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My 02 g20 won't go over 2000 rpms, i just put a new engine

my 02 g20 won't go...
my 02 g20 won't go over 2000 rpms, i just put a new engine in it and it ran great but check engine light was on and it was tps and i just replace it with my old throttle body and since then its been messed up it starts and idles fine just can't get it to get pass 2000 rpms
JA: Does the light stay on, or does it blink?
Customer: check engine light stays on
JA: Are you fixing your G20 yourself? What have you tried so far?
Customer: i've tried to swap throttle body, change MAF
JA: Anything else you want the mechanic to know before I connect you?
Customer: i think thats it
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Answered in 24 minutes by:
9/17/2017
Eric
Eric, Automotive Repair Shop Manager
Category: Infiniti
Satisfied Customers: 32,959
Experience: 20+ yrs. experience as repair shop manager and technician.
Verified

HI,

Did you do the idle learn procedure after replacing the throttle body?

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Customer reply replied 3 months ago
I tried that and it says this function isn’t available for this vehicle
Customer reply replied 3 months ago
I put the old one back on as well

HI,

Ok, there is an idle learn specific for this vehicle.

Vehicle » Powertrain Management » Fuel Delivery and Air Induction » Idle Speed/Throttle Actuator - Electronic » Service and Repair » Procedures » Perform If Throttle Actuator Is Replaced » Idle Air Volume Learning

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icon_prd_right_vehicle.gif 2002 Infiniti G20 L4-2.0L (SR20DE)

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1. Turn ignition switch "ON" and wait at least 1 second.
2. Turn ignition switch "OFF" and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic "PRE-CONDITIONING" (previously mentioned) are in good order.
5. Turn ignition switch "OFF" and wait at least 10 seconds.
6. Start the engine and let it idle for at least 15 seconds.
7. Disconnect throttle position sensor harness connector (brown), then reconnect it within 5 seconds.
8. Wait 15 seconds.
9. Make sure that idle speed is within specifications. If not, the result will be incomplete. In this case, find the cause of the problem by referring to the NOTE below.

10. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.

NOTE: If idle air volume learning cannot be performed successfully, proceed as follows:
1. Check that throttle valve is fully closed.
2. Check that downstream of throttle valve is free from air leakage.
3. Adjust closed throttle position switch and reset memory. (Refer to Basic Inspection.)
4. When the above three items check out OK, engine component parts and their installation condition are questionable. Check and eliminate the cause of the problem.
5. If any of the following conditions occur after the engine has started, eliminate the cause of the problem and perform "Idle air volume learning" all over again:
- Engine stalls.
- Erroneous idle.
- Blown fuses related to the IACV-AAC valve system.

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Forgot to include the pre conditioning that needs to be met before doing the learn procedure

PRE-CONDITIONING
Before performing "Idle Air Volume Learning", make sure that all of the given conditions are satisfied.

Learning will be cancelled if any of the following conditions are missed for even a moment.
- Battery voltage: More than 12.9 V (At idle)
- Engine coolant temperature: 70 - 95 °C (158 - 203 °F)
- PNP switch: ON
- Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)

On vehicles equipped with daytime running light systems, if the parking brake is applied before the engine is started, the headlamp will not be illuminated.

- Cooling fan motor: Not operating
- Steering wheel: Neutral (Straight-ahead position)
- Vehicle speed: Stopped

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Customer reply replied 2 months ago
Is this a manual relearn?

yes

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Customer reply replied 2 months ago
Alright I’ll try this out and hopefully it works

Ok, sounds good and let me know results and will go from there

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Customer reply replied 2 months ago
Thank you!!

you are welcome.

If for any reason, you can't rate my answer OKAY, GOOD, or EXCELLENT/3 STARS OR HIGHER today. Please reply and let me know why, so I can help more/better. All follow up responses are FREE, after completing the required rating

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Customer reply replied 2 months ago
Hi Eric, it’s still not working

Ok, what are the current fault code numbers?

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Customer reply replied 2 months ago
P0325 and P0505

HI,

Ok, P0505 is for the IAC valve. This will cause the issues you are having. Possible causes are faulty IAC valve, wiring harness, vacuum leak or restriction or ecm.

you will need to do the testing in the attached directions

The P0325 for the knock sensor should not cause these issues

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Customer reply replied 2 months ago
Ok I’ve replaced it and still getting the same thing

Did you just replace it or did you do the testing and it tested it bad

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Customer reply replied 2 months ago
I just replaced it and try to do the relearn
Customer reply replied 2 months ago
The check engine light was on and when I started it up it went away.

I am not sure what else it could be. I will opt out and see if another expert sees what I am missing

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Customer reply replied 2 months ago
Alright...thanks
Jay
Jay, Certified Infiniti Technician
Category: Infiniti
Satisfied Customers: 20,791
Experience: 20+years, Nissan and Infiniti experience and currently now working for a Infiniti Dealer
Verified

Hello my name is ***** ***** thank you for your question.

If you have the Dreaded P0505 code, this is normally caused by a bad Idle air control valve.. When this goes bad, it damages the Ecm also. Where if you replaced the Throttle Chamber assembly, since the old IAC damaged the ecm, the Ecm now damaged the new IAC. So the only way to resolve this issue I am afraid is the Replace the IAC valve and the Ecm both at the same time. Then program keys and do the Idle relearn to verify repair.

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Customer reply replied 2 months ago
Dang so the new iac is bad now?

Yes. When you have a P0505 code, both the IAC and Ecm both have to be replaced at the same time, other wise you will never get ahead of the issue. Once one is damaged it takes out the other. So if they are not both replaced, things will keep getting shorted out.

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Customer reply replied 2 months ago
Got ya so I need new ecm and I’ll just warranty this IAC. Do you know where I can get an ecm? Junkyard?

Yeah.. They are not longer available I don't think. But if they are, I would get New, this way you have warranty

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Customer reply replied 2 months ago
Ok I’ll check new and if all else fails I’ll get From junkyard
Customer reply replied 2 months ago
Is it ok to get one from junkyard?

Sure.. I would just try to make sure you know it's a good working unit.

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Customer reply replied 2 months ago
But this should definitely fix the problem?

If you have any more questions on this, please feel free to ask.

If not, and you're satisfied with my help, please Rate me. That is how I get credit for my work. I hope I have provided you with 5 Star Excellent Service.

Thanks Jay!

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If you have a P0505 code.. Yes.. You need to that that and ignore all other codes since it's known that it causes ECM damage. Then if there is any new codes after the repair, then they would be diagnosed.

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Customer reply replied 2 months ago
Do you know what could’ve caused the code

Yes.. There is a Coolant passage on the bottom of the throttle chamber. When the IAC gasket fails, the coolant seeps into the Electrical winding and shorts out the IAC which then damages the Ecm

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Customer reply replied 2 months ago
Dang..ok cool! Well I’ll give this a shot and pray it fixes my problem! Thanks again!

Your welcome and thank you for using JustAnswer.com

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Customer reply replied 2 months ago
Once I get my new computer and iac I’ll have to do a relearn correct?

Yes, you will also need to reprogram all your keys

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Customer reply replied 2 months ago
Ok! Computer gets here tomorrow so I hope this fixes it all

You got it!!

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Customer reply replied 2 months ago
Ok I got everything plugged in new iac new computer. What do I need to do now?

program keys, do a Idle relearn and test drive

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Customer reply replied 2 months ago
Ok how do I program keys?
Customer reply replied 2 months ago
It’s asking for a 5 digit pin???

5523 is the pin

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Customer reply replied 2 months ago
Ok thanks

What the hell is that?

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You have to program the keys with Nats 2.0. There is no 5 digit pin to decode. Nats 2.0 uses pin 5523. If you try to use Nats 5.0 then you have to decode a 5 digit pin

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Customer reply replied 2 months ago
This is for throttle relearn

Oh.. You have to have the vehicle fairly warmed up, ac off.. Then if your scanner has the idle Relearn, you hit start and let you know when it's complete.

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Customer reply replied 2 months ago
Well it shut off and didn’t relearn it
Customer reply replied 2 months ago
Now it’s back doing the same thing with no check engine light

What is it doing? Idle Surge?

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Did you play with the TPS?

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Customer reply replied 2 months ago
It’s just not going over 2000rpms when I rev it up
Customer reply replied 2 months ago
This is driving me crazy

That could be a bad MAF sensor.. What is the fuel trim at idle?

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Customer reply replied 2 months ago
100?

100% is it stuck at 100% or does it jump around a little around that? Did you tamper with the TPS or anything?

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Customer reply replied 2 months ago
I changed it BC when I first got the car running last week check engine light was bad tps.

So you changed the TPS?

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IF you turn the key to the on position, and since you have a scanner, what is your TPS voltage? Also monitor the Open / Close switch of the TPS and see if it's closed and if you just start to crack the throttle by pulling the cable, does it switch to open?

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Customer reply replied 2 months ago
It is running perfect!

ok.. But if your TPS is not set properly, that could cause your issue.. So I wanted to go through that with you as well.

Is it running better now?

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Customer reply replied 2 months ago
Oh yea I had it set up wrong..thanks jay!!

Your welcome and thank you for using JustAnswer.com

Don't forget to Rate me if your Satisfied with my help. That is how I get credit for my work. You can Rate me by clicking the Stars at the top of the page. I hope I have provided you with Excellent Service

Thanks Jay!

Jay
Jay, Certified Infiniti Technician
Category: Infiniti
Satisfied Customers: 20,791
Experience: 20+years, Nissan and Infiniti experience and currently now working for a Infiniti Dealer
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