2002 3.8 Running Rough at higher RPMs or under load


New Member
Hey everyone,

I recently purchased a 2002 mustang convertible with the 3.8L. Everything was running great with it for a few weeks then all of a sudden one day about a week ago it started acting up. It will start and seem to idle just fine but under load it bogs, has no power, jolts, etc.... takes forever to accelerate, just has no guts anymore and flashes the CEL at times. I had the codes ran and it came back misfires on cylinders 1, 2 and 3 as well as a MAF code and a Intake Air Temperature code (dont remember the exact code #s). I went to my local pick and pull and got another MAF sensor (even sprayed mine with the cleaner autozone sells), another (motorcraft) coil pack, put 3 new motorcraft plugs on that side/those 3 cylinders, I even replaced the TPS with one from pick n pull as well, just in case and I'm still having the exact same issue, hasn't really phased it much after doing all that.

I waa starting to think one or both cats on that side might be plugged but I'm not so sure either (not seeing any glowing or anything, but I know that doesn't always mean anything). I do have a laser temp sensor and the exhaust manifold on the side in question seems to be running cooler than the manifold on the other side (which is leading me to believe more of an ignition, spark or fuel issue on cyl 1, 2, 3 side). One of the things I tried tonight was to pull the wires off the coil for 4, 5 and 6 to see if it would fire/start on 1, 2 and 3 (the problem side) and it won't, it sputters a little (barely), but that's about it. I'm pretty sure, compression is ok, plus it's all 3 cylinders on thst side, not one or two. To me it's acting like it's not getting fuel/enough fuel to that side, I unhooked one of the wires on one of the plugs on that side and ran the car for a few then turned it off and pulled the plug and it seems bone dry (shouldn't it be wet with gas if it was getting enough fuel on that side after running it for a few with the plug wire unhooked from that particular plug?). I've checked spark at each end of the wires on that side and I'm getting spark. I cant see all 3 injectors going bad at once over there, unless it was a voltage issue to that side or something?

I haven't had a chance to re-check the codes since I replaced everything mentioned above but will tomorrow as well, but something tells me they probably haven't really changed (I did unhook the batt to reset and get rid of the CEL after changing sensors n such and it's since come back on after a bit since the issue still exists). One thing I was gonna try and check tomorrow was if each injector over there was getting voltage and maybe see if I could get ahold of a fuel pressure guage to test. If anyone has any ideas I'm all ears! It's just getting aggravating.



6 Shooter

Well-Known Member
When you first pulled out the old spark plugs on the passenger side, did any of the ceramics look white? If yes, an indication of blown head gasket with coolant leaking into the cylinder. Have you checked the coolant level and/or had to refill it? A compression check will give you some info and all three cylinders on that side should read out to within 10 psi of each one. A second test would be a coolant leak down test where the system is pressurized to 10-15 psi which should hold pressure for at least an hour or two.


Wrench Monkey
One of my employees had a similar problem on his Taurus and it turned out to be the intake gasket (lower, I think) was bad.