anticreep

Hello this is my first post. I been trying to get my XJ fixed and I can't. It has a good idle and starts ok it just has a lack of power when driving it and don't seam to down shirt unless u have the gas pushed to the floor. When u have it to the floor it has the power u let up like an inch and it goes back to lack of power. It has a new IAC valve cleaned the TB out good new fuel filter New distributor cap plugs and wires.
To me when I give it gas it seems like the engine is being muffled (if that means anything)
Oh MAT sencer is good also.
Thanks for any help I get.

emt_hawkins

As stupid as this sounds (and by no means am i a mechanic) could the catalytic converter be plugged? We had an older jeep with this issue, removed the Cat and it was fine.

SHELBYGT NSM

Just to inform you, this forum frowns or any coversation about removing the cat. Just a heads up!!!

SHELBYGT NSM

Have you replaced the fuel filter? May also want to check the fuel pressure.

anticreep

[QUOTE=SHELBYGT NSM;2785916]Just to inform you, this forum frowns or any coversation about removing the cat. Just a heads up

I'll try and clean it out.

anticreep

No I haven't. I don't have a pressure gauge or no anyone who has one. I'll promptly will just have to buy one.

SHELBYGT NSM

Sometimes you can rent one from auto zone or any other local parts store that offers that. How long has this problem been going on?

anticreep

Been going on for a few months. It seams to get better with the cold air air filter off it. I mean it removed from the TB. If that helps

anticreep

Yes New fuel filter gotta get a pressure gauge to test it.

SHELBYGT NSM

I would check up on the fuel pressure first. If i was you i would use the search feature and look up, Throttle postion sensor (TPS) can be a great help.

anticreep

I'm trying to post a pic of the EGR valve. If the pic show up the two vacuum hoes aren't hooked to the valve itself. Could this have anything to do with it???

emt_hawkins

My bad, thank you very much!

Reading and someone saying fuel filter, my friend nearby has this same issue. Replaced 2-3 fuel filters, and they had to go in the tank and clean the screen from the fuel pump, it was all gunked up. That got it running for a while, but having issues again. Maybe between the two it'll get you your power?

Firestorm500

My first thought was a plugged muffler or catalytic converter.

It doesn't sound like a fuel starvation issue.

You can't "clean out" either one. If the converter is replaced, it has to be done by a certified shop and paperwork has to be done.

$10,000 federal fine for removing a converter. Don't do it.

DFlintstone

Good advice above in my opinion.

Just because it happens to be supper easy on 87 to 90 Jeeps, I'd start by checking the CPS. (Myself). You can rule that trickster out in the time it takes to tie your shoes. Anyone with an 87 to 90 Renix Jeep has two or three minutes to see that their CPS is putten out .35 or better.

AC voltage CPS test; Small clips on the meter leads really helps. (you need contact with those little pins while it cranks)

Unplug the connector at the back of the manifold with wires going down to the bell-housing/cps.
Probe the two wires to the cps with the meter set on AC volts. (a 200 scale on mine).
Crank the engine and note the voltage. (jump it if your battery is low)

Mine somehow works with only .3 my wiring/grounds must be pretty spiffy. .5 seems to be a good mark. One article talked of .5 to .8. **Update, it soon failed. I installed Napa #css980 in my 90, that part will work back to 87.

One test for "constipation" is to loosen the header pipe nuts. It will be pretty clear if power comes back. Or remove the 02 sensor. Or try the vacuum test for a restricted exhaust.

"Pedal on The Floor" , running, put's your Jeep in "open loop" (bypassing most of the sensors) (Cranking, that will CUT OFF FUEL)

Two more fast, easy checks besides the CPS.

There is a brittle little tube. It comes out of a rubber plug, low on the engine side of the throttle body. It runs back to the firewall, then up to your MAP sensor sort of high up there near center on the firewall. CRUCIAL!! The MAP will tell the ECU to dump fuel with less/no vacuum. Any crack or blockage and it will be pig-rich. (Btw., here it's a MAP, not a MAT)

I forget the other one. Check your wires off the injector harness down to the lower sensors. (02, Knock, and CTS). If one is chafing, grounding it might do that. (bad at mid throttle, but go, floored) .

If your sensor ground circuit, or other grounds are bad, you can chase your tail and throw parts at it forever and not get it fixed. Just cleaning the major grounds and checking for 1 ohm resistance or so on the sensor ground circuit will help. The dipstick grounds the trans. puter' (TCU), the ECU, (engine puter'), and something else important I think. The injectors? Cruiser provided us with a great list if stuff that you can find in my signature.

If I were betten' I'd suspect the 5v feed to the 02, or something down there under the manifolds is grounding. Idk if the CTS has a feed, (it's two wire). One of those lower wires grounding can do that.

anticreep

DFlintstone thanks I'll try that out today when I'm messing with it.