Car unable to rev past 3500
 

Hi guys,

I've been working on a 1985 12a RX-7 GS for the past few months. I've had the carb rebuilt and replaced a lot of parts in the ignition system (battery, coils, plug wires, distributor rotor and cap, both ICM and new plugs). I've checked the spark and get a strong blue spark from all 4 plugs. The car starts up hesitantly but once warm will sit at idle no problem. Acceleration isn't very strong and upon reaching 3-3.5k revs the revs suddenly fall down to about 1500 even though i'm still giving it gas and then come back up again. It does this in 2nd gear as well. Any thoughts?

Side note: When the car is idling, if I disconnect the ICM responsible for the trailing and leading spark plugs in housing #2 there is no change in idle. Similarly, the car will start with the T2 and L2 spark plug wires disconnected, and it feels the same as if all four plugs are connected. :scratch:

Appreciate any help with this issue.

If there is no change in idle do a compression test on the engine

If your compression is good (over 90psi on all 6 faces) i would be looking at the cat next

Does it ever bog down and die? Check the Fuel Window on the carburetor. Make sure that it is at least half way filled with fuel. Idling on the driveway rev the car up to 2K for a few minutes and see if the Fuel window depletes. If it doesnt come back up theres an issue with fuel delivery. If its not at least half way full it can be several issues.
1. Fuel filter clogged
2. Fuel pump not working properly
3. Carb Jets are clogged or installed wrong

I've just done a compression test and don't get any reading on the rear housing. Front housing has 110psi. What are my options?

Is absolutely no reading on the gauge normal for no compression or should I be seeing lower than desirable psi? Wondering if I could have made an error.

Options are sell it, or yank the engine and rebuild it, but don't expect it to be a quick rebuild, sounds like your rear rotor housing might be toast and you'll have to find a good used one as new ones are NLA