I am having problems with my 1991 Civic. I have replaced the fuel filter, the fuel pump, the main relay, the throttle positioning sensor, caps, rotors, you name it, it has been replaced. It all started with taking it in for a new timing belt and water pump at about 155,000 miles (I bought the car new and have kept it well maintained.) I mentioned to the mechanic (not a Honda dealer) that it was feeling like it was wanting to stall on me when I stopped at a light, or slowed to make a turn. I got it back after he replaced the timing belt and water pump, caps, rotors, fuel filter, etc. and it was still doing the same thing, but actually stalling and not starting back up. So I then took it to a friend of my dad's who replaced the ignition switch, the fuel pump, etc. Anyway it is running okay now, but it still feels like it's going to stall, and the rpm's go way down when I slow down, but it doesn't stall. My dad's friend wants to hook it up to his compute diagnostic tool, but he can't figure out where to hook it up. He said he has never had problems finding where to hook up the diagnostic tool. I called Auto Zone, and they said it can't be done. Can anyone tell me where you hook this up?
Thanks for the help.
Lisarae

There's a 3-P Data Link Connector, located in the rubber mount, next to the 2-P Service Check Connector. Both of these are located just under the dash, near the passenger's side kick panel.

If that doesn't work out for you, read sections A and B in the link below:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-honda-civics-46563.html

I would:

1. Replace the igniter and coil, both of which are problematic on older Hondas. 2. Run the K-Test on the ECM.
3. Ensure your spark plugs are in good shape (NGK only).
4. Set initial idle rpm and check timing with a timing light (See sections C and D, in the above link).

[[QUOTE=txgreasemonkey]There's a 3-P Data Link Connector, located in the rubber mount, next to the 2-P Service Check Connector. Both of these are located just under the dash, near the passenger's side kick panel.

Hey, sorry to be such a pain, but my mechanic cannot find this port. He looked under the dash and under the kick panel itself, but he cannot find it. Honda wants $75 to do the diagnostic check, but my mechanic can do it if he finds the port.

Please help.
Thanks,
lisarae