92 MTX SHO lean code

[Laurel]

Hey all!!!

I have a problem child and no matter what I fix or replace she’s just angry. The check engine light comes on and off and the code says lean. I have replaced all O2 sensors and spark plugs and I’m out of ideas. Any help??? Plus it’s also bucking and jerking

 

[Jbeck]

Welcome to the group! Sorry you are having problems but the knowledge here can get it fixed up for ya....I would try the following to start.

check fuel rail pressure
clean intake fully, remove and clean inside
clean IAV (idle air valve)
clean MAF sensor ( be careful its delicate)
check spark plug wells for oil, clean out if needed and re seal
check spark plug condition
check spark plug wires condition

I would start with these, they are all very cheap and easy to do but almost always overlooked in the routines of troubleshooting. Keep us posted and good luck!

 

[Laurel]

She has gotten a new IAV and MAF and throttle Position sensor. New spark plugs. But not the wires because I can’t figure out how to replace those with the intake manifold on.
How do I clean out the wells??? I’ve been wanting to but didn’t want to damage anything.

to clean the intake do I remove the whole thing and use what kind of cleaner??

how do I check fuel rail pressure?? I’m hoping that the fuel injectors aren’t going. It only has 180k

 

[Jbeck]

She has gotten a new IAV and MAF and throttle Position sensor. New spark plugs. But not the wires because I can’t figure out how to replace those with the intake manifold on.
How do I clean out the wells??? I’ve been wanting to but didn’t want to damage anything.

to clean the intake do I remove the whole thing and use what kind of cleaner??

how do I check fuel rail pressure?? I’m hoping that the fuel injectors aren’t going. It only has 180k

If the spark plug wells have oil in them then you can use a spray head from a windex bottle or similar to spray the oil from well into a rag or bottle, then wipe real good inside with rag and a screw driver to get rag down inwell to corners real good...To seal the well gaskets you will have to remove the valve cover and either replace the donut seals or put light coat of gasket maker on them and re install cover.

To clean the intake properly it will need to be removed, then break it down into pieces and washed thoroughly inside and out with dawn soap and water works really well for me...I use a large Rubbermaid tub to wash it in so I can submerse it completely and let it soak to loosen up the oil content inside. make sure it is completely dry inside before reinstalling and starting motor.

Fuel rail pressure can be measured with a fuel gauge on the Schrader port on the fuel rail...gauge can be purchased at local parts store for cheap.

wires can be done wile intake is off....

 

[Laurel]

That is immensely helpful!!!!! My god thank you!! If the fuel pressure is good do I need to worry about the injectors??

 

[zoomlater]

clear your codes and read them again. post what codes you find. when my 92 was bucking, it was due to a bad cam position sensor

 

[Jbeck]

That is immensely helpful!!!!! My god thank you!! If the fuel pressure is good do I need to worry about the injectors??

if the fuel rail pressure is good then injectors still could be an issue but it will prove everything behind the rail as being good, that will tell you that the problem is in front of the rail at motor

 

[Laurel]

if the fuel rail pressure is good then injectors still could be an issue but it will prove everything behind the rail as being good, that will tell you that the problem is in front of the rail at motor

Yeah a cam position sensor was my next step. Where can I get a scanner for this one?? I’ve looked online but I can’t seem to find one with the right adapter

 

[zoomlater]

In the thread below are two links (from Luigisho) on how to check codes using a paperclip

https://shoforum.com/index.php?threads/check-engine-light-keeps-coming-on.141281/#post-1534989

some auto parts stores rent fuel pressure gauges if you don't have one

 

[luigisho]

Lean code is either bad sensor somewhere, too little fuel or too much air. You look for vacuum leaks?

 

[NoSlo]

Lean code is either bad sensor somewhere, too little fuel or too much air. You look for vacuum leaks?

Or wiring problem. A recent one was a fault in the ground for O2 sensors, in the harness under the intake. Takes probing the harness connectors to see if they have connectivity.

https://shoforum.com/index.php?threads/i-have-the-sho-ghost-smh.139691/page-2#post-1515093

 

[Laurel]

I think that it is my intake tube for my cold air intake that’s setting off my IAT Sensor.

 

[rubydist]

Please post up what the exact codes are for us.

Lean codes with new oxy sensors on these cars are almost always due to vacuum leaks. There are plenty of places to get a vacuum leak, but the most common nowadays is from cracked or broken vacuum hoses, of which there are several around the intake manifold. Check over all of those carefully.

In your case, if that big hole in the side of the intake pipe is after the mafs, then that will explain the lean codes because the engine is sucking in a lot of unmetered air. So that needs to be corrected right away.

 

[luigisho]

If you have the original intake and swap it back, you will easily have your answer--- but yes with that shape of hole I would suspect you may be correct.

 

[Laurel]

Yeah I won’t ever put the original box back on it’s trash. It’s right above the maf sensor. I’ll get the codes as soon as I can find a scanner.

 

[Laurel]

Lean code is either bad sensor somewhere, too little fuel or too much air. You look for vacuum leaks?

yeah it had a smoke test done. No leaks

 

[NoSlo]

I’ll get the codes as soon as I can find a scanner.

As soon as you find a paper clip or any ol' piece of solid thin wire (or make your own jumper with wire and male crimp terminals):

http://yamahasho.com/eec/eec.htm

 

[Laurel]

As soon as you find a paper clip or any ol' piece of solid thin wire (or make your own jumper with wire and male crimp terminals):

http://taurus.heliohost.org/eec/eec.htm

 

[Ir0nsah]

If the spark plug wells have oil in them then you can use a spray head from a windex bottle or similar to spray the oil from well into a rag or bottle, then wipe real good inside with rag and a ***** driver to get rag down inwell to corners real good...To seal the well gaskets you will have to remove the valve cover and either replace the donut seals or put light coat of gasket maker on them and re install cover.

To clean the intake properly it will need to be removed, then break it down into pieces and washed thoroughly inside and out with dawn soap and water works really well for me...I use a large Rubbermaid tub to wash it in so I can submerse it completely and let it soak to loosen up the oil content inside. make sure it is completely dry inside before reinstalling and starting motor.

Fuel rail pressure can be measured with a fuel gauge on the Schrader port on the fuel rail...gauge can be purchased at local parts store for cheap.

wires can be done wile intake is off....

Thanks for insights, my 92 has 98k and babied , recent power and missing under load. I thought to change wires and plugs but then discovered oil in tge wells, no apprent damage, leak from the valve cover gaskets. Does this sound like a easy fix , replacing donuts and new valve cover gaskets and how many mech hours do you estimate given we need to take of tge top exhaust manifold assembly, yamaha ? Input gratefully received

 

[Irish Pride]

Thanks for insights, my 92 has 98k and babied , recent power and missing under load. I thought to change wires and plugs but then discovered oil in tge wells, no apprent damage, leak from the valve cover gaskets. Does this sound like a easy fix , replacing donuts and new valve cover gaskets and how many mech hours do you estimate given we need to take of tge top exhaust manifold assembly, yamaha ? Input gratefully received

Please start a brand new thread with your issues. Try not to derail an existing thread or revive one that isn't currently active.

There are serveral guides posted on the forum. Search for "drop box" and you will get all the info you need for these cars.

-Chad