Gen 2.5 lean condition help

[Painted Mountain]

I had a lean code driving me crazy when I first picked up my mont. Turned out to be Mass Air Flow Sensor.

I don't think your problem is going to be too complex. It is easy to jump to some horrible problem but usually ends up being something simple.

These mass air flow sensors are not to be cleaned with mass air flow sensor cleaner according to Mitsubishi. I did it anyway without success. So I changed it out when I first got the lean code but I cheaped out and got one off a junk vehicle. It too threw a lean code. Maybe when they start going out they go lean? Just a hunch.

 

[quailchaser]

The MAF sensor was the mechanics first thought. He said that is usually what that code suggests. The timing issue could be from me screwing up during the rebuild. It has "missed" ever since the rebuild. I checked the timing several times, but I could be off a tooth or so. At least it would mean no major expense for parts.

Heck, I had an old Honda car that I rebuilt as a teenager and it was off exactly 180 degrees, so my track record with timing isn't great.

 

[Salonika]

Since your condition is isolated to only one bank, I wouldn't pursue the MAF since that would cause a problem on both banks. An exhaust leak can cause a lean condition, the Venturi effect can draw outside air into the exhaust stream making it look lean. If you have a scanner that can show live data, are you running lean at idle AND under load?

 

[quailchaser]

Update 2, timing was spot on, although the timing belt was too tight which was the cause of the whine and it destroyed at least one pulley bearing. When they fix that, they will run their other tests. They also determined there were no vacuum leaks or exhaust leaks. The next steps involve pulling the plenum and checking the injectors and possibly the valves. They are using a systematic approach to eliminate the easy stuff first. Keep your fingers crossed.

 

[Painted Mountain]

Not trying to be annoying about this but did you change the MAF sensor? Do you have that little gasket that seals the plug to the MAF sensor?

There is not a different MAF for California vs Federal emissions vehicle so I don't think it will throw a code for both banks because on federal there are only 2 banks. These are pretty simple computers. On federal it only throws a code for bank 1.

Sorry if anyone out there knows for certain I am wrong.

I feel like it is really hard to throw a lean code on these vehicles even with a vacuum leak, exhaust leak. I've had leaks all over the place with no codes. But do anything to that MAF sensor at all and that s.o.b. gives you one quick.

How about your Idle Air Control Valve? does that have its proper gasket? How clean is it in there?

Have you hooked up a vacuum pressure gauge to rule out any vacuum leaks?


You are going to figure this out. Hang in there.

 

[quailchaser]

Not sure about the MAF sensor and Idle air. I think that is a last resort due to cost. As far as vacuum, I even smoke tested it with no leaks (well, one small one that I fixed). I'll have them check the gaskets just to be safe. The code says bank 2 only. With the large loss of power and rough running (to me it seems like at least one cylinder is misfiring, but no codes are thrown for that).

I think they suspect something more than just a sensor. I still think it's something to do with the number 2 injector, but I didn't want to just start throwing parts at it. I tested the injector and it seemed to be spraying fine (just by a visual check with a battery to trigger it). I wish I had swapped the injector to see if it changed, but I got so frustrated taking the plenum off an on, I just took it to the shop. We'll see what they come up with.

 

[Painted Mountain]

Yeah my mistake. I got the banks mixed up. bank 2 not likely MAF as Salonika said. 2nd the live data also. Besides you can do that from the comfort of your seat.

 

[quailchaser]

Shop just called. Confirmed 1 failed injector and 2 others not far behind. Bad news is between the diagnostics and timing work, they are already about $1,000 in to it. With parts, it may be close to $2,000 for 6 new injectors. I'm probably just going to tell them to give it back and get some cheaper ones from Rock Auto or somewhere. Anyone ever try remanufactured injectors?

 

[Offroadmuch]

If they are not physically damaged you can have them cleaned at a place like this:
https://www.rceng.com
They have a perfect 5 star rating on Yelp. I have never used this place, it is just an example.

 

[RyanY]

The question is whether they are merely clogged and spraying poorly or have they been tested and found to be out of spec electrically? Having them cleaned and blueprinted won't fix an injector that's electrically bad. I'm guessing the shop has tested their resistance and found them to be bad, but I'm not sure that I'm on board with that diagnosis since injector failure is relatively unheard of on Monteros. Obviously that will depend on what type of fuels the injectors have been exposed to, which will vary considerably by geographic location. (Example: when I worked at an Infiniti dealership service department in the early 90's, we were replacing injectors in Q45s like they were water, but it wasn't nearly as bad in other parts of the country. Turns out that something in the wintertime oxygenated fuel sold in AZ at Mobil stations just ate through the fuel injectors and caused them to fail at crazy rates.)

Just FYI, I recently had my 95 SR's original injectors cleaned and blueprinted by RC Engineering (linked above) - with 264K on them they came back after cleaning with near-perfect spray patterns and flowing within a couple percent of each other.

Also, my personal recommendation would be to stay away from reman parts in general - I've just had too many problems with them myself, and have heard of other people's problems with them many times over. Not sure what price the shop is quoting but this might be an alternative; https://www.parts.com/index.cfm?fus...m=None&Title=Mitsubishi-Montero-3.5L-INJECTOR

 

[quailchaser]

Thanks for the advice. I told them to just replace just the one injector to get it running (I forgot to ask them to save the old one, but I'll ask for it anyway). I will then likely send all 7 to get cleaned and tested. From what I researched all remanufactured ones are just cleaned and tested cores that you swap out. I would rather stick with mine and see. By sending all 7, I hope to have flows matched with a spare if the bad one is just clogged.

I'm suspecting clogging to be the issue as I cleaned them by hand and then they sat for almost a year while I was rebuilding the engine. I could have gotten some junk in them myself or some of the old fuel could have varnished things up. I can'[t keep my old Yamaha carb clean even with stabil. If it sits for more than a few weeks, it gums up. I think you may be on to something with the AZ fuels.

 

[quailchaser]

Update to wrap up the thread in case someone is researching issues. Problem turned out to be 3 clogged injectors. Sent all 6 to cruzinperformance.com to be cleaned and now the truck runs as good as new!

 

[coffeegoat]

Just for future reference - could you watch for any MPG change/improvement associated with the cleaned injectors? I'm always interested in the performance (including MPG) improvements associated with different pieces of maintenance, and since basically everyone has to pull the injectors to do the timing belt job if there is pretty good evidence that it'll help one way or the other it might make sense to include it with the "while you're in there" list of items... Certainly avoiding problems is a nice potential benefit, but if you could show a 1-2 MPG improvement at $20/piece for the cleaning could pay for itself in 5K miles, which isn't too shabby with better performance along the way.

 

[RyanY]

since basically everyone has to pull the injectors to do the timing belt job

Not sure which engine you're working on but I haven't seen or heard of a Montero engine that needs the fuel injectors removed to do a timing belt service.

 

[quailchaser]

Not sure which engine you're working on but I haven't seen or heard of a Montero engine that needs the fuel injectors removed to do a timing belt service.

I can attest to this at least for the 3.5L, you do not need to pull the injectors for timing. You do need to pull the plenum to change the spark plugs, which gives you good access to the injectors. Maybe he was thinking that you should change the plugs when you do the timing belt service...