Loss in acceleration + throttle response ??
 

My car has roughly 3850 miles on it now. I did the oil change this past weekend. I used Red Line + K&N combo.

Ever since the weekend, I have noticed that my car seems a bit sluggish (bogged down), especially at lower RPMs. Now, I know the car is running quieter with the new oil, so subconsciously I could be making a connection/relation of sound to power/speed but I doubt that's it. I think it's just a coincidence that this is happening after the oil change.

There are times with I get on the gas and get little response and then all of a sudden the torque decides to kick in. This typically happens in 1st and 2nd. Also, cruising at highway speeds in 5th or 6th....if I got on the gas the car would move with pretty good acceleration. Now, not so much. Something just does not seem right.

Could it be a spark plug misfiring, in which it needs to be replace or something else mechanical?

Also, my downshifts are not as loud as they used to be. I mean, I can understand the engine being quieter from the oil but the exhaust note should still sound the same, right?

If you try to get on it under 3k or so you will feel a sudden power surge at some point becuase there is absolutely nothing down there.

Well, I swear that prior to this week, the TQ curve felt more linear than now. Like there wasn't such a sudden surge, like you said. I don't know perhaps it's a combination of the reduced engine noise and the little bit of added performance from the RL oil that is making it feel differently. But still, the car feels hesitant under 3K or so. It didn't feel that way before......strange.

Reset your ECU......(disconnect the Neg. Bat. terminal for a few minutes, or do a search for the reset procedure)

Chech your oil level. If you accidental put too much in , it could reduce engine power.

I checked the oil level a couple times. A few on the day of the oil change and again the day after. The level is in between the two punch holes. It's like 3/4 from the bottom punch hole to the top one. Anywhere between those two holes is fine.

^OK. Scratch my idea off the list.:tiphat:

^^ Yup...thanks though. I appreciate the help.

My car is like this also, always has been though. This engine just doesn't have a ton of low end torque. Its the main reason why I think a supercharger will be best for the car instead of the twin turbo.

**Please don't misunderstand my comment, I'm not saying this engine sucks. I love my car, and think is super fast.**

If you're confident that the problem is isolated to the oil change, do the following:

1. check the oil level and make sure its full (but not overfilled). If you're low on oil (significantly), it could affect the VVEL system as it relies on oil pressure.

2. check all the parts you touched. Did you accidentally knock off any hoses or air tubes from the engine while working on the car? Is the dipstick inserted all the way in? Leaving it slightly out, creates a minor vacuum leak.

3. What oil weight did you use? If you used the wrong weight (typically too thick) it could create a small drag on the engine parts and decrease HP. Nissan recommends 5w30.

4. Very unlikely, but you could have a defective (broken) filter which isn't allowing enough flow. Are there any dents in the filter? The bypass mechanism could also be stuck. Its driven by oil pressure and at 3 - 4K RPM most oil filters fully bypass for maximum flow.

Basically, go through every step you did and make sure its right. If its all done correctly, and you still have the problem, I doubt its the oil change. I hate to ask, but did you do anything else other than the oil change?

Good luck and update us.

Fix for sluggish acceleration
 

I had the same problem, starting this spring. I found that if I reset the ECU by disconnecting the battery, everything resets and the car runs really well for approximately ninety days. I repeated the procedure when the sluggishness returned, and the problem was corrected.

Several other things noted:
I run Red Line 5w-30 exclusively, and make sure its always topped off, as I noticed similar symptoms when the oil is not full. I switched to Red Line after reading all the posts on high oil temps. Red Line synthetic will easily handle the higher temperature requirements and contains ester, as recommended by Nissan.

I also noticed that the ECU seems to have issues if I switch gasoline vendors, so I use Shell exclusively.

I replaced the air filters at 10K since we've had a horrific winter with much dust from the sand left over on account of the snow plowing efforts.

Aside from the periodic ECU reset, the car operates really well.

Interestingly, an ECU reset DOES improve things for a while (for me, it hasn't been anywhere close to 90 days), before it reverts to the same old same old. I wonder if it's just long enough for the ECU to develop the long term fuel trims?

I think the cAr just doesn't like intakes. Ever since the injen intakes the cars been running crappy in the lower rpms. It's much better after the tune but when it's real hot out the cars like bla under 3k then when it hits about 3.5k the car takes off

I'm thinking this might be the case. Though I believe the OP is stock...

I should probably put the factory intakes back on and see if I can tell a difference.

DO it up and let me know

Wow, this happened to me too. I took my car in for its 2nd oil change and the very next day i felt the same sluggish behavior you describe. I mean i know one eventually gets used to their car and that after awhile it might not seem as quick as it once did but this was a very noticeable feeling.

I'll have to try to ECU reset thing when i get back to the states in a few months see if that helps it. I have just a little over 6k miles on mine too, and it didn't do this on my 1st oil change.

Is disconnecting the battery to reset the same as reseting with an OBD scanner. I didn't think unplugging the battery would reset the ecu.

Fuel trims are maintained in a volatile memory. You need to de-power the ECU to c;ear them..

hmmm... those of you experiencing this sluggishness.... your AC wouldnt happen to be on would it? just a thought.

I have the intakes and my car takes off like a champ. However, when the AC is on, the car shits its pants.

AC on or off doesn't seem to make much of a difference. The car is just as sluggish down low with AC off as it is with AC on.

I've definitely noticed a difference like what was described with the AC on. It like wants to go but then falls on its face kind of like if the TC was kicking in.

W-e-i-r-d stuff. Hook her up to a Diagnostics Center Computer, dude!

More revs, dude!

Yep, same here.

It's even caused me to mis-time my shift into 2nd because it fell on it's face so bad from an attempted hard acceleration at a stoplight. :shakes head:

What's worse was, I was even under an over-pass, so my over-revving of the engine because of the missed gear got everyone's attention, all the way out to the gas stations on the corner! Yay! Look at me!

:facepalm:

:ugh2:

:thumbsdown:

Now, if I wanna launch hard in my Z from a stoplight => AC and VDC are turned off.

I recently changed my stock air filters and found a lot of debri, leaves and dirt, in the air box. Those with stock intakes should check. The throttle response improved instantly.

I was told by a knowlegeable NISSAN guy that if you don't use the correct oil (nissan ester) that the knock sensor will sense an issue and start to retard the power to the engine trying to compensate for this. Not sure if this is true but it sure sounds like it could be happening here, or does this sound like dealer dribble?

It's always the simplest of things.

Get some CRC MAF cleaner and hit your sensors. Did it today and it helped a lot. The car obviously is not very torquey down low, but it made a pretty big difference in overall responsiveness and pep in the lower RPMs (read street driving).

I'm thinking a dyno tune to optimize A/F ratios with the intakes would do wonders for the car...

Not quite sure why the engine oil would cause an issue with the knock sensor. Doesn't make any sense to me.

If that were the case I think we'd have a lot more discussion on poor performance because it seems like more than 50% of board members are running something other than the Nissan Ester.

Hmmm....good tip. I think I'll give that a shot. It's only $9 on amazon, plus free shipping. Do you know if Pepboys/Autozone/etc. carries it?

I bought a can at AutoZone... can't remember what I paid for it, though. I also picked up a can of PB Blaster just cause. :tup:

Nice, I'll have to stop at a PepBoys or AutoZone and check it out. BTW, PB Blaster worked wonders when removing the stock CBE. I used it this past Friday when installing the FI CBE.

I picked up a can of CRC - MAS Cleaner ($7.xx), as recommended by M4A1, at Pepboys today. I don't know if I'll get to cleaning the MAS during the week but hopefully by the weekend.

It's a quick job, just follow the instructions on the bottle. Shouldn't take you any more than 15 minutes.

where are these sensors located? Sorry if its a silly question, but I'm feeling a lack of power down low since I got it as well.

Right behind the air boxes.

Be careful... DO NOT touch the sensor with anything but the cleaner. They are easily damaged and expensive to replace.

Thanks, I appreciate the info and the warning.

Big thing to keep in mind is that this car is not a torque monster to begin with, so it needs revs. Also, I had 23k on my car when I finally got around to cleaning my sensors... so for you guys with less miles (and probably cleaner sensors), don't expect anything huge!

Oh yeah -- disconnect the sensors before you spray them!

I have 2010 with from the first 20 miles on the car I have the same issue. Now with 500 miles still the same issue. You can't tell me I have Dirty MAF with 20 miles on the car. Also the car came right off the truck.

I was never telling you that. I only said it helped in my certain situation.

And of course it doesn't change the fact that the Z is a complete dog in the low end to begin with. This car has a puny V6 with pitiful low end punch.

Puny V6? I disagree; 3.7 liter is not a puny V6. And, I would rather have my 'fun' in the mid range and top end.

This coming from a guy that had a Stang GT to S13 w/SR20DET to RX8 to 370z.