2001 Tacoma missfire no check engine light

I took my 2001 Tacoma to the dealer to find out what was wrong with it and they said it was bad coils and plugs and that they wanted almost $600 to do the job. I kindly declined as that is a ridiculous amount for something I can do myself. Bought the parts did the job and still same issue (Ialso did new wires) The puzzleing part is there is no check engine light and there never was even before I took it to the dealer. I have since taken it to a local mechanic down the street and it has been there 5 days with no answers. I called and he said he was having issues figuring it out.. Anyone else experience a similar issue or have insight into the situation?

 

Mine was misfiring for a while.. Eventually got around to changing the plugs and it did the job. Are you running aftermarket exhaust?

 

No, everything is stock.

 

I've done ignition coils, plugs and wires

 

Sorry just noticed that.

 

No worries

 

With engine idiling tap lightly the MAF with the handle of a screwdriver if the idle fluctuates the MAF is bad. Other than that if your truck has 130k or more on it I'd seriously think about a new 02 sensor in the exhaust. Sorry, I can't be more help.

 

Ok thanks, I will give the MAF a shot... It actually only has 90,000

 

Have u change sparkpkug before

 

For shits and giggles how old is the battery in the truck?

 

yes

 

Not sure. I got the truck from my dad who rarely drove it.

 

Does it have the same misfire when off-idle? What about cruising at steady throttle? Common issues I have seen with a 1st gen was throttle position sensors. I think before you start changing out parts you should get a scan tool of some type and check your data. Short of that some common issues with misfires are:

MAF sensor
TPS Sensor
Crankshaft position sensor
PCM ground
Battery ground to frame and body
Battery positive to starter
Battery terminals (corrosion/poor connection)

Also on each sensor mentioned above, check the connectors for corrosion or bad condition.

 

Get it tested. ^^ Definitely check ground wire locations.

 

Check vaccum hose

 

It idles really bad and when driving it seems as if more than half the power is gone and my exaust sounds strange.

 

Rub your finger over the vacuum lines.. if black chalky residue comes off on your fingers the lines are shot and you will have to start replacing them. Check the EGR is working correctly, too.

 

cat, check your cat, clogged or even semi clogged it can cause all sorts of problems...

 

Key piece of information. Check the catalytic converter for possibility of being clogged.

 

Thanks guys. I will keep you updated through my process. Maybe someone in the future can use this info as well.