Throttle Body - Throttle Plate Sticking?

[unoriginal]

Hi all,

I'm new to these forums so please forgive anything that is unorthodox. I have posted to other forums about the following issue but I wanted to start fresh with new information and discoveries.

I have a 2010 Nissan Maxima SV, 102,000 miles. I have been experiencing a particular problem with this car since I bought it when it only had 15k miles on it. Whenever the car heats up (especially if it's a hot day) I will experience random lag in performance. By "lag" I am referring to great acceleration from any speed or stop and to feeling like I just downgraded to a 4 cylinder. I'm not exaggerating either. Not only that, my estimated range on my car drops very quickly when the problem is occurring but does not when the problem is not occurring. I have gone through so much gas because my gas mileage is horrible because the problem is there more often than not.

Anyway, I bought the car 3 1/2 years ago and the problem has never gone away. This is what I have done/tried so far:

Completely removed and cleaned Throttle Body with CRC TB cleaner - x3
Cleaned MAF Sensor with CRC MAF Cleaner - x5
Replaced MAF Sensor (generic brand) - x2 (Two brand new sensors to rule out any chance of faulty units)
Professional Smoke test to check for vacuum leaks - x1
Manual ECM Reset - too many times to count
Accelerator Position Relearn - too many times to count
Valve Closed Relearn - ""
Idle Air Volume Relearn - ""
SeaFoam Gas Treatment - x3 Cans
All in one fuel treatment - x2 Bottles
Gas Tank Moisture Remover - x1 Bottle
New Battery - x1
Tested Alternator - several times
Tested MAF Voltage - several times
OBDII Scan for codes w/ torque pro and OBD fusion - don't even get me going on how many times
Graphed/Monitored/Recorded several 45 minute sessions of driving with both apps with multiple PID's
New Air Filter - x3
Changed Transmission Fluid with ONLY Nissan Genuine NS2 - x1 (less than 1k miles ago)
Changed oil with Valvoline Full Synthetic (regular 6k mile intervals)
TSB Transmission Update
Other Stuff I am probably forgetting...

Well, today I was driving south to my house about 3.5 hours away. The problem was occurring and I accidentally "snapped my throttle" several times because I was shifting in my seat. My foot bounced on the gas pedal a few times and voila! The problem was gone! It came back a few minutes later and I put 2 and 2 together and tried snapping the throttle again. The problem went away again. I did this several times during the trip with 100% success.

So, my theory is that the throttle plate (or butterfly valve?) in my throttle body is sticking, especially when the engine is hot and especially on hot days (it was 80 degrees out today). I think it has to be due to either heat expansion or carbon buildup that I just don't see or can't get to. But when I forcefully bounce the gas pedal, it seems to be freeing up the throttle plate for a while. What do you guys think? I am purchasing a brand new OEM Throttle Body this weekend but I don't want to spend it if I don't have to.

Sorry for the lengthy post but I am very OCD about this.

Thank you, in advance, for your help.

[unoriginal]

I forgot to mention that I have never had a CEL nor any codes. I also replaced my Accelerator Pedal assembly a couple of years ago.

[centralcoaster33]

Hi and welcome to the forums! You have been driving a long time with those problems, 85K and 3 years, is that right? It seems to me, that heat loosens things up, so I would guess that things would be less stuck on a hot day. Anyway, I don't have any magic bullets, but a few things come to mind...

Your throttle cable needs to be in good order. You could disconnect both ends and move it with your fingers to test for resistance. Maybe lube or replace that.

Springs on your pedal or on the throttle body could be inspected, should be fine though.

You swapped the pedal a while ago, is there a switch type sensor that goes to your gas pedal? Is it connected properly and does it get stuck in or out?

Ground wires. Test grounds at critical locations like MAF and TPS, check grounds at battery, chassis and engine.

I suggest testing your TPS with a voltmeter. If that is bad, you'll get a non-linear Ohm or Voltage reading as you rotate the throttle (depending on what wires you choose to test). This is my most suspect from your description.

Hmmm, you could test your fuel injectors. Check their resistance is the easiest. I had intermittent issues with power and it was one of the injectors going bad.

Get your FSM if you haven't already.

http://www.nicoclub.com/archives/use-ni ... abase.html

Please keep us posted. Good luck!

[NutriaforBreakfast]

You might try to look at emissions items including;

PCV valve

EGR valve and associated hoses
Sounds like the problem happens when the car is hot
The EGR should fully open-if not-it creates problems

[unoriginal]

Thank you for your quick replies. I appreciate the feedback and ideas.

I don't have a throttle cable as my car utilizes drive-by-wire. As far as ground wiring goes, apparently my whole dash and instrument panel would need to be disassembled in order to get to the majority of the applicable grounds, according to the FSM for my car (maybe I am reading it wrong?). I am trying to avoid that until I try the new throttle body. There are, however, a couple of things I forgot to mention that I just thought about today.

1.) After cleaning the throttle body, performance seems to have improved after each time it was cleaned but it still randomly lags, but not as bad as when I originally bought the car. It is definitely a significant improvement and way less frequent.
2.) I would think if it was a ground issue that it would not be remedied temporarily by simply tapping the accelerator pedal a few times each time the problem arises, but then again I am the one asking for help so I shouldn't be doubting that either. Please forgive me if I sound arrogant or ignorant.
3.) I tested the PCV valve by using a method I heard about on an automotive site (name escapes me). It said that I can test the PCV Valve's functionality if while the car is idling I remove the oil fill cap and check for suction. If this is true, then it is working as it should be.
4.) I have not checked the EGR valve. Is it possible that tapping the throttle several times could clear the EGR valve if it is not fully open at that time and in return remedy the issue?
5.) This sounds crazy but when the car is performing normally, the accelerator pedal physically feels firmer to push by a significant degree. When the problem arises, it feels softer to push. I understand that this is drive-by-wire so please don't call me crazy but I know I am not just imagining this.
6.) I am concerned that I have never seen a CEL..... ever. I had old historical codes but they were cleared by the body shop that did my smoke test but they never returned (I had them check a few weeks after clearing them to verify - this issue was still happening during this time). My other theory is that whatever is causing this issue is minute enough to not trip a code.

I am so at a loss. I will be buying the throttle body in the morning and installing it on Saturday so I will keep you posted. I have a bad feeling that it is not going to resolve the issue. I just have gotten so sick and tired of seeing glimmers of hope and having ideas of what it could be only to be let down. You would think a 30000 dollar car would be a little less flaky.

Again, thank you all for your help. It is very much appreciated.

[centralcoaster33]

I'm referring to grounds for your engine harness, not your pedal electronics. Sorry, I didn't notice the newer year. That pedal you replaced, was it OEM or maybe refurbished? Why was it replaced the first time? Can you get your old one and throw it in there to see what happens? I'm just seeing a few years with a pedal and a few years with this throttle issue. I suppose it has a sensor and maybe that's something that can be measured with a voltmeter, similar to the TPS. I don't even know if you have a TPS! I'm not familiar with your drive by wire setup, so the FSM will have to guide you, but something measures how far the pedal is and how open the throttle is and it will have a sort of potentiometer and that is what I suggest testing.

[unoriginal]

Thank you again for the quick reply, centralcoaster33. The pedal was replaced with brand new OEM from Nissan directly because the shop I went to could not find any aftermarkets. That was actually the first thing I replaced for trying to fix this issue. It's funny you talk about testing voltages for my TPS (it's directly connected to my throttle body on my car). When I was using TorquePro and recording logs, I noticed even at WOT my throttle percentage never got above 87 or 88 % throttle in the logs. I was told this was normal and that it would never be near 100%. From what I understand this is not an accurate statement, however. I will be testing my percentages in the morning for inconsistencies and I will followup with my results. I was talking to my friend last night who is very well versed in mechanics and I was bouncing possibilities off of him. I am supposing that no codes have been tripped because my TPS is faulty but the ECM doesn't know that because it is only being told what throttle percentage the TPS sees and is being told by the ECM how far to open the throttle plate based on the information. Therefore, it is not opening up enough and as quickly as it should be to allow for proper air/fuel mixture but it doesn't know that because it doesn't know any different. So when I tap the pedal several times, I think I am jarring the TPS gears to a certain degree so that they work properly again. The problem is I don't know why it stops working again after a few minutes. My only other guess is that the plastic gears in the TPS are stripped or are slipping so the throttle plate does not get opened far enough. I noticed that from a stop, the car works great until I get moving pretty good. This is where I can sometimes and randomly feel my car jolt forward a little as if the plate is finally catching up. Sometimes the issue even fixes itself randomly when driving even if not from a stop and I can feel it when it happens because gives off the same sensation. If the new throttle body does not fix the problem then I will be ordering a new Accelerator Pedal Assembly and replacing it myself. As for the old one that was replaced awhile back, I can't seem to find it since we just moved and it is probably in a box somewhere ;-)

Thanks again for your help! I will keep you posted.

[unoriginal]

So I used the TorquePro app this morning with my car in the on position but not running. The highest percentage I was able to read from the TPS was 91.78% and that was with the pedal all the way to the floor and it was a consistent reading. I'm not sure if this was coming from the pedal or the throttle body, but either way it is not reaching 100 or even 99% as I think it should???

Along with the new throttle body I also ordered a new OEM Accelerator Pedal Assembly. I am supposed to receive the throttle body this Saturday and the pedal next Thursday. Either way, I will keep this post updated. I honestly hope I figure this out not only so I have a properly functioning vehicle but also because it may help someone else out there who may be experiencing the same/similar issues.

[NutriaforBreakfast]

Went out to look at the shop manual on the TPS for 2010 Maxima

http://www.nicoclub.com/FSM/Maxima/2010/EC.pdf

Appears the car has two throttle position sensors.

At 90 degree angle on the throttle body, sensor 1 should register 5v

At 90 degree angle on the throttle body, sensor 2 should register about .5v (point 5 volts)

There appears to be no "%" threshold to test

There is also a Electric Throttle Control Actuator next to the throttle body
Part of the remedy for your problems described is to clean this actuator.

I realize you should be getting a DTC of P1226 if the TPS has failed but it looks
like you have intermittent functioning/disfunctioning (based on the feel of the pedal)
and the computer might be falsely accepting the parameter

[unoriginal]

Hey NutriaforBreakfast,

I had a hunch that is why the ECM was no throwing a code.

I guess the % is what TorquePro uses as a measurement of how far down I was pushing the pedal but I'm not completely sure on that. The actuator is what I was referring to as the TPS but I just got them confused so thank you for the clarification.

Thank you for this information. It is actually very relieving and morale-boosting information. I feel much more confident that the new throttle body and/or accelerator pedal will fix this issue. At this point, I'm ready to just sell the car and buy a bicycle ;-)

I really hope I will have good news for everyone tomorrow after I install the new TB. If not, well, time for a bicycle.

Thanks again.

[NutriaforBreakfast]

After looking at Auto part stores and the Nissan Courtesy Parts manual
I don't think you car has an EGR valve but I could be wrong

[unoriginal]

Well, that would explain why I can't find it lol. But if it does have one, then Nissan did a great job of hiding it.

[centralcoaster33]

I like Cannondales... great bikes!

No EGR? WTF? I have got to get out of the 90's and to get up to speed with newer engines! I'm gonna start poking around my wife's Nissan, her's if of the new sort.

Yeah, checking voltage and Ohms at both ends seems like useful information. Can your torquepro measure those or is that something else? I use a voltmeter. I got a TPS wet with some engine clean once and it failed withing a couple of weeks. While it sucks to throw parts at a problem, I think you are at least dealing with the correct parts. I wonder if replacing one at a time will allow you to send back the other if it wasn't needed and get a refund. We do look forward to your post back. It will certainly help others in the future. Curious, what are the throttle body and pedal costing you?

[unoriginal]

I hope Cannondale bikes don't cost $30000! My wife will need ALOT of convincing, otherwise I will be walking to work lol.

I honestly don't know if torquepro can measure voltage for a tps. I know it can tell me voltages of other things like O2 sensors and the battery but I guess I haven't dabbled that far into it.

As far as parts that I purchased go, Altogether for the new OEM TB and Acc Pedal it was about 180 bucks with shipping. I got the pedal from a reseller on eBay who also has them listed on Amazon. The seller is quirkparts. I thought they had pretty good feedback so hopefully it's a legit new OEM because it was listed as such. it already shipped so I should receive it soon. The TB I am getting direct from Amazon.

I really hope one fixes it. When the car works it is actually really fun to drive but when it is acting up, it makes me want to sell it.

Anyway, thanks again for your help. I will keep you posted.

[unoriginal]

So I installed the new Throttle Body today and wouldn't you know it, the problem still exists. The only difference is that when the issue is present the car performs a little better, but not by much. I tried resetting the ECM twice. I did the throttle position relearn, the idle position relearn, respectively. However, I was not able to do the idle air volume relearn. I couldn't get the CEL to flash. However, I could still temporarily remedy the issue by bouncing my foot heavily a few times on the accelerator pedal. I still have the new pedal assembly coming and it said it should be here Monday (not Thursday like originally estimated).

So I will keep you guys updated after the pedal install and let you know. I have exhausted pretty much all theories but my last and (hopefully) final theory is that the potentiometer inside the TPS on the accelerator pedal assembly is not making full contact all of the time like it should or their is moisture or something making the contact bad. So when I bounce my foot on the pedal, it is improving the contact momentarily.

Anyways, I hope you all have a great night and I should know by Monday evening if I'll be planning to throw my car into neutral and rolling it off a cliff ;-)

[centralcoaster33]

Well, at least you're a smart shopper. $180 doesn't seem nearly as painful as I would have expected for OEM parts. I'm sorry the TB wasn't it. I look forward to reading about the new pedal and it's effect.

[unoriginal]

Yeah, I have to be smart about shopping because I don't like showing receipts to my wife that have a lot of digits before the decimal place lol.

I didn't get a chance to install the new pedal yet. I will hopefully have time tonight or tomorrow. As soon as I test it out I will let you know.

I get the horrible feeling that this may in fact be a grounding or short issue. I don't know if I mentioned it before but when I am driving, sometimes I can feel the car physically slow down a little even though my foot has not moved the pedal. Its almost as if the proper voltage isn't always there. The feeling is very quick but quite noticeable if I am paying attention.

If this is a short or grounding issue, how would I go about testing? I have a nice volt/ohmeter and I have a little expel with it but every time I've tested other things like the TB plug, I get a code about low voltage for that part on the ECM. I am sticking the prong from the meter directly into the end of the plug that connects the TB, for instance. I guess I'm doing it wrong?

I did the same thing last night to the tps on the pedal I have installed currently and it showed a steady 5v. But then I started the car back up and I got a code about low voltage for the tps.

I would like to reiterate something just in case. When the issue is present, my gas mileage basically plumits. I know this because my estimated range for my tank goes down - fast. When the issue goes away, the range goes back up.

Again, I appreciate your awesome help and thank you for your patience with this.

[ArmedAviator]

I'm surprised nobody asked based on your username but what modifications do you have?

Is the ECU tune stock? Is there a "performance chip" installed anywhere, usually around the MAF?

Are you sure the transmission isn't activating a solenoid it shouldn't be due to an electrical short? If that happens, a second clutch can engage that shouldn't and cause bogging and excessive clutch wear. This theory is backed up by the big drop in fuel mileage - engine gets bogged down by a clutch engaging that isn't supposed to so there's a bunch of excess engine load and a loss of wheel power.

[unoriginal]

Actually my username is sort of a pun on itself lol. I couldn't think of anything better at the time. My car is completely oem/stock. I have made/added no modifications to it.

A little back story may help. I bought the car on 2013. According to the dealership, it sat since 2011. It only had 15k miles on it. Why I was apt to think a ground/short issue is because of the length of time it was sitting. I purchased the vehicle for about $6k under NADA value. This makes me think they knew about an issue and therefore the price drop. Why would they use time and resources to fix it when they could just sell it cheaper?

As far as the transmission goes, there was a historical code for I believe something transmission speed sensing or something and an abs speed sensor code or something too along with multiple other historical codes. They were cleared by the shop that was helping try and diagnose this. They checked for codes 3 weeks later and they said no codes were found/returned.

I am just so confused on why I can fix this temporarily with just slapping the gas pedal a few times while I'm driving. It makes no sense.

[unoriginal]

So, I took it for a spin this morning and the same issue is present, even with the new pedal installed. I made an interesting observation though. Almost 100% of the time, the issue was not present from a stop. But as soon as I would be going and then coast and then try to speed up, it was a 50/50 chance the issue would arise. SOOOOO... I went online just now and purchased a brand new OEM MAF sensor (I'm replacing the cheap ones I purchased that were no-names). I'm wondering if the MAF is not sending the right information all the time but the ECM does not recognize this because it is dependent on the MAF's accuracy. Even if the MAF sensor is getting the correct voltage, it could be sending faulty/inaccurate information to the ECM which is causing inaccurate throttle response??? I did want to mention that even when I installed the new cheapo sensor that it did improve performance quite a bit over the original stock sensor. This was all before I even cleaned the throttle body or anything. So I guess I lied when I said it is 100% stock lol. Sorry.

I should be receiving the new sensor on the 15th of July. I will let you know how that goes.

[NutriaforBreakfast]

I don't see where the fuel system has been checked
i.e. the fuel pump pressure and the fuel regulator

[unoriginal]

Actually, I was looking into just purchasing both pump and filter today to replace anyway. The good news is I replaced the cheap MAF sensor with the original stock one and drove around for 40 minutes. I was surprised and excited to find that if the consistency of performance and feel was not 100%, it was darn close. Not only that, my gas mileage was very consistent and didn't plumit like usual. It even drove way smoother and even the feel was consistent.

So like I said, I will be installing the new OEM MAF sensor this week and will let you know. It shipped earlier today and should be here Thursday.

I don't want you to think I was poo pooing your suggestion about the fuel pump/filter and what not. I was just hesitant because it looks like those are stupidly time consuming to replace. I really do appreciate your help.

[NutriaforBreakfast]

Not offended here-my comments are intended to maximize value by
offering advice for quality diagnostics first before opening the wallet
I have 2 maximas and just when you think you have figured out the
problem.... well it turns out to be something else unless you read and
check closely. I have not always checked enough for diagnostics either.
For instance I got stranded in the health club parking lot for a bad starter.
I just "guessed" it was the starter after finding out from Sam's Club the
battery was still good. I multimetered the battery and the alternator was
around 14.2v so I know my alternator is good, probably. So the parking lot repair
was good enough and I saved $250.00.

You might multimeter the new MAF and check the resistance before you put
it on just for your knowledge later.

[unoriginal]

How do i go about checking it for resistance? The only thing I know about checking for resistance is I understand I have to use the ohm setting on the multimeter? Also, how would I check the actual plug for the MAF sensor for resistance?

Thanks so much again.

[centralcoaster33]

FSM, EC Chapter - MAF starts at Page 171, instructions for testing with consult follow (can you use torquepro for this? interested, maybe I need one of those...), Page 175 has checking with multi-meter.

[unoriginal]

First of all, thank you for that.

So everything was working great after installing the new MAF, and I mean awesome! Well, on the way home this morning, the car went really limp when I was almost home. I pulled into my garage and realized the radiator fan was not spinning at all and when it tried to kick on it was VERY quiet and did not spin that I could tell. I checked the coolant temp with my OBDII and the temp was raising very rapidly - and I was just sitting there idling. So now ANOTHER issue.

How would I go about fixing this radiator fan problem or checking it to diagnose it?

Thanks

[unoriginal]

So I took her in to the shop I use for crazy labor-intensive jobs (I'm currently there as we speak) because I noticed my alternator was whining when i pulled into my garage this morning. They tested the alternator and it was only at 60 amps and it was whining something awful. They are in the process of replacing it. I have high hopes that this will be the final step to performance - consistency for good. The reason why is because on the way here I turned everything off that was not necessary and she drove ALOT better than this morning when I had the a/c and headlights on.

So if you guys don't hear from me again I want it to be known that if anyone else has this problem I have been experiencing, check the MAF sensor and throttle body. If I still have problems, I will update you. If not, I am very thankful for everyone's help and patience. I could not have done this or learned so much without you.

God bless!

[NutriaforBreakfast]

did the alternator change out fix the problem?

[unoriginal]

So I guess I'm at my wits end. Not only is my problem back (albeit much less noticeable), but I read online earlier today something about an ECM ground short and the symptoms. I feel this may be the ultimate cause because when I put the car in cruise control for a couple of minutes, my problem is completely gone after I take it back off cc. But then it arises again after a few minutes of driving after I turned cc off. I am so lost. Why would my car run absolutely flawlessly after using cc and then slowly deteriorate in performance after a while of having cc off.

For the record, I am not just turning cc on, I am actually setting it to a cruise speed and the speed doesn't seem to have any effect on this outcome. I would also like to add that I removed the fuel pump from the tank the other day and inspected it. It couldn't look any more like brand new. However, I did notice lately (and eventually after having used 3 cans of seafoam) that my fuel pump gets really loud after I drive for a while. But this still doesn't explain the cruise control fix since this was not the case with my fuel pump when I first bought the car and had the same problem and same effect from using cc.

Another thing I noticed to maybe fortify my ECM short theory is that after driving a while and the car is warmed up (lately it's been roughly 25-30 mins of driving) my estimated range will go way up and then plumit. This happens like clock work everytime for the past week or so everytime I drive it. Could this be because maybe a gap in the wiring or something is expanding making ECM ground/connection worse?

So, ultimately, my questions are:

1.) Reading the service manual about checking the ECM (ECM ground?) for continuity is only confusing me. Is there anyone who can explain to me how to do this with my multimeter in an easier sense?
2.) Can someone with a similar year of my car try my method above who may be experiencing similar issues and tell me if they get the same result?
3.) Anyone want to donate a WORKING 2010 Maxima SV? (only kidding)

Thank you all again for your patience and help.

God Bless

[NutriaforBreakfast]

checking for resistance = using the omega on the multimeter
use the dc NOT ac when working on your car
"ohming out" = checking for resistance
Looks at the shop manual and it will tell you where to put the red and black
multimeter probes on the MAF, idle air control valve etc. and how much
the resistance (measured in ohms) should be