DirtyBomb

my 96 xj has been running horribly lately. the throttle is jumpy, feels like its misfiring, and has a loss of power and increased fuel consumption. i finally got it scanned and pulled these codes-

p0108 map sensor voltage too high

p0113 intake air temp sensor voltage too high
if this is the sensor on the manifold, i replaced this recently to fix my crazy temp gauge, this did not fix the problem

p0118 engine coolant temp sensor voltage too high
also recently replaced

p0123 throttle position sensor voltage too high

p0130 1/1 O2 Sensor Heater Circuit Malfunction
does this just mean i need to replace the o2 sensor on the header?

p1492 Ambient/Batt Temp Sensor Volts Too High
i have no idea what im looking for on this one


im curious what i should do about the rest.i dont want to throw $200 in sensors into this just to have the same issue. i thought the just because its reading "high voltage" doesnt necessarily mean the sensor is bad. i hate electrical, where should i start?

lilredxj99

It's got an open ground. I don't have a schematic, but check the grounds on the engine.

tjwalker

If you had NO check engine light before this, (please verify) then it is most likely that one thing is causing all of these. Refreshing grounds is never a bad idea. It would be extremely unusual to have a coolant temp sensor, map sensor, throttle position sensor and oxygen sensor all fail at the same time. But if your check engine light has been on for a year, all bets are off.

The one code that I would start chasing if this remains is the P0130. The oxygen sensor HEATER circuit is fused. And that fuse is located inside of the power distribution center (black box) under the hood on the passenger side. For a 98-99, that fuse is in slot 15. Not positive that it is in that same spot for a 96, but it will be close. It should be a 15 amp mini fuse.

Whenever you get a code that has oxygen sensor HEATER in the description, that fuse must be verified before moving onto other possibilities like the sensor itself, etc.

This is an interesting one; good luck and keep us posted.
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

rrich

Good advice! - grounds.

Also check your battery/charging voltage while running it at about 2000 RPM. A dirty or loose positive battery cable can cause the system voltage to be too high causing all kinds of things to happen..

DirtyBomb

Update- I ran a new ground strap at the back of the motor and used the old one as a second ground on the negative battery terminal. cleaned up the battery terminals and hooked everything back up. Its running much better, but still not quite normal. it's still got a bit of a stutter, but drives smoother, maybe I can return the $35 tps I bought just in case. Drove around the block and no check engine light yet. I'll take it on the steet tomorrow.

Also found a broken wire for the battery temp sensor, didn't know I had one of these but is fixed now.

DirtyBomb

bumping this. after refreshing the grounds, i drove to work the next day and she was smooth again, not perfect but i was happy with it. driving home, my problems started coming back. ill have to get the codes read again to see whats coming up. maybe not for a while though, she seems to have sprung an oil leak somewhere :/