Strange power loss?
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Junior Member
Joined: Oct 2008
Posts: 22
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From: Livermore, Ca
Strange power loss?
Hey everyone, new to the forum here.
I just got a 1998 Civic HX and its pretty cool.
I got it for the gas mileage, and so far its great except I am starting to notice something really strange.
I notice it most on the freeway, when I am accelerating past about 60 MPH, at some point (usually around 2400 rpm) the engine looses maybe 30 horse power it feels like... and it takes more throttle to maintain the previous rate of acceleration, and then once you get to about 3500 RPM you feel a little burst of power and the car feels fine again.
What the heck!
It is most noticeable in 5th gear but I can sometimes reproduce it in 4th. I can almost always reproduce it. almost.
I recently changed the fuel filter and spark plugs with 8.5MM spark plug wires.
The spark plugs I am using are NGKs gapped to .044 and after I installed them the car idles much smoother and seems to have much better low end power. So I think they have had a really positive impact. I am not sure if this problem is caused by them.
The car has over 170k miles, so is it possible this issue comes from a bad throttle position sensor, MAF sensor, 02 sensor, or something like that?
One of my mechanics tells me that OBD II is smart enough to recognize when a sensor like this goes bad and will not make drastic changes to the air/fuel ratio so abruptly.
Any ideas?
Thanks!
I just got a 1998 Civic HX and its pretty cool.
I got it for the gas mileage, and so far its great except I am starting to notice something really strange.
I notice it most on the freeway, when I am accelerating past about 60 MPH, at some point (usually around 2400 rpm) the engine looses maybe 30 horse power it feels like... and it takes more throttle to maintain the previous rate of acceleration, and then once you get to about 3500 RPM you feel a little burst of power and the car feels fine again.
What the heck!
It is most noticeable in 5th gear but I can sometimes reproduce it in 4th. I can almost always reproduce it. almost.
I recently changed the fuel filter and spark plugs with 8.5MM spark plug wires.
The spark plugs I am using are NGKs gapped to .044 and after I installed them the car idles much smoother and seems to have much better low end power. So I think they have had a really positive impact. I am not sure if this problem is caused by them.
The car has over 170k miles, so is it possible this issue comes from a bad throttle position sensor, MAF sensor, 02 sensor, or something like that?
One of my mechanics tells me that OBD II is smart enough to recognize when a sensor like this goes bad and will not make drastic changes to the air/fuel ratio so abruptly.
Any ideas?
Thanks!
Thread Starter
Junior Member
Joined: Oct 2008
Posts: 22
Likes: 0
From: Livermore, Ca
Well... I think whoever owned the car before me babied it and so there was lots of buildup in the motor.
When I was first picking it up I floored it a couple of times and my friend behind me said it was making a bit of smoke.
So a day after I got it, the CEL came on and the code read that the signal from the 02 sensor was coming back slow. But after a few days I ran that sea foam stuff through the motor which cleaned out a lot of the gunk I think, and the CEL went away without being cleared.
That was a few weeks ago, and the CEL never came back. I could plug it in again to see if there are any soft codes.
Do you think the coil could be going bad?
Check this out- I measured the ohms on the new wires that I installed, about 100 ohms. I also measured the ohms on the old wires that I replaced.... guess what it was? 10,000 OHMS!!!!
what a difference!
But now do you think my coil has become the bottleneck?
Modified by spitfiremk2497 at 12:20 PM 10/3/2008
When I was first picking it up I floored it a couple of times and my friend behind me said it was making a bit of smoke.
So a day after I got it, the CEL came on and the code read that the signal from the 02 sensor was coming back slow. But after a few days I ran that sea foam stuff through the motor which cleaned out a lot of the gunk I think, and the CEL went away without being cleared.
That was a few weeks ago, and the CEL never came back. I could plug it in again to see if there are any soft codes.
Do you think the coil could be going bad?
Check this out- I measured the ohms on the new wires that I installed, about 100 ohms. I also measured the ohms on the old wires that I replaced.... guess what it was? 10,000 OHMS!!!!
what a difference!
But now do you think my coil has become the bottleneck?
Modified by spitfiremk2497 at 12:20 PM 10/3/2008
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