Engine Knocking/Pinging Dtc's Set.. What Next?

[Kawabuggy]

Have an '03 G35 Sedan that we bought brand new. Currently has 70K miles on it. At 66K miles, it started pinging under light throttle when the car shifted into the higher gears. I did some reading and everything I read said to quit using the 87 octane that we have been using since the day it was bought. Well, we switched to 91 octane, and the problem did not go away. Last week my wife went to start the car and it started up, ran for a few seconds and then shut off. She restarted it and it did the same thing several times. She waited a while, and then tried it again and it started and ran normally, but set the SES light. I brought the car to work and scanned it and found P1121. This code is for ETC return spring problem as the description. I again went on-line and did some reading and everyone said to replace the throttle body to alleviate the knocking/pinging problem.

Update. Today I installed the new throttle body, along with a new gasket. I read about doing some type of re-learn procedure, but do not have a Nissan Scan tool. I also read that you could disconnect the battery, then after reconnecting it you should turn the key on for 10 seconds, and then off for 3, and repeat that 3 times. Well, I did that and now the car is not setting any DTC's. However, the idle is higher than it is supposed to be. This is causing all types of funky driving quirks. When I let off the gas now, the car feels like it is engine braking. You know the feeling when riding on a motorcycle and you downshift, let out the clutch, but don't give it any gas. Also, if I let off the gas for a moment, and then step back on it again, the car surges forward for just a second.

Anyway, the knocking/pinging problem seems to have diminished but is not completely gone. Now I have these other issues to deal with.

Can anyone tell me what you would do next? Please don't recommend going to a dealership as I will not do that. If it comes to a point where the dealership is the only place I can take it to get it fixed, I will sell the car as is.

I know there are some really good technicians working for Nissan Infiniti. However, it has been my experience that there is a very thick layer of BULL **** (Service Sales People) you have to fight with and rarely if ever get to speak to an actual tech. I will never under any circumstances deal with a dealer ship service department. Seriously, this car will be GONE before I do that.

With that said, if anyone has any ideas what I need to do to calibrate, or re-learn the ECM to work with the new throttle body, I would appreciate it.

Otherwise, if anyone knows of a Nissan/Infiniti repair shop in Houston, OTHER than a STEALERSHIP, let me know.

If it matters, I am a mechanic by trade. Old school type. Not great with electronics, but really good with the mechanicals. I can build engines, transmissions, differentials, transfer cases, and most other drive-line related items. If there are any techs in Houston that would like to barter services, I gladly offer my services.

[SteveTheTech]

Hello there and Welcome to NICO!

I am sorry you have had some negative experience with "stealerships" it's a shame, there are some good ones out there. Were not all bad people.

Ok with that said here is the gist of whats going on.

After replacement of the throttle body you need to perform to base relearns. Disconnecting the battery will actually wipe out the memory learning. Ok so the process you listed about cycling the key will reset your closed throttle position learning. You still need to perform this proceedure to reset your Idle Volume Learning (base Mass Airflow reading and throttle angle). NOTE: It is better to count the time accurately with a clock. It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuithas a malfunction.

ITEM SPECIFICATIONIdle speed A/T: 650±50 rpm (in P or N position)M/T: 650±50 rpm (in N position)Ignition timing A/T: 15±5° BTDC (in P or N position)M/T: 15±5° BTDC (in N position)

Idle Volume Learning

April 2003 G35 Coupe

1. Perform "Accelerator Pedal Released Position Learning" .(below)2. Perform "Throttle Valve Closed Position Learning" .(below)3. Start engine and warm it up to normal operating temperature.4. Check that all items listed under the topic PREPARATION (previously mentioned) are in good order.5. Turn ignition switch OFF and wait at least 10 seconds.6. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.7. Repeat the following procedure quickly five times within 5 seconds.a. Fully depress the accelerator pedal.b. Fully release the accelerator pedal.8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stopsblinking and turned ON.9. Fully release the accelerator pedal within 3 seconds after the MIL turned ON.10. Start engine and let it idle.11. Wait 20 seconds.12. Rev up the engine two or three times and make sure that idle speed and ignition timing are within thespecifications.13. If idle speed and ignition timing are not within the specification, Idle Air Volume Learning will not be carriedout successfully. In this case, find the cause of the incident by referring to the

Diagnostic Procedure

If idle air volume learning cannot be performed successfully, proceed as follows:1. Check that throttle valve is fully closed.2. Check PCV valve operation.3. Check that downstream of throttle valve is free from air leakage.4. When the above three items check out OK, engine component parts and their installation conditionare questionable. Check and eliminate the cause of the incident.

5. If any of the following conditions occur after the engine has started, eliminate the cause of theincident and perform Idle air volume learning all over again:1 Engine stalls.2Erroneous idle.Fuel Pressure Check FUEL PRESSURE RELEASEWith CONSULT-II1. Turn ignition switch ON.ITEM SPECIFICATIONIdle speed A/T: 650±50 rpm (in P or N position)M/T: 650±50 rpm (in N position)Ignition timing A/T: 15±5° BTDC (in P or N position)M/T: 15±5° BTDC (in N position

Accelerator Pedal Released Position Learning

DESCRIPTION

Accelerator Pedal Released Position Learning is an operation to learn the fully released position of the acceleratorpedal by monitoring the accelerator pedal position sensor output signal. It must be performed each timeharness connector of accelerator pedal position sensor or ECM is disconnected.

OPERATION PROCEDURE

1. Make sure that accelerator pedal is fully released.2. Turn ignition switch ON and wait at least 2 seconds.3. Turn ignition switch OFF wait at least 10 seconds.4. Turn ignition switch ON and wait at least 2 seconds.5. Turn ignition switch OFF wait at least 10 seconds.Throttle Valve Closed Position Learning

Closed Throttle Position Learning

DESCRIPTION

Throttle Valve Closed Position Learning is an operation to learn the fully closed position of the throttle valve bymonitoring the throttle position sensor output signal. It must be performed each time harness connector ofelectric throttle control actuator or ECM is disconnected.

OPERATION PROCEDURE

1. Make sure that accelerator pedal is fully released.2. Turn ignition switch ON.3. Turn ignition switch OFF wait at least 10 seconds.Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.

I hope this help let me know how it turns out or if you have any questions were here to help.

[SteveTheTech]

The knocking is due to prolonged use of cheap gas. The noise is usually spark knock from preignition as the fuel map is designed to run with premium which has a higher resistance to burning.

The base fuel timing can be adjusted which will resolve most of this issue. Problem with that is this can only be done with a ConsultII and up. I have found that usually 1-2 degrees should take care of this but sometimes as much as 4 degrees are needed.

Maybe there is a Nissan/Infiniti tech in your area that can help you out. I would be more than willing to fix you up if you were in my area, but that's a hell of a ride.

[Kawabuggy]

Thanks for the updates everyone! I will try the information given above, and if that fails, I will try and locate an independant shop to work with.

Someone made reference to me having had a "bad" experience with a dealership. No, I have had years of bad experiences with several different dealerships. From straight up THEFT, to down right FRAUD. I have too many negative stories about personal experiences, and from my customers experiences with dealerships. I NEVER recommend that anyone take their car to the dealership under any circumstances. If you can find access to the techs directly-by all means that is the best way. Just pay them handsomely and bend over backwards for their help/experience. I have relationships with several techs in most of the auto lines, EXCEPT Nissan/Infiniti.

[Kawabuggy]

stevethetech, I appreciate the information that you posted. I was able to re-learn the idle volume and now the car idles normally.

I am still having the pinging/knocking/pre-ignition as I was before though.

I am thinking that carbon build up on the piston crowns, and inside the combustion chamber is causing an increase in compression which is the root cause of the problem.

Someone above mentioned retarding the timing 1-2 degrees. Instead of going that route first, can anyone recommend a good process to clean the upper engine? I have seen the plenum aerosol spray cleaner but feel that this would not be effective at cleaning the pistons and combustion chambers.

I have also seen the aerosol cans that you plug into the fuel rail and allow the engine to run off of with the on-board fuel pump disabled.

of those choices, which would you guys recommend to get the best results?

Thanks again for everyone that replied. I sincerely appreciate it.

[SteveTheTech]

I'm glad you got it, sometimes it takes a few tries to do it the hard way.

There are several engine cleaning products on the market. I am curious to see what other owners have used. I have my own opinions but I would like to see what other people think.

[awdjdmtalon]

I have worked for 2 diff. dealers and 2 independent shops. At both dealers and one Indy. we used BG with great results. At the other one we used Everwear. Wasn't too impressed w/ the delivery system of the upper end cleaner.

It was basicly like an I.V. that you plugged into a vacuum line.

I have also used Seafoam from the local parts store, using the same delivery system as above.

All 3 have done the job. But the BG didn't have the heavy white smoke when doing the cleaning as the other 2 did.

[SteveTheTech]

I have set the smoke alarm off at one dealer with the BG