Had the engine die on my tonight after some "spirited" driving.

I suspected plugged cats a while back because I was getting a foul smell, poor gas mileage, and it would die pretty much every time I would get on the throttle hard and clutch in, or if I came off of cruise control and clutched in. I then replaced the factory cats with Berks HFC, and new rear O2 sensors. Mileage has been a little better, but I still have a slight foul smell, and it has died twice on me in the past couple months since the swap.

Tonight I was out on some back roads, not running the car hard by any means, but I left it in 4th and/or 5th depending on the road and running around 70mph for a little bit of pull out of corners. Got onto a main highway and drove nice at 65ish mph in 6th for about 5miles, clutched in to turn onto another road and the engine died once the R's dropped.

I have a Stillen SRI, and I cleaned/re-oiled the filter about 2500 miles ago. Replaced the plugs about 7-10k miles ago. Fresh oil a couple weeks ago. Nissan did a diag check and re-learn last Nov.

What things should I be looking into?

 

Check your MAF sensor and TB to see if they're dirty.
It might be in your interest to clean those..

I would start there.

 

Today it died after about 10min of constant 70mph in 6th, just driving.

Gonna check the above mentioned tomorrow.

 

Bump

Common guys, I know its not the typical intake and exhaust question that everyone hates but loves to answer. Someone here has to have some more ideas or had a similar issue...

 

Did you try what xdEnbOyx mentioned? Did the problem happen again?

 

I cleaned the MAF, and it almost did it again. But I may not have got it very clean because I was worried about damaging it so I really didnt use much cleaner. cleaning it again today hoping that maybe it was still dirty...

 

What are you cleaning it with?

 

Non-chlorinated brake cleaner. I did a lot of reading and a lot of places said its safe to use the non-chlor but dont spray it in there real hard, so I tried to just drip it in and thats why I think it was still dirty. But the wires didnt look real dirty to begin with.

I tried to find the CRC MAF cleaner but no one has it in town.

 

I used Isopropil Alcohol in my MAF for my 1.8T when I had it. I would assume it can be used with the G35 as well, but correct me if I am wrong.

 

Remember to check your TB too... Cleaning the MAF sensor twice isnt going to solve your problem if your TB is covered with carbon that's preventing air from getting in, hence stalling the engine at lower RPMs.

Is your car idling rough? Does it feel sluggish?

Your not going to damage your MAF sensor by spraying it with cleaner... Just make sure you dont drop it and that it's dry before plugging it in.

 

Nah it seems to run fine. Only time I noticed a hiccup in pull was right before I swapped the cats. but its hard to determine how a car runs here cuz it was flippin cold as bawlz until recently.

Just cleaned the MAF again, let it sit to dry for a while, and went for a drive. Maybe seemed a little smoother and stronger pull, but still died when clutched in. It also idled up for a sec at a stoplight before dropping down to normal idle speed.

When you talk about cleaning the TB, I'm assuming you dont mean with that TB spray cleaner, but actually taking it off and cleaning it?

 

^ Both, actually. Take the TB off and use TB cleaner. Make sure to use TB cleaner. Strong solvents can easily damage them. After you clean it you'll have to do the idle relearn.

 

I'm having issues with the re-learn. I've followed the steps I found here, https://g35driver.com/forums/5661867-post2.html and the CEL light blinks and then goes steady, and it idles fine at start-up, but once you start driving it idles high. And its also like it doesnt close the TB right away as you release the pedal. When you release the gas it holds the rpms for about a second like you are still on the gas, then you can feel the TB close and like you let off the pedal. I've got the battery disconnected again and going to try the re-learn again, but I've done it 3 times now. Is there something I am missing?

 

alright I've done this damn re-learn over and over and over, and no dice. It will re-learn the idle at first, but you get 3 blocks down the road and its up to 1500rpm idle.

 

Clean your TB. Clean your MAF.

Drive your car to make sure it's warm. Reset the ECU. Reset throttle body position. Set your idle.

Get some fuel injector cleaner as it should help clear crap out of your fuel system.