mustang guy Posted May 9, 2016 Share Posted May 9, 2016 (edited) That means your lock up filter/valve may need replacing. It should be a smooth back and forth transition which is very noticeable at 42/43 MPH. JJK It could even be a faulty electrical connection to the transmission. Even the tiniest added resistance can cause the transmission to act differently. That means your lock up filter/valve may need replacing. It should be a smooth back and forth transition which is very noticeable at 42/43 MPH. JJK I think what's happening is that the engine is experiencing it's highest torque load at that speed. Ignition problems will generally rear their ugly head then. It could also be something about that RPM causing the buck when in lock up like a bad coil pack. Drive the truck in 2nd gear and go that exact RPM. Edited May 9, 2016 by mustang guy Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 9, 2016 Author Share Posted May 9, 2016 It could also be something about that RPM causing the buck when in lock up like a bad coil pack. Drive the truck in 2nd gear and go that exact RPM. It doesn't do it if I downshift. Only happens if I'm barely accelerating in a high gear at like 42 mph. If I gun it and it downshifts, there's no issue. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 9, 2016 Share Posted May 9, 2016 It could also be something about that RPM causing the buck when in lock up like a bad coil pack. Ignition under a load, yes. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted May 9, 2016 Share Posted May 9, 2016 It could also be something about that RPM causing the buck when in lock up like a bad coil pack. Drive the truck in 2nd gear and go that exact RPM. It doesn't do it if I downshift. Only happens if I'm barely accelerating in a high gear at like 42 mph. If I gun it and it downshifts, there's no issue. What are your RPM's when you are going 42 MPH? Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 9, 2016 Author Share Posted May 9, 2016 Can't remember, probably 1,500? When I'm at 65 mph I'm probably 2,000 and 75 maybe 2,200-2300. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted May 9, 2016 Share Posted May 9, 2016 Even with a healthy engine the torque is very low at that RPM. The bucking is likely a combination of a locked up torque converter and very low HP. When you lug an engine it will sound like a diesel. This is what Carl is talking about I think. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 9, 2016 Share Posted May 9, 2016 (edited) Even with a healthy engine the torque is very low at that RPM It's like shifting into 6'th gear with a standard at a low speed. When the motor lugs, ignition is under a load. I've always checked for ignition problems this way. It seems they'll show up quicker there than at normal rpms and a normal load. Have you tried power braking it at a standstill to see if you can simulate the issue? Edited May 9, 2016 by CECAA850 Quote Link to comment Share on other sites More sharing options...
jason str Posted May 9, 2016 Share Posted May 9, 2016 I recommend you taking it over to a reputable Ford dealer as they will know your product best. 1 Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 9, 2016 Author Share Posted May 9, 2016 I recommend you taking it over to a reputable Ford dealer as they will know your product best. Wednesday, come quickly. 1 Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 9, 2016 Author Share Posted May 9, 2016 (edited) Have you tried power braking it at a standstill to see if you can simulate the issue? It doesn't really do it much at all in this situation. Friday it started missing real bad upon doing this but I am convinced it was the gas, as it was missing all the time in other situations, but is now back to normal. Doing so is when the real bad rotten egg smell was noticeable which is why they were doing the catalytic converter test, they think it was getting excessively hot and is clogged up. Which, makes no sense at all to me. If it was a predetonation issue where it did this under a load, why doesn't powerbraking reproduce it? If it was the catalytic converter, why wouldn't powerbraking reproduce it? The engine nor converter doesn't know that it's not actually rolling down the road. Edited May 9, 2016 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 9, 2016 Share Posted May 9, 2016 Try and run all the fuel out of it (if possible) and fill up at a different station to eliminate a bad fuel issue. Quote Link to comment Share on other sites More sharing options...
jason str Posted May 9, 2016 Share Posted May 9, 2016 High sulfur content gas will smell like rotten eggs when burned. I recommend a different fueling station. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 9, 2016 Author Share Posted May 9, 2016 (edited) Just heard from the muffler shop, the catalytic converter pressure test checked out, there is nothing wrong with the converters. They're a mechanic shop too, had two guys looking at it this afternoon, both basically said they have no idea what it is. Hopefully the Ford dealership can tell me something. If not, I don't know whether to sell it with a disclaimer, or just drive it until something major blows up which may be never, or just keep it but get a car and use this as a farm truck. Edited May 9, 2016 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
jason str Posted May 9, 2016 Share Posted May 9, 2016 Pressure test will not tell you if a converter has broken apart, it will flow well either way. Thermal test may but if the center is blown apart this will not help either. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 9, 2016 Share Posted May 9, 2016 Could be as simple as crap gas. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 9, 2016 Author Share Posted May 9, 2016 Is there nothing that is the equivalent of a throw out bearing on an auto that could sound awful under the right torque? Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 9, 2016 Share Posted May 9, 2016 Maybe an input or output shaft bearing but you'd think you'd see a leak as well. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted May 9, 2016 Author Share Posted May 9, 2016 I've got an old tractor whose throwout bearing chatters. Quote Link to comment Share on other sites More sharing options...
jason str Posted May 9, 2016 Share Posted May 9, 2016 No clutch release bearing equivalent on an automatic transmission as there is no clutch. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted May 9, 2016 Share Posted May 9, 2016 And make sure to tell them the tranny TC might be locking up at 1500 RPM. I have basic experience with programming transmissions via software (an older TCI TCU and TCom software) is that you can set a minimum speed at which lockup occurs. You also set percentage of lockup (duty cycle) based on the where the throttle is (TPS). It doesn't seem like 42 MPH is high enough. Quote Link to comment Share on other sites More sharing options...
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