Modertor. I put this in the wrong thread, could it be moved to the G35 Coupe V35 2003 - 07

I have been more of a lurker than anything but I came across a problem a couple times in the last week.First of all in the last month I have installed a Hi-Power racing true dual exhaust with berk hi-flow pipes, a shorty intake and a throttle body spacer I saw that was talked about a lot on various forums about ten years ago. I figured it wouldn't hurt to to try it out.I also replace the spark plugs last week.

One day last week when I started my car up it was idling fine. When I started going down the road(without letting it warm up) it started running like it was missing. I had a bad smell coming from the exhaust(full throttle burt cat smell). The check engine light was also blinking erratically. I pulled over and checked and made sure no electrical plugs around the spark plugs was loose or unplugged. They were not. The car went back to idling fine, no flashing check engine light and drove fine and pulled as normal. The car was also warmed up by now. No problems until today.

The same thing happened today as well. Started it up, it idled fine, 30 secs later it was running like before. But now I have a constant check engine light, it blinked a lot like before but now constant. I am going to pull the intake pipe off tomorrow and make sure again I did not overlook something from last week. Then will slide down to the parts store and have them pull the codes to see what it threw before I pull the plug packs and plugs and reseat them. That is the only thing that has been touched in this time period. After the car warmed up(or shortly after it was running fine again).

I would like to note that the two days that this happened was a decent change in the air temp outside and I am wondering if that has something to do with it. The first time was over a 40 degree change. I would like to get some opinions and will follow up tomorrow with what codes were thrown. I have worked on my own cars for a long time but I am not a mechanic by no means especially when it comes to the ecu part of it.

When we replaced the exhaust I did pay attention to the o2 sensors and they looked fine for their age. But they are stock so I will replace those in the next week or two as my car has 130k miles on it. I need to replace the wheel bearings and lower ball joints before I get to them. I have never reset the ecu since the exhaust upgrade but I have pulled the battery cables a few times for an hour or so. Does this reset this ecu or do I need to use the manufactures method.

Thanks for any replies.

 

Today when I started up the car, no cel. The people at advance would not check the codes to see if there was still one lingering since the cel was not on. I checked all the hoses, plugs and packs and saw nothing out of the ordinary. I put about 100 miles on the car today. Drive it normal and also really hard. No blinking CEL no hesitation, knocks or odd sounds. So I am really not sure what to think. Only thing I did not check was the pcv valve. I really doubt that is the problem but can never tell.

 

i would think it has more to do with the spark plugs. i would pull them all and check them. make sure all the coil packs look good. and everything is is plugged in tight.

 

They looked good when I pulled them. The coil packs well they look good but nothing much to look at, I checked the tips and they were not dirty. I am surprised the car even ran as the center electrodes were almost gone on all the plugs(image below). The plugs are NGK R's that was in the car and I replaced them with Autolite Iridium XP's. One thing I noticed is the new plugs do not have resistors in them and I wondered if this can truly cause interference.

I have done a lot of research and quite a few options have came up anywhere from a clogged fuel filter/bad fuel pump, dirty maf to a vacuum leak on the intake manifold caused from hardened gaskets. I am thinking this happening is just a coincidence timed with me replacing the plugs. I will clean the maf tomorrow and check/replace the fuel filter then will be getting a plenum spacer from Motordyne in the next few weeks so if there is an issue with the gaskets that will be fixed.

 

Not the pvc valve, crossing that off the list. Also happened again yesterday afternoon(monday). First time the car was ran since day before 12hrs give or take. It did throw a cel and stayed lit the next day. But of course soon as I pull into the parking lot of the parts store it turned off. Go figure.

 

still check the code. i might have a stored code but not active.

 

I was finally able to do that today. Borrowed one from my sisters boyfriend. Cylinder 4 was misfiring(2x one from other day and today) which is what the car sounded like. I pulled the plugs again and that cylinders plug smelled like gas(which I have to admit I did not do when I pulled them the last time). So I am thinking either the coil pack is going or a leaking injector. I am leaning towards the injector as I think about the times it has done this the car set for an extended period of time (10+ hours) and seeing it runs fine after a period of time. But in any case I am going to replace them both all around and maybe even get bigger injectors for later mods down the road.

 

switch the plug to another cylinder to be sure it is the plug or the injector. if the misfire changes cylinders you know its the plug. you could prob also switch the injector to another cylinder also. no use in throwing money at a problem when you are not sure what the cause is.

 

That is a good idea and will do that. I will switch them out tonight so the somewhat same circumstances happen for starting tomorrow.

 

Here is a photo of my plugs from my previous 06 G35 6 speed sedan when changed at 106.7k miles



Telcoman

 

Look a lot better than mine, I have 125k miles now so I am figuring they were never replaced.

 

rdozier.. when i got my 03 6mt coupe it was bolt on modded thru the roof.. but the spark plugs looked worse than yours when i pulled them out at 113k as soon as I bought it to diagnose similar problems to what you are having. who does that.. mods a car to the point of even installing headers.. and never even checks the plugs..

why did you replace the stock cats? were they plugged/clogged? if you have a leaking injector(s) figure it out now before it destroys your new HFCs.

i had my injectors rebuilt because they were leaking badly, even causing the car to stall at a stop.

solved all my problems

 

Man that sucks lol. Luckily nothing has been done to the car when I got it, is a one owner and purely stock down to the factory radio that I replaced. One thing that nags at the back of my head is this all started after I installed the new plugs. It could be just random chance. Later today I should find out if it is a injector or not. I switched packs and plugs on the problem cylinder and will see if the problem moves or not.

Well originally I was not going to replace the cats and just go with the catback system. Doing some research and youtube browsing of different types of exhaust sounds for the car, I came across down pipes and cats. From what I read for the most part they had good reviews and gave pretty decent gains so I decided why not.

I have a set of headers that came with the exhaust, but after reading a lot on them I may not install them. Mainly being such of a pain in the butt to install and the minimal gains over stock. I will keep them for now, I still may install them down the road.

What I do have planned after I get this current problem resolved is get a junkyard upper and lower with the tb and port match and polish the interior of those along with a spacer, the thermal one looks promising. I was thinking of getting aftermarket intake, but tbh for me the price is just not there for those advertised gains.

Eventually I will work on the internals and heads but that is a bit further down the road and work on the re-inforcing the rear end along with a tower brace, this one does not have it. I plan on keeping this car for the long haul.

I am just not sure when or if I should get it tuned. I know with the mod's I am doing now, I would get better gains from them with a tune, but being N/A is it really worth it. I have read a lot of conflicting threads about it on various forums.

 

So last night I switched #4(problem cylinder) plugs and packs with #2. Made a brilliant error of not plugging in one of the packs... I reset the ecu this morning and was out most of the day, at least of 50 miles of highway and city driving. No problems, no loss of power, no smell, no cel. I pulled the codes tha were stored but they were from the unplugged cylinder from last night. I am sending a message to one of the techs at the nearest infinity service center and hopefully they may have encountered this before. I think the main problem in trying to diagnose this, is it does not always happen which is just weird.

 

So this morning, had the same problem. Cutting the car off and then restarting again stopped the problem this time before the car warmed up. I found that odd. The CEL was flashing like it had somewhere to go. So I took it to the parts store and they pulled nothing, not even pending. There was one code, but that is from the steering. When we replaced the exhaust the person that helped me disconnected steering rod, even though I told him it was not necessary. It was not lined back up when it was reconnected. I will get that fixed when I do the ball joint. The slip icon is driving me up the wall.

I pulled both plugs I swapped and they are below. First is plug from #4(problem cylinder) that was put in #2). No gas smell at all and it had gas smell . Second plug is #2 that was put in #4. It now has a gas smell. I also had switched the packs and did a reset on the ecu yesterday, so I do not think it is a problem with them, unless it is a ground.

#4 plug that was switched to #2, no longer has a gas smell


#2 plug that was switched to #4 now has a gas smell


Finally decided to stop procrastinating and put in the rest of the cold air intake. My only complaint is the vacuum hose is on the underside of the intake pipe. It is more of a pet peeve than anything