mp470 Posted April 22, 2018 Author Share Posted April 22, 2018 Peeling the onion! One layer down - how many to go? The codes you are getting are as follows, from this page, with O = Key on Engine Off (KOEO), R = Key on Engine Running (KOER), and C = Continous Memory: 41 R Injectors out of balance on 5.0L SEFI; EGO sensor voltage low (except 5.0L SEFI) 34 O,R,C Canister or EGR valve control circuit or EVP voltage high So, you will have to check out the O2 (EGO) sensor. And coming from underneath is the way to do that. Thanks Gary. I have seen quite a few descriptions for code 41 but none of them had anything to do with injectors, mostly the O2 sensor / system too lean. Now it is EFI, but whether SEFI or something else I'm not certain. It could lead one astray if unsure of which one. For the code 34, the EVP circuit is OK. I've read up on this site as well as a few others but there isn't really a theory of operation anywhere that I could find. Perhaps the lack of vacuum at the line is normal during idling, I'm not sure. Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 22, 2018 Share Posted April 22, 2018 Thanks Gary. I have seen quite a few descriptions for code 41 but none of them had anything to do with injectors, mostly the O2 sensor / system too lean. Now it is EFI, but whether SEFI or something else I'm not certain. It could lead one astray if unsure of which one. For the code 34, the EVP circuit is OK. I've read up on this site as well as a few others but there isn't really a theory of operation anywhere that I could find. Perhaps the lack of vacuum at the line is normal during idling, I'm not sure. I don't think yours is SEFI, which stands for Sequential Electronic Fuel Injection. If you look at Page 61 in the 1986 EVTM you'll see that injectors 1, 4, 5, & 8 fire together, and 2, 3, 6, & 7 fire together. That is "bank fire" not sequential, which didn't come until later. On the code 34, I don't have a theory of operation on the EEC's. I haven't really seen one that I could put up. And I don't know about the vacuum at idle. Sorry. Link to comment Share on other sites More sharing options...
85lebaront2 Posted April 22, 2018 Share Posted April 22, 2018 I don't think yours is SEFI, which stands for Sequential Electronic Fuel Injection. If you look at Page 61 in the 1986 EVTM you'll see that injectors 1, 4, 5, & 8 fire together, and 2, 3, 6, & 7 fire together. That is "bank fire" not sequential, which didn't come until later. On the code 34, I don't have a theory of operation on the EEC's. I haven't really seen one that I could put up. And I don't know about the vacuum at idle. Sorry. No EGR vacuum at idle, not if you want it to idle. Red line from intake is vacuum source to control valve, it should have vacuum with the engine running. Link to comment Share on other sites More sharing options...
mp470 Posted April 22, 2018 Author Share Posted April 22, 2018 No EGR vacuum at idle, not if you want it to idle. Red line from intake is vacuum source to control valve, it should have vacuum with the engine running. It does. I'll assume that part of the equation is OK. Will wait for the vacuum pump to see if the valve operates correctly. That O2 sensor is damn near impossible to get to from below or above, might just leave that one be, especially if the testing needs to be done hot. Link to comment Share on other sites More sharing options...
vjsimone Posted April 25, 2018 Share Posted April 25, 2018 It does. I'll assume that part of the equation is OK. Will wait for the vacuum pump to see if the valve operates correctly. That O2 sensor is damn near impossible to get to from below or above, might just leave that one be, especially if the testing needs to be done hot. There is a connector just up from the O2 sensor on the passenger side just above the exhaust manifold. If you disconnect it carefully, and attach your meter, you should be able to measure the output of the sensor. The range is about 0.0 - 1.0 volts dc, lean to rich. When it is working properly, and warmed up, it will switch between about 0.4 - 0.7., providing the ECA/Computer is adjusting the Fuel Injector pulse width, and there are no vacuum leaks, spark failures, fuel pressure or Air Bypass issues. Link to comment Share on other sites More sharing options...
vjsimone Posted April 25, 2018 Share Posted April 25, 2018 Thanks Gary. I have seen quite a few descriptions for code 41 but none of them had anything to do with injectors, mostly the O2 sensor / system too lean. Now it is EFI, but whether SEFI or something else I'm not certain. It could lead one astray if unsure of which one. For the code 34, the EVP circuit is OK. I've read up on this site as well as a few others but there isn't really a theory of operation anywhere that I could find. Perhaps the lack of vacuum at the line is normal during idling, I'm not sure. Does your EVP look new ? Unscrew the EVP, lift it up/out, leave the electrical connector attached, run your KOER to see if the Code 34 goes away. Unless you are creative, you will get other Codes for this test. Link to comment Share on other sites More sharing options...
85lebaront2 Posted April 25, 2018 Share Posted April 25, 2018 Does your EVP look new ? Unscrew the EVP, lift it up/out, leave the electrical connector attached, run your KOER to see if the Code 34 goes away. Unless you are creative, you will get other Codes for this test. A friend and I used to file the plungers on the EVP sensors when you could not get the code to go away. Worked great on a lot of them. Link to comment Share on other sites More sharing options...
vjsimone Posted April 25, 2018 Share Posted April 25, 2018 A friend and I used to file the plungers on the EVP sensors when you could not get the code to go away. Worked great on a lot of them. Yes, that's where I am going with this... Link to comment Share on other sites More sharing options...
mp470 Posted April 25, 2018 Author Share Posted April 25, 2018 Does your EVP look new ? Unscrew the EVP, lift it up/out, leave the electrical connector attached, run your KOER to see if the Code 34 goes away. Unless you are creative, you will get other Codes for this test. Not new for sure but it gets voltage and the resistances are close to spec as per Haynes, including when the plunger is adjusted in and out, could even be original. I will try this trick. Link to comment Share on other sites More sharing options...
mp470 Posted April 25, 2018 Author Share Posted April 25, 2018 Yes, that's where I am going with this... What does filing the plunger down do? I've yet to find out if the valve is actually operational, waiting for vacuum pump to see if it will at least hold vacuum. Does the KOER test actually attempt to operate the valve? I think I read this somewhere. Link to comment Share on other sites More sharing options...
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