A good friend of mine just purchased a cherry '90 CRX, new paint and perfect interior. When I took a look I saw no HF emblem but the throttle body was PGM-FI, when I checked the engine code it was D15B2 which according to my Chiltons manual is the DX engine. If somebody swapped a DX engine into a HF they did a good job other than leaving the HF fuel injection and throttle body. The tach redlines at 5k which would be an HF as well as the cat bolting directly under the exhaust manifold. Has anybody heard of people swapping a DX motor into a HF without changing the PGM-FI to DP-FI and if so does it make more power? The thing is pitifully slow right now but he bought with the intention of dropping in a D16Z6 so I told him my concerns about the engine being weird only mattered at all if he were going to keep the engine. Any insight?

the HF engine's had MPFI not DPFI(aka PGM-FI) so he would need to rewire the car for two injectors instead of the four that the HF and Si had. the only forseable advantage to this swap would be the approx. 20hp the DX engine adds to the HF engine.

The throttle body says "PGM-FI", the piping from the airbox to throttle body is a lot thinner in diameter than the piping in my SI. The valve cover is a 16 valve (the HF is 8 valve?) and the engine code is D15B2 (DX) not D15B6 (HF). I've only had experience with SI's so I really didn't know what to tell him, it idles a little jumpy i'm guessing it's the use of an HF ecu on a DX motor. He's planning on swapping the motor so I didn't think it was a big deal especially since the interior and exterior are so cherry.

he prolly really has a DX and has some other internal problems causing the rough idle and stuff, such as the Throttle Position Sensor, fuel pump, etc.

tell him to look over the car more carefully to determine what is really wrong with it.

the Hf was 8v and the DX and Si were 16v.

It's not really a rough idle, it jumps as if your tapping your foot on the gas while waiting at a light.

HF characteristics:
1) 5k redline
2) no passenger side mirror
3) PGM-FI
4) cat/conv mounted to exhaust header
5) no clock
6) no rear wiper

DX characteristics:
1) D15B2 engine code
2) 16 valve head

The above list makes it seem like someone just swapped a DX motor into an HF without making any other modifications. Weird but whatever, anyone have any good theories?