i just bought a engine off of someone for my 91 crx hf. the motor is a 90 si motor and i just swapped it in using all of my hf parts such as tranny wiring harness, ecu, distributer, fuel injector...etc... when i went to start the car after i swapped it in, it did not start, it almost turns over but doesnt. i checked the compression on all 4 cylinders and the first three were 125 and the last was around 30. is there any way to fix this problem any suggestions or anything would help....i could get a different si motor but it would be a huge pain to go through the swap again b/c i have to rent out garage and if anyone in the central jersey area wants to come look at it to give me advise let me know. thanks a lot in advanced.
later

 

the problem is the wiring harness and ecu. the si is fuel injected and the hf is multiport inj. (one primary inj and one secondary) the si has four injs and the ecu is confused.

 

The 91 crx hf is multipoint fuel injected.. I believe that you might want to do a leakdown test to determine if indeed that cylinder is bad. You might have gotten a motor that needs a rebuild.

 

hey sorry to hear about your luck but if your 4th piston is at 30 lbp it does sound like you bought a motor that needs to be rebuilt.