Hello,
As you may remember, I swapped a 94 1.5L engine into my 91 Civic, after my original 1.5L died. It runs well, but the exhaust smells a bit rich and I'm only getting about 36MPG, vs the 43 I used to get before. There is also a hint of hesitation at lower RPM's.

I noticed that when I pull the plug wires on either plug #3 or #4 (#1 being next to the distributor), it has a MUCH bigger effect on idle and performance than when I pull wires 1 or 2, to the point that with wire 3 or 4 disconnected, it will not idle. With Wires 1 or 2 (or BOTH)disconnected, it will idle happily. My first thought was that I had a blown head gasket, so I did a compression check. Both are at about 185 lbs. My other thought was that the injectors in those two cylinders may not be firing correctly, but then I remember that this is a throttle body injection system, with a wet intake manifold. I have replaced the wires and plugs, and yes, there is spark in all four. I also checked the firing order (1342). Plugs look good, with a light greyish color.

What could be happening??

Thanks,
Mikel

 

I am in the process of the exact same swap..

did you check the coolant temp sensor? it is a single wire connector under the distributor, it may explain your hard start issue as well.

Questions:
You kept the throttle body injection from the 91 car, did you also keep the distributor?

I have a 2 pin connector on the back side of the D2 block that is not there on the D7 block. Obviously a sensor of some sort, You have any idea what it is?


one more thing to consider, you're loss of mileage may be the loss in efficiency, going from direct injection to TB.


Thanks,
Chris

 

Hello,
These are the differences I found from my 91 to the 94 engine:

- Motor mounts are different - Had to use the old ones.
- Fan switch mount is not threaded in the 94 block. (this is the two pin sensor you see in the back of your engine)
- There is an extra coolant outlet in the metal hose that runs behind the block, that was not needed and had to be plugged.

I used all the sensors from my old engine, distributor and intake manifold. All I used from the donor 94 was the block, head and reciprocating assembly. I left the transmission in the car and I simply unbolted both manifolds and lifted the old engine out.

I have not checked the coolant temperature switch - I did replace it with an spare old one I had, but made no difference. How do I check it?

Good luck with your swap.
Mikel

 

How did you resolve the fan switch?

I do not remember if it is normaly open or closed, but you can Ohm it from the end of the connector to ground, if it is open then you can ground the connector to "close" the sensor and see if that helps your start up. or if it is closed when you test it, the simply try running it with the connector disconnected.




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Chris,
The switch seemed to be located in the coolant outlet, so I wired it to that switch - I haven't checked if it works.

The sending unit under the distributor is for the temp gauge. The other one (with the two wire connector) seems to be the temperature switch - Unplugging it gives me a check-engine light and makes it run a bit rough when warm.
Mikel

 

I've got my engine in and done, and am also running rich, blowing black smoke, but it is intermitant. going to try seafoam and an O2 sensor. just checking to see if you resolved your issues.

thanks,
Chris
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In mine the exhaust smells a bit rich, but nowhere near blowing black smoke. My plugs don't show a rich condition at all (light greyish color).
Other than that, engine runs pretty good - My MPG is now about 39MPG, so it can't be doing that bad.

 

Any luck?

 

from what i have read, at least about my 88, is that the TB gets better gas mileage then the port fuel injection.

 

I disconnected the idle air sensor and it runs great now, I;m going to Junk Yard and get a TB and swap it out to see of that will fix it.


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