Bronco Forum - Full Size Ford Bronco Forum banner

1 - 4 of 4 Posts

·
I'd rather be sleeping
Joined
·
665 Posts
Discussion Starter #1
I have an '89 F250 w/460. I get a CEL every time I drive it.
Starts, idles and drives without issue. It has lots of power and can accelerate up a hill (easily an 8% grade or better) without effort. It's a 460 so gas mileage is crap.

Every time time i drive it after 15-20 minutes the CEL comes on. Stop, turn off the truck, wait 5 seconds and turn it on. CEL is gone. 15-20 minutes later it comes back on. CM code is 41. No other codes. Every time.
 

·
Registered
Joined
·
1,779 Posts
I have an '89 F250 w/460. I get a CEL every time I drive it.
Starts, idles and drives without issue. It has lots of power and can accelerate up a hill (easily an 8% grade or better) without effort. It's a 460 so gas mileage is crap.

Every time time i drive it after 15-20 minutes the CEL comes on. Stop, turn off the truck, wait 5 seconds and turn it on. CEL is gone. 15-20 minutes later it comes back on. CM code is 41. No other codes. Every time.
Oxygen sensor indicates lean, not switching. Either bad O2 sensor or you are running lean on the passenger side bank.
 

·
I'd rather be sleeping
Joined
·
665 Posts
Discussion Starter #3
There is only one O2 sensor so I assume it is a general lean condition. There is no pinging or other issues.
 

·
Super Moderator
Joined
·
26,042 Posts
I have an '89 F250 w/460. I get a CEL every time I drive it.
Starts, idles and drives without issue. It has lots of power and can accelerate up a hill (easily an 8% grade or better) without effort. It's a 460 so gas mileage is crap.

Every time time i drive it after 15-20 minutes the CEL comes on. Stop, turn off the truck, wait 5 seconds and turn it on. CEL is gone. 15-20 minutes later it comes back on. CM code is 41. No other codes. Every time.
yo M;
41
HEGO sensor circuit indicates system lean (right side) for cont memory code 41
No HEGO switching detected always lean (right side - BANK 1) for KOER


as I mentioned in another thread here; In place of the breakout box, go to the EEC pin instead
HO2S circuit, MAP, ECT, injector, etc. Wiring Diagrams @ http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=21138


DTC 41 Pin-Point Test by Ford via SigEpBlue @ http://www.fullsizebronco.com/forum/showthread.php?t=141552

Take a look back at the Ford MAP test I posted @ http://www.fullsizebronco.com/forum/showthread.php?t=305697&highlight=vref
PIN:

46 is SIG-RTN GY/R

26 is V-REF BR/W

45 MAP LG/BK

By RYAN again;
"... An important note we must cover now is that the EEC operates a majority of the sensors at 5-volts DC. ... the alternator and batteries are not dependable for voltage supply when it comes to sensitive electronics. The automotive electrical system ranges from 10-14 volts on an average day. Inside EEC is a voltage regulator, this steps the voltage down to a constant 5-volts. This voltage is called Reference Voltage (V-REF ). The sensors are supplied with this Reference Voltage and the sensor returns a variable amount of this to the EEC to indicate the status of the system the sensors is watching.

Some of the sensors need a special ground to get rid of the left over Reference Voltage that isn't sent to the EEC as a status. The EEC also provides a 5-volt ground loop for these select sensors. This special ground is called Signal Return (SIG-RTN). Lets quickly explain how this all works. The EEC sends a 5-volt Reference Voltage to a sensor; the sensor sends 1.87 (in your case MAP) volts back to the EEC as the sensor status, and the rest of the voltage (which should be 3.13-volts) down the Signal Return (SIG-RTN) ..."

Ryan's EEC IV Pin LEGEND @ http://web.archive.org/web/20131029020805/http://oldfuelinjection.com/truckpinouts.html

& his EEC IV Connector Pin Diagram @ http://web.archive.org/web/20131229163930/http://oldfuelinjection.com/images/eec04.gif
 
1 - 4 of 4 Posts
Top