My 1990 f150 just came back from its quarterly shop visit. They did the basic clean injectors, throttle body, etc..At least it idles now..anyway check engine light is on (as always) 33, 41 in memory, 12, 44,66 running... as for 33 it has new egr and evp, 41-new o2 sensor, as far as the 12 44 66, they a air injection problems (i think).would these cause running problems or just pollution (I'm not worried about a hole in the atmosphere) anyway , is there anything that can tie these together? Does anyone REALLY know how to fix these things?
Thanks

 

Im sure it can be repaired , It seems like you have a few problems , Code 33 indicates the Egr isnt opening when its supposed to , The only way the Ecu knows if the Egr opens or not is by the signal recieved from the EVP Sensor , Check it . For the O2 sensor problems , verify the fuel pressure is within specs & that you have no intake or vacuum leaks . The rest of the codes deal with Air Bypass ( 12 ) Which you say was cleaned , so perhaps thats been solved . Code 66 is a trans code , maybe a result of the engine not running to specs .

 

thanks for the input

 

Another thing you should check is the evr solinoid near the ignition coil. This is what tells the egr what to do. Just follow the hose from the egr to the evr. You will see that you can remove it from the bracket it is mounted in. After removing it you can carefully remove the top and the bottom covers. Under the top is a small foam filter which can be cleaned. Under the bottom is a rubber coated metal disk and a small spring. Be carefull as you disassemble this item so as to see how it goes together. Clean the rubber side of the disk and the valve seat. I had a bit if dirt stuck in mine and it caused a rough running engine as the valve was causing the egr to be open all the time and allowing exhaust gasses to return to the intake. Made for a rough idle.

One other thing you can look at is the hose for the pcv. I read that the stock hose runs directly into the #8 cylinder intake runner and can cause problems with the #8 cylinder, possibly from excessive oil or air getting in. Anyway, I replaced the hose with a longer one that hooked into the vacuum tree in the middle of the intake plenum. I blocked off the old port with a piece of hose and a bolt of appropriate size. My truck is a standard so I had a spare spot on the tree, but I am not sure if the automatics have this although you could tee it into another line, say the one for the cruise control. This made a remarkable change in the way my truck ran, especially when going up hills where it had a bad miss causing a significant loss of power. Also I blocked the egr right off with a tin plate between the valve and the manifold.Don't need those nasty exhaust gasses polluting my nice clean intake manifold. There were no side affects from this mod and the egr system doen't even know it is there, ie: no check engine light warnings. Good luck, SR.