Is it bad for my engine if i put 89 gas in my tank one time i have a 02 rsx type s and i know it needs 91 but my girl friend put 89 and i burned a whole tank of it. is that gonna mess my car up

The '96 pump will not work with TBI, so no, that wouldn't work. If the tank mounting is the same, and the hole for the pump is the same, you might be able to use the tank, and then buy a pump for your '91. Or look for a gas tank from salvage.

Check applicable trouble codes. Some of the national brand auto stores will check p0 codes for free. I'm not sure of engine liter size?
I looked at your owners manual, 91 octane recommended, but not required. 87 octane is ok.
Sometimes after filling up, the fumes in the gas tank are stirred up, You may have to check evap system?

For the Acura RSX 2.0 engine to replace valves you need to remove cylinder head.if you talking about timing chain you have to support engine to remove timing cover to replace timing chain and tensioner.

You might want to check the wires that go to the 02 sensor it sounds like when the tune up was done the wires may of become dis-connected. Unless of course the tune up was done to correct the problem. In that case first check for gas leak under car and around gas tank, if OK then, next ( I take it there's no check engine light on) borrow a fuel pressure tester from Auto Zone and test the fuel pressure After you've hooked up the tester run the engine a few minutes then shut it off and watch the gauge it it slowly drops you more then likely have a leaking fuel injector.If in fact this is the case, before you replace the injector run the fuel down to 1/4 tank and add a good fuel injector cleaner to the gas and run until close to empty. Put fuel in tank and drive at least 50 miles to allow fuel system to clean out. If still the same then the injector is bad. Note; You could also have a bad 02 sensor but that should set the check engine light.

misfire in all 4 cyclinders hmmm...... compression tester check compression 125psi is good 100 and lower is bad (head gasket they go bad) if that is good, do fuel filter,, or charge system is bad, or bad ground or bad coil

yes you can use 89 octane, but at first it may seem like the car is not running right. don't worry the car is okay it is that the 89 is thicker than the 91. just give it some time.

the only thing i can help you with is the replacement. go to a big scrap yard, give them your measurements, and they will find a gas tank for you. my gas tank was about $100 and my friend put it in for free so i cant help you there.

Jaguar recommends the highest grade of gas for the best overall performance. usually this is between 91 and 95 octane, however many of our Jaguar customers just put the mid- or low grade fuel in the car. Now you can do this but the performance and in most cases the gas mileage wont be as good as the premium gas.
The way I see it is if jaguar did all that testing and engineering for that car and they came to the conclusion that it works best with high octane then i would do it. But hey, its your choice, i hope i helped you out.

If you are talking about the brakes, then try to replace the masrter cylinder.

i got the same computer reading on my 2002 rsx-my emissions reading was just fine. i have done nothing about replacing and/or repairing the oxygen sensor for the past year and no surging or anything. i also wondered if using ethanol gas had anything to do with messing up the sensor as it was too much of a coincidence that after using two tankfuls of ethanol gas, the engine light came on