Need Help Trouble Shooting!
 

Alright so i bought an rhd rx7 with no motor in it, went out and bought a used jdm motor with transmission, ecu and everything. The car i bought came with an aftermarket ecu that i had installed. I put the motor and transmission in a couple of weeks ago and when i started for the first time i had some problems right off the bat. The car would start normally then rev up to about 1500 rpm while smoke is pouring out of the exhaust, then it would drop to just below 1000rpm and idle like shit and eventually stall!:( I have chaged the spark plugs already, but i have not checked compression, which im wishing i would have done before i bought the motor, but im stupid and didn't lol. I have also swapped the ecu back to the stock one to see if it would make any difference but it didn't. P.S. The check engine light is NOT on! I really need some help on this one, so if you have any ideas on what it might be it would be greatly appreciated! :D

Thanks so much

most JDM engines have fogging oil in them, how long did you run the engine for?

If the car is not a North American car, chances are it doesn't have a Check Engine Light on the dash. You'll need to use a LED light to get the engine codes (if there are any):

https://www.rx7club.com/showthread.p...hlight=cel+led

I would start with checking the engine codes and making sure the TPS and other the throttle adjustments are correct first. If you need info on the TPS, check this thread:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fixed-my-idle-problems-backfiring-bucking-more-170731/

Also make sure you have all the ground locations accounted for correctly.

I ran it until it stalled so maybe about 2 minutes, but i have started it like 10 times since i put the motor in and all those times i ran it until it stalled as well. The previous owner swaped the jdm dash to the north american dash so i does have an engine light because it iluminates when i turn the key to the on position. I will go over and check all my grounds again but i think they are all correct, and i will also check the others things you mentioned

Thanks

Make sure all the sensor connections are ok, make sure your grounds are tight, definitially check the ecu codes, check the tps to make sure its within its correct values....so many things..

What happens when you give it gas?

So i checked my tps and it is in spec. When i give it gas in neutral it revs up slowly and when i let off, it drops below 500rpm and it sounds like its about to stall

compression test.

So I did a compression test, the front camber has good compression but the rear chamber has 0 compression! FML :mad:
Looks like im pullin the motor again :)

Typical JDM motor, they all need to be rebuilt before installing. We get at least one a month and have never seen one that did not need a rebuild. Not that they are all blown but they have stuck( or rusted) apex seals and side seals from sitting so long, even though thye are lube prior. We are always taking them apart for parts so it is not a big deal.