centuryhouse

My 2000 XJ 4.0 has never had any problem running. I just got back from a 1,500 mile trip in it Friday night, and had no problems driving it around town Sat, Sun or Monday. I'm still on the same tank of gas I bought on the way into town on Friday.

This morning it started fine, drove fine. I stopped at 7-11 to get a drink, came out, and after I started it again it ran for 15 seconds and suddenly died. No stumbling or rough idle - just suddenly dropped RPM and died.

Since then, it died about 15 times on the way from 7-11 to my work. It has so far only died when in idle, sitting at a signal or in a parking lot.

Over the last 30 minutes of driving, it does seem to be running a little rougher than it was when the problem first occurred, and stumbles slightly when in idle, but only sometimes.

The only other odd symptom, is that twice this morning while running the spedometer dial swung all the way from zero to 70 several times!

Could it be coil packs, a grounding issue, or something else? Probably not fuel filter or pump, right - because otherwise it would bog down when giving it gas and would stumble more?

Is there a way to check for codes? This is the first modern car I've had where I couldn't get the codes by turning the key on three times.

There are no shops around here that I know are honest or I'd have someone diagnose it. Last time I had a big issue (cracked distributor cap on a Mustang) two different shops told me the engine was blown and would have to be replaced :-/

centuryhouse

A little additional info.

It is also bogging down / stumbling now when I try to accelerate. If I really punch it, it also will backfire.

I got under the hood and cleaned / tightened battery connections and grounds, unseated and reseated various connectors, etc. No change. The battery isn't very old (2 years) and should be fully charged after that long trip.

quneur

The odb2 port should be on the driver side below the dash. An auto parts store should be able to loan you a scanner to retrieve codes.

denverd1

or do it while you wait. My '98 won't do the key/code thing either. I think that stopped in '97.

you can check the fuel pressure at the rail to rule out a fuel issue
you should have a distributor on a '97. pull the center wire off and hold it close to the plug. turn over the engine, you should see a bright blue spark

centuryhouse

I've got a 2000 XJ, so it has the coil pack.

I'd like to check the fuel pressure to rule out a filter or pump - hopefully they rent those out at Autozone?

Also, I can't find a fuel filter. Tell me they didn't do something stupid like put it inside the tank??

t.mcginley.jr

Sounds like your alternator is going. With it running check the voltage at the battery. Car off battery should be 12-12.5 volts. At idle should be 13-15 volts (because the alternator is charging it). Bad alternators do sometimes cause weird dash/warning lights to come and go. Parts stores will also test your alternator for free, but you would have to remove it to do that.

t.mcginley.jr

There's no fuel filter on the 2000+ XJ's, just the fuel pump pickup screen attached to the bottom of the pump itself.

centuryhouse

Aha, good to know!

I hate the whole fuel pump inside the tank thing. On my old Fords I could change a fuel pump in 15 minutes with just a wrench.

I'll test the alternator.

t.mcginley.jr

Yeah it's more of a pain, but that's because the old mechanical pumps could only support ~10 psi tops. When you need 40+ psi for injectors to work you need an electric fuel pump, which gets hot. So they put it in the tank to keep it cool. My 00 XJ is on the original fuel pump at 202k miles, so they should last a while.

quneur

There's something more going on here. A bad alternator would let the battery drain then the vehicle will die. You wouldn't be able to start it again (on auto trans) without recharging the battery.

Constantly stalling on idle, back fires when acceleration, running rough and jumping speedometer are systems of possibly a larger problem or a simple one like a clogged exhaust.

Get codes first. That will tell you which direction to start.

centuryhouse

As I drove the car home from work last night, it still died a time or two in idle; again, no stalling at idle, just a quick shut off as if you'd turned the key off.

While driving, the XJ got much worse, chugging and bogging down while accelerating, backfiring if you give it too much gas. It barely made it home, as it got to the point you could barely accelerate.

Put a scanner on it last night at Autozone: no codes, and no check engine light.

Put a fuel pressure gauge on it, and pressure at idle is 49 (which is normal).

Checked battery under load and alternator - both good.

Replaced the TPS - no change.

I went to clean the AIC and it was caked with carbon, and appeared broken. The plunger part should move in and out (based on others I've cleaned) but instead the end just pulled right out. The plunger has a threaded screw end that goes inside the AIC and into a plastic part. That was stripped out / broken. So today I have to buy a new AIC and install it - but that still wouldn't account for the stalling and bogging down / backfiring when accelerating.

I have also purchased new spark plugs (just because they were already due for replacing) and a new coil pack and new boots, which I will install later.

centuryhouse

Also, can someone tell me more about the location of the Crank Position Sensor? I had read that it is at either 11 o'clock or 1 o'clock (depending on where you are looking from) on the bell housing of the transmission.

I am unable to see anything there from up top or from underneath. I don't see a harness leading down that what from on top of the driver's side of the engine.

centuryhouse

RESOLUTION maybe?

Today I replaced the AIC (which was obviously broken), spark plugs, and Coil Pack.

I believe the Coil Pack resolved my issues. The AIC needed replacing as it was obviously broken, but I don't believe that caused the main issues I faced. Neither did the plugs. I think the coil pack did it.

Now it seems to be running fine - no dying in idle, and accelerates just fine.

quneur

Backfiring is an issue of either timing being off or fuel/air mixture (or clogged exhaust). I'm surprised the vehicle didn't throw any codes. I was expecting lean or rich issue. :P

I personally believe it was the broken IAC. But congrats on fixing your Jeep.

denverd1

FYI CKS (crank sensor) is on the bell housing at 11'oclock if you're looking forward on the driver's side with the trans by your right ear. Glad you got it fixed!