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Discussion Starter · #1 · (Edited)
I am not getting these codes on my 2002 Coupe and even when I clear them they come right back:

P1149 Air/Fuel Ratio (A/F) Sensor (Sensor 1) Range/Performance Problem
P1149 Air/Fuel Ratio Sensor (Sensor 1) Circuit Lean Range
P1189 Pump Speed Signal Fault

From there the car runs in Valet mode so I have parked it.

I have these questions: Should I be replacing the MAF? Is the left or right fuel pump?

Can this be caused by bad O2 Sensors?

The car runs like a stripped ... ape in the morning when its cold but in the afternoons it has been throwing codes, when the air is warmer.. Let me also say I have the DBW from Jeff as well as his piggy back ECU but this even happens when they are capped off. I have read that a bad O2 sensor will set off a P1149 but Kent and others here will know exactly what this is.

Another clue is that while turning hard in a corner the other day, the car lost power, like it lost fuel pressure... Once the corner was over the car resume perfectly. I am begining to think it's a fuel pump, heat would cause a weak one to lose pressure and as the day went along and temperatures outside went up, a weak fuel pump would cause some problems.

So chime in here and let me know what I should be replacing... Also what fuel pump tester do you recommend? A simple vacuum/pressure tester won't work with the Schrader valve so what are you using..
 

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Let me check the exact wording on these codes tomorrow at work. From what it sounds like to me you could have a fuel pump issue. When turning the vehicle it can starve the one pump and not produce enough fuel pressure to keep up with demand. It can also be a bad O2 giving the wrong inputs. The part where you say it runs well in the morning but poorly in the afternoon when temps go up makes me think that the hotfilm MAF sensor could be bad. You have a real head scratcher here. I will check the codes in the morning and get back to you. Also ITARESAM is a tech. He is very good at answering these questions. Dont worry we will sort this out for you.
 

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Discussion Starter · #3 ·
Let me check the exact wording on these codes tomorrow at work. From what it sounds like to me you could have a fuel pump issue. When turning the vehicle it can starve the one pump and not produce enough fuel pressure to keep up with demand. It can also be a bad O2 giving the wrong inputs. The part where you say it runs well in the morning but poorly in the afternoon when temps go up makes me think that the hotfilm MAF sensor could be bad. You have a real head scratcher here. I will check the codes in the morning and get back to you. Also ITARESAM is a tech. He is very good at answering these questions. Dont worry we will sort this out for you.
Bugattitech I really appreciate your help! I can do the work, just not sure where to start and don't want to buy all the parts if I don't need them...
 

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I've PM'd you a few tips as well, let me know if we can help!

Best Regards,
-- Jeff
 

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Discussion Starter · #5 ·
Itaresam

ITARESAM Are you lurking? Sure would like to hear your opinion before I buy a fuel pump pressure tester and then head down the fuel pump/MAF (Clean first) replacement route...


Kent?
 

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if you have a recently oiled aftermarket air filter (non-paper), you may have an oil-contaminated MAF. You might want to buy a can of MAF cleaner and try that first - cheap fix as I'm sure you know.
 

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Discussion Starter · #7 ·
if you have a recently oiled aftermarket air filter (non-paper), you may have an oil-contaminated MAF. You might want to buy a can of MAF cleaner and try that first - cheap fix as I'm sure you know.

Vincenzo I appreciate you reminding me of this. This will be my first move! I do have the BMC, but have never oiled it, this year is the first time I will be doing the rinse and re-oil but that doesn't mean the stock stuff didn't work it's way up the tube!
 

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ITARESAM Are you lurking? Sure would like to hear your opinion before I buy a fuel pump pressure tester and then head down the fuel pump/MAF (Clean first) replacement route...


Kent?
Sorry I had a really busy day today. I really wanted to get a better idea of what those codes meant in particular. I am going to ITAESAMTECH's house where we will formulate a game plan on how to diag. this thing correctly. I know you are anxious to get driving again. Tomorrow I will PM you with a diagnosis path to follow and then we will better understand what is wrong.
 

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Remove the shrader valve on the fuel rail and check the fuel pressure. Removed the shrader and check fuel pressure when it is cold. Let me know your results. I am leaning towards fuel pump.
 

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Discussion Starter · #10 ·
I will pick up the fuel pump pressure tester tonight on the way home, the one I have now is the cheap type and then I will let you know the pressure off both rails. I remember Kent saying I needed to have a minimum of 52 pounds on each rail. I will check it with the engine off, with the engine first started, then check it after the engine has fully warmed up. I will let you know here this weekend what the numbers are.
 

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Discussion Starter · #12 · (Edited)
I should have the numbers tomorrow.

I bought the fuel injection pressure tester, with a ton of attachements but the shrader value attachments don't fit my Maserati. I will have to get the attachment tomorrow and then test the pressure. I did find a tiny hole in the fuel line on the drivers side, right where the fuel enters the fitting that attaches to the fuel rail. I cut the line clean but found that the line is actually two lines, a plastic like inner line and then a rubber line on the outside. The inner line is very stuff and brittle and I am wondering what tricks you use to get the inner line more pliable. I could use a hair dryer but would rather hear from you guys before I go that route. So what is your trick? BTW, looking the service manual these are not the original fuel lines...


I cleaned the MAF with CFC, as well as changed LOF in both of my Toyota's today so I am going to wait till tomorrow to get the fitting and provide the pressures...
 

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Discussion Starter · #13 ·
Remove the shrader valve on the fuel rail and check the fuel pressure. Removed the shrader and check fuel pressure when it is cold. Let me know your results. I am leaning towards fuel pump.
54 PSI LH, 55 PSI RH, cold and warm...

I cleaned the MAF yesterday, ended up soaking the fuel line in boiling hot water for 10 minutes, then it slipped over the fitting with some work but it is all hooked up and now leaks so far...

Anyway, I took it out for a drive, it's only 41 degrees here today, and the car ran fantastic, no codes, was out for about 35 minutes or more, pushing it hard, taking it easy, everything and it's running smoother than it has before as well.. Anyway I am going to wait for a warmer day, something over 65 degrees and see what happens then as it ran fine the other morning, but then in the afternoon wouldn't cut it at all and was throwing the codes.

So anyway, time to vacuum, clean, wax and put it away for now as it's supposed to snow tonight.

Can the MAF cause the computer to throw those codes? When I took it out there looked like a rust spot across the wires but after the CFC was sprayed on it that spot went away...
 

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Discussion Starter · #14 ·
I will be updating my thread here this weekend. I should have good enough weather to go out for a spin and then will report back.
 

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Discussion Starter · #16 ·
So today I broke out the car after the snow melted and the roads dried up. I was out for over an hour, the temp was slightly above 50 and it ran like a champ! No codes, ran perfectly so now I am going to wait until it's over 60 and try it again. I have cleaned the MAF so far, nothing else.
 

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Glad to hear...hopefully that's all it was and you're only out a few bucks for a can of CRC MAF cleaner! :) I'm sure you thoroughly enjoyed the drive time.
 

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Discussion Starter · #19 ·
Second test done...

So yesterday I drove the beast to work. It was 75 degrees here in Denver and it's 100 miles round trip via E470 and I had no problems what-so-ever so everything seems to be fine at this point in time. Before even with lower temps I couldn't make the entire trip without throwing a code.
 

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Reviving this thread

been having limp mode issue. Throwing P1149 and P1189 codes. Sometimes I can get it to go away with a reset. Has gotten worse in the last week - I did spray my BMC filter with carb cleaner (not a good idea) and was thinking that the MAF is fouled -cleaned it but same problem. Cleaned it again, same problem, and then went out few hours later and she's ok - not sure for how long.

Guess I'll try the MAF ($300) first before I start looking at the O2's - which are new.

Any thoughts ?
 
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