Hey guys,
99 runner v6 auto, 240,000 miles
It started stumbling and hesitating under power yesterday. Fresh problem, been running fine.
I cleaned the MAF and throttle body and there are no codes
Any ideas on where to start?
Thx, kenny s.

 

Take a look at spark plugs and cable, air filter, check vacuum hoses and intake tube for cracks/leaks....

 

^ Spark plugs and wires.

 

Any smoke out of the pipe? Have you checked the TPS?

 

I started by a visual inspection around the wires and out of the corner of my eye, i saw one of my plug wires had popped off the plug tube . Loose.....and wiggling.
WOW....THATS GOTTA BE IT !! Right ????? NOPE!
I replaced the single plug to rule out a fouled plug.
Still stumbling..l.
I sprayed water on the wires......nothing
Sprayed carb cleaner around vac lines and tubes..... Nothing
Tightened up my throttle body cables while i was there.....dang.....they were loose !
Not sure where to go from here.

No smoke that i can see. At times , it is a violent stumble....seems more electrical to me than fuel. Like an immediate cut out for a fraction of a second.
It is not consistant...and more random. How do i check my tps?

Ks

 

From what your describing, it also sounds like a bad injector(s). In this case the car will feel like its not running on all 6 cylinders. Are there any vacuum or air leaks?

 

I would start by checking for vacuum leaks and all electric connections.

Then change plugs, not just because they might BE the problem, but because they may have become fouled because of what the problem actually is. Then look carefully at the OLD plugs, cylinder by cylinder, as that can tell you a lot. Soaked in gas= bad spark. Super clean=head gasket leak. Oil soaked=rings. In the absence of codes, best diagnostic you can do.

 

i finally got a check engine light today after hammering down to merge on the hwy........over to autozone......came up cylinder 5 misfire, too many misfires. P0300 multiple cylinder misfires P0305
So i pulled the number 5 plug.....looked ok.....just to rule out the plug, i replaced it with the plug i removed from the 4 cylinder yesterday. I also rechecked the interior sensors on the the maf sensor and shot them with cleaner again. Truck runs much better now.....i'll report back after driving to and from work tomorrow.
Hats off to Autozone for providing a printed readout of your codes and what the code number represents.

kenny s

 

Just drove it again and it runs much better but the stumbling and hesitation still pops up randomly. Not nearly as intense as before. I'll drive it to and from work tomorrow and see.
I must be on the right track.....i guess!
Kenny s

 

I drove it this morning and the check engine light flashed a few times while merging on the hwy.
Then went off.
Still stumbling but ran good yesterday for an hour....strange!!

 

I don't understand only checking 1 and replacing 1 plug? The plugs will be one of the best indicators of how your combustion is doing. Use the cheap dual electrode copper core plugs. Less that $20. Wires are still likely even though you misted them with water. In my experience they jump spark down in the cylinder near the boot anyway. This is indicated by darkened/discolored plug boots. Carb cleaner never really helps me find a vac leak either, the ECU is really good at compesating for leaks and you might not notice until you get a large volume of air on the highway. Crankshaft position sensor can occasionally go bad and will cause a multiple cylinder misfire code. Also, if you crank pulley bolt never got torqued down good (say after a timing belt change) it can cause the crank to walk and cause the crank ring to not be read by the crank position sensor. Inspect your crank pulley to see if it's lined up with the rest of your pulleys.

 

Check engine light on again...went again to Autozone.....cyl 5 misfire & multiple cyl misfires. 300&305
Plugs look fine....still puzzled

 

I'm not in the habit of changing parts to diagnose a problem so i found a boot off a plug and bought a plug to replace that possibly fouled plug.
The plug was fine as was the number 5 plug which is misfiring and causing a code.
Not fouled and looks normal. As for wires......they can be around 100 bucks depending on where you go. I dont think its the wires.

This issue developed over the course of a single turn of the key. Driving fine......turn car off......start car.......thats where the problem started. Running great before that.
It is also a random problem.......drive for 20 miles on the hwy with no problem then you touch the gas pedal and it bucks and stumbles.
The timing belt has never been done.

I just read a post from T4R.org where a guy replaced plugs,wires, cleaned maf, new coil pack and it was the cylinder 5 injector that was throwing the 300&305 codes.

 

After more research......faulty injectors and those codes are more common than i thought.
Might be time for an ohm meter .......

 

I just disassembled the #5 plug wire connected to the coil pack and pulled the electrode and spring out. It all looks like brand new with no burn marks, cracks or discolorations in the silicone boot or long metal electrode.
I'm down to the coil pack or the injector.......after seeing multiple 300&305 code threads leading back to the injector....i'm sold. Most of these forum members replaced everything else before doing the injector. Looks like the the 1/3/5 side of the engine is a bit easier to pull the injector rail. Looks like i might just have to remove the throttle body ....no?
Thanks !
Ks

 

I ran into the same problem last night when we went on a drive! I've been stumped trying to figure it out. Hopefully you find out what's up.

 

The injector rails are connected by a crossover in the back. You'll need to remove the intake plenum. It's easy. Remove intake from throttle body. Remove the coolant lines and aic line from throttle body. Remove throttle, trans linkage from throttle body. Rmmove a couple vacuum lines from back of intake plenum. Remove intake plenum bolts and remove plenum. Easy least to remove injector rail from there.

 

I have the same problem. Went for a drive the other night and got stuck in a hole and banged up the door and quarter panel on the passenger side. After winching it out it would chug and act the same way, then the dome lights, power locks, seat belt light, stereo, and the clock stopped working. After they stopped working it ran just fine. I pulled the fuse that says DOME out and it was blown. Just replaced the fuse and went to go on the interstate and had the same problem, I couldn't get it past 30 MPH. So we pulled the fuse out and it's running fine again. Not sure if this is the same issue but try pulling the fuse and driving it. I have a short somewhere and I can't find it anywhere!

 

No, that's not the same problem at all. Make your own thread please.

 

Still trying to decide whether to do the injector......napa seems to have the best price anywhere at 109.00. Plus Arizona insane 8% sales tax
Imagine that.....you get to pay 8 bucks for the priveledge of buying local.
No wonder the internet rules!