1995 Corolla Fuel Issues - Pre-1997 Toyota Corolla and Geo Prizm

Hello to everyone out there, this is my first post. I recently bought a 1995 Corolla Dx 1.8, the previous owner didn't do regular maintenance on the car. She regularly changed oil and if there was a check engine light, she would get it fixed. I have recently changed the spark plugs/wires. Flushed the coolant, replaced valve cover gasket because it was leaking , oil change (twice) in 5,000 miles, replaced all belts and I'm about to replace front engine mount because it rattles like crazy. Recently, my car has been running rich and I'd like to know what could be causing this. Could it be the O2 sensor, fuel injector...Please excuse my ignorance, this is my first car and I am learning. If there is anyone out there who is willing to provide some advice I would greatly be in debt to you. My friends mechanic, says I should change the oil immediately if there is gas in the oil, which I plan on doing this week or next. He also recommends Castrol 10w30 or Mobil 10w30.

Thanks in advance.

Mykecorolla haha

What makes you believe that the car is running rich? Black smoke on start up? Poor fuel economy?

There are several systems involved in the control of the air/fuel mix. The most direct is the O2 sensor, it is the one providing the feedback information to control the overall mix. But components like a faulty coolant temperature sensor, leaking exhaust system, clogged injectors, worn ignition components, bad ECM, etc. all can cause an excessively rich air/fuel mix.

I'd monitor how much fuel dilution there is in the used motor oil. Also remove and read the sparkplugs, note any deposits and conditions of the electrode. If the car is running rich, it will show up on the plugs first (heavy soot, "wet" plug ends, etc.)

Hey fishexpo 101, thanks for the reply. The reason I suspect its running rich is I can smell a strong odor of gasoline in the oil, as well as a heavy smell of what appears to be raw gasoline coming out the tailpipe. I will check the condition of the spark plugs as soon as I can.

I forgot to mention that there is no visible smoke, the fuel economy seems about the same as the day I got it. About 30 or more mpg. I should note though, the gas gauge doesn't appear to be very accurate, its not consistent with the amount of driving. One more thing, the exhaust needs to be pushed back, its to far out.

Fuel odor in oil could be from worn rings - pretty normal for mixed driving or conditions where you idle the car for extended periods of time, even for a couple of minutes. But I'd get a used motor oil analysis just to have - gives you an idea of what the engine conditions are in terms of level of wear metals, coolant contamination, fuel dilution, etc. Catch little issues before they turn into expensive ones.

From your description of no visible smoke and decent fuel economy (30MPG is pretty good for a 7th gen with the 1.8L 7AFE engine) - I doubt it would be an O2 sensor issue or even running overly rich. The exhaust sticking out too far is more interesting - could be a leak in the exhaust system somewhere. Even one that is running perfectly will have a strong gasoline odor in the exhaust if there is a leak somewhere there. Can also cause the O2 sensor to read incorrectly, allowing for slightly rich mixture (not enough to cause smoke).

But my money will be on the plugs, plug wires, cap and rotor. Probably won't hurt to clean the throttlebody and check on the induction system (air filter, airbox, all the tubing running from that system). More so, since the early maintenance of the car is unknown.

Do you need to replace the distributor cap and rotor every 15,000 miles or 30,000?. I agree with you in early prevention, this will mostl likely prevent costly repairs in the future. The car has 140,000 miles, if I fix everything is it possible to reach at least 200,000 miles or beyond? I know that these cars can reach 250,00 if properly maintained. I realize you do not know the previous maintenance the car has had, but judging on what I've told you is this possible?

Could you recommend some services I might want to do since I just bought it from the previous owner?

1. transmission fluid flush?

2. timing belt

3. pcv valve

Anything you think I change please let me know..

I really appreciate the feedback.

I forgot to ask where do I get a motor oil analysis and how much will this cost?

For use motor oil analysis I use Blackstone labs - http://www.blackstone-labs.com/ - their standard analysis cost $25.

As for how long the car will run to, all depends on maintenance and a little bit of luck. Not knowing the history of the car makes lifespan determination very difficult. Even if you jump on all the maintenance requirements from now on, depending on what happened in the past - you may or may not hit 200K miles or more. Used motor oil analysis and some other tests, like compression testing, monitoring oil consumption, etc. should give you some idea of what the car is doing.

As for the cap and rotor replacement interval - depends on how the system looks. Generally, your plugs will last between 10K-30K miles for copper plugs, about double that for platinum plugs. Stay away from multi-pronged plugs like the Bosch+4 or similar, works great in other cars but reported to run poorly on Toyotas. Bosch single platinum are great though, but personally, I'd only run NGK or Denso plugs in the Toyota - proper reach, heat range, and known performance.

As for services, there was a pretty through discussion on this forum before, I don't remember the link off-hand, but you should be able to search for it.

Definitely stay away from transaxle flushes, unless they hook it directly to the pump, not suck it through the dipstick or backflush through the cooler lines. You'll know it is the better one if they have to drop the pan to do it. Timing belt - replace every 60K miles to be safe, waterpump, timing belt tensioner, and accessories at the same time as well, since all that stuff has to come off anyway to get to the timing belt. PCV valve every 10K-30K miles, depending on how much blowby you get. A quick test is the rattle check, remove PCV and shake it, if it makes a rattling noise, it is still good. But replace it at 30K miles, regardless if it rattles or not - as the spring inside can get tired by that point. Don't forget the other fluids - powersteering (every 30K miles), brake fluid (every other year or 30K miles), coolant flush (use distilled water and Toyota OEM coolant for longer life - every 60K miles, timing it with a waterpump/timing belt change is a good idea). Fuel filter - every 60K miles, good fuel injector cleaner once a year (Redline, Gumout Regane, etc.)

Thanks for the feedback I'll check it out.

95 corolla should be the 1zz I think kungfu master No??

Nope - 95 Corolla were the A-series engines. With the 1.6L 4AFE or 1.8L 7AFE, assuming this is the North American models. The 1ZZ-FE didn't appear until the 8th generation Corolla, starting with the 1998 model year.