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Discussion Starter #1 (Edited)
Hello Guys,

Maybe some of you can help me out. I am getting both P2187 and P2189 codes with the check engine light. I started to analyze the fuel trims to try and understand a bit of what is happening.

At warm idle
Short term Fuel bank 1= -6
Longt term Fuel bank 1 = +3
Short Term Fuel bank 2 = - 5
Long Term Fuel bank 2 = +5

As the car is idling warm the fans turn on, when the fans turno on,
The Short term fuel bank 1 and 2 get pinned to +25 and long terms stay at +5 and +6

When this is happening, If i give it throttle, the fuel system goes to Open Loop and the short term fuel trims goes to 0 and the car starts to hessitate. When the fans turn off, the trims goes back down.

If i give throttle with the fan off, everything stays normal.

Can somebody please advise what is happening here? any other thing i should look at?

Thanks
 

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The fan motors put a pretty high amp draw on the system. I would first check and clean the battery connections and chassis grounds. Then monitor the voltage when the fans kick on. Could be the battery or alternator is no longer able to keep up just among a myriad of other possibilities...
 
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The car is lean on both banks...The short term trim being +25 is telling you it is adding fuel...Check for vacuum leaks for starters...Jason
 

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Discussion Starter #4
The car is lean on both banks...The short term trim being +25 is telling you it is adding fuel...Check for vacuum leaks for starters...Jason
Thanks for the replies. That is what it seems, but this only happens when the fans kick in. When the fans turn off, the fuel trim goes back down. I have tried spraying carb cleaner around the engine to see if there is a change in rpm, but have not found anything. is there a particular place i should check? Or any other test to perform?
 

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Discussion Starter #5
The fan motors put a pretty high amp draw on the system. I would first check and clean the battery connections and chassis grounds. Then monitor the voltage when the fans kick on. Could be the battery or alternator is no longer able to keep up just among a myriad of other possibilities...
Thanks,

I will monitor battery voltage with alternator sending charge, and check if there is a difference in voltage when the fans kick in.
 

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you are not likely to see a momentary spike with a meter. these spike generated codes are usually caused by a bad ground or a tired battery. the battery is an important "filter" for line surges. if the battery is over 5 years old, it may be time .....
 

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Discussion Starter #7
you are not likely to see a momentary spike with a meter. these spike generated codes are usually caused by a bad ground or a tired battery. the battery is an important "filter" for line surges. if the battery is over 5 years old, it may be time .....
Ok, did a load test on the battery and the battery turned out to be good.

Not really sure what could be happening that the load on the fans makes the car go lean and ECU compensates for it +25%.
 

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While I am not saying your battery is the problem, they will always check "good", especially if they will start your vehicle. I chased a similar problem for 3 years until the battery died, then my problem went away. Also test your ground circuit. Check from your battery negative to the chassis, the body, and engine block. You need close to 0.1 ohms there.
 

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Discussion Starter #9
While I am not saying your battery is the problem, they will always check "good", especially if they will start your vehicle. I chased a similar problem for 3 years until the battery died, then my problem went away. Also test your ground circuit. Check from your battery negative to the chassis, the body, and engine block. You need close to 0.1 ohms there.
Ok Thanks. I will try another battery just to be sure, and will check the grounds. Is there any diagram where I can see where the grounds are located?
 
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While I am not saying your battery is the problem, they will always check "good", especially if they will start your vehicle. I chased a similar problem for 3 years until the battery died, then my problem went away. Also test your ground circuit. Check from your battery negative to the chassis, the body, and engine block. You need close to 0.1 ohms there.
You are really gonna have a time of trying to only have .1 ohm in a ground circuit...Jason
 
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i personally dont know of ground diagrams - simply check from the negative battery terminal (not the screws) to the engine block and some metal screws around body, that should tell the story. and yes 0.1 is hard to achieve, but if you see 3,5,10 ohms or more, you may be looking at an issue.
 
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Yeah, I don't know about all that...The correct way to test is a voltage drop test under load...Not a continuity test...J
 
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Discussion Starter #14 (Edited)
Ok thanks,
I have been monitoring the problem. When the car is real hot after a drive the problems shifts.

The long term trim is the one going +

This is after drive fan off
135251
71D79ED7-8B60-4009-B59C-BFDC6353B420.jpeg


This is after drive fan on
135252


is it normal that after a while the short term affects or shifts to long term?
 

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Discussion Starter #15
So this only happens at idle. Under light acceleration everything is good.

light acceleration
135253
 

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Just to cover a few more bases, go ahead and check the readings on the coolant and intake temp sensors through the range to make sure they're accurate as they also play a role in the fuel map and fan operation. They should normally throw a code on their own if they fail, but.... I've seen stranger things.
 

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Discussion Starter #18
Just to cover a few more bases, go ahead and check the readings on the coolant and intake temp sensors through the range to make sure they're accurate as they also play a role in the fuel map and fan operation. They should normally throw a code on their own if they fail, but.... I've seen stranger things.
I am going to double check, but coolant temp is around 88C and intake temps around 60C. I believe there are 2 coolant sensors correct? Does the ECU average both? Or is one for the gauge and the other for the ECU?
 
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You are going down the wrong path...We would normally swap an air mass sensor in this case...They go bad occasionally ...Especially if you use a cotton gauze air filter....Jason
 
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I have a good general knowledge but not the resources nor expertise of a brand specialist to dig into the ECU coding. The intake air temp seems high to me. You may just have to wait for Jason to chime in.... I think he truly loves fixing these things over the interwebs, maybe you could describe a sound that it makes to him as well. Haha, jk.
 
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