Help! Jumpy Idle No Power, Car Goes Into Limp Mode When Hot

[416BRAND]

2005 SE.

Jumpy idle all of a sudden and no acceleration then car goes into limp mode. This happens more so at slow idle like speeds but it also did it to me going 80mph the other day on the highway.

I took the car to the dealership before and they replaced the Negative Ground Cable to the battery. The issue went away for 2 months. Now its back with a vengeance. AS SOON as the car gets to normal operating temperature. Its done. I can't even drive it for 15-20 minutes. I've been to SIX shops. 2 DEALERSHIPS. Nobody knows whats wrong.

What I have replaced with new parts mostly OEM:

- 2 Upstream NTK Oxygen O2 Sensors (Air/Fuel Ratio Sensors)
- Swapped Mass Air Flow from a Murano. No change.
- All new NTK Spark Plugs (coils seemed to have no signs of cracks either)
- Throttle Body (TPS is on it)
- PCV Valve
- Air Filter
- Oil changes always on time. But car burns Mobil 1 5w30 like crazy.
- Negative Ground Cable
- Right Rear Wheel Hub (originally though it could be ABS Speed Sensor there too but nope)
- Power Steering High Pressure hose (aftermarket POS) and OEM Pressure Sensor Switch (now I have that lovely little whine that most people get with the aftermarket hose lol)
- Did 2 idle relearns at the dealership too

I've done all of this to my car in 6 months. I just bought this car last Sept. I'm pretty ****ing pissed off. I've spent more than I paid for the car in repairs and rental cars since I bought it. I miss my 4th gens.

I saw someone mention they re-grounded the MAF. But I haven't tried that myself. But still. this only seems to happen soon as car gets hot.

Alternator ground wire strap or whatever I have asked the mechanic to look at and he says its good.

I have a crack in my exhaust where the downstream right side O2 sits. Giving me a code for that O2. Where that pre cat is. But that surely couldn't be the issue could it? Why would this cause limp mode. Unless that cat was totally clogged as well or something?

PLEASE. No codes are coming up other than the downstream O2 P1273 but I know thats because of the crack in the exhaust right beside it. Everyone says not to buy aftermarket Cats either because then it wont pass emissions. I'm in Toronto, Canada.

Could this be caused by a vaccuum leak maybe by the valve cover or intake gasket idk? Metal expands when hot yes so maybe its making a tiny crack soon as engine is hot causing vaccum leak somewhere? This could happen with old hoses too I'm assuming?

[centralcoaster33]

Someone in a previous post of yours told you about your lights being on for low brake fluid. You posted an update there, but it was not an update. It wasn't even on topic. It was just a cut and paste of this topic. Then you had a heated seat, noisy heater issue, but never bothered to reply to the help you got there. So, people that are following along and want to help you are still wondering if you had low brake fluid, if you topped it off and if your lights went back to normal. We're also wondering what became of your heated seats and heater noise. Since none of your problems are getting fixed and you keep having more issues with things, then maybe you need all new wiring harnesses inside and out.

Also, someone in your previous thread suggested unplugging your MAF as a diagnoses procedure. Did you bother to try that? What were the results? I've had a bad MAF before and it did not throw a code to the ECU. What about that heater noise, did you get it located? What about your heated backside, is that still not working? Another time I had a bad injector and that didn't manage to throw a code to the ECU either. And yet another time I had a terrible leak in the vacuum hoses on my intake and that didn't throw an ECU code. All three times, my car ran like crap, but no codes.

You could fix your cracked exhaust and you should replace your bad o2 sensor or wiring. I've had an O2 sensor go bad and the car ran terrible, but it did have a check engine light and threw a code.

[NutriaforBreakfast]

You are going to have to fix the exhaust/vacuum leak before
you fix anything else probably.