Intermittent loss of power, clears immediately after restart
 

This has happened twice now on my Q40: just driving along and the car is running smooth but at some point I try and accelerate and it just crawls like a 3 cylinder yugo. Flooring it the car will downshift and RPM's will verrrrrrry slowly raise to 5-6k range and engine still runs smooth but just has no power whatsoever. No check engine light at all.

Both times I turned car off and as soon as I restarted it was 100% back to normal (this morning just turned it off and immediately back on). Limp mode wouldn't let it rev that high would it? Or it would set a CEL? Since when did rebooting your car fix issues like a windows PC lol

I don't have a scanner to see if it has pending codes but it's only done it twice now in about 6 months so maybe it just never repeats enough to trip an active check engine light..

Curious if anyone ever heard of an issue like this?

Just went through this on a '14 Q60 / Rebadged G37.

I read through multiple threads (G37 and 370Z) that all noted the problem, with the newest threads from around '08 (IIRC), and each ended with a trip to the dealer and silence.

My symptoms were sporadic fits of no power and slow revving that were the same as you mentioned. I will say that this low power symptom is borderline dangerous when it happens as the car does not accelerate, especially at highway speeds. Sometimes it would be this way right after a cold start, (have fun with today's commute...). Sometimes it would go into low power mode while just driving along.

It would go back to normal acceleration if i shut off the car for bit and restarted or did an ECU reset. Regardless, the symptoms always returned during the current drive or on the next drive. I only got the CEL for a MAF issue one time, more on that later. It seems as if the symptoms are some form of a sadistic limp mode.

i used the Torque Pro app while the symptoms were active and noted that the left bank fuel trims were off the scale in the negatives thus adjusting for extremely rich exhaust stream and the timing advance wouldn't move much past 0.

The one time the CEL stayed on, i pulled the code and it indicated a failed left MAF sensor. Instead of changing it, i first tried cleaning it with MAF sensor cleaner and believe it or not, everything worked afterwards. That was a about two weeks / 200 miles ago and all is still well. Not sure what it was all about, but it seems ok now.

I would suggest taking it in to the dealer if it is still under warranty, otherwise, try cleaning the MAF sensors. I used CRC MAF Sensor Cleaner.

Best Regards.

Thanks, ordered a Bluetooth obd scanner to see if there's anything weird going on. It's only happened twice in six months so guessing there's not much the dealer could do unless there's something weird in scan results.

Finally happened again, caught the pending codes with a scan tool. It's both P0101 and P010B - basicly getting weird MAF readings on both MAF's. Just like before immediately clears up after restart the car. Funny there is a repeatable pattern to when it occurs. For sure 2/3 times and I think 3/3 I leave house in morning and drive to local 7-11 for gas, fill up, then moved car to park and grab a soda inside and then come back out and drive away and feel immediate loss of power / lack of acceleration. Shut of car, restart and it's back to normal.

All I can think of is that maybe the short trips starting and stopping interrupts some sort of MAF monitor / calibration operation and leaves the PCM in weird state thinking the voltages are off? Doubt it's dirty sensor as the car runs perfect except for every 3 or 4 months this trips and then goes away just from a restart.

Google shows a TSB for this issue back on 2009 cars, fix was ECM reprogram. Maybe it's just a random software glitch...

OBD scan after restart shows both MAF signals more or less right on top of each other

https://cimg3.ibsrv.net/gimg/www.myg...4bf3016bad.jpg
https://cimg1.ibsrv.net/gimg/www.myg...e0a962af0f.jpg
https://cimg2.ibsrv.net/gimg/www.myg...cdef4e3df8.jpg

Thanks for the info.
this has happened to me on my 07 nismo 350z dual tb and my 13 IPL. Both have aftermarket cold air intakes. Really short commutes. Morning / colder starts. No codes. Just limp mode that clears after a restart. Dangerous indeed.

Intermittent loss of power, clears immediately after restart - 2013 G37X
 

Equipped with Stillen 402847 Ultra Long Tube Dual Intake Kit 09 for 2 years , but only recently (last 3 months) throwing both P0101 and P010B (non-pending) codes with no CEL. Car performance and fuel mileage are excellent after restart - but car will fail New York inspection, according to Blue Driver "Smog Check" function. Have checked for intake leaks, and switched MAF sensors. Will try cleaning MAF sensors with CRC MAF Sensor Cleaner., coating MAF sensor seals with Permatex, and cleaning the MAF sensor ground connections with DeOxit. Looking for other suggestions to solve problem before end of May when inspection is due.

Update to my 04-06-2021 post. Cleaning the MAF sensors with CRC MAF Sensor Cleaner PLUS lightly coating flexible rectangular MAF sensor seals with Non-Hardening, Non Silicone Permatex sealing compund has permanently solved this problem over the last 5 months. The minimal cost and labor involved here, makes this solution absolutely worth trying. I had spent hours before this - doing repeated OBD scans and replacing both MAF sensors to no avail. I believe that even slight air leaks through the MAF sensor seals are at the root of this problem - especially with the aftermarket dual intake kit installed.

thx for the info
Which permatex is it - tried looking that up but couldn’t find that exact one
could u post a pic of u have time
Mahalo 🤙

Some more details on the Permatex sealer that I used and recommend.This is the original Permatex #2 Form-a Gasket Sealant, slow drying and non-hardening. The 1.5 oz tube is Part #80015 and is widely available in automotive and hardware stores. This is a non-silicone product, which, unlike silicone sealants, is safe to use in proximity to, or before O2 sensors. Be sure to use very sparingly to avoid a mess! Here is the link to the Amazon page for this product:

Appreciate the info brother - cleaned the mafs today & did the ecu reset & drove it hard for 20 minutes
car was alive again with mega power lol

Ordered! thanks, man i hope this works. Family borrowed my coupe a few weeks ago and it went in MAF limp mode. Not a good thing.

The thread that never ends..... i know its old, but i feel compelled to provide an update on how I fixed this MAF gremlin.

The limp mode continued to happen and happened again, again, again and the fix was always the same. Clean the MAF, swap the MAF, rinse – repeat. So since I did begin to notice it was always the same side -Bank 1 (passenger) - I bought jumper cables that let me connect the right wiring to the left MAF and the opposite is true.

Drove, limp mode showed up, codes said Bank 1 (pax side). Note that this is now years later ater having grown accustomed to limp mode (muscle memory?).

Regardless, I had an epiphany! so I chopped one of the jumper harnesses in half and then chopped off a section of the Bank 1 MAF connector wiring (cut back several inches into the car harness) and spliced in the newly created pigtail.

This new connector and section of wiring fixed the issue and it continues to stay fixed over the past several years and several 10’s of thousands of miles.

Not to be happy with having it fixed, I decided to re-fix it. So I ordered two pigtails from a reputable eBay huckster and then replaced both sides using proper heat shrink splices, staggered, wrapped etc. Looks and works good! I claim victory!