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  Topic Review (Newest First)
01-09-2015 01:40 PM
Chasekt98 I have not yet checked fuel pressure, however fuel filter has been replaced, cps sensor is getting good signal. Im hoping on being able to replace plugs with copper resistor plugs today. Ill let you know how it goes.
01-09-2015 10:57 AM
Uniblurb
Quote:
Originally Posted by ZeeJay1997 View Post
dont go changing all the sensors again because they're not mopar. they may be fine. if your problem has not changed since you started changing things, it's probably okay
While I'll always push for Mopar sensors I'd tend to agree with Zee since you have so much money invested in them. When I came on here a few years ago he taught me testing since I was throwing so many parts at my 96 4.0 for a stalling problem along with an erratic no-start condition. Turned out a bad engine/PCM ground on the coil stud took out a couple PCM's along with a couple Mopar crank sensors.

Having said that I did buy a couple crank sensors from Advance which were just as bad/finicky as the bad Mopar one I was trying to replace. But I know Zee is running a jewel of a crank sensor from NAPA which hasn't given him any problems. Does this mean all crank sensors from Advance are bad while all NAPA crank sensor are good, probably not. It's a crap shoot since so many parts are outsourced overseas these days and even Mopar does it.

RCS1300 brings up a real good point about checking for fuel/pressure which didn't see on your list. Many auto parts stores have loaner fuel pressure testers and spec is 49psi +/- 5psi. Also the fuel system shouldn't bleed off below 24psi after 10-30 min if everything is working correctly. Taping the fuel gauge face to the windshield is a trick I learned from Zee to check pressure while driving.

It should be noted there was a TSB issued on the 96 4.0/5.2 fuel pump in particular for overheating problems. It sure isn't going overheat a -30 but as with any other motor overheating does shorten the motor life. I had to change my 96 OE fuel pump out at about 195-200K miles since it was failing.

Great below deal at $120 for a new Bosch fuel pump module but again, do some extensive testing first. Bosch is OE and Mopar just repackages the same pump module while selling them for a whole lot more.

http://www.ebay.com/itm/NEW-BOSCH-67...2512b8&vxp=mtr

Lastly, the fuel filter is easy to change out on the 96 and you may want to try this if it hasn't been done in a while. And it doesn't hurt to add a fuel additive like "Heet" to your fuel system to try and clear any water out which happens at those low temps. Good luck!
01-09-2015 04:24 AM
ZeeJay1997 dont go changing all the sensors again because they're not mopar. they may be fine. if your problem has not changed since you started changing things, it's probably okay
01-08-2015 10:13 PM
rep-tile
Quote:
Originally Posted by Uniblurb View Post
If you go to ZeeJay's ignition section in his dirty dozen thread you'll see a link to the Denso plug wires for your 4.0 for only $20.

You've replaced all those sensors but what brand did you replace them or are they all aftermarket? While some aftermarket sensors work, many won't, especially when it comes to the crank sensor.

When I had a bad Mopar crank sensor often my 96 4.0 would fail to start 1st thing in the morning when cold. Not as cold as there but complete the below crank sensor test in a no-start condition to see if you're even getting a crank sensor signal? Let us know what you find and good luck.

http://troubleshootmyvehicle.com/jee...crank-sensor-1
X3

When it comes to sensors, always go OEM. Most aftermarkets are cheap junk... and some are good in term of quality, but aren't calibrated right for the Jeep (like the Bosh O2 sensors being notorious for causing issues on the 4L).

Quote:
Originally Posted by RCS1300 View Post
Please test before replacing.
This can't be said enough. Whenever possible, test it instead of throwing parts at it.
01-08-2015 05:08 PM
RCS1300 I have not had my ZJ for a while. Check the fuel pressure at the fuel rail and see if it meets specifications. Sounds like the engine may not be getting enough fuel at idle. Could be a weak, tired fuel pump, clogged fuel filter or clogged injectors.

Please test before replacing. I believe you can borrow a fuel pressure gauge from an auto supply store.
01-08-2015 04:38 PM
ZeeJay1997
Quote:
Originally Posted by Uniblurb View Post
If you go to ZeeJay's ignition section in his dirty dozen thread you'll see a link to the Denso plug wires for your 4.0 for only $20.

You've replaced all those sensors but what brand did you replace them or are they all aftermarket? While some aftermarket sensors work, many won't, especially when it comes to the crank sensor.

When I had a bad Mopar crank sensor often my 96 4.0 would fail to start 1st thing in the morning when cold. Not as cold as there but complete the below crank sensor test in a no-start condition to see if you're even getting a crank sensor signal? Let us know what you find and good luck.

http://troubleshootmyvehicle.com/jee...crank-sensor-1
^^ whut he said
01-08-2015 10:14 AM
Chasekt98 I was just thinking because if the FSM calls for 3000 ohm resistance im blowing that out of tbe water saying as the plugs and wires both have 0 ohms. If i got wires that were 3000 ohm resistance or close i was just thinking it would substitute.
01-08-2015 10:14 AM
Uniblurb If you go to ZeeJay's ignition section in his dirty dozen thread you'll see a link to the Denso plug wires for your 4.0 for only $20.

You've replaced all those sensors but what brand did you replace them or are they all aftermarket? While some aftermarket sensors work, many won't, especially when it comes to the crank sensor.

When I had a bad Mopar crank sensor often my 96 4.0 would fail to start 1st thing in the morning when cold. Not as cold as there but complete the below crank sensor test in a no-start condition to see if you're even getting a crank sensor signal? Let us know what you find and good luck.

http://troubleshootmyvehicle.com/jee...crank-sensor-1
01-08-2015 09:18 AM
rep-tile
Quote:
Originally Posted by Chasekt98 View Post
Quote:
Originally Posted by rep-tile View Post
Temperature changes the impedance of the plugs; so yeah this could easily explain your symptoms. You will find an abundance of documented issues caused soon or later by using plugs with the wrong heat range on this engine. Let's put it this way, before you throw any more money at your problem, change the plugs. It's like $1.50 per OEM Champion plug.
Okay, ill give it a shot, do you think that a pair of oem wires will do the same as the plugs? Id rather buy a cheap set of oem wires and put them in saying they are easier and that its -30 degrees out right now.
Really? No the brand of wires don't matter and isn't going fix the plug issue.
01-08-2015 08:19 AM
Chasekt98
Quote:
Originally Posted by rep-tile View Post
Temperature changes the impedance of the plugs; so yeah this could easily explain your symptoms. You will find an abundance of documented issues caused soon or later by using plugs with the wrong heat range on this engine. Let's put it this way, before you throw any more money at your problem, change the plugs. It's like $1.50 per OEM Champion plug.
Okay, ill give it a shot, do you think that a pair of oem wires will do the same as the plugs? Id rather buy a cheap set of oem wires and put them in saying they are easier and that its -30 degrees out right now.
01-07-2015 10:18 PM
rep-tile
Quote:
Originally Posted by Chasekt98 View Post
If the plugs/wires would be the problem wouldnt it happen regardless of operating temperature? In the summer it runs like a dream.
Temperature changes the impedance of the plugs; so yeah this could easily explain your symptoms. You will find an abundance of documented issues caused soon or later by using plugs with the wrong heat range on this engine. Let's put it this way, before you throw any more money at your problem, change the plugs. It's like $1.50 per OEM Champion plug.
01-07-2015 07:53 PM
Chasekt98
Quote:
Originally Posted by ZeeJay1997 View Post
with two pcms already i would look elsewhere. you didnt say that earlier.

here's a consideration for you.

the FSM gives minimum 3000 Ohms Per Foot and maximum 12,000 Ohms Per Foot for plug wires. the oem plug wires are carbon core. those granatelli mpg + claim to be zero ohm wires and are wire wound.

i agree that the plugs you are using and/or the wires could be the cause of the problem

take a look in the ignition section of the link below.

If the plugs/wires would be the problem wouldnt it happen regardless of operating temperature? In the summer it runs like a dream.
01-07-2015 05:40 PM
ZeeJay1997 with two pcms already i would look elsewhere. you didnt say that earlier.

here's a consideration for you.

the FSM gives minimum 3000 Ohms Per Foot and maximum 12,000 Ohms Per Foot for plug wires. the oem plug wires are carbon core. those granatelli mpg + claim to be zero ohm wires and are wire wound.

i agree that the plugs you are using and/or the wires could be the cause of the problem

take a look in the ignition section of the link below.
01-07-2015 08:35 AM
rep-tile Dump the silver core plugs. Don't listen to that "we make the best spark plugs in the world" bull****. The 4L needs copper core plugs.
01-07-2015 07:57 AM
Scrubberguy Follow ZeeJay's advise PCM's are "ODD" in the ZJ's don't ask me how I know, LOL!
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