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peterpete190
peterpete190, Auto Technician
Category: Infiniti
Satisfied Customers: 27644
Experience:  Auto repair Technician with 17 years experience.Past ASE and other certifications.
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When starting car idles rough RPM will not exceed 2000 RPM

Customer Question

When starting car idles rough RPM will not exceed 2000 RPM when pushing accelerator
JA: Is the rough idle intermittent or consistent?
Customer: Consistant
JA: What is the model of your '00 Infiniti?
Customer: 2003 I35
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: yes fix myself
JA: Anything else you think the mechanic should know?
Customer: car is giving code foe catalytic converter
Submitted: 11 months ago.
Category: Infiniti
Expert:  peterpete190 replied 11 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

If you have the P0420 code for a catalytic converter and the rough rpm with no power the most common cause is a fault with the catalytic converter being partially restricted.This is very common.

What needs to be done from here is to have an exhaust back pressure test done to see if the back pressure exceeds 1.5 psi at any rpm range.If it does then the catalytic converter needs replaced.You can usually rent a back pressure tester from a local parts store.It threads into the hole where the pre catalytic converter oxygen sensor is and the engine ran at idle to wide open throttle briefly to see if there is excessive back pressure.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,a rating of 4 or 5 is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 11 months ago.
Car will not accelerate past 2000 rpm then starts to and die out, knock, shake ect?
.
Expert:  peterpete190 replied 11 months ago.

These are all symptoms of a restricted catalytic converter.The exhaust is trying to flow out as the engine produces it and with a restriction it isnt able to fast enough and causes the low rpm limit as well as rough running,knocking shaking etc.Kind of described as like trying to blow through a plugged straw.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.A rating of 4 or 5 is appreciated

Thanks Pete

Customer: replied 11 months ago.
This is a car i am looking to purchase very inexpensively. The body and exterior are in good condition. The car can not be driven do to not being able to accelerate enough to get it to move. The seller is telling me that the only issue is this catalytic converter. I just want to know the probability that a bad catalytic converter would cause these symptoms?
Expert:  peterpete190 replied 11 months ago.

Yes it would for sure.I have dealt with allot of restricted catalytic converters that cause these exact same symptoms here and once it is replaced it corrects all of these issues.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.A rating of 4 or 5 is appreciated

Thanks Pete

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