Stutter while accelerating

Hey I have a 1999 Tacoma with the v6 and it started misfiring today. I was on the way back home from an OHV park and noticed the truck felt weak and took a while for the rpms to go up. The engine light came on flashing and I pulled over and restarted the truck and it went away. It never showed back up for the rest of the 1.5 hour drive home but felt still felt weak the entire time.

At home I let it idle and it sounds like it’s misfiring but I put my code reader in and it shows no codes. Help me please.

 

start by checking your secondary ignition components (plugs, wires and coils). Look for worn plugs, cracks and signs of arcing. Spray soapy water mix at the whole lot with the engine running. Sometimes that'll coax out a spark leak. Pull stuff out and physically look at it. Look for ignition wires rubbing on stuff and arcing. If a wire breaks easily in your hand then it need new ones anyway. If the plug gap is wide open replace them.

If you go looking for problems on those older ignition systems you'll usually find something

Or drive it until the light starts flashing again and check the codes before turning it off. A code would hopefully narrow it to a specific cylinder

 

Thanks I’ll try to get the engine light to go off again. I changed the coil packs less than 5k miles ago and just changed the wires and it’s still sluggish so i’m thinking maybe the fuel injectors?

 

What about the plugs? What brand is everything?

I wouldn't throw any money at it until a code shows up.

 

I got duralast coil packs and duralast plug wires and denso spark plugs. I’m not planning on spending any more money until I know what the problem is.

 

Update: I checked the spark plugs and they all looked fine, no cracks or anything. Coils are known good and plugs are know good and still have the misfire. Tried to get code, been driving to school and back with it and no code. I have no idea what it could be and I really want it fixed soon. Can you guys help me?

 

If your spark plugs have 100k miles you should go ahead and replace them with some Denso dual electrode units.

Ignition coils should be OEM or Denso which is the same as OEM. It is not good to use generic coils.

I have had those symptoms on a couple of toyota v6 vehicles; it was caused by worn out spark plugs. This may or may not be your issue.

 

I changed the spark plugs 10k miles ago with denso dual electrode so I doubt that’s the problem especially after examining them today.

Also, i don’t know if this is relevant or coincidence but it started after hitting a big bump while I was off roading.

 

I had the same sounding prob on my 99, 6 cyl. it was a fuel injector. Just one failing practically made my truck not drivable. Similar to what you said, like hitting small speed bumps, no power, stalling sensation. I ordered used ones, ended up replacing them 3 times on one weekend. By the third time, it seemed easy to do but I was nervous about it at first. Been running great ever since. Bought it in 99, new, see no reason to get rid of it, just keeps going!

 

Maybe the bump stirred up some junk in the fuel tank and clogged up the fuel filter. A flow test could determine if enough fuel is in play.

 

Okay i’ll check that next. Can i take the fuel filter off and check there or do i have to do it through the fuel rail?

 

It would be simpler just to swap the fuel filter if you're not sure how old it is; it probably needs it anyway. A wix or bosch can be ok if you don't want to get an OEM filter.

 

My truck was sitting for around 10 years at 165k miles and before i started it for the first time i replaced the fuel filter with a wix filter so it’s pretty new. This was about 2 years ago.

 

When they sit around the fuel pump gets gummed up with varnish then stops moving. I have seen this many times. I would like to see someone try to free up an old pump with solvents.

Did you ever run some fuel system cleaner? Redline and amsoil are good products. After the amsoil PI my sending unit was sticking for a while; it loosened up some deposits in the fuel tank probably. It works ok now. It also dissolved some of the glue around the base of my charcoal canister...these usually leak and can be sealed up with black silicone. Its just a plastic box, nothing elaborate.

 

I actually replaced the entire fuel tank and the pump twice because i bought a cheap one and it broke so I got a duralast one from autozone.

I did this again before I first started the truck. The tank was filled with bad gas and completely rusted on the inside from it sitting for so long.

Maybe the fuel lines could be clogged and fuel cleaner could help? Never cleaned them.

 

The cleaners do help for sure. PEA is an important ingredient for them to have because it works. Some of the cheap gasoline can be pretty dirty

 

Ok thanks, I can try some fuel cleaner and see if it makes any difference. If not i’ll try a fuel pressure test and give an update.

 

Remember that the fuel pressure can test ok but it needs a good flow rate also.

If your scan tool provides real time data, have a look at the fuel trims

 

I did look at the short time fuel trim at idle the other day and I forgot the numbers but i searched it up and they were normal.

 

So I just got a cel and it was a p0304 code so now I know that cylinder 4 is the problem.

I just changed the spark plug with a new one to completely rule that out and it’s still misfiring. I know it’s not the plug wire because I changed them and it made no difference.

I also put the fuel system cleaner in and no difference so I’m thinking maybe the injector?