd2 and see if the pcm was going bad and the ignition timing is 10.0 to 19.50 at idle
at 2000 rpm its 40 to 42.
Any in put please advise....
Is that timing do high or low. ?
i have no codes and the temp dont matter.
But $400 for another pcm is way a lot of money for m.
03-15-2012, 09:46 PM Thread Starter #2
Re: 98 4.0 Liter timming
Can the timing 10 through 19.50 cause the jeep to stall?
03-15-2012, 10:34 PM #3
That's normal timing. My Cherokee usually sits at about 15-19 at idle and will hit 40 at Rpms.
03-15-2012, 10:40 PM Thread Starter #4
So the timing droping to 10 is no worry? I was told the 19.50 is to rich and is flooding the motor..
But if its normal im sooo happy.. I saw to zip tie thebpcm connectors in tight .. so ill try that since i have many ties. And i saw using 1/4 screws also can help the pcm.
Any info on these things?
03-15-2012, 11:06 PM #5
Nope 8-10 is normal. But the fluctuations should be smooth if it's irratic timing has nothing to do with mixture. It's when it's burned. All my big block Chevys are locked down at around 35 degrees all the time. It takes a lot of timing to stall an engine. I would look at all the PCM grounds and connections. Make sure the pins are tight etc.
03-15-2012, 11:08 PM #6
Not sure on the screws as all my controllers are plastic wrapped and not mounted with anything. Just ran a separate ground.
03-15-2012, 11:12 PM Thread Starter #7
Im making a lock in thing to keep the 3 plugs allll the way in. the grounds i can find are all really good. I will lock the plugs in with my strap/ zip thing and ill look again for a bad ground and post back.
03-16-2012, 11:20 AM Thread Starter #8
I took the pcm off and and duck taped a old tee shirt behind it.
In front i pluged the connectors in.
Now the space between the coolant jug ans the pcm connectors i put some cut cardboard to make a good force keeping the connectings tight. I can only pray this works.
03-17-2012, 09:05 AM Thread Starter #9
I was taking mom to the hospital ER and jeep stalled.. ong.. so keeping force on the plugs is not a fix..
Any advice besides swaping the pcm since money is very tight .. Or is there any test i can do for the pcm. Or a after market pcm thats cheaper. ?
03-17-2012, 09:54 AM #10
Hope moms ok? Are there any dtcs. Any other symptoms.
03-17-2012, 10:06 AM Thread Starter #11
No codes i got a brand new obd2 pro from discount. i sold my only rifle to buy it.
03-17-2012, 12:31 PM Thread Starter #12
I just added an extra ground from the motor to the frame. the guy at part store said it cant hurt to try it. if this dont work i gona get the pcm... that will suck... wow $400 bucks...
03-17-2012, 12:51 PM #13
I wouldn't chuck parts at it. With the reader display freeze frame data
03-17-2012, 01:00 PM Thread Starter #14
I don't understand what you mean by the freezer display are you saying look for specific item or .. o b d 2 is saying everything is fine.
03-17-2012, 01:14 PM #15
Freeze frame data is data that's stored in the PCM before and after events. Can you view live data on the obd2 pro. Do you have access to a fuel pressure gauge.
03-17-2012, 01:19 PM Thread Starter #16
Yes sir the low psi is 50 and high is 55 ish... fuel psi is great.
03-17-2012, 01:29 PM #17
What did you gap your plugs to.
03-17-2012, 01:30 PM #18
Check and clean the asd relay and fuse terminals.
03-17-2012, 05:10 PM Thread Starter #19
Plugs are 35 all new with wires and ig coil and cam/crank censors. Every fuse is good. i checked.
03-17-2012, 05:13 PM Thread Starter #20
The asd relay looked good when i chwcked it. But for 4 bucks ill pop a new one.
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