I have a 93 pickup 3.0 V6. I was doing a routine tune up this last weekend, distributor cap, rotor, plug and plug wires. When it was all said and done, it sounds like it is misfiring, it idles at 500rmp, and it smells really rich. I checked timing, it was ok. I checked spark (with the inductive timing light) on all plug wires, they were all firing. I verified the correct wiring from distributor to the correct cylinder. I ohm'd out the pick up coil and the ignition coil, they were ok. I'm baffled, anyone have any suggestions on what could be wrong?

 

what brand of plugs and wires did you use ?i f there not ngk or factory denso id take them back

 

Pull the plugs again and make sure one (or more) isn't "floor gapped" (gapped too small due to dropping)
You can pull the wires off of the cap (while it's running) one at a time. When the offending plug wire is pulled and it doesn't make a difference in the way it runs..... that is your offending cylinder.

Let us know.

 

Just make sure you are not touching anything metal when you pull a wire! Even pulling them off the cap can shock the crap out of you.

Make sure the wires have clipped properly onto each of the plugs.

Make sure the rotor is on the correct way and there is not any shipping material on the button or anything. I put a new cap and rotor on something, dont remember what it was but after it was installed the car wouldnt run. Couldnt figure out what the heck was going on so I pulled the cap back off and sure enough, there was some of that clear plastic protector film stuff on the rotor button! Never seen that before or sinse. Weird.

On a side note, you reminded me of a saying I heard from the foreman in one of teh shops I worked at: "Always drop a spark plug twice; once on the floor and once in the trash can."

 

double check that you have the correct firing order too

 

If nothing else above works, swap back all the old stuff and see if the problem is still there. Btw I hope you used all oem parts because that auto parts store stuff is crap as far as ignition components are concerned.

 

I bought NGK's, and I checked all spark plug gaps before installation. I've haven't checked to see if there's shipping material on the coil button though, I'll look into it. When I pulled the spark plugs back out to verify earlier, they were all fouled with fuel. I cleaned them and put them back in, but it didn't make the truck run any better. The old plugs that I replaced with NGK's look fine though.

 

Make sure you didnt knock any vacuum lines or electrical connectors off when you did your tuneup.

 

did you jumper E1 and TE1 to shoot the timing and/or forget to unjumper it? i really doubt this will be the problem, but just wondering

 

No truer words have been spoken. Nothing will ever match the quality of OEM Toyota ignition parts.

I've brought this up before, but I had a 1990 FJ62. I bought it with 262k on the odometer. The plug wires still had the production date of "1989" still on them. They were perfect. The cap and rotor had probably been changed (with OE), but 17 year old plug wires still checked perfect (per resistance testing) and looked close to new (after I rubbed the mud off of them).

Spend the extra few bucks and buy the cap, rotor and wires from Toyota. WELL WORTH IT!

BTW, stick with Toyota thermostats too....... another story for a different time.....

 

I did jump E1 and TE1 for the timing check, but I did remember to disconnect afterwards.

 

Seconded. It is extremely easy to cross a wire when replacing a distributor cap. I've done it, and it runs a lot better when it's right.

 

^ i would hope so or youve got bigger issues 0_o

 

Did you happen to remove the air cleaner? If you did maybe the flap door was moved to the wrong position..

 

I did remove the air cleaner to blow it out. What flap door are you talking about?

According to my chilton's manual, the firing order of the 3.0L is 123456. The distributor cap rotates counterclockwise, and supports that firing order. I checked the plug wires and they all go to the correct cylinder.

 

Mystery solved! It was in fact the MAF sensor flapper door. It was stuck wide open, effectively flooding the cylinders with fuel and fouling the plugs. All is back to normal, thanks for all of your help!

 

It probably got stuck when he replaced the air filter. Looks like he just freed it up. I dont think he replaced it.Glad its working now.