A friends car with really high millage. Started to miss fire when it rained out. When it is dry it runs perfectly. Took it to the dealer and they pulled the codes (I guess) and said he had a bad coil. He replaced all the coils and the problem is still there. Needless to say he is a bit annoyed.
Any thoughts on what it could be? Where is the computer in these cars? I am wondering if it is really water getting to the computer and or in to some part of the harness.
Could it be an AFM related?
Any insight / help is greatly appreciated.
I'm curious about this too. SWMBO's '99 Galant has this exact problem. I've replaced the COPs, boots, etc. Nothing electrical is visibly wet in the engine bay when the problem occurs. The misfire/hesitation goes away after driving for a few minutes.
Pull the codes again. Does it have an AFM? That could certainly act up in the rain. Or is it a MAF? I would think it would not be an AFM. Coil on Plug or Coil Packs? 6 cylinder, right?
Probably a bad connection in the harness somewhere. When it is missing, try to narrow it down to a particular cylinder by disconnecting stuff temporarily one cylinder at a time. Like: Disconnect the spark at one cylinder either with the plug wire or the wire going to the coil on the plug. Any change? Put it back on and try the next cylinder.
COP not coil packs in this one. Yes 6 cylinder.
TGMF
New Reader
2/27/15 3:52 p.m.
ECM is behind glove box inside the car. unless the floor is all wet, the ECM is probably dry.
These engines.....sucked. Till the PCV system was revamped for the third or fourth time in 03 or so, and piston rings were changed in 02ish, they were crap. Oil gelling due to weak pcv function, Blow by and low compression is very common on these, as well as rapidly drinking their oil pan dry on the highway and going boom. easy inspection is check the air filter, if its yellowed with oil, that's a bad sign.
Also, Air/fuel sensors being junk. very common. I would suspect a A/F sensor is on the verge of E36 M3, and is causing false signals when wet and cold.
Its a MAF setup. Excessive blow-by, because the engine is crap, causes the MAF to get coated in oil. so make sure the two tiny wires in the MAF are clean with some electronics cleaner. note the intake air temp is built into this unit, and is two wire with a glob of sap looking thing. cleaning that wont help, the MAF portion is down inside the tube of the unit.
Also making sure the Idle air control and the throttle plates are cleaned goes a long way to making these lumps drive better.
If its got A/F codes, check the front manifold very closely for cracks. usually around the bracket near the A/F sensor on the driver side of the manifold. The rear manifold usually doesn't crack.
Here are some tips that might help you diagnose as well as another to help delay the need to fix.
Diagnose:
While it is dark out and with no lights on, let the car idle while spraying down the engine with a typical Windex style bottle filled with just plain, clean water. This light spaying combined with the darkness might produce some arcs which will look like little bits of lightning jumping around the engine. This may help show you where you problem is originating.
Delay:
You say this only happens when wet. Keep a can of WD-40 (water displacer, 40th formula) in the car. When this misfire happens, spray WD-40 liberally over the entire engine and especially the electric components. WD-40 will not harm any parts nor will it harm paint, but, it will displace the water that has gathered on these components and the car will return to running correctly.
