Codes And More Codes!

MercXr7-5speed

SCCoA Member
Posting for a buddy of mine.....

He ust bought a 92 sc auto with 140k. Has a idle of 2k all the time. IAC? codes he got

KOEO
125 TPS voltage lower than excpected
172 O2 sensor indicated lean condition, right side
175 O2 sensor unable to sitch, left side
176 O2 sensor indicated lean condition, left side
181 Adaptive fuel limit reached a part throttle, system lean, rt side
189 adaptive fuel......left side
212 Loss of TACH input to eca; SPOUT signal grounded

KOER
411 Unable to control Low RPM during self test
412 " " " High " " " "

Anyone have any ideas? Thanks in advance.

Ps. He got it for 800 bucks and the body is strait as an arrow.

Joe
 
OK MERCXr7-5speed

125= faulty throttle position sensor it is broke not hooked up or has a bad connection.

172 and 176 = You are not getting enough gas to both heads or banks. Possible that you have a weak fuel pump there are some many problems that once you fix them the EEC will be able to send the proper amount of fuel The O2 help adjust the amount of fuel as you step on the gas bad sensors will cause the motor to run rich or lean.

175= broken O2 sensor or bad connection not able to switch between a rich and lean condition.

181 and 189 = once again not enough fuel getting to cylinders on the right and left sides.

212 = A serious bad connection. this could be caused by a faulty cam sensor or crank sensor but in your case your car is starting and running so those are probably OK. The spout plug is a jumper in the wire loom that sends the signal to the TACH and EEC yours is bad or the connection is bad. It is a square black plug in the wire loom it is not connected to the engine it usually sits on top of the AC compressor.

411 and 412 =not sure but could be vacume leaks or the fact it is not getting enough gas.

This cars EEC will try to keep the car running by going into FMEM (failure mode effects managment ) this means even if you have faulty sensors the EEC will use what is called a K.A.M processor KEEP ALIVE MEMORY. This feature use past history readings to predict and guess. This is what help the car to lean to idle again.
You have got alot of problem and need to start knocking them out one by one. First place I would start is code 212 loss of Tach input spout grounded it is the biggest problem here and once it is fixed it might help correct your other problems. You need spout to help the EEC and motor learn to idle. GOOD LUCK
 
You have a bad IAC that is whats causing the 2K idle.
That will also give you false codes for the other items you listed.
Once you get the idle working again 95% of thoses codes will disappear.
 
I suspected the IAC and gave him my extra. All codes gone! He got such a great deal. I's a 91 not a 92. I has all options. Half tweed seats and the moonroof has the cover with the vents in it. Only thing the car doesn't have is keyless and lighting group. His 800 dollar sc looks 50% better than my 800 dollar xr7.

Joe
 
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