Morning all - I am trying to chase down a P0300 code on my 04 Burb AWD. It only seems to appear when in tow/haul pulling my small (1500lb) camper, it does not crop up when towing my utility trailer in regular mode even if it is loaded as much/more than the camper in tow/haul. It seems to happen at various speeds and load conditions but I cannot see any perceptible loss of power or feel any distinctive miss characteristics. I am going to throw the Tech2 on it later today and see if it is localized to any particular cylinder - anything else I should be looking for?
P0300 only when in tow/haul
- Thread starter shegarty
- Start date
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MassHoe04
Full Access Member
Bad plugs, bad coil packs, and faulty/cracked plug wires can cause misfires.
For multiple misfires... I would want to look at Crankshaft Position Sensor (CPS) and what it is doing.
Tech 2 has a recalibrate Cam/Crank (or recalibrate CPS) function. I don't think it would hurt to run through a recalibrate session on that sensor. See what others say, but that is my thought at this point.
For multiple misfires... I would want to look at Crankshaft Position Sensor (CPS) and what it is doing.
Tech 2 has a recalibrate Cam/Crank (or recalibrate CPS) function. I don't think it would hurt to run through a recalibrate session on that sensor. See what others say, but that is my thought at this point.
Plugs and wires are new. I’ll see what the Tech2 returns for location and then investigate cool packs from there. I’ve read that it could also be an intake leak as the plastic manifolds can warp over time with heat cycling.
So, I didn’t get a chance to connect the Tech2 before a short road trip but it appears that this P0300 is only appearing in tow/haul mode - even without pulling the camper and even when not towing anything. Should I be looking for wiring or transmission issues when I get home
Got the Tech2 on it and it is recording misfire in cyclinders 1&6. On a test drive it is showing marginal misfires on 1&6 as well - my guess is that the tables for tow/haul are more strict on recording/detecting misfires? This would explain the flashing check engine while in tow/haul but not in regular driving mode. Once the engine cools down again, I am going to check the plugs on 1&6 and try switching the coils for junkyard spares to see if that makes any difference.
If that gets me nowhere I guess I am onto fueling? Fuel trims look good (minus 2-3%) and O2 sensors seems to be cycling normally. How would I check for a sticking injector?
If that gets me nowhere I guess I am onto fueling? Fuel trims look good (minus 2-3%) and O2 sensors seems to be cycling normally. How would I check for a sticking injector?
The Tech 2 should have a cylinder (or injector) balance test.
Moving a coil from 1 to 3 had no effect. Plugs and wires are new(ish), within 25k km. #1 plug shows good. Tech2 is still showing persistent misfire in tow/haul but only occasional in regular mode. Should I be looking at cam position sensor or just move onto fuel?
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What brand of plugs and wires? Aftermarket or OE? Miles on the engine and has a compression test been done recently?
The injectors and coils balance inspection is a great recommendation as well.
