EVILXJ

95 cherokee 4.0

running real rough, this started about 6 weeks ago and the jeep not being my daily im just now really getting on this problem.

when this problem started it was running rough while cold and seemed to have a miss, as i would drive it and it warmed up it ran alot better, very small miss here and there.

took it out this past weekend with some other jeeps and it really started running bad, barely running

new parts are: plugs, wires, cap, rotor, wires, TPS, CPS

i rebuilt this motor about a year ago and replaced almost all sensors that i can think of and has always ran great, until now

anyone have any other ideas? im wondering maybe pickup coil? distributor? ECM?

Potatowalker

Have you checked the fuel pressure? Ground wires? How old is the battery? just throwing out things you didn't mention that are common issues...

EVILXJ

yes fuel pressure is perfect, the optima red top is 3 years old this month, all the grounds are new and done in 1ga, also all vaccum lines are new

DFlintstone

Just to be sure...I think your MAP sensor is up on the firewall. There is a small, brittle little tube that comes down and plugs into the inside of the TB. That's gotta be flawless. You can pull it free from the bottom of the MAP and feel for vacuum if it doesn't immediately die.

Also, did you try the "key trick" ?;

OBD1 Models: 1991-1995
1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost. Code 55 indicates end of fault code display.

EVILXJ

The line to the map is new but I will check for vaccum

And I couldn't remember how to key up the codes on the odbI so thanks. I will try that tomorrow also

DFlintstone

Others are gonna know your 95 better than me, I still learning about my 90!

I don't fully "get it", but I've seen posted plenty, (and potatowakler mentioned,) the battery. In my experience, (with older rigs), if the alt is keeping the voltage up, you are good to go. Might not start with a POS battery though. BUT, plenty have posted a weak battery can cause running problems. I really don't get that. Anyway 3 years Is a long time for any battery, regardless of the months on the pro-rated warranty. Maybe something to at least check. You might want something newer to head into winter with anyway.

Btw, not in my town, but in most places the parts store or somewhere will read your codes free.

Potatowalker

If the problem started when it was cold, maybe it's related to the outside temp? Did you take out the IAT sensor and clean it off recently? Also maybe pull the Coolant Temp. sensor in the t.stat housing and make sure it's not all covered in corrosion?

My red-top is about a year old now, and I surely hope they hold up longer than 3 years. I've had cheap lead acid batteries that went 5 years or more even with seeing -20F every winter! You could probably get a parts store to give it a free load-test to make sure. I like to get at least 2 different shops to do those because I've had one tell me my battery was shot once when it was actually fine and went another 2 years before failing.

EVILXJ

Map vaccum seems plenty strong. Can't get any trouble codes to come up unless im messing up the sequence. Tried the pickup coil. No luck with that either

Coolant sensor is brand new also

DFlintstone

No supper ideas here at the moment. I might just pull the cap and have a look inside in case there might be condensation in there..is all I have.

Turbo X_J

What is the fuel pressure in psi?

Edit:
Done a compression test yet?

EVILXJ

that was one of my first things, cleaned all contacts with some emery cloth

salad

So have you tested any of these newish sensors? Unless they're all dealer items I wouldn't trust them.

DFlintstone

??? You cleaned the contacts in a new cap?

I hope there is no dust or anything inside there. I bring mine to the sink and clean it like any other dish with detergent and a brush. You can't leave anything there for the spark to follow to ground. (not suggesting you didn't know that)..(the book is wrong. #1 is at 5:00 viewed from the side. (153624, clockwise)

As a young man I had an asse smog guy tell me he wouldn't smog my Power Wagon unless I did a valve job on it. I did the valve job on that 318, only to find later it was carbon tracks in the dist. cap. (black on black).

That's my story anyway. Info in this link has fuel pressure:

http://www.jeep4.0performance.4mg.com/tech_specs.html

Potatowalker

X2 on this - I've definitely had a new sensor (TPS) that was bad out of the box. I believe it was from Omix-ada/rugged ridge. I got a mopar one and it was a TON better running as well as shifting. I had a bad IAC out of the box once too, it was a "SMP" or "Standard" brand.

Another thought I had was bad gas or contamination in the tank. Have you gone through a tank or two since it started acting up? Or maybe there's water getting in there somehow, like a hole in the filler hose or something?

EVILXJ

New when I rebuilt the motor 3k miles ago. I cleaned the cap with electrical cleaner after