Hey all....i'm a newbie to this forum and to the "Honda experience"......my son just bought a 98 civic hatch and is having a severe problem....

Symptoms:

- Idles great and performs well when accelerating

- when running through the gears, especially in the lower 1/2/3 gears if you try to maintain speed it bucks/jerks pretty significantly until you apply more throttle

- when sitting still and running, you can increase the throttle and whenever you settle on a rev amount, it will begin surging up and down by itself even though you are maintaining the exact same position on the throttle mechanism

Attempted Diagnosis/fix and specifics of his crazy setup:

- Changed out the TPS and get the same problem

- Now the crazy stuff. This motor is a D16y7 and has had many mods done to it previously. First it has a D15 intake (not sure which one) manifold on it and the harness has been modified somehow to accomodate the injectors from that manifold. It looks like this was done to turbo the car although it is not turbo'd now. The harness was also modified because it was clearly originally an automatic, but my son's car is a 5-speed...The ECU is the correct "manual" ECU though. Oh yeah, it also has a different header/exhaust mated to the engine w/o O2 sensor (had the CEL removed) with aftermarket cat and exhaust backwards.

So with all that craziness going on, can anyone give me any idea of where/what I should look at first to try and narrow down what the problem is?????????

Thanks for any help.....

 

What ECU is installed? Post the ECU code on the label.

What CEL codes are thrown? See Codes sticky at the top of the forum.

Are you saying that no O2 sensors are connected?

Post pictures of the engine and engine bay.

 

Yikes with the mish mash of wiring and mods its hard to say...
I know you bought it that way but who in their right minds chops up a car like that and calls it transportation?
Keep us posted.