VARG7

hi i just baught a 1990 jeep cherokee 4x4 with the 4.0 engine. I am gettin a hesatation under accelaration with lower rpm's, and its backfiring through the intake can anybody help me on where to start

thanks, John

Olivegreenxj

i have the same kinda proble, check the throttle position sensor is withing range.

VARG7

how do u go about doin that whats the range it should be

jspecfever

Mine had the same thing.. i just replaced the TPS

VARG7

did the tps fix it ????

VARG7

What should the range be in the tps and how do u know what wires to be checking. im new to this jeep please help me
thanks

DEVILSTOY

have you fixed this preoblem yet ? mines doing the same thing , i even replaced the tps once and it didnt change anything

chadtheman

Yes i am having the same problem with my 99 cherokee.

Slick761

Here you go... for renix like your 90 http://autorepair.about.com/library/faqs/bl232i.htm

maktub

I had a similar problem. I ended up unplugging the upstream O2 (had codes), and resetting the computer. Problem went away. O2 still unplugged.

BuckB91XJ

Before you go dropping a bunch of cash on a new TPS or O2 sensor that you might not need, do a really good inpection all over the top end of your engine for loose, disconnected, rotted and/or cracked vacuum lines. A hesitation with surging or backfiring is almost always caused by a vacuum leak.

cruiser54

The problem with that link is they have you only checking the Trans side of the TPS. That won't help you find a driveability problem. You need to check both sides, Engine and/or Trans as needed.

PM me your email address and I'll send you a simple but complete little poop sheet on checing and adjusting the tPS on a Renix.

It also includes a check for sensor grounds, which if compromised will cause all sorts of driveability issues.

DFlintstone

My 90 started all sorts of ruckus. The whole works. It would hesitate, miss, pop back out the intake. (the confetti blowing out the grille is how I found the mouse nest in the air cleaner). No start a few times. Run like a (frightened) ape if you floored it, but stumble on even throttle. Or run fine for days. Found that most of the usual suspects all seemed to be about $50 each, and some are a ***** to change. I didn’t want to just throw money I didn’t have at it, so I just did normal tune up stuff. Odd symptom (you may or may not have). Could start and run all day , no problem. Turn it off for 2 minutes then “the tantrums”. The sitting business really had me. Oil dripping around the CPS sensor, engine heat migrating to the coil or TPS or something? Something involving the manifolds and a vacuum leak? Catalytic converter. Had to be heat migrating while it was off. It took over a year to figure out that the HEAT SHIELD over the manifolds was expanding into the INJECTOR WIRES at the front. Really easy to check. DonAppril 2012---Actually it was something in the gang going down to the lower sensors from the injector gang, knock, temp, or 02

Slick761

I found that adjusting the tranny side to 83% then playing with .01 volt at a time got it right. My ecu side is .61 and it works perfectly. Also for parts rockauto.com is much cheaper.

eriejeep

98 4.0 103K-clicks had the check engine light on when i got it, bad downstreat O2 - the one in the cat. I have replaced both front and rear O2's, new cat, new muffler, new tailpipe.
Now when i start it, it will run fine until about 30 seconds in then it will huff and puff and backfire through the intake then run fine until i shut it off.