DillonWithTheFeelin

Okay, so I've got a 1995 Jeep Cherokee Sport 4x4 (XJ) straight six. I replaced the head gasket, intake/exhaust gasket, 02 sensor (BOSCH universal), both valves on the valve cover, dist. cap, rotor, wires, and plugs. RAN GREAT before this work. First few start ups, no issues, however, very quickly it began to have starting difficulties/rough idle/low rpm (500-0) a few starts later. I can run it steady at 1,000 rpm manually by opening the throttle. I also noticed the tach is wigging out. It will sit at 0 rpm while it's really at 1K then jump up by itself a second later or if I push the gas. (It has also idled too high, like 1200-1300 rpm after driving it) The check engine light comes on every time I push the gas after starting up, I've got codes for MAP, TPS, and Air Intake Temp. (I dropped the intake sensor, broke the plastic cage around the diode (wich did not seem to be damaged), and put it back in the manifold anyway, could this one sensor be screwing everything up, like no shift?) I took the jeep on a test drive, and it will not shift out of first gear. (I only have 4 quarts of tranny fluid in it, not 6...and wasn't sure of the right tranny fluid (no it didn't say on the dipstick) so I put dex in it...maybe it needs merc?) I noticed that turning the jeep off, restarting and driving off without the light on, RIGHT when I should be shifting into 2nd gear, the RPM's drop back down and the check engine light will come on, while remaining in first gear.

I'm pretty damn confused, I hope somebody here has an idea or has had the same problem before. I'm so close to driving my jeep again; It would hurt to have to take it into a shop.

I did unplug the computer and plug it back in at one point also, somebody suggested I may need to get some programming or something....any advice? GREATLY appreciated.

-Dillon

cruiser54

Did you have the ground wires off over at the dipstick tube stud at any time?

How about the ground strap from the back of the head to the firewall?

DillonWithTheFeelin

I had the ground strap off but I put it back on. It was slipped over the head bolt with a nut on top of that. Looked like somebody did that after forgetting to put it on the block first, then the bolt. But it ran fine then. So I put it back like it was. As for by the dipstick, I don't THINK I touched any ground wires...plus I looked there yesterday and didn't see anything...

Might need to look again...

-Dillon

SeriousOffroad

CEL on?
What are the error codes?

DillonWithTheFeelin

"The check engine light comes on every time I push the gas after starting up, I've got codes for MAP, TPS, and Air Intake Temp. (I dropped the intake sensor, broke the plastic cage around the diode (which did not seem to be damaged), and put it back in the manifold anyway, could this one sensor be screwing everything up, like no shift?)"

I know it's a whole paragraph, but the answer to your question was in there...how can you help me if you don't read the whole post?

Thank you.

VTJeep

Could be MAP sensor.. Throwing all those codes from one sensor is possible.. MAP sensor giving wrong info could result in TPS and IAC valve running out of whack... If it was running great, why the tune up?

Edit- Dex-III is proper transmission fluid.

SeriousOffroad

How can you expect help if you don't post adequate information?
Post the actual code numbers and you might be surprised at the info you are given.

DillonWithTheFeelin

"Could be MAP sensor.. Throwing all those codes from one sensor is possible.. MAP sensor giving wrong info could result in TPS and IAC valve running out of whack... If it was running great, why the tune up?"

Well it WAS running great, but the heater control valve broke and the head gasket was leaking...other than that it didn't have this other **** going on. So maybe the manifold absolute pressure sensor? Is that the one in the manifold or above it on the firewall?

EDIT: Okay good, got Dex III in it. Just 2 QTS. shy...

Thank you.

DillonWithTheFeelin

Why would you need numbers? I got the codes for MAP...TPS...AND INTAKE TEMP SENSOR....is that not adequate enough? Don't have the numbers on me, just know that's what I've got according to the service manual.

VTJeep

Ok ok.. You did.. Either way, I'd still say replace that MAP sensor with a good OEM one, and see what happens front there. Dropping it may have compromised it. I'd also say don get a MAP sensor from some online distributer, either. I've had bad luck with sensors like the TPS and IAC when ordering from places like autopartswarehouse.com.. Just sayin..

If the body of the MAP is cracked, try putting sealant on it carefully? Idk... Good luck!

SeriousOffroad

Because I'm the guy has an FSM at my finger tips that tells me exactly what to look at based on the Error Codes and it provides far more info than any Chilton or hynes manual.

I was willing to help but you don't want to do anything to make the process faster so your rig is back on the road.

Fine.

Done here.
No need to reply.

DillonWithTheFeelin

Okay, thank you. It'd be nice if it's just one of the sensors...how are the sensors contributing to the shifting mechanism? I'm ignorant...but I assume there must be a correlation to the speed/rpm and gear changes...TPS?

DillonWithTheFeelin

Apparently you're also the forum dick. Thanks anyways.

VTJeep

Just looking over first post again, you said you unplugged computer. ECM? Either way, disconnect battery cables and leave off overnight. Touching leads together for a few seconds before reconnecting will help to dissipate residual current. ECM should be reset a this point. It will take 50 starts for ECM to relearn trim levels.

SeriousOffroad

No I'm just one guy that was willing to do the research for you and provide you with facts and figures so you could properly diagnose your rig...and the help was free without any obligation.