Engine Miss 1999 2.5 Liter

[nbates55]

1999 2.5 liter manual. Engine has developed a miss. Really bad when its cold. Once it warms up, its better most of the time, not always tho, sometimes its worse after its warm. Check engine light does not work at all. Dont even know where its supposed to be, on the right hand side of the instrument cluster I think. The battery light has been an off and on thing ever since Ive had the truck. Alternator tests good. Needle in the cluster says its o.k., and I have an extra LED meter in the cig lighter socket that also says alls well with the charging system and battery, altho O'reillys said the battery tested "bad", yet it starts the truck fine.
Took it to O'reillys auto parts and they hooked up their code reader. No trouble codes. Has a new fuel pump already. Im thinking a plug or plug wire. The guy at Oreillys said his code reader would show that, but Im dubious on that one.
Ive had the truck for 2 and a half years. Have never put a new air filter in it, but the old one looks pretty clean. Dont think its water in the gas since its been going on for a couple of weeks now and I did put a bottle of "Heet" in it and switched gas stations. Just wondering where I should start first? With whatever is cheapest I guess, since it looks like it will be a process of elimination. Any input appreciated.

 

[Mark_88]

If it's plugs or wires I'd imagine it would be on the passenger side of things since that gives you your biggest bang for your buck...so check that the plug wires are actually connecting to the tip...and that the tip is on the plug properly.

If that doesn't help...pull each plug on the passenger side and check for problems...like cracks on the plug insulator...and look inside the plug wire boot to make sure the connector is not pulled up and away from the plug tip...this actually happened on mine once and drove me crazy trying to find it...that's my excuse for the way I am...

Other than that...someone else will have to chime in with their 2¢ worth because I'm still learning about these elecricality things...

 

[black_demon69]

also check for cracks in coil pack usually around edges on top of coil. side note would be 1 if you haven't changed plugs you might just want to do so same goes for wires. 2 while pulling old plugs check gap and do what mark said above. 3 if it was me i would have parts there before i started work (you can always take them back if not used)

 

[94RoadkillRanger]

Determine whether the miss is always a particular cylinder by either disconnecting the fuel injector connector or the two spark wires one cylinder at a time. If you do determine a specific faulty cylinder then you can swap parts, be it spark plug, wire, or injector. If the problem does not move to the cylinder that you traded parts with, then suspect the coil packs. This is just a free way w/o buying parts.

If all the cylinders seem to ramdomly missfire then check the Intake Air Temperature Sensor since the engine acts up mostly when cold. The problem could be the connector so tap on it while idling. I don't believe cleaning the business side of the sensor would help much but cleaning corroded electrical connectors would help. I don’t have any multimeter specs for testing it.