Since I have a rare lean code cel and have been through several things I have a small
oil leak around the pan and will replace it the next oil change in ordering the uro
gasket from rockauto they had a reman maf for this '98 on clearance for 44 bucks since
it's a one piece for that price bought it - let the collection begin

 

Lean is rarely MAF.

Do the usual checks if you want to find it.

 

Hi reelthing,

I'm not sure why you would think a lean code is rare. If you search these forums you will probably find hundreds if not thousands of threads on lean codes.

The most common cause of lean codes is one or more leaks in the plumbing between the MAFS and the intake manifold gaskets allowing unmetered air into the engine.

Common leak points include cracks in or deterioration of the corrugated accordion pleats in the main air pipe, the gasket where the air pipe meets the throttle body, the plastic breather pipes, the VVT solenoid gaskets, the brake booster vacuum pipe, the camshaft cover gaskets, the oil filler neck and cap, your oil pan gasket leak, etc. One easy clue is if you can see oil leaking out, unmetered air will be inhaled under engine vacuum/depression.

Obstructed fuel injectors are also on the list of suspects. Do you use a good PEA fuel injector cleaner like Techron Concentrate Plus at each oil change?

If you don't find any leaks by visual inspection, a smoke test by someone knowledgeable in how to inject smoke at all the available access points might be your next step.

Which code do you have? P0171 or P0174?

Cheers,

Don

 

by rare I just mean it's rare for this car to post them maybe once in 2 or 3 weeks
of near daily driving - happens when the engine drops back to idle, the idle trims are
too high at around +15% and go low or negitive at 2k rpm or before pointing to a vacuum
leak..I have been through the easy access areas and when oil pan gasket is replaced a
smoke machine is ready to go -code wise it will post bank 1 and/or 2 when it happens -
fuel injector cleaner has never been used that I know of but thar's about change.
By the way I've spent many hours reading these forum pages learning a lot and
very thankful for this forum.

 

I still like to watch STFTs and squirt small amounts around the engine bay till the trims go wild.

 

John,

I believe you mentioned that you sold your 2004 STR some time ago. What did you replace it with?

 

squirt what ?

PSA:
I’ve seen owners have their classic car cars towed into restoration shops where I’ve worked with very crispy engine bays. Most were caused by wiring that was just too old and neglected. But more than a few engine bay fires were caused by the owners squirting a flammable spray here and there whilst looking for a vacuum leak.

A little fire ensued, fed at first by the flammable spray, then got really going from the oily engine bay surfaces.

A very good substitute for spraying a flammable spray liquid is to spray plain tap water. If there’s a vacuum leak, the engine rpm will vary quite a bit, and with zero fire danger.

Z

PS: most shop fires I’ve been called upon to put out took all of one fire extinguisher and most of a second one.

Theres not much sadder than having a fire extinguisher emptied out, with the fire still a long way from being extinguished.

Always have a back up. The chemical type leave a nasty residue that’s both caustic and nearly impossible to remove from all engine surfaces. While the Halon type are effective, they can get very pricey. However, Their size does make them attractive for carrying in the car.

But the old standby CO2 extinguishers, while being bulky, are a good choice for a garage or shop. No residue and no involved cleanup.

Z

 

Do not buy the URO gasket unless you want to redo this 6 months later.

As for the MAF, before proceeding, check to see what your codes are. You can buy a new MAF for what that reman one you mentioned costs, from a Mazda dealership. Check the sticky thread on OEM and aftermarket interchange parts.

Also, are you sure the problem is the MAFS? Have you tried cleaning it first?

 

Most leaks you can find spraying water, but it's not really a fine enough spray. Failing that use small amounts of propane or whatever small molecule stuff you like. That's SMALL because the trims react instantly if you find the leak.

Squirting enough to cause a fire is WAY TOO MUCH. Also, though, there should be no sparks or flames in these engines. If you have those something is TERRIBLY WRONG so sort those out first.