Code P0106 Not Boosted

kaliwraith

Vehicle mods (No Tune):
1. Z1 CAI
2. Beluga Racing Exhaust (will replace soon, came with the car, is pretty banged up).

Last night I started my car and got the SES light. I ran a short errand and the car felt OK. I didn't hit it hard though, because of the code.

When I got back I use my Autel reader to get the code P0106. I cleared the code. I drove to work and back today and it hasn't returned.

After reading threads, specifically this one, I took a few measurements with my reader.

Baro: 14.4 PSI
MAP KOEO: 13.6 PSI (???)
MAP idle: ~5 PSI
IDLE RPM: 650

My next steps are to:

1. Check the input voltage and ground impedance for the wiring to the sensor
2. Check the sensor impedance (unlikely to find anything useful as the sensor is still working).
3. If i can get a probe in there, check the sensor output voltage with KOEO (key on engine off).

Anyone seen this type of issue where the MAP sensor is not quite showing atmosphere with KOEO? Most threads seem to suggest electrical problems (intermittent shorts, open circuits), although no one has provided PSI measurements to compare. How can I determine if it's my sensor kicking the bucket?

Thanks for the help.

SouthArk370Z

You should see a pressure rise when the throttle plate is opened (less vacuum). If you don't see the drop then I would check, in order: MAP port for plugging, sensor, wiring.

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kaliwraith

Yeah, the pressure rises when I hit the gas. I didn't rev it to red line but it easily went up to over 12 PSI when revving. Is there a specific RPM/vacuum test I should do?

Jhill

I’ll check my data tomorrow but I thought the z used the map for baro on start up. With different readings I guess I would have to assume it has a a separate baro sensor, maybe built into the pcm like Honda but no so common on MAF cars. Maybe try disconnecting the map koeo to confirm they don’t share the sensor.

If it does have a separate sensor then do the basics at the sensor, 5v ref, v drop on the ground, voltage output on the sig wire and if your scanner has the ability compare the sig out voltage with the sig voltage in pcm data to confirm there is no v drop accross sig wire/terminals. But yes koeo map and baro should be the same (as far as any other line I’ve ever seen).

MotorvateDIY

This may help:
Nissan has a TSB that covers this: http://www.370zcoupe.com/TSB/1TS2.PDF

kaliwraith

Thanks guys, I'll check out the sensor basics as Jhill suggested.

Looks like if I can't diagnose the problem I'll have to show up at a Nissan dealership with that TSB? Seems like Consult 3 Plus is not a cheap diy tool lol

Thesmoke90

How clean are your throttle bodies?

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kaliwraith

Not sure. I've had the vehicle for 1 year (almost exactly). I installed the intake but I didn't clean the throttle bodies.

For an update:

1. I checked the ground impedance and it seems like it's a very good connection.
2. I unplugged the sensor and found that BARO still gave me a 14.4 reading.
3. Not sure how to check the sensor output voltage as the pins are well encapsulated when the sensor is connected to power.

Since the sensor is just reading less pressure than it should but I haven't seen the CEL come back after a couple of weeks, I might just replace the sensor (they're $70 at z1) and see if it gives me the right reading. I'll update you when I'm able.

Thesmoke90

My car threw a P0106 when my throttle bodies were dirty (40k Miles)

The actual code might suggest there is an issue with the manifold, but really it can be caused by the throttle bodies prematurely shutting at stops due to gunk and buildup. This creates an 'unexpected' amount of air coming into the manifold, and that can cause this code.

Take a look at the backside of your throttle bodies. Cleaning them is pretty easy, there are a lot of videos on it. Biggest trick to it: disconnect your battery before you start, and do not remove any wires or couplings to the TB from the car. You only need to remove the 4 alan screws on each side to get a good look at them.

The code went away after a while, but after cleaning the TBs, the car idles much nicer now.

Could be unrelated, just hope this helps in some way.

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kaliwraith

Thanks, I can definitely do that. I've got 85k miles and no oil catch can so I can imagine that they're pretty dirty.

kaliwraith

Hey so here's an update. I cleared the code and drove it for a month. The 'permanent code' turned into a 'trouble code' in my reader (which made it clearable, and CEL never came back on, so not a current code).

I replaced the sensor (found a used one on eBay for $45 - 15% eBay promo, why not?). Still have same reading, 13.6 psi KOEO. Must be the computer. Once I get a new exhaust (current one is cheap and banged up), I'll get ecuTek, so at that point they can get the sensor reading right.

I cleaned my throttle bodies, which were filthy. Probably never had been cleaned. Thanks for the advice. I should have taken a second look... I didn't disconnect the battery. Thankfully I also didn't disconnect any wires or couplings. I performed the 3 reset procedures in this video: https://www.youtube.com/watch?v=HIiaF0VaTlQ and everything seems good.

I can't tell if I've got reduced lag (seems like it? could be placebo), but I'm glad I cleaned those dirty TBs. Idle was OK before, seems OK now too. ~700 RPM.

ByThaBay

There is a service bulletin for this code from Nissan that requires a firmware update. I can do it for you at no charge, just PM me and I can get you squared away.

fechavez

Know anyone in San Diego that will do this for me for free haha