After curing my truck of its fuel problem. Was getting 9mpg now a solid 18. I now have a pinging issue. Sometimes, not always and only after it has warmed up It will seemingly shift too early and begin to ping until I let up on the gas or stomp down to downshift. Very much like trying to climb a hill in too high a gear. My fuel problem was a bad fuel pressure regulator and had probably existed long before I bought the truck. The timing is correct at 10 degrees(spout dis-connected) New plug wires (no crossfiring I'm aware of) I tried a can of sea foam through the brake vacuum line. I followed instructions and it did smoke quite a bit. My thought was that with all the extra fuel that had been shooting at 100 psi I might have a lot of carbon build up that would cause the pinging. Would all the extra fuel cause carbon build up or would it have the opposite effect and keep everthing cleaner? Also if there is heavy build up would sucking up another can of sea foam be a good idea? Otherwise it runs well, idles well. The only code I get is one refering to "thermactor not by-passing" 46 I think it was. Any thoughts? Thanks

 

what are you working on?

 

88 f150 4x4 5.0 302 Trying to get rid of the pinging. It did not ping when it was running way too rich. Only after I replaced the fuel pressure regulator. It is now at 35 lbs and getting great mpg's The only code remaining is 46 "thermactor not by passing" I assumed it would take a few cycles for the ecu to settle in but it has been 2 weeks an a couple hundred miles. Again it does not pre-detonate until it warms up. With a steady throttle it seems to shift early resulting in over taxing and the pinging begins. I can let up on the throttle and allow the rpms to come up to stop it from pinging or as I said earlier I can give it more throttle to force it to down shift. I used the sea foam believing that I might of had a lot of carbon build up. It may have been running rich for a year or more. I used 1 can it smoked like hell for a while but did not improve on the pinging. Is it possible I have programmed my ecu with my driving habits? I generally apply very little throttle and drive slowly in an effort to save fuel.

 

Replace plugs, and lifters may be bad due to oil starvation. Removeing long term carbon can expose lots of problems, valves not sealing to ports or blowby into crank case. Find A realy nice Tech to help you out.

 

Thank you for the reply. Plugs are new and when removed look perfect (tan color and clean) Lifters are quiet and unless Im mistaken I would not be getting good MPG's and otherwise good performance if valves were not seating? I am leaning toward something causing a lean condition. I do not quite grasp the role of the thermactor. Pehaps it is the culprit?

 

EGR or EVAP ?? solenoids makeing ping? Thermactor???

 

your code 46 "thermactor not by passing" could be the key to the puzzle. if it is not working right it will effect the reading your computer is getting from the O2 sensor and it could be playing with the timing and the fuel mixture.

 

did you unhook the battery to clear the computer after you changed the regulator?

 

Yes I did clear codes. There is a vacuum line I believe that connects the thermactor valve to a solenoid. It sets next to the coil pack on the right. I tested the vacuum line and it is good but when I pulled the electrical connection I see a hard green substance? Would this be di electric or corrosion? Does anyone know how to test the solenoid? Thanks again for the replies

 

Green is bad!! Clean all connecters until bare metal appears. Dialectric is like a clear paste when new, never green when old. Test the solenoid by doing a continuity test between both terminals and check specs for resistance value. It might not have power or could be stuck.