cleaned throttle body and MAF and now problems - I need help

teemoney

teemoney

Member
Car
2007 Infiniti fx35
Just had my mechanic change my plugs,change my air filter, clean the throttle body and clean the MAF sensor. When i start the car it idles rough and i get the check engine soon light. The car is running really rich now. We checked the code and we get p0300 which is random misfires. We double checked the plugs and the coils and they are fine. My mechanic thinks the MAF sensor is now bad. Anyone else get that code before and what was the problem? I might buy a new MAF sensor tomorrow but don't want to throw money away if that's not the issue. I left he FX there worried i might mess up my catalyc convertor. Any guidance is appreciate
 
Thank you for the response Zebra. So does the idle learning work when the car is running rich. I drove the FX home like this yesterday and there's no power. When i idle at a light the car shakes due to the misfiring. The mechanic told me he cleans throttle bodies and Maf sensors all the time on other cars. I printed the procedures and i am thinking of giving them to him tomorrow. I have read many stories about cleaning the throttle body but people were getting a different code. Are my symptoms the same as others
 
But did he breathe on it? lol
J/K, & dont sweat it yet
Try the idle learning reset. If that doesnt work, you can do it by Nissan Consult. Any Nissan or Infiniti dealer can do it.
Could fix everything, & if not, they can reliably scan the car & diagnose
 
We checked all the coils and we're getting spark. When you stand outside my FX while its running all you can smell is gas. I searched here and no one got code p0300 after doing a tune up. This is frustrating. Any other thoughts

---------- Post added at 04:52 PM ---------- Previous post was at 04:51 PM ----------

So from the problems i am describing you guyswork? think the idle learning could really
 
Knock on wood, I can't remember how many times that I have done the tb cleaning. I haven't had the need to the idle relearn yet.
There are a couple times I had to unplug the MAF sensor and plug is back in to get it going again.
 
I always end up having to redo stuff after having the MAF unplugged or mess with the TB. Just weird that you are getting misfires and stuff.
 
I asked him to disconnect the battery but he insists clearing the code with the computer is just as good. Funny thing is no one no where says to get a new MAF sensor but my mechanic seems to think thats the problem I have also been told if you disconnect the MAF sensor when the car is running and it runs better then the MAF is no good. We did that and the car still ran bad which would suggest the MAF is not bad. Well i have till the morning to figure it out cause he's ordering a new MAF tomorrow and i don't think that's the issue. I am going to have him disconnect the battery for a hour and see what happens, if not try a new battery, if not try the idle learning. If all that fails, should i order a MAF or take it to Infiniti
 
Have you had issues with this guy before? He's sounding a little suspect. Hopefully he's not charging you for the MAF if it doesn't fix the issue.

Clearing the codes with a computer should be just as good as unplugging the battery.
 
In your case, you already having a rough idle, unplug the MAF sensor will not give you much info though. Once the MAF is disconnected, most likely it will be rougher or just as rough idle as now. So it will still be a hit or miss situation. If your car doesn't start as it is and you disconnect the MAF; the start then it will most likely is a bad MAF sensor, but it not the case here. I have a feeling there must be a lose connection somewhere.
 
i have been dealing with him for a while. Since he has to order the part and since it's electrical, if he installs it i have to pay.

---------- Post added at 06:39 PM ---------- Previous post was at 06:36 PM ----------

My FX has no problems starting at all, even in the cold here now
 
Just wondering, everything was fine before I'm assuming, he "cleans" the MAF, now blames the MAF and wants to replace it on your dime?
 
Have you take a closer look at the MAF senor to see if there is no breakage. You have to take it out of the sleeve to get a better look.
 
No i haven't looked at the MAF, i will look tomorrow though. So i am looking for breakage? Everything was perfect when i brought it in. I did have a bit of a cold start issue but the FX always started and ran great. So i decided to do the plugs, air filter, throttle body, maf sensor since i am at 80k miles
 
when i cleaned my tb, i did all the resets. no issues yet. could be the coil. wen i changed mine, the passenger front coil was a pain to get off. felt like i snapped it
 
Check for any leaks, any high pitch wheezing sound, if none. Disconnect the battery for a couple of hours and do the "pedal dance" immediately after reconnecting the battery.

Oh make sure the rubber gasket of the oil cap is not caught between the upper and lower plenum. It happened to me before causing an air leak and my CEL lit up.

Good luck.


Sent from my iPhone
 
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He might have drop it while cleaning. Google for picture of how it should look like to get an idea what you should be looking for. Cold start problem is nothing like what you have (rough idle with CEL on). May want to check if the coil connectors if they're in proper order. As I recall the coil connectors on driver side can easily swap spot if not careful. I almost did when I change plug on my FX35. Also, a coil could be bad too.
 
It doesn't sound like your MAF. When the car cranks up, it's in open loop so basically reads airflow from the MAF and then uses a fuel table. But at idle, there isn't that much airflow so even if the MAF were off, it should idle fine. If you unplug your MAF and crank up your car, it should idle decently. If you give it any gas, it might die or immediately throw a code for the MAF. The fact that you were able to drive your car and not throw a MAF code P0100 would seem to indicate it's not a bad MAF. They are very sensitive, and the code trips pretty quickly.

How do you know that your coils and plugs are fine? Because the same guy who thinks it's a bad MAF when it probably isn't tells you he checked them? Your symptoms sound basically the same as on my old Maxima (VQ30) when I blew a coilpack. One cylinder wasn't firing so the car had no power, threw crazy misfire codes, and smelled like fuel. So either he messed up one of your coilpacks reinstalling it or he swapped the plugs as someone mentioned. That will also result in your symptoms since the firing order is messedup.
 
I may have missed it in the reading but what did he use to clean the maf sensor with? I'm guessing that he used brake parts cleaner or carb cleaner to clean the throttle body and if he used the same stuff on your maf sensor, it can damage it. CRC sells a maf sensor cleaner spray that I've used for nearly 10 years on my 04 STI without any issues. The only reason that I've had to clean the maf sensor was due to oil from blowby or from a K&N filter. On the FX, I dont see the need to clean the maf sensor every now and then unless you're using an oiled air filter.
 
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