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2018 rs400 rwd went for a swim, help!!!

3K views 18 replies 7 participants last post by  Vr30boy 
#1 ·
So my other half decided to buy a 18 rs400 rwd last month in Miami Florida. Car was a r title due to ds impact on doors and b pillar, cosmetic repairs were done in an acceptable but rushed manner( clear runs). anyway we flew from pittsburgh to Miami to drive the car home on a Friday evening (June 12 iirc) and it drove beautifully until Sunday after noon. We pulled off of wv 19 near oak hill wv for fuel and food. While getting lunch it began to hail so she pulled the car to a near by gas station to avoid damage. 45 minutes later the hail let off and the rain slowed a bit so we pulled out behind A local cop onto the main road, there was 3 or 4 inches of water in the road at that time. We made it 100 yards up the road when a storm surge/ flash flood hit us and water went over the hood and the car immediately stalled. We sat in water up to 18 inches deep for nearly an hour before being pulled out. I went to the local parts store and bought a pump and maf cleaner and went to work I pumped out nearly 5 quarts of water from the intakes and turbos and cleaned the mafs. On the 5th attempt the vehicle started and settled into a normal but steamy idle. I shut it down and checked oil (good at the time, more on this later) and restarted it, no cel strong idle, let it idle for nearly 25 minutes and came to op temp. Revved a few times to 4k or so to clear it out and proceeded down the road to 19. Made it 7 miles up 19 north and lost all throttle response and the car stalled again and would not restart. Checked oil and it was severely milky but no I'll noises from the engine. Towed it 3 hrs home next day, stopped at local nissan dealer and borrowed consult(I'm a 5 year Nissan tech) and pulled 5 pages of codes from the ECU. Took it home and drained oil, aproximately 7 qts came out of it. I changed the oil 2x more times (0w20 mobil 1 and OEM nissan filters) and sent it to my local infinity coughrapistcough dealer for further diag. They hit me 4 days later with my engine is shot and we need 8 hours approval to tear it down and assess. Bullshit( compression was good and oil is now clean, no noises or debris in oil when drained) cam and crank sensor codes present along with a p0643 ecm voltage irregularity and throttle body codes (screenshots will be posted) went and picked up the car and replaced the throttle bodies but still no start. Ordered a used ecm 2 days later and married the key to the new ECM via snap on Zeus. On second start attempt car fired and ran roughly for ten seconds and stalled, 3rd attempt yielded the same result with no throttle response. Attempted to do a throttle body position relearn and the car wouldn't start any longer, called it a day. I'm near ready to throw in the towel but this is my fiancees dream car and I'm not ready to see it totaled yet again. First list of codes was pulled after a hard reset and 3x start attempts earlier this evening. Remaining pics are from a few days ago after repeated start attempts.


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#2 ·
Not sure what "r title" nor "wv" means??
 
#4 ·
I would have expected the water ingestion to hydrolock the motor. That and an insurance claim would have been the perfect scenario in my world. I suspect being a five year Nissan tech that you came here hoping to find other techs to help you rather than a bunch of old, retired blow-hards with nothing better to do since we can't do to McDonalds and sit around drinking coffee because of The COVID. My guess would be a water soaked wiring harness is causing all sorts of scrambled signals to the various computers.
 
#5 ·
Given what happened and the insurmountable number of DTCs that was posted, I'd say the OP is better off taking the insurance money and starting over. Throwing more money at a salvaged vehicle that failed as a submarine is a poor financial choice IMHO. Even if you get it running again, flooded cars will inevitably suffer from corroded components and harness connectors over time. If any of the interior got wet then mold becomes a problem also.

If it were me, I'd take my lumps and start over.
 
#8 ·
Pillboy I appreciate the input and honestly I was hoping for hydrolock and some internal engine damage but so far it looks like she just swallowed some water and dicked up a few sensors. I appreciate the old farts at mcdonald's they have seen some **** and are content sipping shitty coffee and bullshitting. Some days that's all you need.

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#13 ·
Well ladies and gents after 5 exhaustive fun filled (not) weeks the rs400 lives to fight again. Root of the cars issues were all related to p0643 and p2138 5v reference signal voltage from ecm to app(accelerator pedal position sensor) which was subsequently throwing codes down the line for cam and crank position sensors, throttle body/throttle position sensors, boost sensors, waste gate actuator sensors, turbo speed sensors, multi function valve (electric thermostat) sensor and fuel rail pressure sensor were all affected by this voltage inconsistency. Also worth mentioning I took the car to my local nissan dealership and using consult 3 plus I was unable to find any unusual readings in can bus diagnostics(with the exception of front radar sensor being a bag of dicks) but strangely tons of dtc codes were still stored in the ecm. I back probed the ecm and discovered that this 5v reference line between ecm and app was only showing .5 volts and the hunt began from there. I systematically unplugged and cleaned the contacts and sensor bodies/surfaces followed by a application of diaelectric grease of all the above mentioned sensors only to find i still had a voltage issue. Oddly enough I never had a mass airflow code but part of one of the diagnostic procedures out of the fsm stated to unplug the bank 1 maf throttle body and several other sensors and after doing so I noticed my voltage at ecm jumped to the correct 5v signal. I began plugging sensors back in and I noticed when the maf was plugged in the voltage would drop and if the car was running it would stall. So all in all I replaced the throttle pedal assembly for 100.00 throttle bodies for 350.00 oil change 3x at 35.00(OEM nissan filter and mobile 1 synthetic) each, a pair of mafs for 65.00 (all parts were ordered via car-part.com from salvaged low mileage vehicles) a few cans of electrical contact cleaner and a small tube of diaelectric grease. So for a little over 600.00 and about 20 hours of time sweat and beers my girls 18 Q50 is alive and well again . Thanks to all those that helped along the way


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#15 ·
: - O

Wow
 
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#14 ·
A happy ending to a HUGE project. 👍🏻👍🏻

I'm very impressed.
 
#16 ·
You are a better man than I.
 
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#17 ·
Congrats on getting it fixed Brandon!
 
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