Hi guys,
I'm not a "Honda guy" but I've been tasked with installing a AEM EMS in a 00' S2000 race car.
The car had a 2.0l engine which now has a large hole in the side of the block. A 2.2l crate motor was purchased and installed in the car. I recieved the car with the original 2.0l factory ecu in the car which the motor would run on but not well, along with the AEM ECU and associated literature.
The AEM was a plug and play unit, so I intalled it and uploaded a base map provided by AEM. The engine fired right up and idled even better than on the stock 2.0 ecu. I then (next day) put the car on a chassis dyno and proceeded to tune the fuel and spark timing. This is were the problems arose.
I did a short run up to 5500 rpm on the base map and saw that the fueling was slightly lean so I increased the base map to get the fuel in the 12.5-13.0 range. At this piont the engine was only making around 100 ftlb/tq and 124 rwhp! I then turned to the ignition map which I found was set a a very conserative 24-25 deg of advance. I bumped the total advance to 28 deg (baby steps) and did another run. Gained 2 rwhp. Continued to increase the advance to a total of 34 deg with not much gain in rwhp, fuel curve still looking good though the rpm band.
As a reality check I popped the factory ecu back in and did a pull. The factory ecu made almost the identical rwhp and torque.
The motor is supposed to be stock, the only add ons that I can see are a Toda header with staight exhaust and a cold air intake. It seems like the engine isn't breathing so I checked the intake for obstructions. The only other thing that I can think of would be cam timing but I don't know how that would be off if this was a complete crate motor.
This thing is missing a good 80 rwhp and I don't know where it went, any ideas?

 

With an untested motor, compression and leakdown tests would be the first thing to check.

 

I do plan on doing a compression test today but I don't plan on finding anything wrong there. This is a brand new motor from Honda and there was no indication of compression problem. No smoke to speak of and you can tell by how it cranks over that it is very tight.
But I will post what I find.
Thanks,
Mike

 

Another thing to try is to verify VTEC operation. You say the car has a straight exhaust? So no cat to get plugged?

 

The V-TEC is definetly working, there is a nice jump in power at 5400 rpm. There is a "bullet" style resinator mounted just behind the header collector followed by another "bullet" style muffler and turn down tip just before the rear axle.

 

I think I found the problem.
I started the car up and ran it at idle until it was up to operating temperature, I then pulled the plugs one by one inspecting their condition.
Plugs 1-3 were burning perfectly, but when I got to #4 the plug was wet and carbon fouled.
I then proceeded to do a cranking compression test. The results were 240-242-242-242 (running from 4-1)so all is good there.
I then re-installed the plugs (cleaned #4)and coils. I then realized that I had mixed up the coils and didn't know which one was over top of #4.
I started the motor back up and then took a Raytech non-contact thermometer to the header primaries. One of the header pipes was not getting hot, this time it was cylinder #2. I had left the hold down bolts out of the coils so I then proceeded to lift the coils off the plugs one by one to see how this would effect the idle. Lifting #2 made no differece to the idle, #4 also made little to no difference (but #4's header pipe was up to temp). Lifting either #1 or #3 would just about kill the motor.
I then swapped the suspected bad coil (#2) to #1, restarted the motor and again checked the header primaries temp. #1's header pipe was staying cold and now if I lifted the coil on #1 there was no change to the idle.
So I guess it pretty clear that I have a bad coil. So it's off to the parts store for me.....

I have to say that that is the smoothest 3 cylinder engine that I have ever felt/heard!

 

Glad you found the problem