this is very frustrating...

ok, so ive searched the net, and everywhere else, and a bad TPS is the only thing i can coem up with... my my 88 2.5l starts a little rough, you have to give it a little gas to start it up. and it idles poorly most of the time. and on my drive to cincinnati last weekend, i started to notice a massive power loss below 3000RPMS when it warms up. when its cold it isnt bad, i notice a little power loss in the low revs but once it warms up i have to peg it a roast the clutch to get rolling from traffic lights and keep the revs up to keep moving. sometime when i turn, especially at low RPMs my engine shutters and i loos alot of power. now, when i say i loose power, its liek im all of a sudden not getting any fuel into the engine, then at a certian point it revs out, usually about 3000 PRMS. i have already replaced the fuel filter, spark plugs ect and it ran fine for about a month after all that, then it sat for about a month while i did some front axle work, and now its doing this. any ideas would be greatly appreciated.

if it is the TPS, how do i adjust it? i looked alreay and YES it is adjustable according to the one they are selling at auto zone!..haha

swap in a 4.0. problem solved.

my grandmother won't drive a 2.5L hahahaha. buy a real jeep bitch!

Flamin is done on PBB not on . That said, I know nothing about 4cylinder Jeeps but you might find something if you search. Read the search guidelines.
Oh, and this is not a flame, but use your spellcheck because it makes figuring out what your problem is so much easier if you can read it.

O2 sensor, most likely.

And if it's loosing power under load, check the ignition system, to include plug wires, and cap and rotor condition. Make sure the coil wire post on the cap isn't corroded/rusted.

Jeff

I have a 2.5L. Glad to see I'm not alone.

Is it fuel injected?

first two dudes...rot in hell.

secondly, i did search. thanks.

thirdly, i get great mileage, and it suites me fore what i do.

that being said, is there any way to check my 02 sensor or check for codes? its TBI. i only loose power under load when its warm. i recently replaced cap, button wires and rotor, about the same time as the fuel filter and rest of the tune up. thanks for the legitimate replies, and fark off anyone that wants to share how small there penis is, IE the 2 dudes that flammed my thread.

98XJeep said:

X2 on the o2 sensor, mainly because you say it runs ok when cold,(pcm dosen't look at o2 untill it's warmed up) then when it does start reading it, if it's not reading corectly it'll throw off your fuel mixture.....BTW don't let those guys get to you,some guys around here just like to flame anybody they can.

Click to expand...

thanks man. is there any way to check for a code?

not positive how to do it on yours, try searching for "checking codes" it can be done with the key and counting the flashes from CEL

yeah thanks, i was just going to edit it. there is no way to check codes that old according to one thread. said something about renix and no codes. also said you just have to use a multimeter. if you see something different id be glad to give it a shot.

Throttle position sensor, air intake and coolant temperature sensors, the HV coil and the electronic box under the igntion coil. I am also thinking low fuel pressure, so check the fuel pressure regulator, fuel pressure check. And maybe even the Crankshaft possition sensor. if the others don't pan out. O2 sensor is possible, but your symptoms sound more like the other sensors, or low fuel pressure, or low spark voltage, or low CPS voltage.

No way to check codes on an 88, unless you own a very rare obsolete scanner. Multi meter is all you need plus ohms/volt specs from an FSM for the sensors. I think they may be at 5-90's Yahoo Renix site group in the files section.

Oh, and does yours have an EGR valve? IF yes, it might be leaking!!!!

where is the EGR valve located? i was thinking TPS also or fuel pressure issue. my fuel pmup primes well though and work fine until it warm up, then i loose power. where is my fuel pressure regulater and where is the EGR, ill check them asap. do you have any idea on how to adjust the TPS?

See: http://autos.groups.yahoo.com/group/RENIXPower/

Then go to the files section.

I don't even know if the '88 2.5L had an EGR. If it did, it could be the problem. If you have one it would be on the side of the intake manifold (normally) with a tube running down to the exhaust manifold. Exhaust Recirculation Valve. It is vacuum operated, so also look for vacuum hose on it.

Ecomike said:

See: http://autos.groups.yahoo.com/group/RENIXPower/

Then go to the files section.

I don't even know if the '88 2.5L had an EGR. If it did, it could be the problem. If you have one it would be on the side of the intake manifold (normally) with a tube running down to the exhaust manifold. Exhaust Recirculation Valve. It is vacuum operated, so also look for vacuum hose on it.

Click to expand...

im going out to check right now. thanks for the link too!

x2 on the oxygen sensor and then egr.... which it has to have as its smog related. If not those then make sure all of the points on your cap and rotor are clean. Finally check your fuel pressure at the rail.

it does have an EGR valve. is there anyway i can eliminate it? there is no fuel rail. its TBI. and the cap and rotor are fine, they wouldnt cause it to only run bad once its warm. it would be a constant problem. thanks guys. looks like im gonna try EGR and 02. my EGR loooks OLD, and my jeep has 150000 miles on it and ive ready the 02 sensors go bad about every 75000 miles.

I just put my third O2 sensor in my MJ a couple days ago (190K-ish miles). It would intermittently sputter/cut out like yours, and only after about 2-3 minutes of running. It would have it's issues, then settle down and run fine so long as I didn't turn it off. If I did, even for a few seconds and then restart, it would run fine for another 2-3 minutes then go thru the whole cycle again. Troubleshot it to the O2 by disconnecting it while it was in sputter-mode and it smoothed out immediately. I've been running with it disconnected, and like others said it will run, just not very economically. Finally ponied up the $$$ for a new sensor and installed it and all is well again.

Coincidentally, the last time I drove it, it would start to buck hard under load, just like yours. I troubleshot to find the #1 plug wire bad, and the center post on my dizzy cap was all corroded, as was the clip in the wire coming from the coil. Replaced all the wires and cap, no more loss of power under load.

For the EGR, you can pull the vac line off it and plug it to see if it runs any different, or you can pull the wire off the solenoid (which won't allow any vaccuum to it). It should be closed at idle, and you can check to see if it's operating by pushing it open slightly from underneath. As soon as you feel it unseat, the engine should start to stumble. That will only tell you if the valve is operational, though, and if it reseats completely. It's controlled by the ECU depending on engine RPM and throttle position, which energizes that solenoid to open when it's supposed to (and NOT when it isn't) and allow vaccuum to the valve to open it.

Good luck....these 2.5's aren't too complicated, and are only controlled by a few sensors (O2 being one of the primary ones, along with the MAP and TPS). Get the sensors all functioning in range and keep a basic tune on the engine overall, and they run very reliably.

Jeff

how bad was youre mileage with it (o2 sensor) disconnected? where is the MAP sensor located?

bad....like 13-15 mpg . But some of that I know is due to my lift and tires (about 6" and 33X12.5's), and the gears I'm running. I'm going to fill it up and drive a full tank thru it over this weekend (it's not my DD and I only drive it once a week, if that) to see what difference it made.

Also, I just picked up a new MAT sensor, and will be putting that in on Saturday.

The MAP sensor is on the firewall, sort of right above the rear of the engine on the driver side. It has a little cover over it, with one vac line going to it from the TB, and an electrical connector. I'll try to find a pic of mine for you so you can see what it looks like. BRB.

Jeff

edit: here's a pic of my engine bay. The MAP is the thing on the firewall slightly to the right above and behind the engine. HTH...