mazda b3000 code p1151

[jinxlee]

mazda b3000 code p11311

I got this code when i read the code reader, and it said lean condition on cylinder # 2. have replaced injectors, plugs, wires, pcv valve, maf sensor, egr valve, traced vacuum lines and replaced one that was split.have replaced fuel pump, and fuel filter. have replaced 1 upstream o2 sensor. truck is still running like it's running on 4 or 5 cylinders instead of all 6. it's a 1999 Mazda b 3000 with a 3.0 motor. i erased the codes in order to try to get a new code to tell me what is still wrong with the truck. can't get it to code or run well. been trying to fix the truck for about three weeks now. i am at a loss of what else to do. can anyone please give me an idea where to go next? i am very desperate to get this truck fixed. it's my husband's truck, and i have done everything i know to do to it. he has had my ranger because his truck isn't running right. if you take the vacuum line off the evap sensor ( if that's what it's called) the truck changes it's idle and goes up. when you put the vacuum line back on, it's runs like crap again. Please help if any one can!!

 

[RonD]

Reads like you have replaced alot of stuff.
p1151 is not related to cylinder #2, it is a general O2 sensor warning about a fault in the O2 wiring or sensor.
Because the 3.0l uses a high vacuum in the crankcase for "blow-by" recovery, a loose Oil Cap or dipstick not all the way down can cause this code and lean codes/conditions.

I assume you got another code about #2 misfire??

A common problem for missing is reversed spark plug wires, I have been working on engines for a long time and I still goof that up, and even check it twice, however 3rd check usually gets me my "homer moment"......D'oh

You need 3 things for a cylinder to "fire"
Fuel(in the correct mixture)
Spark(at the correct time and strength)
Compression(above the minimum for fuel/air mixture)

Pull out spark plugs and label or ?? so you know which cylinder each came from.
Then look at each and compare it to the others.
"normal" firing will show a brownish patina on the white electrode.
"rich" will have brown to black carbon build up(mis-fire as well)
"lean" will have white electrode.

With spark plugs out I would then do a compression test.
Cold engine
Hook up pressure gauge to #1
Push gas pedal down about 1/2 way, not all the way though.
Crank engine until you hear the "compression stroke" at least 4 times
Write down the number on the gauge
Remove gauge and check the tip, there should be fuel on it, write that down as well
Clear gauge wipe off tip
Move to #2

Continue until all 6 are done
One cylinder's compression number is useless, the compression test is done for all cylinders at one time so all the parameters are the same, so the numbers can be compared.
These numbers
120-125-120-115-120-125
or
170-175-170-165-170-175
are the same, just done with different parameters, different gauge, low or high battery, throttle open or closed, engine cold or warm, ect....

So if someone posts, "is 120psi OK for compression", there is no good answer because there is no comparison numbers.

Also for diagnostics a Vacuum gauge is not expensive, $15-$25, and can tell you alot about engine condition and problems.
Good read here about tests and results: http://www.gregsengine.com/using-a-vacuum-gauge.html

On the upper intake is the IAC valve, (idle air control) valve, the computer uses this to set target idle of 700rpm(800 on auto).
If engine is warmed up and you unplug this control the idle should drop to 500rpm, or engine may even stall, either is OK, it means you don't have a vacuum leak.
If idle remains the same then there is a vacuum leak.

 

[jinxlee]

Wow lots of information there. Sorry I put in the wrong code. It was p1131. Yes, I got a misfire code on #2 cylinder. I also got a lean condition on right bank. I did replace the right side o2 upstream sensor, but not the left side upstream sensor. Need to go pick up the left side o2 sensor. Have replaced so many things that I have lost count. Having some trouble being able to get a canister purge valve. I guess I can try to clean the one on the truck. The only other thing left to replace on the truck after that would be the three injectors on the other bank. This truck is driving me crazy!!! I have never had this hard of a time fixing a truck or anything else. I've been a shade tree mechanic for more years than I care to remember. I am just completely stumped by this truck. I really would like to get it fixed so I can have my ever trusty Ranger back. I miss my widow. That's the name of my truck. We don't want to know what I would name his truck at this point. Driving my vintage Jag as a daily driver at this point is killing me, as she has a V 12. Hopefully I can the answer sooner rather than later on this site. So far everyone has given me some pretty good advise. If you can think of something else, please let me know. Sorry I put in the wrong code the first time. I've been working on this truck so long that everything is starting to run together. At this point, my wallet is hurting more than my head. lol.

 

[RonD]

Well you shouldn't be replacing that many parts, buying another truck would end up being cheaper

As you surmised lean doesn't always mean lean, lol, could be a faulty O2 sensor, I had an O2 sensor that started to unscrew and was sucking air in, so O2 was reading too much air in the exhaust and my MPG went down because computer was running engine rich on that bank.

Anytime you replace anything on a computer controlled engine you have to "notify" the computer about it.
The computer is not very smart, so the only way to "notify" it is to reboot it with a code reader or unhook the battery for 5 minutes, both do the same thing.
It clears the "learned" operating parameters so next time computer starts up it will relearn any new sensors or controls.

 

[jinxlee]

OK I erased the codes with a code reader, but will also try unhooking the battery. I will try that in the morning and let you know what happens. I still went and picked up the o2 sensor for the left upstream sensor. i will put that on before trying the rest. Thanks.

 

[jinxlee]

tried all the things you suggested, and it's still running the same. Got any other ideas? Maybe the brain?

 

[RonD]

The code reader should also have the option to reboot or reset computer, that is what you want to do after changing anything on the engine.
Clearing codes is what you do if you fix mechanical issue, like a broken vacuum line or EGR Valve, these have no computer connection so wouldn't require a reboot.
So you just clear the codes to see if they come back after the repair.

And just as good practice , any time you work on the vehicle unhook the battery first thing, that way computer will always be rebooted next time it starts up.

Post the current codes when available.

O2 sensors can not be used until they get heated up above 600degF, so computer ignores them until engine temp gets above about 160degF, that takes about 5 to 8 minutes.
Computer is in Open Loop for this time period, it runs preset fuel/air mix.
Once O2 sensors are warmed up computer switches to Closed Loop, this is also called Feedback Loop, as the computer is adjusting fuel/air based only on O2 feedback.
There are preset limits for rich and lean though, and that's what can set a code, if computer is adding too much fuel based on O2 sensor data it will set a code about that, also the same for too little fuel being added.

O2 sensors do wear out just like spark plugs, but in general sensors are never the problem when the CEL comes on.
Changing a sensor because of a CEL is like "shooting the messenger", lol, the CEL usually means the sensor is working and it has monitored a problem so is reporting it.

Current engines have the same problems older pre-computer engines did, well actually less problems because of EFI and no distributor or points, lol.
Benefit of the computer and sensors is that if there is a miss or poor operation the sensors can help point you in the direction of a problem, very rarely do the diagnose the problem, but they can give you clues.

Engines still get vacuum leaks, cracked spark plugs, leaking valve guide seals, shorted wires and water in connectors, which was the same for older engines.

 

[RonD]

tried all the things you suggested, and it's still running the same. Got any other ideas? Maybe the brain?

First, does it run better or worst when cold(open Loop)?

Or is it the same cold or warm?

Firing order for 3.0l Vulcan is 1-4-2-5-3-6
Coil lay out is:
4-6-5 << special note, these are easy to confuse
3-2-1

There are only 3 coils in the Ford Coil Pack, so this is a Waste Spark system, that means when #1 spark plug fires, #5 spark plug also fires, same for #2 and #6 also #3 and #4.
And when #5 sparks #1 would spark again, ect.....

If there was a computer issue then #2 and #6 would most like both be miss firing.
Because #2 and #6 are in series one can fire weakly, to check this just reverse them on the coil.
so you get:
4-2-5
3-6-1

If mis-fire code moves to #6 then coil is the issue

What does #2 spark plug look like compared to #1?

Compression test would take that mechanical issue off the table for #2, it is kinda like chasing your tail if compression is the issue and you don't find that out.
2003 and up 3.0ls had valve seat issues that caused cylinder specific lower compression and misfires, but that could just be when Ford had to release the TSB, lol.

An intake manifold leak at #2 could effect just that one cylinder, you can spray quick start or carb cleaner at that location to see if idle changes.
Do this on cold engine, both sprays are flammable, which is the point of using them, but hot exhaust manifolds could start a fire.

 

[jinxlee]

You give very interesting information. It seems like you may be a pro mechanic, as opposed to my shade tree. I did tell him that at this point, I would do a compression check. I didn't know about reversing the wires on the coil. The coil pack has been replaced, as we thought that it may be the problem. That didn't change the way the truck ran. unhooked the battery to reset the computer, and it's still running the same. i am beginning to wonder if it is compression, a bad valve, or the brain on the truck has maybe taken a dump. have traced all the vacuum and only had to replace one line. it had a slight crack in it, but not where it would leak. might try the starter fluid on the cold engine before trying to get into tearing the engine down. have been trying to avoid that. could it be possible that the truck suddenly jumped timing a little? i'm not even sure how to check the timing on a 1999 truck. if i had a 60s, 70s, or 80s model i wouldn't have a problem. this truck has about 190,000 miles on it. have had the truck a long time and it's always been a good truck. we keep the maint. up on all of our vehicles. it just started running rough one day, and has gone down hill from there. since at this point i am stumped, i am just about willing to try anything to figure out what's wrong with it. it has the 3.0 flex fuel engine in it. i know the truck is a mazda, but that just means it's a ford. My truck is a 2004 ford xlt 4x4 fx4 off road. working on it is a bear because everything seems to be stuffed in the truck with no room to work on anything. mine is also a 4.0. if i replace the engine in the mazda with a 4.0 will it work? will i have to relocate motor mounts, and change the tranny? since he has been driving my truck, he has found that he likes of my truck over his. working on my jag is even harder. he's a big guy, so he doesn't like to drive the jag. it's too low and his knees hit the steering wheel even with the seat all the way back. being a v 12 it doesn't get good gas mileage, but it was my dream car and i didn't buy it for the gas mileage. i didn't think it would have to become my daily driver though. by now i probably sound as if i am grasping at straws to you. thanks for all your help. your advise has been very good so far. you have been very helpful, and thank you for allowing me to pick your brain.

 

[txgocartB3000]

You are doing everything except the compression test that has been mentioned on several posts.

Hey.... how about a compression test?

Ray

 

[jinxlee]

When my husband doesn't have to work, we are going to do a compression test. That will probably be this Thurs. or Fri. I will post the results when we have gotten it done. At this point, I am almost ready to sell my Jag, just to get a different truck for him. You know how it is when things drive you crazy. Thanks for all the advise everyone has given me. It has been very useful, and I've even learned a few things that I didn't know before.

 

[txgocartB3000]

Well you must be a very good wife to sell your possessions in order for your husband to have a good truck.

Hang in there until the compression test results get done.

RonD is very good at helping people go in the right direction.

Even if the ultimate decision is to get another vehicle, he/and others will teach you a thing or two about your current truck.

This place is great because of all the people that unselfishly try to help others.

Ray

 

[RonD]

Yes, like to see those results.

Just for future reference, engines still fail in the same way they always did, electronics can't change that, sensors can give you a "heads up" when a problem first starts but that's about it.

For example: if an engine ran fine at idle but would start to lose power and sputter at highway speed, people might check the MAF sensor or fuel injectors or Throttle sensor or .............anything else.
But the problem is just an old fuel filter, $10 and you are driving at 80mph no problem, lol, well except for the speeding ticket.

Don't over think a problem, engines are still just engines, the electronics rarely fail, not never, but rarely

 

[jinxlee]

Did the compression check and got 0 on cylinder # 2. Couldn't get a good read on #5 because of blowby. Head gasket definitely blown. Contaminated antifreeze, but the oil is still ok. Can I drop a 4.0 in this truck without relocating the motor mounts, or having to change the tranny? It's a 99 Mazda B3000 4x2 4dr. supercab, with a 3.0. He has been driving my Ranger with a 4.0 and likes the power. I think he sees that as a fast way to fix his truck, and a way for him to be able to tell me that I can take my Jag off the market. He knows how much it hurt me to put my car up for sale in order to get him a different truck. He wanted me to find out about changing the motor. If anyone can tell me the answer to if I can drop a 4.0 in his truck, please let me know. If I have to make any changes to the tranny, will I have to change out the whole thing, or is there some parts I can change? Thanks for everyone's help.