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Jay
Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 18890
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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2001 Infiniti G20 problem, bogs down when full throttle, ease

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2001 Infiniti G20 problem, bogs down when full throttle, ease into it it will rev up, falls on face when let off to idle?
what is the fuel pressure? what if any are the trouble codes?
Customer: replied 7 years ago.
The fuel pressure is over 40psi- w/ the regulator unplugged it was 44psi. The only code that came up was multiple random misfires. We put a new distributor in it w/ cam sensor built in.
that is good fuel pressure. I woud next try cleaning the IAC and throttle body assembly. Carbon build up can cause sticking which could cause lean conditions. I use a soft brush(pipe cleaner style) and throttle/carb cleaner You could check the egr also, they get carbon and stick also. was the distributor new or reman?
Customer: replied 7 years ago.
the distributor was reman. I cleaned all those places, and to tell you the truth they weren;t even dirty to begin with, I know this car has a IAC-VV which may be the problem.
Hello and thank you for using JustAnswer.com

Do you have access to a scanner to monitor the air and fuel mixture readings at idle car fully warmed up? I think I may know your problem. But I need to see these readings to be able to give you my thoughts on your problem.

Let me know, Thanks Jay!
Customer: replied 7 years ago.

unfourtunatly we cannot get the car to run long enough to warm up. the mass air flow reading is 4.7 g/s running for about a minute.

Try this and let me know what happens. Unplug the MAF sensor, then start the car and see if it runs and idles. This is just a test to be done at idle. Do not drive the car like this.

Let me know, thanks Jay!
Customer: replied 7 years ago.

I unplugged the MAF , the car won't idle on its own and when you try to give it gas it bogs down and stalls.

ok. Now do this. Clean the throttle chamber of all carbon build up and try this again. It should idle on it's own afterwards. Give that a shot and let me know what happens.

Thanks Jay!
Customer: replied 7 years ago.
we have already cleaned all of that, no change. It wasn;t dirty to begin with
Does the car run when it's cold? Do you have this problem once it's fully warmed up?

Let me know, thanks Jay!
Customer: replied 7 years ago.
car won't run cold or hot, b/c can;t get the car to run long enough to warm up
No codes? Were you able to keep it running longer when you had the MAF sensor unplugged?

Let me know, Thanks Jay!
Customer: replied 7 years ago.
no it won't stay running either way.
You have no codes stored any more correct?

Do you know if your getting spark?

Let me know, thanks Jay!
Customer: replied 7 years ago.
right, no codes stored. Yes plenty of spark, not cutting out.
I am leaving work. Can I get back to you in about 2 hours. That is when I will be on again.

Thanks Jay!
Customer: replied 7 years ago.

I will be out of the office until tommorow @ 7:30am, the car isn't going anywhere.

I work during the day. So responce time may vary during the day. Normally we have the day buttoned up by 1 pm. So I will try to get back to you as soon as I can. In the mean time, let me know if you have a multi meter to check voltage and ohm wires.

Thanks Jay!
Customer: replied 7 years ago.
yes, we have all diagnostic tools available to us. I will talk to you tommorow
Do this and let me know what you find. First off, does the car run at all by it's self? You mentioned it bogs on full throttle, and that you have to ease into it to get it to rev.

See if you can get me a air and fuel mixture reading. I would like to see if the car is running rich or lean. Any one of those conditions can cause problems like you are having. That is why I was inquiring on the MAF. The MAF sensor never seems to throw a code, and is know that when it goes, it doesn't really fail, it just meters air incorrectly, which can cause problems like what you are describing. Which to me sound like text book MAF sensor. But I would like to try to be more sure. That is why I would like those readings also.

Let me know tomorrow. Thanks Jay!
Customer: replied 7 years ago.
Good morning, the car will not run on it's own, you have to feather the throttle to get it to rev at all, if you floor the gas pedal the engine will just bog down real low. I am using the OTC Genisys scanner, on the datastream I don't see just a air/fuel mixture reading.
I agree with everything The other techs have had you ck. I hasve seen this before and the replacing the maf sensor on the breather housing repairs it. I know you said you cleaned it but it sometimes won`t help. Do you know where the fuel trim is running?Shoud be between 95% and 105%.Usually if it is bad it will be to the extreme one way or the other like in the 120 to 130 %. Let me knoe if I or my colleagues can help.
Good After Noon. The first thing you will need to check is those air and fuel mixture readings. That will explain alot that is going on. I think you may have a MAF sensor issue, but would need to see those readings to confirm it.

Thanks Jay!
Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 18890
Experience: 20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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