ok i had a previous post kinda like this..but was never really solved... well it still bogs every so often, but the thing that bothers me the most is the really rough idle. IDK what the cause is. Its so rough that i can feel the steering wheel move slightly. Once i start moving it stops. What would be the causes? I was thinking maybe a tune up would help it but idk. Also the exhaust doesnt have a leak. and theres a high pitched noise comming from the front right of the car.

p.s its a 1988 convertible

 

A tune up is always a good place to start. The high pitched noise could be a failing bearing on one of your engine accessories.

 

+1 ^^^

Check and adjust/replace as necessary:
- Throttle Position Sensor - Set idle speed to 750
- Timing
- Spark Plugs and Plug wires
- BAC Valve
- Vacuum Lines

Clean and reseat all engine and frame grounds

Nonspecific rough idle can be tough to track down and fix

 

what do you suggest for spark plugs n wires? im going do mod it at some point soon. I figured OME but what do u all think?

 

Plugs should be NGK's; 2 leading and 2 trailing. The leadings have an L on them, and the Trailings have a T so they're easy to identify. As for plug wires, a good set of 8mm wires. There are lots of opinions as to which to use. I use the ones from Mazdatrix.com and they've worked just fine.

Run a search on plug wires and you'll see what I mean about differing opinions.

 

my firend that knows about rx7s said that my BAC valve might be gone, i know you can check i some how but its kinda confusing.. can any 1 explain plz ty

 

That's easy. Let the car idle with absolutely no accesories on (blower, lights, radio, defroster etc). Check the idle RPMs. Now turn on the blower or headlights. Is it idling at the same RPM? In both cases it should be at 750-800. If the idle drops when you turn on the accessory and doesn't come back up to the good range then your BAC valve is bad. I think there's another method in the FSM involving a multimeter but this is easy to do and tells you if the air bypass system is working.

 

after you do the above test, you can double check it. Remove the two nuts on the BAC, and pull it back. Turn the car to ACC and see if the little "piston" vibrates in the BAC. Be careful as the wireing will probably be brittle. Also You may need a replacement gasket for the bac with this method. so your call.

As far as the tune up. Look up the instructions on how to set the TPS. That will also help for a tune up.

Good luck

 

did tune up...car runs great rough idle gone, but the damn bog is still there just not as bad, ill check the BAC 2day and see if its really bad thanks for the help =)