running rich

[88mkiisupra]

I have an 88 n/a mkiii. The cat plugged up and I had to remove it. Now it runs rich, and I can't get it to lean out. Is there something that I can do to resolve this problem short of putting a cat back on?
thanks,
Aaron

Also, I'd like to know how to pull the codes as my check engine light is on.

 

[lil_dcb7]

i dont think theres much you can do except for putting the cat back on...:aigo:

 

[88mkiisupra]

i dont think theres much you can do except for putting the cat back on...:aigo:

do you think it would help to use a high flo cat?

 

[jetjock]

Uh, your catalyst plugged because the engine was running rich, not the other way around. A new cat will also fail unless you fix the mixture.

 

[BlackMKIII]

How are you attempting to lean the mixture? I had issues with my 86.5 about the same. Check O2 sensor, Water Temp Sensor, and Air Flow Meter. My problems were solved by replacing all 3 using the "shotgun diagnostics" method. :nono:

 

[88mkiisupra]

How are you attempting to lean the mixture? I had issues with my 86.5 about the same. Check O2 sensor, Water Temp Sensor, and Air Flow Meter. My problems were solved by replacing all 3 using the "shotgun diagnostics" method. :nono:

Well put new o2 on, and afm tests within specs, ordered new temp sensor, but if i knew how to retrieve trouble codes on this thing it may be easier. When i bought it, some kid had ripped all of the emissions stuff and vacuum hoses off, put a cold air intake on it, and the entire intake had about an inch and a half of carbon buildup in it. the head had been replaced no doubt because of the carbon buildup, and it had what looked like a new cat. when i pulled the throttle body to replace the plugs, i found out that all of the vaccuum ports were plugged with carbon. i cleaned this out and sealed any vaccuum leaks. still ran rich. I then rehooked the egr and all vaccuum that I could figure out from routing diagram, and still had problem. I think I may have lost feul management or at least mixture control. also there is this slight ticking sound coming from the head on both the intake and exhaust sides. Possible weak valve springs?

 

[BlackMKIII]

To pull codes from MIL, hook a jumper from T to E1 in the "Diagnostic" box under the hood. With the key on, the MIL will flash the codes. (51, 42 etc.) Count the flashes (for example, three flashes, short pause, four flashes = 34) Long pauses are a seperation between different codes. Codes are only 2 digits.

Oh, and welcome to the club!

 

[88mkiisupra]

how bout a bad knock sensor?

 

[88mkiisupra]

To pull codes from MIL, hook a jumper from T to E1 in the "Diagnostic" box under the hood. With the key on, the MIL will flash the codes. (51, 42 etc.) Count the flashes (for example, three flashes, short pause, four flashes = 34) Long pauses are a seperation between different codes. Codes are only 2 digits.

Oh, and welcome to the club!

thanks:icon_bigg

 

[jetjock]

Sad to see yet another case where an owner gets screwed by previous owners yanking off emissions gear and otherwise not having a clue about what they're doing.

The engine is obviously not in fuel control. Short the block as MKIII said and read any codes. While it's shorted connect a voltmeter to battery negative and terminal Vf. Hold the engine at 2500 rpm and check to see if the meter is rapidly switching back and forth between 0 and 5 volts. I'd also be checking fuel pressure if I was you.

 

[88mkiisupra]

Sad to see yet another case where an owner gets screwed by previous owners yanking off emissions gear and otherwise not having a clue about what they're doing.

The engine is obviously not in fuel control. Short the block as MKIII said and read any codes. While it's shorted connect a voltmeter to battery negative and terminal Vf. Hold the engine at 2500 rpm and check to see if the meter is rapidly switching back and forth between 0 and 5 volts. I'd also be checking fuel pressure if I was you.

ok, i'll give that a try and let you know what i find. the only code i had was 52 for the knock sensor. only thing is i don't know where to find it.none of my literature has its location.

 

[BlackMKIII]

The knock sensor SHOULD be, iirc, on the driver's side of the engine block.

 

[jetjock]

You'll need to fix that, it's serious. It's either a bad sensor or more likely bad wiring. The sensor is located on the drivers side of the engine block below the intake manifold.

Was the check engine light on? If not clear the code as it may be old and the ECU treats this code in a special way when it comes to the CEL. If it comes back you can go from there. Remove the EFI fuse for 20-30 seconds to clear codes. Continue on with checking for fuel control using Vf.

 

[BlackMKIII]

You'll need to fix that, it's serious.

Ditto that. It controls the ignition timing through the computer. It listens for knocking (detonation) and retards timing if you use low quality gas.

 

[88mkiisupra]

You'll need to fix that, it's serious. It's either a bad sensor or more likely bad wiring. The sensor is located on the drivers side of the engine block below the intake manifold.

Was the check engine light on? If not clear the code as it may be old and the ECU treats this code in a special way when it comes to the CEL. If it comes back you can go from there. Remove the EFI fuse for 20-30 seconds to clear codes. Continue on with checking for fuel control using Vf.

thanks

 

[88mkiisupra]

I'll keep you posted on my progress as I can use the help. When it comes to domestics, I can generally figure them out, but i still get a little lost when it comes to imports.

 

[88mkiisupra]

knock sensor unhooked wire missing. my literature says it should be single wire white. hoping this will fix prob as there is also a red/green or orange green and black/pinkor black/orange or black/red also hanging down there.

 

[BlackMKIII]

Perhaps it is time to invest in an TSRM?

 

[88mkiisupra]

Perhaps it is time to invest in an TSRM?

have a haynes book on the mkiii, but unfortunately it doesn't cover a whole lot of the wiring. took a guess at the wiring and got lucky the first wire i picked was for the sensor. now my cel is off, it smells as if i am running lean, and when i get on it alt high rpm it emits an almost transparent white cloud of smoke, then a black one that resembles carbon smoke. took it out last night, i have most of my power back. left a 50 foot posi mark leaving a stoplight after being cut off by a trucker. couldn't even get it to bark them before. still need to check the vaf again along with the o2, coolant sensor, and feul pressure. I'm also going to check the timing and inspect the timing belt. I appreciate all the help, and will keep you posted on my results. looks like i made a good deal on an 800 dollar screamer, because the owner had no idea what they were doing.:evildeal:

 

[88mkiisupra]

OK. O2 SENSOR IS AT AVERAGE OF .488, BUT VAF IS BOUNCING ALL OVER THE SCALE. PRICING A VAF, AND REPLACING THE COOLANT TEMP SENSOR. ALSO PUTTING A CAT BACK ON WITH NEW FLANGE GASKETS, AS WELL AS PERFORMING AN ENGINE FLUSH.