HELP NEEDED!! FROM ACROSS THE POND.



Hello All

Since Infiniti pulled out of the UK and Europe a few years ago, owners are now very much on their own over here so I'm hoping you guys can offer some much needed support...

I bought a 2011 G37x in March of 2021 as a lock down project. The car ran perfectly but the bodywork was in need of some tlc! I removed the front bumper to prep it for paint and basically left the car sat in the garage over last winter. When I came to start it earlier this year the battery had gone flat (no surprise there). After replacing it the car started but ran quite roughly at tick over. It quickly went in to 'limp mode' with the rpm limited to about 1400 max if memory serves and has been like this ever since despite reseting:-

1. Check engine light on along with the ABS/Slip warning light.

2. Throttle bodies have been cleaned in situ and didn't seem particularly dirty to my untrained eye.

3. Fuses all appear to be good (unless there are yet more that I haven't found).

4. I've done the reset procedures detailed in a couple of YouTube videos for Accelerator pedal position, idle air and throttle closed position - the check engine light comes on pretty much straight after.

5. DTC's reading as follows:-

P0123 - Powertrain. Throttle/Pedal Position Sensor/Switch 'A' - Circuit High Input.

P0223 - Powertrain. Throttle/Pedal Position Sensor/Switch 'B' - Circuit High Input.

P1233 - Powertrain. Multiple Descriptions!

P2101 - Throttle Actuator Control Motor Circuit Range/Performance.

Not sure how to proceed from here gentlemen.... Your thoughts would be greatly appreciated.

Cheers
Simon

 

First, Simon, welcome to the forum. Was this car stored in a garage while it was out of service or was it parked outside in the elements?

If you have not already, I would suggest you download the factory shop manual for your car from here. The NICOClub website is painfully slow but it does work. For this issue you will want sections EC (Engine Control) and PG (Power & Ground) though I would take the time and download the whole manual while you can (these links have a history of going blank). Please keep in mind that while these manuals are for USDM models, there may be some slight differences compared to your RHD EUC model version. But you'll get the gist of what needs to be checked.

Section EC will explain the diagnostic procedures for each of your codes. Section PG should show all ground (earth) connections. Assuming you have and can use a digital multimeter, you should be able to test for proper ground and voltage signals at each connector. From what I gather from those codes, I would lean more toward a bad ground connection at this point and/or a potential fuse issue as those are the only two items they have in common.

Keep in mind there are three (3) different fuse panels. Next to the battery in the fender well (IPDM/er), driver footwell, and at the positive battery terminal. Anything could have shorted out as the car sat dormant. These cars get VERY cranky when voltage gets low...

I would check all of the fuses- particularly the ones in the battery box/ fender well. Double check that your connections to the throttle bodies are tight and not damaged. Check for anything along the wiring loom that could have been pinched or improperly reconnected. Redo the "relearning" steps (the timing is very critical). And, if the car had been/ is stored outside, ensure that there is no water leaking into the cabin (though this issue seems to plague LHD cars moreso than RHD models). Never hurts to check.

This should get you started for the time being.

 

good points to mention

 

Those seem to be codes generated from the throttle relay, usually when it doesn't receive power or it registers a problem in the throttles.
If you can delete codes, start with deletion and retrying to see what you get.

 

Besides all the above check your brake fluid level also and battery health condition. Sitting in the cold environment for a while could possibly degrade the plates inside.
And clean your MAF sensors you can pick up cleaner for them at any auto store for a few bucks.

 

The car was kept in a large unheated shed over the last winter. I did however go up to Scotland where the winters are colder, to buy it and have noticed a higher the normal amount of corrosion in various places. Its likely the car may have sat outside over previous winters and the cumulative corrosion may now be causing a connection issue. I have unplugged the throttle body connectors and couldn't see any problem.

Thank you for this I will get on and download the manual over the next couple of days. I have a cheap multi-meter so will have a go at diagnosing and let you know the results.

 

Thank you to everyone who has taken the time to comment I very much appreciate your advice and will report back once I get chance to go through your suggestions. Its the school summer break here in the UK so am juggling work and children but will get on to this ASAP.

Thanks again.

Simon

 

Hello again guys
Its been a while but finally got to the bottom of the issue. I always find it slightly irritating when someone starts a thread but never comes back to report the 'cure' so here it is...
I was chatting with one of my customers back in October who runs a newer Infiniti Coupe. He knew of a fairly local guy who is an Infiniti trained mechanic/technician and had set up up his own workshop Danny at Infiniti Specialists Ltd in Wakefield, UK. I called him and arranged to have the car trailered over. He very quickly determined that when the ignition was turned on the left bank throttle body wasn't opening fully when compared to the other side. I was slightly embarrassed to see such an easy check revealed the cause of the problem! When the ignition is turned on both throttle bodies should open fully before closing to the idle position. He tried doing a throttle position re-learn but this had no effect.
Nissan in the UK wanted circa 800GBP for one of these so second hand was the only economically viable option. There are so few G37's on the road over here that finding a used throttle body wasn't particularly easy but I managed to find a breakers with a 370z in stock and got hold of the throttle body for a mere 100GBP! Fitting this and performing a reset via Infiniti's proprietry diagnostic software now has the car running perfectly again with no warning lights being displayed!
If any of your members are anywhere near Wakefield in the UK I would strongly recommend they visit Danny at Infiniti Specialists. He knows his stuff and his prices are more than reasonable.
As for my 'lock-down' project, it's getting a full service next week followed by some paintwork to the front bumper and rear quarter and a couple of tyres. Once done the car should be in tip-top order and ready to be enjoyed.
The car will be for sale later this year as another project beckons but in the meantime thanks again for the amazing welcome and great advice.
Happy New Year!