Hi Everyone,

New here! I have an 03 G35 Coupe / 5 AT / 120,*** miles

My problems first started shortly after replacing my t-stat & radiator (had a leak in the rad)

After doing the above work with a couple buddy's I went to start up the car, and she died immediately (left MAF unplugged) Plugged it back in and was good to go with the exception of a CEL.(as expected)

Went to O'Reily's and got the codes ran just to see what they'd be.. At this time I had NO performance or MPG problems.. Got home & cleared the light successfully using the pedal reset procedure. Codes below (listing these codes because a couple stayed with me as youll see later)

C1130
P0550
P0102
P0327
P0113

After the pedal reset I was good as far as full performance, but never checked again for codes, as everything was operating properly.. Then..

I left to work one morning.. started fine, and drives fine until you give it gas.. I tried passing a rusted Civic EX driven by a smiley douchie looking 16 y/o.. I was in 3rd gear (sport mode) & I had absolutely NO pull.. Feels like half of the usual performance... (i know these arent the best on low end torque but this was HORRIBLE). was as if I was in 4th or 5th gear.. I then downshifted to second, where i experience a lag in which I normally do not encounter.. Upon downshifting, power still feels decreased by at least 10-15%... Didn't pass him. I looked.... Retarded. Fast looking, fast sounding, but couldn't pass this asshat. Keep in mind I have NO CEL..

The car has NO low end torque. If I floor it at a dead stop, tire spin is out of the question Any rpms under 4.5k are extremely slow and lacking of power for any gear. Once i hit 4.5+ its as if im in a sh*tty honda again, and Vtec kicks in

Idle seems unsteady. sometimes stays at 650, sometimes it steadily flucuates betwen 450 - 550 rpm

Anyways... Decided i should go get the car run for a ghost code... Sure as Sh*t..

P0327
P0550

So.. I wrongly assumed the PSP sensor couldn't throw me in limp mode, and decided to attack the most logical thing causing the immediate issue. P0327 -- knock sensor short or open circuit..

From my research; 8/10 people who have gotten this code ended up having a faulty harness vs the sensor itself being bad.. So.. I ordered one from Z1 & put it in myself.. Upon inspecting I see the old knock sensor looked fine.. Was confident it was the harness then..

I start it back up after getting it back together (easy job BTW) & bogging/bad MPG was still present.. Still no CEL..

Went to Autozone, and ended up with..

P0550 -- this f*ckin guy...
P0328 -- Knock sensor high input

So... I did what I thought seemed the most probable culprit next.. Knock sensor... $40 one from Autozone.

Got it in, and I am STILL have the same issues, and the same code! & i STILL DONT HAVE A CEL ! From my research I am the only person where one or the other DIDNT fix the bogging down/clear the code(s)...

My current thoughts are... OEM sensor (praying to GOD)

Should I start looking into the P0550? (PSP sensor) or get an OEM sensor in first? I don't see anyone else with this exact combo of codes.

From my research, I have seen others use cheap $15 sensors off ebay without immediate issue.. Only negative i have seen using aftermarket is they would die prematurely or almost immediately after driving BUT it still fixed their problem PRIOR to failing... I have even seen other threads where people used the same AEM Autozone sensor i got, without it dying prematurely at all..

At a complete loss of ideas outside of having a DOA sensor, or a truly bad PSP sensor.

I cant help but lean towards the PSP sensor as I overheated several times before I replaced my radiator & t stat. (never hit H) (coolant was barfing out of radiator and possibly leaking onto PSP sensor & pretty much all over the bay on 2 occassions)

I have also checked the throttle body for build up(was surprisingly clean)

I have performed ECU rests everytime i went back in for the sensor..

Oil is fine, replaced injector o rings, cleaned MAF sensor & wire connector with CRC.

Cleaned air filter, re oiled (K&N)

Mods include:
Transgo Shift kit upgrade
HKS Hi-Power cat back
Z tube intake (from Z tube)

What could this be?!?!?!

ANY help or recommendations will be highly appreciated.. I love this car more than my pregnant GF. (JK) (or am I) I plan on keeping it (talking about the G) (bad joke I know i know haha) and eventually with time and money building it into a beast!!! I have spent ALOT of time & money with this car so far, and it kills me knowing shes sick!!!



Thanks!!

 

PSP sensor directly affects engine rpm, if the potentiometer crapped and shorted out then yes it absolutely would kill your fuel economy and limp mode the car.

 

Thanks for your response man!

That's exactly what I''ve read, and heard directly from Northshore Infiniti today..

What would explain the P0327(replaced sub harness with Z1) && then the odd P0328 coming on after, and in place of the previous KS code, and then remaining on after replacing both?

Can the timing retardation trigger the knock codes?

 

Someone.. Anyone??

 

Bumpitity bump bump. Can someone maybe.. I don't know... say anything?

 

Read this chapter in the FSM

http://www.nicoclub.com/service-manu.../Coupe/2003/ec

Better take good care of your GF.

After she has your first child you're going to have to get rid of the coupe anyway.

Telcoman

 

Read what chapter?? There's like 20 different chapters.

& wow quite the helpful response. Any advice on fatherhood since you seemingly can't provide a realistic solution or solid advice without throwing the FSM at me

Perhaps you can tell me more about how using regular unleaded fuel is perfectly fine for Infiniti's

& BTW, the coupe isn't going anywhere. Will be getting another vehicle shortly here. Trying to get this fixed. Thought some people here would help me but apparently not.

 

I wish I could help, but this seems pretty deep. Could the lack of power directly deal with your past overheating? Check if you are getting similar compression across all cylinders. Maybe you are losing some power through the loose rings or the block warped and you are losing power through another source.

 

Thanks for the response, Urban. Can't say that hasn't run through my mind. That sounds like a wrecked engine to me, and I'm praying that's not what it is..

Temp only shot up on a few occasions.. Like i said; never went past the last line before H, and when it did raise up I pulled over immediately, cooled off, added fluid and babied it home.

Very frustrating considering everyone else with these codes (with the exception of P0550) got theirs fixed by doing what I've done.. Only thing i can think of is that i used the aftermarket KS vs. OEM..

The radiator that sprung a leak was in VERY bad shape. I dont believe it was caused from increased compression from failing internals/exhaust gasses entering the system.. The leak was in a very common spot for our cars. Also, the car drove fine after replacing it for about 3 weeks before i got loss of performance.. Both of those codes supposedly limp mode a G..

oil has been fine, with the exception of a little burning between changes & the coolant looks spectacular (Asian Blue throughout) no drips or leaks..

Should i throw the PSP sensor in it?