my cars running rich, wont pass inspection. HELP!

[thechori]

well, i went today to get the car inspected and the guy said it was running really rich, wasn't near passing.. definitely explains why i've been getting pretty crappy mpg (around 12-14)

is there something i can do on my own to adjust this? or do i have to take it to a mechanic, any info is appreciated

oh the car is an 89 N/A

 

[CRE]

The first things to check are your O2 sensor, plugs, plug wires rotor and cap. If they're fine then you should look at the AFM, TPS and ignition coil. There are a couple other possibilities, but these are the most common.

 

[cypher02xd]

o2 sensor would be my first suspect. if you wanna check your plugs/wires start the car and pop the hood. what you're going to do is pull a wire off and listen to hear if theres a chance in the engine sound. if there is then that cylinder is operating correctly, if not then somethings up. either the plug or wire.

pull the rotor off and look at the rotor/cap. look for scoring of the material or carbon. carbon is a result of it arching constantly would might suggest a crack in the rotor. if the rotor is worn too much then it won't make proper contact with the cap resulting in a weak spark.

with that bad of mileage i'm leaning towards the o2 sensor. with the o2 not operating properly the ecu will throw itself into a limp mode. it'll dump fuel and pull back timing most of the time. this is to ensure that damage isn't done to the engine but severely reduces gas mileage and power.

 

[isnms]

First thing to do is check your codes:
http://www.cygnusx1.net/Supra/TechTips/engine_error_codes.aspx

 

[supradan22]

If you need an 89 na AFM let me know I got one.

 

[thechori]

alright, i'll check the codes tomorrow, a few months ago the car was spitting out code 52, but my friend fixed it and i haven't checked since.. will also replace the o2 sensor and see if that fixes it

thanks for all the help

 

[BoostLess7mge]

i had the same problem as you, my fuel pressure regulator was bad. not sure how to check if thats working or not, but just letting you know. good luck!

 

[Anomili]

Not to hijack the thread, but this reminds me just how happy I am that in Canada (Ontario) my 87 is 20 years old so official a historic car that does not need to pass emissions.

On topic, the above info is really good. Have you changed/modded anything?

 

[CRE]

True, a bad Fuel Pressure Regulator or even Damper can cause the engine to run rich. It's less common, although on my car that's what started the problems... A Toyota Service Department should be able to test them, I think it cost me about $30. Replacing them wasn't nearly as inexpensive, but if either of those is your issue hopefully you won't be replacing both.

 

[thechori]

alright well i ran the diagnosis, and on idle the car was fine, but if i rev'd it up a little, i got the code 51, something about a switch signal.. i didn't understand what that was on the TSRM, could that be affecting the richness?

i went and bought a new set of spark plugs for the car and will be picking up a new O2 sensor tomorrow, hopefully this'll do the trick

 

[BoostLess7mge]

you WILL get a code 51 if you rev the car with the jumper wires in. it will show the code for a few secs, then when the idle is steady, the code will go away. if your just checking codes, the car can stay off. if your trying to adjust the TPS, then the car must be on.

on a side note, i hope you bought NGK or Autolite plugs. just stay away from Bosch, their evil!

 

[thechori]

you WILL get a code 51 if you rev the car with the jumper wires in. it will show the code for a few secs, then when the idle is steady, the code will go away. if your just checking codes, the car can stay off. if your trying to adjust the TPS, then the car must be on.

on a side note, i hope you bought NGK or Autolite plugs. just stay away from Bosch, their evil!

oh alright, i thought that i had a problem. it would go away after it got back to normal and i thought that was odd, coolness

yea i got the NGK plugs, b/c i heard good things about them

 

[thechori]

oh i forgot to mention, the car has created a pretty huge buildup at the end of the exhaust pipe that looks something like really dark grinded coal or something (i replaced the exhaust system maybe 3-4 months ago), i know this is a sign that the car isn't running correctly..but what could cause this?

 

[CRE]

Is it oily? Or perhaps oil along with the remains of your cat's guts?

 

[thechori]

well, the cat is relatively new, i got it along with the exhaust. the car is using/leaking coolant as well, is this connecting in any way?

 

[CRE]

You could be burning oil... Where is the coolant leaking? Have you run a compression test? Is your coolant showing any signs of contamination?

 

[thechori]

You could be burning oil... Where is the coolant leaking? Have you run a compression test? Is your coolant showing any signs of contamination?

i don't believe the car is burning oil, i checked the level and it looked normal. the coolant is leaking ONLY from the overflow tank, i haven't run any compression tests, but the car is running perfectly so i don't think it should be bad. BUT.. in the overflow, the tank is pretty dirty, and it is contaminating the coolant, could this cause the car to burn it though? it could be a leak but i don't know how to find the leak

 

[JAB89]

This is deja vu all over again for me. I had all of these symptoms with my son's '89 N/A 5-speed. I believe you have two separate problems, as I did.

coolant is leaking ONLY from the overflow tank, but the car is running perfectly. BUT.. in the overflow, the tank is pretty dirty, and it is contaminating the coolant, but i don't know how to find the leak

Coolant being pushed out the overflow and an oily film on top of the coolant in the overflow tank after it sits overnight, strongly suggests a BHG to me. I had this and found the most conclusive way to check it was to pressurize each cylinder (80 psi) for 5 minutes and look for air bubbles in the radiator. Note; my BHG was a very small leak (preliminary to a big one) so I was able to fix it with a re-torque. I would address this problem first when you are changing plugs. See my posts in this thread:
http://www.supramania.com/forums/showthread.php?t=16296&page=3

well, i went today to get the car inspected and the guy said it was running really rich, wasn't near passing.. definitely explains why i've been getting pretty crappy mpg (around 12-14)

Been there, done that. My emissions were 10 times the maximum limits. This was a long row to hoe for me. Turned out to be the ECU but you have to eliminate a whole bunch of stuff first unless you happen to have access to a spare for testing. And besides you might find another cause along the way. Good advice from CRE and cypher02xd on starting with the O2 sensor. Note; if you finally decide it is the ECU get a used one (new = $hundreds).

I used the “Inspection of Oxygen Sensor” routine on page FI-118 of the TSRM to tell me what was going on and to tell when it was fixed (thats important). I also connected an A/F Ratio gauge to the diagnostic block (as well as the voltmeter) to show me a picture of what was happening. Here is the link to the TSRM (site seems to be down right now):
http://www.cygnusx1.net/supra/library/TSRM/index.html

Also, my thread on this problem:
http://www.supramania.com/forums/showthread.php?t=14266

the car has created a pretty huge buildup at the end of the exhaust pipe that looks something like really dark grinded coal or something

I too had a lot of black crud in the exhaust system and the plugs were very black. I believe it was a function of running so grossly rich. The other bad news is that once you get your mixture corrected, you may find the Cat has been damaged from all that rich mixture. Sorry to be the messenger on this one.

Hope this helps. Good Luck.