Codes 57 & 76 need help please

[Ron41]

Hi guys, I keep on getting these 2 codes, the car is duel fuel so I reset the computor and ran it on Petrol, the both codes come up, so reset the computor again & ran it on gas and the same codes come up again.

Going by my Gregories code 57 is " Injector power supply monitor } [voltage variation, terminal B12]
I had this trouble once before & thought it was gone but apparently not.
I ran some injector cleaner in it once before [ a few months back] & check voltages at the injectors which seemed to be ok, could the injectors need cleaning professionaly ?
I only run petrol when warming up the engine and switch it back to petrol a few klm away from home.

Code 76 - air/ fuel ratio [ variation between left & right banks ]
this has got me stumped as it throws this code on petroll and gas. [just had the lpg serviced as well but made no differance]

So any help would be appreciated

thanks

[hako]

Geez Ron, you have to stop pulling these codes up....they cost money to fix! Are you having any other problems...missing, chewing juice, black smoke etc? I also remember reading somewhere that it pays to check the earth to the ECU when voltage variation faults appear. Good Luck.

[Gunzero]

Is it standard lpg like from holden or is it aftermarket?
With code 57 i would check the injector connections maybe there dirty
and with code 76 might be the o2 sensor or it might be the computer not recognizing the LPG as fuel cause even if its doing it on fuel to the LPG does not go though the injectors it goes the throttle body so it could be giving false readings

[Brett_jjj]

Check all the ECU wiring and engine earth points.

[Ron41]

Geez Ron, you have to stop pulling these codes up....they cost money to fix! Are you having any other problems...missing, chewing juice, black smoke etc? I also remember reading somewhere that it pays to check the earth to the ECU when voltage variation faults appear. Good Luck.

Yeah hako I know mate, but still cheaper for me to fix [ if I can ] than the alternative.
The reason I checked the codes again, i had the lpg serviced & it started backfiring madly the next day, but been back to him & he said he tweaked the mixer a bit more and it seems to be going ok now [ not backfiring yet ] but those 2 codes remain.
It does seem to be using more Gas for any long distance trips than it used to, no black smoke though.
I will try to work out were the earth to the ECU is.
thanks mate.

[Ron41]

Is it standard lpg like from holden or is it aftermarket?
With code 57 i would check the injector connections maybe there dirty
and with code 76 might be the o2 sensor or it might be the computer not recognizing the LPG as fuel cause even if its doing it on fuel to the LPG does not go though the injectors it goes the throttle body so it could be giving false readings

The lpg guy tolde me it is a impco copy, i will check the injector connections again, if it was an O2 sensor wouldn't throw up a code ? I hope its false readings

thanks mate.

[Ron41]

Check all the ECU wiring and engine earth points.

Thanks Brett, I will try to work the earths out in the morning.

thanks mate.

[Ron41]

Turns out that one of my oxygen sensors is stuffed, so I should change the both while I am at it, seeing they haven't been touched since I bought the car 12 years ago and now on 210,000 klm.

Can someone tell me if its best to get the 02 sensors from Holden or are any of the after markets ones still as good ?

GHM wants $115 each
Ebay - Bosch type $56 each

thanks for any advise.

[Ron41]

I have changed the oxygen sensors and it still shows code 76 , weird.
There is definate miss on lpg and petrol, it backfires occasionaly only on lpg when I rev it quick, I believe lpg needs more spark than petrol so I have checked the plugs again, there good, just checked the plug leads and one side of the engine are lower resistance readings than the other side.

setting the multimeter to 20k
L/side ........................ R/side
2.11........................... 1.3
1.95........................... 1.12
3.54 .......................... 0.63

checked coils they seem to be ok.

After the car was already warmed up, I reved it a few times and it coughed and splattered a bit then i noticed at the end of the exhaust, some wet stuff mixture with a black oily looking bits mixed with it on the garage floor., never seen this before.

Anybody have any clues, really need some help please.

[Brett_jjj]

Id be checking for a vacuum leak an one side of the engine.Spray wd 40 or similar around the engine inlet manifold joints with the engine idling .Listen for a change in revs, or smoke out the exhaust when the spray gets sucked into the leak.Also make sure the exhaust manifold is not leaking ahead of the oxygen sensors.

[Not_An_Abba_Fan]

The resistance on the leads is good, the RHS will show a lower reading because they are shorter. Rule of thumb from memory is 1K of resistance per foot of lead.

Some people have gotten the code 76 and never resolved it. The VS also has a voltage leak problem through the earth on the RH O2 sensor heater circuit. The quick fix is to cut the pink wire on the loom side of the plug for the O2 sensor, the complicated fix is to rerun the earths right back to the ECU.

[Ron41]

Thanks a lot Brett, I will check that out.

thanks again.

[hako]

Plug gaps should be around 1.1mm on LPG cars.

[Ron41]

Thanks everyone for your help, after a lot of stuffing around the miss & backfire are gone now after putting in new plugs [ gapped at 1.1 mm ] it was decieving as the old plugs looked ok, also the leads were a bit loose at the plug end so I tightened them all up as well, its running well now.

I tried to check for a vacumn leak with wd/40 spray but couldn't find any leaks, I hope I was spraying in the right place [ just along the top side of the rocker covers ] motor revs didn't change, I put a lot on, It still brings up code 57 though.

For the code 76, do you just cut the pink wire were the 02 sensors are [ not the 02 sensor wire's plug side, but the plug conection were the 02 wire plugs into ? ] and do you cut both sides ?

thanks very much everyone.

[Not_An_Abba_Fan]

Just the RHS had the issue for some reason.

[Ron41]

Just the RHS had the issue for some reason.

Ok, thanks mate, so that is the drivers side correct ?,[ not looking at it from the front of the the car]

[aceventura]

Yep, drivers side

[Not_An_Abba_Fan]

^^^ What he said.

[Ron41]

No worries, thanks guys.