My check engine light will come on at start up and stay on for about 2 days or 3 or 4 key cycles. Then one start up it will go off and won't come back on for a couple weeks. It is always the same codes and cel always comes on at start up never driving down the road. I am doing spark plugs tonight. MAF is next on my parts throwing list )

 

A tune up is always good for any car, but, there comes a point where throwing parts at it is just a waste of money, and it should be properly diagnosed.

 

Totally agree! I had a 2005 Jeep Grand Cherokee that became a money pit with no fix in sight. It was a right bank catalyst error...even the dealer who we traded it in at, took two weeks to discover that the cause was a pin hole leak at the exhaust manifold. Even after replacing the dual cat assy, 4 o2 sensors and tune up parts it was a tiny exhaust leak.

 

Dont forget the all important too much ethanol in the vehicle. Or in your case a bad oring will not be present with smoke but thru a simple vacuum test. Simply use an oil filter wrapped in tape to the correct size of the hose and then tighten it down and start it up. if there is a leak it will take a few seconds to stall but as it does the whistle sound you hear is from the vacuum leak. locate it and you locate your problem.

 

I do not suggest plugging the intake to find a leak, this was a method recommended by Land Rover early on, however it can cause oil seals to fail, as a fair amount of vacuum is applied to the entire crankcase system, and not all of those seals are designed for that kind of pressure reversal.

The simplest way to diagnose a fueling code on one of these trucks is through the adaptive fuel trims, however the correct diagnostic system is required. But with as many different issues as these engines have with lean codes in particular, it may be worth paying for the diag, just make sure they get you a copy of the adaptive trims before anything gets cleared.

 

Roverguy7

I followed your advice and replace the ignition capacitor. The new one was different then then my old one. I have not had the lean codes return since I changed this out. It has been about 3 weeks and it has always come back by now in the past. Could changing the capacitor fix my problem or are they unrelated? Thanks again for all your help.

 

In theory, yes, it could... A high resistance through the capacitor would cause a voltage drop in the coil power supply, which could create a weak spark and cause incomplete combustion not allowing all of the fuel to burn and allowing unused air into the exhaust, and hence a lean fault... However, I haven't seen the replacement of just the capacitor resolve these faults. But as I said, I usually do it in conjunction with a tune up, which I have done many times to resolve lean codes.