Power dip between 2500-3000 RPM?

[JoeSchmoe]

Hi guys,


Ive noticed a slight power dip between 2500-3000 rpm recently. Its pretty apparent if I put it into 2nd at 1500 RPM and give it some gas. The car will accelerate until 2500 and then it will slack off. When it reaches 3000, it seems to pick up significantly. Everything beyond 3000 seems normal.

Ive ignored it in the past. I recently looked at some people's torque curves and I didnt see any dips between 2000-4500 which is getting me worried.

Anyone else exprience this? Anybody know what can cause such a thing?

 

[Edo]

I had the same problem but after careful inspection found out that it was just the TCS engaging prematurely at exactly 3500rpm's. It didnt engage very abruptly, and was just a minor loss in power, so I passed it off as a "normal" NSX thing. I turned the TCS off and the problem went away, I've since changed tire sizes and the problem is gone.

If that isnt the case, (if your car isnt new) I'd have the ignition looked at (Spark plugs etc etc.) It could just be a fouled plug, which usually beecomes MOST apparent when you give it alot of gas at low rpm's.

 

[JoeSchmoe]

Originally posted by Edo:
...it was just the TCS engaging prematurely at exactly 3500rpm's...

Hmm... I'll check and see if TCS was the cause. I hope thats the culprit.

... It could just be a fouled plug...

Shouldnt be, got new plugs ~3000 miles ago. The last set came out looking fairly clean.


I'll give the first one a go and see what happens.

 

[JoeSchmoe]

Hmmm...

Got it back from the dealer last week after timing belt/water pump swap and they said that they suspect that either the fuel injectors or coils on 2 of the cylinders is flaking out. As usual, their recommendation is relace everything.


So... 3 questions:

1) Has anyone else experienced this sort of problem and did replacing the coils/injectors fix it?

2) How much did it cost you?

3) Where is the cheapest place to order a set of each?


Any info will be appreciated.

 

[Chris W]

I have the same problem with mine at the same RPM in 2nd gear ONLY. I do notice better acceleration with TCS off so you're not alone. After 3000 RPM it starts to take off like a rocket. I think it's probably normal.
Do a little more research before you let the dealership rape you for something you may not need to replace.

 

[JoeSchmoe]

Originally posted by Chris W:
I have the same problem with mine at the same RPM in 2nd gear ONLY.

I had some errands to run today and all through the day I noticed that it ran totally crap 2-4KRPM in first gear. At the end of the day, it was really getting on my nerves.


The plugs are only 7 months old. The fuel injectors were cleaned 6 months ago. It doesnt seem to be the fuel pump since it runs over 4KRPM just fine. Im not sure what else to check.

Im dreading it, but I may have to subject myself to dealer rape if nothing turns up soon.

 

[Chris W]

Last night I let a friend drive my NSX (who has never driven one before) and he also felt the strange phenomenon that we are experiencing. I'm pretty sure it has done this since I first bought it used in October but I just figured it was normal.

I'm really curious to see what others on this forum have to say on this issue and what the rememdies were.

Keep us posted on your findings.

 

[Edo]

I also noticed the same thing, but after VERY careful inspection found it to be the TCS.
The TCS only engaged prematurely in 2nd gear and at roughly 3500-4000rpm's.
Since my tires are not *exactly* the same as the factory tires, they make the TCS think that they are slipping when they are not. Another odd thing I found was that this minor TCs engagement only happened when my tires were worn. I can only guess that this is due to the fact that the rear's wear faster than the front's and further sets the front/rear ratio out of whack.

Try driving around without TCS for a while..if that doesnt solve it, it just might be those injector's..

 

[JoeSchmoe]

Originally posted by Edo:
I also noticed the same thing, but after VERY careful inspection found it to be the TCS.
The TCS only engaged prematurely in 2nd gear and at roughly 3500-4000rpm's.

Nope... Ive been driving with TCS off for some time now to try to verify that this isnt a TCS problem. Its been happening on and off regardless of what TCS setting its on. 3.5-4KRPM is a little higher than where Im experiencing the dip. Its strange how everything seems to go away after 4KRPM though... I guess its just trying to tell me to stay up there longer

Strangely enough, it didnt really feel that bad this morning with TCS on, but it felt like crap yesterday in both on and off modes.

Since my tires are not *exactly* the same as the factory tires, they make the TCS think that they are slipping when they are not. Another odd thing I found was that this minor TCs engagement only happened when my tires were worn. I can only guess that this is due to the fact that the rear's wear faster than the front's and further sets the front/rear ratio out of whack.

Hmm... shouldnt be an issue. I had the tires swapped out in March and that was only 2000 miles go (my commute is under 2 miles)... almost all miles are accumulated during "stress relief" trips.


I'll wait and see if anyone else has any ideas and off to another dealer it goes for a second opinion. I hate to blow $1600 on parts alone and find that it wasnt the cause. (and the blow another couple grand on another piece of string). Thanks for the response.

 

[ilya]

Check at least one thing before going to the dealer. Do you have the stock coolant bottle or not? I have an aftermarket and this was causing problems for me. What happened is one of the hoses was sticking out too far towards the lever that controls the throttle. AT the tip of this lever is a screw. This screw was rubbing against the hose and having trouble pushing through. This caused a lag during lower RPMs until it pushed through the hose.
Just tie that hose down out of the way to something and the problem is solved.

Second thing, I noticed I was getting some poor response at that RPM until I just got my last oil change. I decided to put in some Redline and so far so good. I have doubts that the oil will make that kind of difference, but I'll update the post if it goes away completely for a week. My oil was very dirty and black when I changed it (about 3500 miles, synthetic) so changing it may have fixed the problem.

If you have an aftermarket coolant bottle though, be sure to check for this. Larry diagnosed my problem in about 20 seconds which tells me that he has seen this before.
It pays to have such a knowledgeable tech close by. An average dealer would never have known.