RPM drop with false odour
03-28-2018, 10:13 AM
#1
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RPM drop with false odour
Basically i own a 1999 Nissan Maxima. My old engine got messed up when the gasket got blown and engine totalled. I had it replaced.
Ever since then ive been having problems with the car. I replaced the throttle body twice, MAF and Knock sensor(for which i had a code upon checking).
The car runs SMOOTH AND RUNS AMAZING. But very often drops the RPM while driving or at a traffic signal and upon revving it gets fine after some efforts and gives a weird odour.
The wiring and sensors are said to be proper. Did a fuel injector clean too.
Could it be another bad MAF and A FAULTY ECU?
I really love this car and any help would be much appreciated.
Ever since then ive been having problems with the car. I replaced the throttle body twice, MAF and Knock sensor(for which i had a code upon checking).
The car runs SMOOTH AND RUNS AMAZING. But very often drops the RPM while driving or at a traffic signal and upon revving it gets fine after some efforts and gives a weird odour.
The wiring and sensors are said to be proper. Did a fuel injector clean too.
Could it be another bad MAF and A FAULTY ECU?
I really love this car and any help would be much appreciated.
03-28-2018, 12:52 PM
#3
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Location: Portland, Oregon
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Why do you think you have a faulty ecu?
The smell would have little to do with idle drop.
Are your spark plug wells free of oil?
Are the spark plugs NGK?
The smell is probably an oil leak. The oil leak might affect the cam and crank position sensors, or others.
I'd say work on stopping leaks. Might solve your idle issue, and leaks need to be fixed anyway.
The smell would have little to do with idle drop.
Are your spark plug wells free of oil?
Are the spark plugs NGK?
The smell is probably an oil leak. The oil leak might affect the cam and crank position sensors, or others.
I'd say work on stopping leaks. Might solve your idle issue, and leaks need to be fixed anyway.
03-28-2018, 01:45 PM
#4
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The sparkplugs were replaced by OEM Nissan SparkPlugs and the coils were also fine
03-28-2018, 01:47 PM
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Why do you think you have a faulty ecu?
The smell would have little to do with idle drop.
Are your spark plug wells free of oil?
Are the spark plugs NGK?
The smell is probably an oil leak. The oil leak might affect the cam and crank position sensors, or others.
I'd say work on stopping leaks. Might solve your idle issue, and leaks need to be fixed anyway.
The smell would have little to do with idle drop.
Are your spark plug wells free of oil?
Are the spark plugs NGK?
The smell is probably an oil leak. The oil leak might affect the cam and crank position sensors, or others.
I'd say work on stopping leaks. Might solve your idle issue, and leaks need to be fixed anyway.
There arent any leaks and the smell isnt OIL smell its more of a fuel kinda smells and only comes to notice when the car starts dropping RPM and goes towards shutting down.
The reason i said ECU maybe faulty is because i have tried all other things and thats something i am doubting on.
help is needed. Thanks
03-28-2018, 02:01 PM
#6
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You should know that these cars are known to have issues wit their fuel injectors. They can leak excess fuel into the cylinders. Other symtoms are difficult starts after the engine has been off for a while. This is because the fuel pressure in the fuel rail drops.
or the fuel pressure regulator might be at fault.
you might want to test your fuel pressure.
I doubt that your ecu needs to be replaced.
or the fuel pressure regulator might be at fault.
you might want to test your fuel pressure.
I doubt that your ecu needs to be replaced.
03-28-2018, 08:08 PM
#8
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Seems that you are bound and determined to change your ecu. Your money, your car, your call. Doubt it will solve your problem though.
I did say that the injectors on our cars are problematic, as many have reported.
I have driven my car for 110k miles over 12 years.
I have had my injectors rebuilt.
Last edited by JvG; 03-28-2018 at 08:10 PM. Reason: Spell check
03-29-2018, 09:46 AM
#11
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One additional consideration.
Have you thought about vaccuum leaks?
That could also result in idle drop off, followed by misfire due to running too lean. Which in turn would cause the fuel smell.
I'm trying to help you.
Have you thought about vaccuum leaks?
That could also result in idle drop off, followed by misfire due to running too lean. Which in turn would cause the fuel smell.
I'm trying to help you.
03-29-2018, 01:55 PM
#12
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Hey! Thanks for your reply man ik you are trying to help me.
I’ll consider rebuilding the injectors but maintly the mechanics are too messed up so gonna look for a good reliable one.
On the other hand yes i have dropped the idea of swapping ECU. And i was recently told by a mechanic that ive a vaccum leak and he needs to figure it out so ima hand it over to him!
03-29-2018, 04:27 PM
#13
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Hey! Thanks for your reply man ik you are trying to help me.
I’ll consider rebuilding the injectors but maintly the mechanics are too messed up so gonna look for a good reliable one.
On the other hand yes i have dropped the idea of swapping ECU. And i was recently told by a mechanic that ive a vaccum leak and he needs to figure it out so ima hand it over to him!
I'm thinking back on the carburetor cars I had long ago. They would also die at idle, or misfire.
Often times the cause was a vaccuum leak.
The prime location was the gasket at the base of the carb, the power brake booster hose, followed by the small hoses.
While our car does not have a carb, it does have a gasket at the base of the throttle body. Essentially the same thing. There is also huge gasket at the base of the upper intake manifold.
Then there are the smaller hoses. They can crack and leak since they are 20 years old.
It's possible to test these sometimes by spraying a combustible product like carb or brake cleaner at the suspect areas. An unlit propane torch works too. Listen for a change in engine rpm.
Otherwise, cheap scanners can be found on Amazon.I bought the one by BAFX . My phone communicates with it. The phone shows dis lay screens. I paid about 22 bucks. One of the screens shows fuel trim. If the fuel trim is higher or lower than normal, it indicates that the ecu is compensating by sending more or less gas through the injectors than usual. Like if it runs rich, it's compensating for an air leak .
By the way, your way of spelling odour tells me that you might be in Great Britain? Canada?
Please indicate your location on your home screen
The reason we ask is that car issues crop up more in certain climates. A car used in a dry desert will have different issues than those where it is damp and humid a lot. Or very hot or cold climates have different issues as well.
Last edited by JvG; 03-29-2018 at 05:58 PM. Reason: Spell check
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