My 2000 Honda Accord VTEC 4-cyl popped a CEL, and now starts a lot harder than normal. It runs a bit rough at first, but will calm down in about a minute and idle fine at 1000 rpm. But on acceleration it runs fine up to 2500 RPM, then suddenly drops off to about 1800 RPM like it’s gonna die, then picks back up and surges at 2500 RPM. It’s drivable and runs normally if you keep the RPM below 2500.
The ODB 2 connector doesn’t seem to work (3 different checkers show no connection). I verified all the pins are connecting (using aluminum foil).
I pulled the plugs and have checked the spark plugs, wires, and coil (all 4 plugs show good spark on cranking).
I’ve checked the MAP by disconnecting with no change. And I’ve replaced the VTEC pressure sensor/solenoid assembly with no change.
What else could this be? It happens exactly at 2500 RPM, every time! Could it be the ECU?

 

I moved your thread to the General Tech Help section. Please do not post help questions in the DIY section, per the forum rules.

 

Describe exactly how you used aluminum foil to show all the pins are connecting. I'm wondering if the foil shorted among the pins??

 

The problem occurred before the aluminum foil trick. As you probably know, often a malfunctioning ODBII connector is due not making good contact on all of the pins in the connector itself. Trick# 1 is to gently bend the pins slightly to improve the connection. In this case I couldn't do that, so trick #2 is to use tiny rolled aluminum foil (~ 1/4 x 1/4" piece) and roll it tightly and stuff it into each of the female ODBII holes that have electrodes installed (usually 6 of the 16) ... the foil conducts and will ensure a good contact. Yes, of course, one must not be sloppy and allow for the possibility of pins shorting.

 

FYI for anyone interested, I took the car to the dealer, who says it's the PCM. That's what I suspected since the PCM feeds data signal to the ODBII, which is probably why that doesn't work. Now I need to find a reasonably priced PCM.