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  #1  
Old 04-07-2007, 12:48 AM
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Default Fuel trim malfuntion

Throwing a P0170 and P0173.So,have a fuel trim malfuntion on both banks.OK,in english,what the "H" is this and what am I looking for.I want to note that sometimes in the cabin I can smell fuel;not very strong,but the oder is present.I looked and don't see any leaks present. I'm looking at Mazda specific codes.Do the P1170 and P1173 go in hand w/these generic codes?
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  #2  
Old 04-07-2007, 11:03 AM
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Default RE: Fuel trim malfuntion

very common problem with the 2.3. you have a vacuum leak. most likely is at least 1 "tee", and there are several. only 2 are acual "T", the rest are more like a "Y". most likely are the 2 right under the intake. you remove the black plastic cover, and that huge conglamoration coming off the compressor, which i call the intake, not to be confused with the intake plenums. underneath that mess are the "T's" in question. if only 1 is broke, replace BOTH. because you will just have to do it again. after you remove all the stuff, you will see one that is right near the front of the motor(by front i mean water pump side) and you will think that you could have gotten to it without removing the intake. but the second little ***** is buried, so you would have to take it off anyway. it is not a hard job, it just takes a while because so much stuff has to come off. couple three hours.
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  #3  
Old 04-07-2007, 12:35 PM
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Default RE: Fuel trim malfuntion

I failed to mention this is a 2.5.......I just had the intake off and went back w/new gaskets.I took out the K&N air filter and replaced with a paper Fram.I did some searching and I'm finding out this can be either a rich or a lean condition.I'm going to retorque the intake and "poke around" a bit.
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  #4  
Old 04-07-2007, 04:26 PM
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Default RE: Fuel trim malfuntion

although i am not familiar with the vacuum routing on a 2.5, those codes are fuel trim malfunction, and it is a vacuum leak. put a vacuum gauge on, you will see low vacuum at idle. since it is both banks, it is something that is common to both intake plenums, which is vacuum line routings, or a tee connector. you probably left a vacuum line disconnected.
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  #5  
Old 04-07-2007, 06:30 PM
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Default RE: Fuel trim malfuntion

Yeah,I'm on the hunt keninn.
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  #6  
Old 04-08-2007, 12:39 AM
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Default RE: Fuel trim malfuntion

The older models when OBDII first came out were not specific about if the fuel trim malfunction was lean or rich, only that is has maxxed at one or the other. Adaptive fuel control just allows the PCM to make changes in how rich or lean the engine is running on a long term and short term basis. See if your Auto Xray will give you freeze frame data or operating conditions that occured at the time the codes were set. You will want to be looking for something that looks like LFT, Long FT, SFT, Short FT etc that would give you an idea of what the Long Fuel Trim and Short Fuel Trim numbers are looking like. Should be stored as a % but may just give you a positive or negative number between -25% and +25%.
Adaptive fuel control works kind of like this. Base setting is 0%. If you were to say develop a small vacuum leak then engine would be running leaner than normal. Adaptive fuel control would start increasing the Short Fuel Trim ( adding fuel by keeping the fuel injectors open a few miliseconds longer ) untill the oxygen sensors were cycling normally and not staying too long on the lean side. When Short Fuel Trim has been increased approx 20% then Long Fuel Trim would increase to 1% and Short Fuel Trim would drop back to zero and start the whole cycle over. If the vaccum leak were larger then short fuel trim cycling from 0% to 20% would continue untill Long Fuel Trim reaches a preset maximum of 20-25%. At this point the PCM would respond by saying to itself " self, I have increased the amount of fuel untill I can not add anymore within my programming so I am going to turn on the CEL and inform the driver that there is a problem".
Positive numbers in the fuel trim mean the engine is running lean and fuel is being added. Negative numbers mean the engine is running too rich and fuel is being subtracted.
P0170 is for a fuel trim malfunction on the right bank of the engine and P0173 is for the same thing on the left bank of the engine. Since both are being stored I would guesstimate that you have a vacuum leak at intake manifold which is affecting both banks or the intake air boot between the air cleaner housing and engine is torn or otherwise allowing unmetered air into the intake air stream.
There is a large diameter hose that connects to the front outer corner of the right side valve cover. Make sure it was reinstalled after the intake was off and any other hose that were removed. Have forgotten that one myself more than once.
The P1170 and P1173 are telling you that after the engine was sufficiently warmed up and oxygen sensor should be sending rich/lean signals to the PCM but are not. Sensor outputs remained unchanged for longer than 20 seconds. The oxygen sensor should be cycling from a rich to lean indication approx once per second at a hot idle and much quicker with rpm raised. Vacuum leak of sufficient size could definitely cause this so basically all four could be tied together with only one problem. Something is causing the engine to run either too rich or too lean for an extended period of time. The fuel trim numbers being positive or negative will tell you which way so hopefully the scanner will provide you with this information. For all we know that vacuum line that you reconnected for the P0400 could have been the culprit. Scanner will clear codes but not reset the fuel trim numbers. You will need to disconnect the negative battery cable to get those trim numbers reset.
Wheeeew. After all that typing on a Sat night, I would say that it is Miller time.
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  #7  
Old 04-08-2007, 02:49 AM
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Default RE: Fuel trim malfuntion

Sure enough was a vacuum leak.Found a vacuum hose off at a switch mounted on the air filter box,going to the area of the intake just behind the distributer.Yesterday when I first got the scanner,I really did'nt understand that it tells you if the moniters are ready (?) or not.Other words,it goes from codes (scrolling down),to moniters that are ready (reads "ready"),then goes to moniters that are incomplete (INCPL).So when scrolling down,I was seeing EVAP.,CATALYST,MISFIRE,etc.So immediately I'm thinking-WTF;I just put all new plugs and wires in it.So reaching down to feel if any plug wires had come off of the distributer I must have knocked that vacuum hose off.It's an AX700 Code Scout.80$ at NAPA/nothing fancy.I'm not aware if it has freeze frame capability (I very much think not).It gives codes very quick,and comes with a book giving the generic codes then I go to the following web page to getMazdaspecic codes.http://www.obd-codes.com/trouble_codes/mazda/
So since buying it,it has helped me twice to get to the general areas triggering the CEL.I cleared the codes and have since driven (cycled) 3 times in agout 25 miles of driving.CEL is still off.
I really appreciate your respectful and charitable coments and input.I am absolutely new to OBD,and am amazed by the quickness and advanced technology.New school is cool,especially w/the help and advice from fine folks on this website,because I've never worked on or owned a Foreign-fuel injected-aluminum engined car before.
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  #8  
Old 04-08-2007, 06:47 PM
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Default RE: Fuel trim malfuntion

Give it a little while of driving and then check and see if the O2 monitor has registered complete or maybe CPL. Just has to be driven under certain driving conditions for each of the monitors to be run by the PCM with either a pass or fail and all should complete.
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  #9  
Old 04-10-2007, 11:59 AM
 
Join Date: Apr 2007
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Default RE: Fuel trim malfuntion

Hey BABY Huey i think that he should be sending you some of your hard earned miller time for that essay. Trust me though guys like us reallly need the help.. So thanks budd Hope you were able to have a Miller time.
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Old 04-10-2007, 11:59 AM
 
 
 
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Tags
2000, fuel, im, lean, mazda, miata, millenia, negative, p0173, p0400, p1170, p1173, reset, rich, shor, term, trim


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