I have a 2002 S2000 with 14k miles. Just curious if anyone has any ideas on this.

I went to an autox and my first run i had a somewhat weak VTECH and acceleration from a stop. The second run and future runs while car is hot - no matter how you start, it will bog alot more. I'm a pretty serious autoxer and can only "guestimage" 0-60 was about 8 seconds hot and maybe 6.5-7.0 cold. It's obvious it's way down on power (worse as car get's hotter).

Well, i checked:
- oil - full and fresh.
- coolant - full/fresh.
- plugs - dealer said changed before 10k miles for some sort of recall.
- air filter - clean (but i have K&N on way but shouldn't relate)

So, today I ordered a new Map Sensor to swap out (just in case)... On the way to the honda dealership, I thought i'd open up the acceleration to see how it was doing.. Well, it only went 136mph. it would go no faster in 5th gear.. i shifted to 6th and it seemed to slow down. I've had another s2k up to 155 before so i know it should be pulling WAY better in the 130's so, this is evidence that the power is WAY down even on a cold engine. This supports what I thought before that even on a cold engine my power was down (just not as bad).

At the time of this posting I wanted to log my findings, but have not yet installed the map sensor. I will post a followup tonight.

Here's how I'll go about comparing data:
ODB data -
1)I have some OBD-2 reading from about a week ago with normal driving.
2)I'll get another odb reading before i swap the sensor out this evening.
3)I'll get a reading after the map sensor is changed.

Accel test -
1) I'll do another acceleration and mark my mph again on way home but do it from a specific starting/ending point. I'll use mph as the indicator.
2)I'll do this again after I change the map sensor.


I'll report the results so that it could help others, but if this is not the fix - what do you guys think I should look at next?

Thanks,
Chris

=========================
Noteworthy Vehicle History that could impact findings:
Only 2 possible things could have happened to damage this car since I've had it:

1)miss-shift going straight from 3rd gear (9k rpm) to 2nd gear . Happened real quick, but going straight probably made it worse. The clutch went in about as fast as anyone could have - but still - it could have an impact.

2)ran 6 autox runs with recently aquired vehicle that ONLY had 2.6 of 5.1 quarts of oil in it. Didn't realize until after! the car ran VERY slugish in transitions and turns. The car was somewhat slugish on straights but not as bad.

 

The first thing i would do is try a compression test. Thats always my first step when a car is acting seriously funny power wise.

 

The S2000 is known to heat soak, which is most notable when leaving the line. Turn off the engine and open the hood between runs. Spraying a little won't hurt either.

 

Holy crap Chris, if you've brought the 10AE Miata Curse down on the S2000 I'll never forgive you!

The VTEC actuation relies on oil pressure. People have had VTEC not engage when their engine is low on oil. That is the likely explanation for the sluggish performance at the autocross where you were low on oil. Perhaps the mechanism can be damaged if it's run too low? I don't know, I'm just guessing wildly.

 

Yah, Ortho --- I've brought bad luck to autocrossing.. we'll see.. keep fingers crossed.

U in a S2k now a day's? Will A-stock be fun?

 

Oh boy, is A Stock fun! I got the S2000 and sold the Miata almost a year ago.

 

I'd try different gas. Maybe you got a batch of super that wasn't quite 93 octane. That'll detune the engine. Intake air and coolant temp readings would be interesting.

I'd be leaning toward a bad tank of gas. For me, octane changes are pretty noticable. Maybe try some 100 octane race gas for a tank and see if the symptoms change. It really livens up my to honda's. ECU takes a day to learn the new octane though.

 

[QUOTE=drivefast617,Sep 12 2006, 01:12 PM]1)miss-shift going straight from 3rd gear (9k rpm) to 2nd gear .

 

Chris put a OBD2 scanner on his car and at start up the water temp is reading 400deg. There is no check engine light but I am thinking that is the problem, the ecu pulling all sorts of timing out of the motor thus making it feel like poo. He was replacing the MAP sensor tonight but I have not talked with him since.

Kery

 

well, i changed the map sensor and couldn't notice a difference.

After i put my same obd on a friends working s2000 and got the same 419 degrees F on the ECT reading.. so this value is wrong on both cars (and not the problem). another reading shows ECT 190ish.. but this freeze frame one shoes none or 419 each time..

Another wierd data point is that neither of our cars ever register any higher than 90% TPS throttle position sensor. maybe that's the way it's supposed to be, but we get the same results..

We did many acceleration tests side by side and my car accelerates just as well as his (somtimes a hair quicker). It appears maybe I don't have a problem right now. Maybe it was gas at the autox and just a hot day without enough runway for the top speed test.

i'm still testing away as i want everything in tip top shape.. so thanks for the advise and i will check out the possible damage from the 2 bo-bo's i had.

thanks again.