New here and need some serious help

[Zep]

The other day I changed my spark plugs and after changing them now my vehicle every couple of starts or after sitting and getting cold will have a rough start. I thought was the plugs and went and puchased another new set but same issue. Once I put the 4Runner is drive to go the rough idle goes away. The rough idle is not happening at every start up but mostly after sitting a couple hours but sometimes it does occur closely. I've tried check for vacuum leaks with using propane and a rubber hose but nothing at all.

Yesterday while trying to figure things out under the hood I heard a high pitched hum like a hum pitch and a high pitch at that. The sound is coming from the drivers side area and can't figure it out.

Worried about both but really worried about the rough starts and idle before going into drive.

2004 Toyota 4Runner SR5 V6 4WD

Help please.

 

[Lowetony]

what plugs did you install?

 

[Zep]

what plugs did you install?

I started with NGK Iridium and now after that I switched to Bosch Double Platinum and issue still present like it was with the NGK's. All I did was replace the plugs so I'm really lost as to what happened.

 

[BlackWorksInc]

Did you disconnect the battery at any time and/or did you check every hose? there's a couple hidden from view ones if I remember right?

 

[Be_Original]

Did you check the gap on each plug? This issue only started after changing the plugs, never happened before?

 

[Zep]

Did you disconnect the battery at any time and/or did you check every hose? there's a couple hidden from view ones if I remember right?

While changing my plugs I never disconnected the battery as I thought it wasn't needed or that I've heard before so I left it plugged up. I checked all the hoses and everything was together as it should be. Now the only thing I can come up with that happened during the process is the two plastic tabs attached to the wheel well that holds two of the what I believe are vacuum air hoses snapped - these are the two plastic tabs that broke that hold the lines in place. I'm not sure if these two tabs breaking giving the lines slack and able to freely bounce causes this issue or not. I went outside a minute ago and rigged it to hold still as tight as possible with metal wire so now the lines aren't freely bouncing. I thought since the lines were still connected and just had some play and bounce that it wouldn't cause much of an issue but is it possible that with the clips breaking and not holding the lines still it could cause this?

 

[Zep]

Did you check the gap on each plug? This issue only started after changing the plugs, never happened before?

On the NGK's I never checked the gap because supposedly they are pre-gapped which means nothing I guess lol and second I don't think you can gap a NGK Iridium plug because of the possibility of damage to the center. On the Bosch I never gapped these either as their suppose to be pre gapped. Is it possible this could be it? I know pre-gapped probably means nothing but yeah.

Issue never happened before, only after changing the plugs - leaves me scratching my head and frustrated.

 

[Be_Original]

On the NGK's I never checked the gap because supposedly they are pre-gapped which means nothing I guess lol and second I don't think you can gap a NGK Iridium plug because of the possibility of damage to the center. On the Bosch I never gapped these either as their suppose to be pre gapped. Is it possible this could be it? I know pre-gapped probably means nothing but yeah.

Issue never happened before, only after changing the plugs - leaves me scratching my head and frustrated.

You are right when you say they are pre-gapped but I personally still check my gap and compare to the FSM specs. .039-.043 for the OEM Denso K20HR-U11. When you gap the plugs don't rotate the gapping tool, find the correct gap and slowly slide it in towards the electrode. A lot of people damage plugs by rotating it to gap. Make sure all coil plugs are pressed in tight until you hear/feel a click. Torque your spark plugs to 15 ft lbs, or tighten by hand until bottomed out then give 3/4 turn with ratchet. I would think that a loose spark plug can cause rough idle. Just some thoughts
Whatever lines, or parts you removed for easier access make sure you properly re-installed.

http://im.toyota-4runner.org/attachments/4th-gen-t4rs/54727d1324244919-spark-plug-gap-00301810.pdf

 

[preacher35]

After reading about your issue post spark plug change, I have two questions for you. 1) are you sure that the "high pitched hum" is directly related to the rough start/idle that you were encountering immediately following said plug change? And, 2) is it possible that you damaged one of your coils when pulling them off of the plugs? My wife used to have a GMC Acadia (massive piece of dogshit btw). I partially damaged one of the coils whilst changing the plugs and had VERY similar symptoms (minus the hum). Just food for though. Good luck!

 

[Be_Original]

While changing my plugs I never disconnected the battery as I thought it wasn't needed or that I've heard before so I left it plugged up. I checked all the hoses and everything was together as it should be. Now the only thing I can come up with that happened during the process is the two plastic tabs attached to the wheel well that holds two of the what I believe are vacuum air hoses snapped - these are the two plastic tabs that broke that hold the lines in place. I'm not sure if these two tabs breaking giving the lines slack and able to freely bounce causes this issue or not. I went outside a minute ago and rigged it to hold still as tight as possible with metal wire so now the lines aren't freely bouncing. I thought since the lines were still connected and just had some play and bounce that it wouldn't cause much of an issue but is it possible that with the clips breaking and not holding the lines still it could cause this?

If these are in fact vacuum lines, trace them and make sure they did not come loose from their fitting or connection. If you broke the retainer tabs you may have disconnected the line as well with the applied force.

 

[Zep]

You are right when you say they are pre-gapped but I personally still check my gap and compare to the FSM specs. .039-.043 for the OEM Denso K20HR-U11. When you gap the plugs don't rotate the gapping tool, find the correct gap and slowly slide it in towards the electrode. A lot of people damage plugs by rotating it to gap. Make sure all coil plugs are pressed in tight until you hear/feel a click. Torque your spark plugs to 15 ft lbs, or tighten by hand until bottomed out then give 3/4 turn with ratchet. I would think that a loose spark plug can cause rough idle. Just some thoughts
Whatever lines, or parts you removed for easier access make sure you properly re-installed.

http://im.toyota-4runner.org/attachments/4th-gen-t4rs/54727d1324244919-spark-plug-gap-00301810.pdf

Tomorrow when I get home from work I'll take them all out and check the gaps and do my best to gap them correctly if need be. Thanks

 

[Zep]

After reading about your issue post spark plug change, I have two questions for you. 1) are you sure that the "high pitched hum" is directly related to the rough start/idle that you were encountering immediately following said plug change? And, 2) is it possible that you damaged one of your coils when pulling them off of the plugs? My wife used to have a GMC Acadia (massive piece of dogshit btw). I partially damaged one of the coils whilst changing the plugs and had VERY similar symptoms (minus the hum). Just food for though. Good luck!

To be honest I'm not sure if the hum is related in any way and most likely not in my opinion. I think the hum might just be the engine normal wise but I'm just frantically going insane over this idle crap lol.

Is there a way to find out if a coil is bad or good?

Yeah I'm not much of an American auto person myself lol.

 

[Zep]

If these are in fact vacuum lines, trace them and make sure they did not come loose from their fitting or connection. If you broke the retainer tabs you may have disconnected the line as well with the applied force.

Tomorrow with some daylight I'll take a look at these lines to figure out if they disconnected or slipped. Will let you know. Thanks

 

[Zep]

Btw not sure if this helps figuring out a possible cause but like when I start the engine and I get the rough idle if I take the 4Runner from Park to Drive the rough idle goes away and the 4Runner sounds normal and if I shift back into Park the idle is no longer present. So shifting from Park to Drive the rough idle goes away. Not sure what this might mean

 

[zonianbrat]

So I assume there is no CEL on? Do you still have the old plugs? If you do I would put them back in and see if your idle problem goes away. May seem dumb and tedious but when troubleshooting phantom problems sometimes you have to go backwards to establish a baseline. The hum you are hearing from the drivers side could be the accumulator pump on your master cylinder abs module. Get real close to it next time you hear the noise and see if it is coming from there. Good luck!

 

[Zep]

Well everyone since the post started the rough idle continued and out of nowhere the Check Engine light pops up this morning along with VSC Off and Trac VSC lights. From research it seems these two lights go off when the Check Engine light goes off as well. So just incase someone doesn't know I guess it's worth mentioning that the VSC Off and Trac VSC will flash on and stay on along with the Check Engine light if the Check Engine light is to go off.

So anyway's I ran through all the hoses for air leaks over the weekend and used the propane and hose method. I unplugged each coil harness to hear a difference in engine rev and what not. After testing each plug by removing the harness and plugging it back in I turned the vehicle off and started it back up. As soon as I started the vehicle back up the Check Engine light is on along with the VSC off and VSC Trac. I was worried I left something unplugged or something so I shut off the engine and checked all plugs, lines and hoses and nothing to be found. Next I unplugged the battery to reset the Check Engine light to see if the issue will pop up again incase it was a loose wire, cable or something and I might have got a good connection by tapping or wiggling it. After hooking the battery back and turn the vehicle the Check Engine light stayed off along with the VSC Off and VSC Trac. But I still had my rough idles and rpm's not looking right.

I drove like this for a couple days confused as to what could be the issue. This morning when I was going to work and started the 4Runner up I automatically get the Check Engine light and VSC Off and VSC Trac lights. Well at least I knew I could take it to the local parts store and get my codes read and figure out what the issue is and fix it possibly. On my lunch break I took my vehicle to local O'Reilly's Auto and had them check the codes. I don't remember the specific code it through as the printed results are in my car and I'm back at work now but the code read Cylinder 4 misfire. Of course on the print out they give you it tells possible issues, fixes and more. The one thing that stood out to me was the Ignition Coil. The O'Reilly's store had none in stock at $99 but my local Toyota Dealer and parts store had them in stock when I called for $109 without tax. I drove to the local Toyota dealer and picked up a new Ignition Coil and drove over to the local Home Depot and changed it out in the middle of the parking lot lol. Got back in the car and it started perfect, no rough idle and RPM's were perfect. When I got back out on the road the vehicle had much better acceleration, pickup and a more sporty pickup feel to it and I haven't felt this in this vehicle in a long time. I drove over to my local O'Reilly's to have the codes cleared to see if anymore codes or the same code's pop back up. I've drove about 20 miles and no lights on the dash and running smooth as butter.

I hope or lets hope the issue is resolved. Thanks everyone for all your help, suggestions, input, advice and everything. Nothing worse than trying to figure something out and no help and relying on the stealer-ship lol. You all have been great :thanks:

 

[fullboogie]

If it pops back up, see my thread on Bosch spark plugs - they caused a huge problem for me. Thread is titled "engine woes and all too obvious fix"

 

[Zep]

If it pops back up, see my thread on Bosch spark plugs - they caused a huge problem for me. Thread is titled "engine woes and all too obvious fix"

Well I thought I was good to go and this morning when I went to go to work the truck idled rough like it was about to kill out and it shacked a little bit. Almost like it was about to die out of gas or power - I've never in my life ran out of gas so I'm kind of going from what you see on TV lol. I had put the car in drive and as I started to pull away the sound continued so I put it in reverse and backed up to not go to work and it continued but out of nowhere it started to idle correctly and sounded normal so I was running behind by now and went out to work.

I'm thinking about changing these spark plugs out again and seeing if it will help.

I'll read your write up about the Bosch spark plugs too and see if that helps me. If anyone has any comments or something at all they would like to add or whatever please do so. All opinions are appreciated and will be looked into. Thank you guys and I'll keep you guys posted. :redbrick:

 

[fdbyrne]

Any chance at all that it's the head gasket issue that just coincidentally happened at the same time that you changed out your plugs? The symptoms sure seem similar.

 

[Zep]

If it pops back up, see my thread on Bosch spark plugs - they caused a huge problem for me. Thread is titled "engine woes and all too obvious fix"

Just read your write up and it's quite interesting. I originally had purchased NGK's but possibly the issue all along was the injection coil and not the NGK's. After pulling the NGK's out and swapping in the Bosch plugs it's possibly just running like s**t now because of the plugs being the Bosch. I'll call Toyota and see what spark plugs they have in stock for the 4Runner and pick some up. I've read and heard many of stories about not using anything other than NGK and Denso but at the parts store it was either NGK, Autolite and Bosch for the 4Runner - for some reason I'm not trusting parts stores for spark plugs or it's I don't get the best of feeling getting my plugs from a parts store that is lol.