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Some of you know me others don't. I was an S2000 pilot for awhile. Have driven other cars and now I own the soul of an S2000. It sits in a Lotus 7 clone with total weight of 1400lbs. You would think it would be sick fast but engine issues are keeping my eyes for peeling off of my head. Any local engine experts?

Here's the info:
New plugs and MAP sensor
Honda S2000 ECU
Fuel is getting to the engine
Not getting fuel back into the return line on the tank
donor car 2002 w/ 48K miles
aftermarket gauges and speedo (still having speedo issues)

Engine starts and idles w/o issues
Under light acceleration engine will pull fine sometimes bucks
Will slowly climb to 9K seems to pull better at 7K, not sure if VTEC is kicking in. Been awhile since I drove an S2000.
On highway engine will lose power and slowly drop, blipping throttle does not help, most allow it to idle down before applying power.

Could lack of return fuel indicate not enough fuel? If so why does it seem to pull stronger in the upper RPMs?

Would non-functioning speedo impact ECU? Limp mode? What is limp mode and what does it limit?

Thanks

 

You're using the stock ecu, correct?

Fuel pump is sufficient to feed the injectors? No issue with the fuel filter? Fuel pressure at the fuel rail within specs?

No issues with the exhaust, ie no restrictions?

Oil pressure ok?

Valves adjusted? Compression ok?

There are many variables...I've seen a similar symptom to what you describe a couple times on an s2k. Once was due to a bad cat restricting the exhaust. The other was from vtec not engaging because the sychro pin wasn't engaging to lock the cam lobes to the high rpm profile.

For a non-stook...I've seen this symptom where the fuel was restricted to the fuel rail. Either clogged lines, pinched lines or old collapsing lines.

 

Thanks for the reply. Answers in CAPS

You're using the stock ecu, correct? YES

Fuel pump is sufficient to feed the injectors? No issue with the fuel filter? Fuel pressure at the fuel rail within specs? NEED TO CHECK PRESURE

No issues with the exhaust, ie no restrictions? NONE

Oil pressure ok? YES

Valves adjusted? YES Compression ok? NEED TO CHECK.

 

Hey Ken .. welcome back to the s2k engine. i know it's pretty hot in Texas, but still this is a shot in the dark.

wondering if you hook up the OBD2 while running to see if anything jumps out (if IAT is over 170F ish, then the motor should pull about like a miata).
any chance this is heat soak on the IAT and it's getting hotter in there?

Anyway, that's about the only area I have some realworld knowledge on.. good luck.. can't wait to DRIVE it!!

also, why not use that maxqdata instead of "eye's peel back" method to measure acceleration?