I am experiencing some serious acceleration problems. There is a substantial loss of power, especially when accelerating from a stop. I know some of you are going to suggest that the car just "feels" slower because I've gotten use to it, but it's not that. For example, I use to be able to smoke anyone from a dead stop acceleration off the line... now, they're smoking me! They're either accelerating faster or having no problem keeping up with me. It is very embarassing! I'm not even going to mention the vehicles that have taken me off the line... and these are not modified vehicles. What's going on?

I would appreciate any feedback - please try to keep comments focused on what may be causing the power loss, rather than telling what modifications I should make to my car. Thanks.

 

First of all, what mods do you have (if any)?

G

 

No mods.

 

Take it to the dealer, it's happened to me bofer, they fix it. but htey never tell you what it is. It has to do with the ECU. Also let your car warm up, I do it but some people hate doing it so don't get on their bad side!

 

What did you tell the dealer? Talking to the dealers here is like talking to a wall. They are going to run some usless diagnostic (like they always do) and tell me everything looks normal. I would really like to have a better understanding for what may cause such a significant loss of power. At least then I can have them check specific things when I take it in for service.

 

Have you tried resetting the ECU? It may help but, I would try that before taking it to the dealer. If there is no Check Engine light, I doubt that the dealer will find anything, It could be a mechanical problem such as clogged/dirty air filter, dirty spark plugs, etc.. Good Luck!

http://www.technosquareinc.com/350reset.htm

 

I notice this too... if I mash the throttle, anything below 4k is boring. I notice the tach rises a lil slower, and then once it passes 4k it feels stronger and rises quicker.

With my new tires, accelerating in 1st is like doing the same starting in 2nd gear. Once the revs got past 4k, it felt a lil better.
Overall, it doesn't surprise me much anymore.

Upgrades? Pop charger... nothing more besides Volks + T1-S.

 

I'm considering upgrades but I don't want to modify anything until I make sure that the existing essential parts aren't fubar!

Anyway, I am going to replace my air filter (I recall replacing the stock filter with a K&N filter almost a year ago... maybe its clogged). If that doesn't work, I will try resetting the ECU.

By the way teh215, do I just follow the instructions for resetting the ECU or should I do all the procedures listed under the link you sent me as well (i.e., accelerator pedal release position learning, throttle valve closed position learning, etc)?

 

Before taking it to the dealer, get a dyno run. If you're power is well below what it should be, that'll give you the evidence you need for them to take a deeper look beyond the OBDII diagnostic.

 

Where do I get a dyno run? What costs am I looking at? And how do I know whether or not the results are normal - what do I compare the dyno run to?

 

is your traction control off?

 

I dont have traction control.

The problem is simply this, I am hitting the gas pedal and the car is not taking off like it used to... it's sounds a lot louder when i try to accelerate but there's just no pick up... it doesnt go... well i'm exaggerating... it goes but it just doesnt go like its supposed to. It's as if 1st and 2nd gear are completely useless... all the punch that use to be packed in those first 2 gears... not there.

Has no one experienced this problem?

 

How much will performance be affected by a dirty air filter in your opinion??


I notice on occasion what I perceive to be inconsistent performance characteristics, but there are way too many variables to have to consider....mainly temperature, altitude, angle, and "throttle usage." (Will explain later).

 

You need to get a dyno done before anything to see how the car is performing. You being extremely vauge, what kind of cars have "smoked" you of the line?

For example here at altitude (5500 ft a.s.l) a simple Civic pushen 8psi can keep right up with me. A lot of turbo cars are more than fast compared to the Z. Stock STI's, Evo8's, are more than a challenge. Overboosted for them, it's no contest, the Z cannot hang at all. But assuming you in NYC, I'd think you'd be better off against a lot of cars.

How many miles are on the car? Do you notice the car not really going at all when you mash the gas pedal? (Like do you notice it hesitate?) there could be a possibility you have a slipping clutch.

 

If you havent cleaned the K/N in a year, it is probably pretty dirty. Soak it with the K/N spray cleaner, let is soak in for 10 minutes or so, rinse it really well from the reverse side, let it dry out, then oil it. DONT OVEROIL! It will foul your MAF sensor. If there are any red oil drips, wipe them off before installing.

After that, reset your ECU, then pour in a bottle of this
http://www.berrymanproducts.com/default.htm B-12 cleaner right before you pump gas in the tank next time. It will clean out any deposits in the injectors or combustion chamber. Only 1 can per tank though. Might have to repeat a few times to get full benefit. If you were running rich from a clogged air filter, there probably is a lot of carbon on the pistons etc. which will cause the ECU to retard timing to prevent knock and ping. This will kill power.

 

You say it is louder than it used to be? Just how loud? An exhaust leak can cause low end power loss. It sounds like a lot of good simple recommendations have been made and I would do the following as well:

1. Check air filter - if you have the stock air box, I have seen leaves and crap get up into the box causing performance issues. Karl was correct in making sure you do not over oil the filter if you clean it with the kit. A damaged MAF sensor would be pricey and would also cause performance issues.

2. Check for possible exhaust issues - with the Z being fairly low, you could have hit your exhaust on something causing a hole or a leak in the exhaust somewhere. Also some have had issues with some aftermarket CATS, but if the stock CATS were damaged in any way, you could have an exhaust blockage downstream which would effect performance.

3. Reset the ECU - If this fixes the problem and the problems returns, then take it to the dealer as you may have a bad knock sensor or something else may be wrong.

4. If there has been a poor A/F condition, your plugs should be checked and replaced if necessary.

 

If you were running rich from a clogged air filter, there probably is a lot of carbon on the pistons etc. which will cause the ECU to retard timing to prevent knock and ping. This will kill power. [/B][/QUOTE]

You can't really run overly rich from a clogged air filter.

The airflow will be decreased but this will be detected by the MAF sensor. Your short term fuel trim will go slightly richer to maintain power, but your long term fuel trim will react differently. Over time, the ECU will respond by decreasing the injector pulse width to maintain the preset A/F ratio. You will have less power as a result but you will definitely not run rich. Similar to running at higher altitude. You may run slightly richer than "normal" but only within the tolerances of the stock ECU which certainly isn't enough to cause the kind of deposits you are referring to.

Also, can you explain why these deposits would cause the engine to retard timing. If the car is running rich, there is no reason the ECU should retard timing. That would only occur if the ECU senses a lean condition, I thought.

 

another reason to check your air filter... the stock air box is bad about sucking in debris. First time I cleaned mine I had a sheet of paper and $1 bill partially blocking the filter (no lie!). Obviously, the blockage was chocking the air supply.

 

Unwanted deposits reduce chamber volume and can create "hotspots". Reduced chamber volume means higher compression. Higher compression can lead to pre-ignition (pinging) and/or detonation (knock). Sensors detect ping, ECU retards timing to protect motor.

 

clutch wear??? sounds like you may have wearing it out quite a bit at all these stop light races