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Car Forum / Dodge / Dodge Trucks / August 2005Code 43 has returned :(
It's back, and this time back with a vengance. P0307 (cyl #7 misfire) Those who have followed my plight know this saga began a year or more ago. Various things at various times have solved or rather mitigated the problem to a greater or lesser extent for a while, but this time it's back and not quite but almost a steady-state hard failure. Clearing the code and it comes right back within the first 5~10 miles of town driving. '97 Ram 1500 5.2L, 80k miles Work done over the past year to date: (all Mopar parts) new coil new plugs new wires new rotor cap plug wire rerouting TSB applied flushed injectors (several times) cleaned combustion chamber checked compression (135~144 lbs all cyls) 52.8 psi fuel pressure swapped #5 & #7 injectors, problem stays on #7 Problem seems to occur most often when decelerating from 25~30 mph to a complete standing stop in gear, i.e., approaching and then sitting at a light with your foot on the brake. All of a sudden you feel a faint flutter in the idle and 10 secs later the MIL lamp is on. Sitting in the shop idling in gear and you can see the misfires counting up, 8~10 in the course of a couple minutes, all on #7. The only code being set is P0307. What next, Doctor? > shop idling in gear and you can see the misfires counting up, 8~10 in the > course of a couple minutes, all on #7. The only code being set is P0307. While this is happening (misfires counting up), if you give it a slight bit of throttle, do the misfires go away? >> shop idling in gear and you can see the misfires counting up, 8~10 in the >> course of a couple minutes, all on #7. The only code being set is P0307. >While this is happening (misfires counting up), if you give it a slight bit >of throttle, do the misfires go away? Interesting you should ask. In fact they do. The misfires appear to be happening at "loaded" idle (idling in gear). > Interesting you should ask. In fact they do. The misfires appear to be > happening at "loaded" idle (idling in gear). Checked/cleaned/replaced the Idle Air Control motor? >> Interesting you should ask. In fact they do. The misfires appear to be >> happening at "loaded" idle (idling in gear). >Checked/cleaned/replaced the Idle Air Control motor? Not that I'm aware. Thanks for the tip. Will give it a try. This is beginning to drive me nuts. >> Interesting you should ask. In fact they do. The misfires appear to be >> happening at "loaded" idle (idling in gear). >Checked/cleaned/replaced the Idle Air Control motor? Any tips for R&R ? Or is this a shop job? > Any tips for R&R ? Or is this a shop job? Real simple - it's on the back of the throttle body. Two Torx screws and an electrical connector. While you're at it, just remove the whole throttle body (four bolts from the top, once you take the air cleaner off), strip off the IAC, the MAP sensor, and the TPS sensor (all remove the same - just a couple of screws), then give it a good thorough cleaning with some TB cleaner. When you put it back together, leave the IAC uninstalled. Plug the electrical in, and while holding it, have someone turn on the ignition (but don't start the truck - it will rev to redline!), and watch the movement of the IAC pintle. It should cycle all the way out, then all the way in, then settle to a position somewhere in the middle. This should all be smooth movements. If it's not, or if in doubt, you can try cleaning it as well, but a replacement isn't that much money, either. Before embarking on this, pick up a new throttle body gasket - 50% chance you'll trash the old one while removing the TB. Thanks. Autozone sells one for $56 & tax. If this damn Texas heat ever lets up I may attempt this myself. >> Any tips for R&R ? Or is this a shop job? > [quoted text clipped - 13 lines] >Before embarking on this, pick up a new throttle body gasket - 50% chance >you'll trash the old one while removing the TB. Well, 100% chance of trashing the old TB gasket so your suggestion to pick up one paid off. Harder to get my a.s up in there to reach everything than it was to R&R Okay, all squeaky clean now. Had lots of carbon. Tried the IAC test OK. Reassembled, drove over to Autozone to have them clear the code. Darn thing coded again sitting in their parking lot idling. MIL lamp didn't come on but the code came up again on their scanner within 1 minute of restarting the engine. Trans in Park, idling w/AC on. Shut the eng off, cleared it again and restarted once more. Idling it comes backwithin a minute. Cleared it again. Restarted the truck again and immediately kicked the idle up to 1500 RPM. Sat there 2+ minutes at 1500 rpm wasting $2.59/gal gas, all seemingly well. Let it idle back down and it gave a P0307 almost immediately. What's next? Could the plug maybe be fouled again? This is beginning to get a little tiring. >> Any tips for R&R ? Or is this a shop job? > [quoted text clipped - 13 lines] >Before embarking on this, pick up a new throttle body gasket - 50% chance >you'll trash the old one while removing the TB. Additional; Went back to Autozone and REPLACED the IAC. No help. They were even nice enough to allow me to return it. >Well, 100% chance of trashing the old TB gasket so your suggestion to pick >up one paid off. Harder to get my a.s up in there to reach everything than >it was to R&R >Okay, all squeaky clean now. Had lots of carbon. Tried the IAC test OK. >Reassembled, drove over to Autozone to have them clear the code. Darn [quoted text clipped - 29 lines] >>Before embarking on this, pick up a new throttle body gasket - 50% chance >>you'll trash the old one while removing the TB. I just went through a similar experience and found that one of my engine valves was running right at the end of the range of a hydraulic lifter and as the engine got hot stopped the exhaust valve from totally closing causing a misfire. Ended up taking that engine apart twice. The second time took .025 off the end of the valve and problem went away. Yes before I did this I replaced the Idle Air Control motor which didn't help at all. I also was going to replace the MAP sensor before I determined it might be a valve but didn't so saved that $50. After the second assembly I ended up with a tappet noise but found I had only installed it backwards so it didn't have chance to pump up. 5 weeks later I believe I might have an engine that will go another 75,000 before it will need much work. Good luck, Ron > It's back, and this time back with a vengance. > [quoted text clipped - 28 lines] > > What next, Doctor? Ahhh yes, the old "grind .025 off the valve stem trick. Had to do that once to a 396 Chevy motor with solid lifters that got a little over-zealously cammed and the springs were going into coil-bind, popping off keepers and dropping hardened-steel valves deep into fragile aluminum places where they weren't welcome. Sucking a valve at redline while reaching for 2nd gear makes a very distinctive sound. The second time it happens, the phrase "Awwwshit!" just doesn't seem adequate ;-) >I just went through a similar experience and found that one of my engine >valves was running right at the end of the range of a hydraulic lifter [quoted text clipped - 43 lines] >> >> What next, Doctor? |
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