vacuum leak detected, le sigh

2001 Cherokee 4.0

Check engine light, multiple codes. Mostly miss fire detected, OK new plugs and the coil pack (all coils on the same "bar") replacement, easy enough.

Vacuum leak detected. le sigh. hopefully it is just the Vacuum leak detection pump like the cryptic code is referencing. that or the line to the evap charcoal canister, I will start with that line.

I hate vacuum leaks....

Spray brake cleaner and wait for the rev.

Sounds like an EVAP leak based on your description. Can be a real pain sometimes to find microscopic holes in the system. Maybe you'll be lucky and just have a loose/bad gas cap.

There is a TSB for the purge valve sticking open. Those are usually inexpensive and easy to change.

Thanks! I'll check the valve

I'll have to look up whereit is located, lol.

"Vacuum leak detected?" Never heard of that one. Evaporative system small leak or evaporative system large leak, yes. There is a pretty large difference.

In reply to Streetwiseguy:

It is probably a pump related code. A lot of the handheld scanners are worthless with the actual code description.

Its a 4.0L... Someone said it best; "TADTS". They All Do That, Sir...

I'm surprised the crank position sensor hasn't been mentioned yet

Jeep? Is the idle really high? You may need an intake manifold gasket.

stanger_missle wrote: Its a 4.0L... Someone said it best; "TADTS". They All Do That, Sir... I'm surprised the crank position sensor hasn't been mentioned yet

Already changed

I am replacing the Ignition coil bar (it is orriginal and the Jeep has 180,XXX miles) along with plugs.

I am picking up the $40 Solenoid pump.

SUCCESS !!!!!

OK so it was the Solenoid pump, that's nice it was only $40. Also it was right on the firewall passenger side on TOP! the easiest part replacement I have ever done. One electrical connector and two vacuum hoses.

While I was in there I took care of the Miss fire codes as well. It was on 1 and 2, and also on 3, but not 4, 5 nor 6.

So, I figure the 12 year old coils are failing, also I replaced the spark plugs. I gapped the new plugs to .035 and just for giggles I checked the old plugs, LIKE. OH MY GOD! 4 of them the gap was too big to mesure with my gage! the other two were well above .080. I am surprised it ran at all. I guess I could of gotten away with just replacing the plugs and not the coil bar, but it does have 180K miles and I use it to tow my trailer all over the USofA with my family so I feel better with a new coil rail in there.

Anyway, the check engine light is out and it idles so much smoother, and the throttle response is so much better as well.

The Magic (old) parts ( replaced the air filter because I had one in the garage )

Well, OK, then. Glad to hear you're back into good shape.

That's not a gap, that's a chasm.