Noob needs help understanding codes

[Guido0136]

Hello all: I'm very new to owning a SHO and have only had mine on the road for a month.
It runs fairly decent, but I noticed the C.E.L. coming on after I do a wide open throttle.
It stays on for a bit then cycles on and off until the car is stopped and started. If I run the SHO with out gunning it, the C.E.L. never comes on, only after a WOT.
I'm guessing it has to do with the exhaust as the exhaust system is in bad shape, and maybe it is the emissions?

I got the link to flash the codes and I need some help understanding where the numbers start and end. I did the KOEO test and here is the sequence of the codes:

3-3-5-3-3-5 pause 1-1-7-2-1-7-6-5-4-3-1-7-2-1-7-6-5-4-3 end of flashing I checked this sequence three times to make sure it was correct.

I'm not quite sure what codes I have. I'd really like some understanding these codes.

Thanks a bunch!:thankyou:

 

[marSHO]

Afaik the code sequence is presented twice.
335,335 /1=separator/172,176,543_172,176,543/

See:
http://www.shotimes.com/php-bin/mod...le=article&mode=thread&order=0&thold=0&sid=84

 

[Guido0136]

Okay that is great, I think, so I have the following:

172 = HEGO Sensor indicates system lean (RH)
176 = HEGO Sensor indicates system lean (LH)
335 = DPFE Sensor voltage higher or lower than expected.
543 = Fuel pump secondary circuit failure

So now it's off to see what I need to do to fix these.

Thanks for your quick reply!:thankyou:

 

[jmpSHO]

Before you go and buy 2 new O2 sensors usually when both banks are lean or rich it usually means that the car is actually running lean. I would try cleaning the MAF and if that doesn't work you might even want to replace it with a good working MAF.

 

[Guido0136]

What is the best thing to clean it with?

 

[jmpSHO]

Auto parts stores carry a MAF cleaner and it usually works however sometimes the MAF does need to be replaced even after cleaning.

 

[Guido0136]

Sweet, I'll go get some today and give it a clean. Thanks!

 

[Guido0136]

Okay, got the MAF cleaner and cleaned up the wires, that looked fairly clean to begin with. Put it all back together, clear the codes and ran it hard. CEL came back, guess I have to change the O2 sensors?

 

[shonuffmine]

hey

check your codes again

 

[SHOtime2511]

did you make sure to clear the codes my reseting the ECU?

 

[Guido0136]

After I cleaned the MAF I pulled the negative battery cable for 10 minutes and then ran the codes again before I tested it. The only codes I got were the 335, 335 then just 1 1 1 . Then I drove it and got the CEL. I'll pull the codes again and let you know what is there.
Thanks for the advice.

 

[jmpSHO]

Definately check the codes again cleaning the MAF won't take car of thhe 335 code.

 

[Guido0136]

Okay, I have checked the codes again.

I still have the 335 (DPFE sensor voltage higher or lower than expected)
I still have 172 and 176 (HEGO sensor indicates system lean (RH) and (LH))
543 has not shown up, but from my research if you are getting this code and the car starts than it's a false code.

So if I have cleaned the MAF is my next step the O2 sensors?

Thanks,

 

[Guido0136]

BTW - what is involved in fixing the 335 code? I'm not sure what this code relates too.

Thanks again.

 

[jmpSHO]

Cleaning the MAF doesn't always fix it, sometimes it actually needs to be replaced.

 

[jmpSHO]

335 might be a bad DFE sensor.

 

[Guido0136]

So how do I know for sure before I get another MAF, that the MAF is the issue. It seems to be down to the O2 sensors or the MAF.
What ones should I try first?

 

[Guido0136]

Okay, I also own a 1994 explorer to match my 1994 SHO.
To help me know if my codes are from a bad MAF or my O2 sensors, I have swapped the two MAF's. The known working one from the explorer, to the SHO and vise versa.
The MAF's were swap-able, but had slightly different part numbers.
I'll clear the codes again and drive this for the next few days and give everyone an update.
Any thoughts on the part number differences?
Thanks,
G.

 

[jmpSHO]

If the part numbers do not match it's not going work right in the SHO.

 

[Guido0136]

Well after a day of swapped MAF's, there was no change in either of the cars. The explorer ran perfectly with the SHO's MAF (No codes or CEL), and the SHO ran the same, throwing the same codes at the same predictable times.
So I'm going to look at replacing the O2 sensors and see it that works, as I now believe the codes are not from the MAF.