DBTre50z

Hi all, got a question about this SEL I got today. I used the diagnostic trick (depressing gas pedal) and reading the blinks. If I got it right it's a P1239 throttle position sensor.

http://engine-codes.com/p1239_nissan.html

Found this website. Question is if this is the issue, can just the sensor be replaced or is it integrated with the TB? And if I were to upgrade throttle bodies would it resolve the issue?

Thanks,

K20Gear

I have the same code, the tps is indeed integrated with the TB. As far as I know you need to buy the whole throttle body. I just ordered both of mine off amazon for around 278, ebay may have them a bit cheaper. Have you already tried cleaning them?

DBTre50z

Nope, haven't had time to look at it yet. I just hope it's not an electrical problem somewhere in the harness.

K20Gear

what are your symptoms?

DBTre50z

I was driving my car Saturday morning no issues. Later I go to start it up and it didn't want to start. Would turn over but immediately stall out. After two tries it was running fine but threw the SEL code. Since then I haven't had an issue. Power is there and car starts right up. I feel like this was an isolated incident but don't want to risk messing anything up.

Any ideas?

K20Gear

Same exact thing happened to mine, eventually your z may not start or may go limp mode on you. Check your cables too, I've read the cable connecting to the throttle body is very sensitive, it will throw a bad signal if anything is impeding it. I tried cleaning mine(very dirty) with no success and now everytime I start it the revs climb over 2k rpm, they eventually drop to around 500-450 at idle and 650-750 with A/C on. I'm either not doing the relearn procedure properly or my throttle bodies have crapped out on me. Either way I'm still getting a p1239 code so I'm just going to replace them, I should have them installed by the weekend. I'll post an update then.

DBTre50z

Awesome. Thanks buddy. I'm going to fool around with it hopefully after work. If I need to go with new TB's I'd like to just invest in some ported ones instead.

Wonder if this could be the by product of having CAIs installed?

K20Gear

Doubt it, I'm running stock intakes.

DBTre50z

It seems like half the people who clean their TBs are back to running normal and the other still experience problems. It's apparently hit or miss.

I just pulled the negative off the battery to reset the code. Could've been a one time fluke? if I get it again I'll try cleaning and if not then new TBs it is.

K20Gear

So I installed the new throttle bodies this past weekend, so far no CEL/p1239. My idle still acts somewhat strange though(maybe I'm not doing the relearn procedure correctly?). Symptoms include idle rising up to 950 almost 1k sometime(when my AC is on) & sets at about 500 with AC off. Also, If the car is in neutral and I rev it to about 3k rpm and then release the throttle completely my rpms dive down and hang at around 1400-1500 for a split second then goes back down normally. Finally if Im coasting in gear and I let the rpm's go below 1k and then push the clutch in before I come to a complete stop my rpms will rise from under 1k rpm( let's say 700) back up to around 1200k then gradually goes back down. Any input on whether this is normal or not and what it could be? Please help!

zakmartin

Which cable are you referring to? Our throttles are drive by wire and the throttles are controlled by actuators (THROTTLE CONTROL MOTORS). There are no throttle cables on the 350Z (unless I'm totally missing something here).

OP: I don't know what year your 350Z is, and that makes a big difference, but based on your stating that you replaced throttle bodieS, and not a throttle body, I'm assuming you're 2007-2009. Have you gone through the diagnostics procedure outlined in the FSM before you just swapped out the components?

K20Gear

Yes, it is a 2008. The cable I was refering to is the wire which connects to the actuator case."sorry" didn't know I couldnt use those terms interchangeably. I'm going to look at the FSM and go from there. Any input is still appreciated though thanks!

K20Gear

ok took a look at the FSM. Zakmartin, are you suggesting my irregularities could be a cause of a short or open circuit in my TB harness and not a faulty TPS?

DBTre50z

I feel like my car did that from factory. My car still hasn't thrown a code since and runs perfectly fine. Going to play the waiting game

K20Gear

best of luck! Hoping that MIL stays away. According to the FSM normal idle should be
650(-+50)

zakmartin

"You're forgiven." But yeah, a cable generally refers to something that is responsible for mechanical transfer of motion or restriction. A wire is responsible for the electrical transfer of a signal. Using the right terms really helps people who take the time to offer their experience and guidance on this forum.

K20Gear

Great! I appreciate it thanks for the link to the FSM

K20Gear

So recently I've been having some more idle issues, and I feel may have a leak more than anything else. The car idles over 2K rpms initially during a cold start then dropping immediately to around 1,800k, after about 4 min the rpm's settle to around 1,100 and stay there until i reach normal operating temperature then drop to normal. When i depress the clutch during a stop while coasting in gear the needle still jumps above 1k rpms and back down. Has anyone experience similar symptoms due to an intake leak? I also received a p0420 code(catalyst efficiency below threshold) about 2 months ago before it turned off on its own in a matter of a week, and currently no SES light.

jhc

Your rpms sound typical for cooler weather, is the idle consistent though? If it jumps around irregularly you should do a vacuum test on the upper intake plenum.
I had this problem after installing a plenum spacer. Huge vacuum leak even after correct torque. Reinstalled with a thin bead of silicone, problem solved.
Let us know what happens!