mainly looking for some advice or your 2 cents from people who know the G35 well


just picked up this 2005 AT coupe clean title for $3500
drives super smooth its a bad *** car
183k miles, its got AEM cold air intake (the long tube), High flow cats (thats what the guy said)(its loud but sounds pretty damn nice)
and some kind of upgraded aluminum radiator.




its got a few problems so im trying to figure them out

1. it gets an occasional misfire (blinking ses light) under heavy load but doesnt go into limp mode at all
2. most of the time starts right up, sometimes it will just crank and crank for 20 seconds or so
3. tiptronik works sometimes and sometimes wont (will say its in drive, so its not activating)(also when it does work sometimes it will automatically downshift)
4.almost overheated once while idling and doesnt look like its leaking coolant but u can smell coolant under the hood sometimes, 99% of the time it runs a little cold which is good
5. my cheap code scanner works on my f150 truck but acts wierd on this car, sometimes it will read 96 codes, sometimes 20, sometimes no codes, sometimes the scanner will freeze. also moniters are all pretty much n/a except for misfire and fuel which will say not ready sometimes and ready sometimes
6. gas gauge is wierd. seems to work sometimes, in the morning it will show 1/4 tank less than whats in there but by the time i get to work it will be back up to where it should be. after 1/2 tank on the gauge it goes down real fast (probably 30 miles before its completely empty)


-i did all the computer learning reset procedures i think its 4 procedures in a certain order
-i changed the spark plugs even tho they looked brand new.
-checked all the spark plugs and coils for oil, all clean, in fact no oil anywhere on the engine its pretty clean
-throttle body is very clean, i would probably eat off it

im just looking for advice since im new to this car. ive rebuilt my f150 engine and my R6 engine succesfully and countless hours of other work on those two vehicles so i know some things

1. im thinking maybe fuel injectors or fuel pump for the misfire, possibly coils and possibly rings, still need to do compression/leakdown tests as well
2. i think the starting issue is related to the misfire thing maybe possibly, thinking fuel pump....
3. tiptronik issue possibly TCM??? based on the little research ive done
4. overheat/coolant issue im thinking i need to burp the system?? im stilll trying to find some good info on doing this procedure.
5. code scanner issue im thinking i just need a different code scanner? any recomendations?or possibly an ECU problem? ive already reset the ECU properly
6. gas gauge is not a big problem, obviously has to do with the 2 floats im just wondering if this is common or if theres some easy fix out there

hope i didnt **** anyone off for this post
any and all advice/help is much appreciated. thanks in advance

 

Welcome.
Sounds like you've got a handful of problems there, some that may be related.

I'd make sure I had a working obd2 code reader before troubleshooting much further.

You didn't mention if the SES / CEL dash light is on ?

 

yeah the check engine light is on. Deff. gonna get a different scanner. i also have an cheap elm327 bluetooth scanner but my phone will pair but wont connect so im gonna try a diff. phone or tablet. im gonna guess that something is up with the fuel pressure in the gas tank or lines possibly a gas cap but it looks ok. the injectors on the engine dont look new so im guessing they could probably be replaced, and im sure i will notice a difference after swapping those out but well see. at this point its just a matter of waiting for each friday to get those paychecks

 

Have spark plugs been changed at all or anytime recently? Might be time to change them if not and use the recommended OEM plug type and gap. Also check for oil leakage around the plugs which could be indicative of a valve cover leak that could be getting into the tube on the coil pack and preventing proper electrical conduction to the plug and a misfire. It's best to be able to pull a code to find out more specifics on the misfire once you figure out a way to get your OBD reader working. It probably wouldn't hurt to clean your MAF sensor too with MAF sensor cleaner, although I highly doubt it's the problem but is certainly worth eliminating from the equation.

Could be crank angle sensors.... again, pulling codes will tell you more. Don't want to throw money at random parts in hope of catching an inconclusive lucky fix.

Dunno... I don't have any real experience with auto transmissions in this car.

You may have air pockets in your cooling system if a flush or coolant change was done recently and the proper purging process wasn't followed. These engines can be a bit finicky about the air purge process in comparison to other vehicles. It's also common for the electric cooling fans to fail on these cars. They aren't too expensive or difficult to replace and it's easy to test if they are dead. It's almost a sure thing that this is the cause of your overheating since it only happens when stopped.

You may have to get a better code reader. Cheap ELM327 bluetooth clones don't always work on this car if that's what you're using. You might want to try manually setting the protocol if you're using one of these rather than letting it auto-detect, since it might be detecting and using the wrong protocol. Your year G35 uses ISO 9141. I've used a Scangauge-II and an OBD-Link MX and both work fine for pulling or clearing codes on Nissan and Infiniti vehicles.

Pretty easy fix if you pull the rear seat, pop off the fuel pump assembly and clean out the sensors on the fuel sending units with Q-tips and reinstall.

 

thanks for the reply partyman. ill buy one of those obd2 scanners you recommended. and the gas gauge fix sounds pretty easy. ive already changed the spark plugs and theres no oil on the coils or in the tubes but i havent had the starting problem or the overheating problem at all this past week or even the misfire but ive been easy on the pedal. also ive put 87 gas to fill it up and after some research learned that thats no bueno, so 91 gas from here on out. wonder if thats related to any of those issues at all....