Hey Guys, glad to be here. This is my first post. 😁 I have a 2002 RL with 280,000 miles. I’ve owned it since 100,000 miles. Over the past couple years, it has developed a few issues, and I’m wondering if the issues are related. I’d (obviously) like to do the work myself, if possible…just not quite sure where to start. Here are the issues:

Engine starts, but reluctantly
18-19 MPG, at best (versus 24-25 I used to be able to achieve)
Engine surges when idling
Engine hesitates off the line with heavy-ish throttle (scary in traffic)

There are some engine codes:
P1456
P0132
P0401

I’m looking to sell it, and I’d like to fix these issues. Any advice is greatly appreciated. Thanks!!

 

Engine starts, but reluctantly/ dirty throttle body, starter issue- worn brushes/bearings , dirty battery cables, low battery voltage, worn spark plugs, incorrect gapt
18-19 MPG, at best (versus 24-25 I used to be able to achieve)/ dirty air cleaner, blocked EGR passages in the intake manifold, intake air temp sensor and eng temp sensor (not coolant gage sensor) out of range
Engine surges when idling - dirty or worn IAC motor, blocked throttle body passages, stretched throttle cable, incorrectly adjusted cruise cable
Engine hesitates off the line with heavy-ish throttle (scary in traffic) - blocked throttle body, incorrect plug gap, worn plugs,, dirty air cleaner bad knock sensors (would give an engine light)

These cars dont like anything but premium gas they will run on regular but not well as the knock sensor retards the ign timing. The only way to properly clean the intake mainfold is to dismount it from the car dismantle and clean there is a picture blog out there how to do that The egr valves almost never go bad but the passage from that to the int mani gets blocked like an artery as its only pencil thick
you can remove the iac motor and clean it once the engine is mechanically sound you can get it back to spec but it has high mlge and these things have to be addressed Mine is a 2000 with 247k You should also check the engine grounds as well as they can get corroded
that eng has 225 HP its a good engine but you have to evaluate how much you want to fix on it, Are the Oxygen sensor's working fine? what about the fuel trims short and long the scan should be able to tell you that not the code reader that analysis usually leads you in the right direction

 

Thanks! That’s a lot to take in. Some I understand, some I don’t. Looks like I’ve got some research ahead of me.
Engine turns over just fine, so I’m not inclined to think it’s a battery/starter issue. It just isn’t getting something…fuel, air, spark…timing? New-ish air filter and plugs. There have only been a couple of times that I’ve run anything other than Premium fuel, and only as a means to get to a place that has it…never a full tank. I HAVE experimented with premium non-ethanol in the past.
I was inspecting, and realized that there is a crack in the “air flow tube” (17228-P5A-A11). I just found another thread about this, but didn’t see an answer to this question: Can a crack such as this cause any of the issues I’m experiencing over the long term, since that air is bypassing the air filter?
I’ve never heard of “fuel trims scan”, but if this can help narrow things down it sounds like the way to go. It also sounds like a detailed cleaning of the intake components is in order. Thanks again for taking the time. I really appreciate it!

Dan

 

The crack shouldn't affect the idle but be aware that unfiltered air is entering that crack
dusty air damages valve seats so you should fix that asap

If you get a blue driver
and download the app you can read the fuel trims in the live area of the menu

to understand fuel trims look on you tube for Schrodingers Box - fuel trims thats how I learnt about them you also have to inspect ALL of the vaccuum hoses for leakage its a lot but you'd be surprised how a little crack can affect everything, squeeze them gently with the engine idling leaks will affect idle

 

if you hold the throttle part way open does the engine start better as this will give it more air. if this helps the fuel mixture is too rich
Have you cleaned your injectors 1 or more might be sticking

 

My money is on the intake. Many people reflect this service. I do mine once a year. The EGR tube and the bottom of the intake clog. This causes alot of the issues you describe.