ok so my friends tl has misfire codes on.. it was cylinders 2 3 5 6. so we changes the coils for them and all 6 plugs. everything from factory. the engine light came back on with cylinder 2 misfire and the code p1399. that random misfire code. so wut now should i change the rest of the coils that i didn't change?

 

I have the same problem......... It comes on wen it feels like it....... Right now it hasn't came on for a week(used to come on every morning). I cleaned the egr valves and tb.... Also make sure the oil level is right because low oil causes random missfire... It it comes on again i'll change all the plugs and coils.

 

well i've already did plugs and 4 coils.. maybe i have to clean the egr valve and throttle body.. should i do the egr port also?

 

You might have wanted to try cleaning the carbon out of the system first before buying new coils.

Try a seafoam treatment. Big thread in main TL area has all the info needed.

I had misfires and the dealer was about to change out all the fuel injectors, but under pressure from the warranty company, they found that it was just carbon.

 

I've done it about 4 times and eveery time I'd get a CEL light on wen I first start it. Does that mean I have excess carbon built up?

 

From what I've read, getting a CEL after a treatment usually means the carbon burning off is fouling the O2 sensor. Usually that clears itself after a bit of driving. It might be a clue though. Will a failing o2 sensor cause misfires? I thought it was more for air mixture.

When my car was at the dealer to fix my misfires, they said they took off the plenum (they said "plentum", but I'm pretty sure that was a typo) and cleaned the carbon out. I don't know where this is or how to do it. Maybe someone else can elaborate.

 

Yes, 02s will cause the code, ive seen it on my car and there have been others.

The plenum they talked about is the Upper Intake Manifold. Cleaning it has been discussed and there is DIYs in the DIY thread. Just look for EGR cleaning.

 

What I don't get is it a random thing..... 2 weeks it would drive fine no codes then the next week every morning boom all the lights(check engine/VSA's) would come on. It would still perform the same(no noticable loss in performance).... The dealer says lets pull the engine apart (a my expense of at least 2k in labor)and maybe a bent valve or something but that should be hard evidence and the CEL should come on every time right? I've been checkin up on my oil level and keeping it level and so far no CEL's.......Also sometimes I get rough starts it would take a couple of seconds to start........

 

sooo i should seafoam the engine, clean the egr ports, clean the o2 sensors... and i should put back the old sparkplugs before i seafoam. btw how many o2 sensors does this car have? 2 or 4? cuz i know some v6 have 4.. 2 primary and 2 secondary..

 

I believe we have two O2 sensors.

 

DO NOT clean the O2s. That will damage them and you will be out buying new ones

 

Honestly. It could be any number of things. It could be the motor needs work (ie a bent valve, low compression on a cyl) it could be the ECU, it could be wiring, could be a O2 sensor.
Oil level doesnt have any thing to do with it.

 

i heard somewhere on this form that seafoaming the engine messes up the o2 sensors or something. tahts y we have to clean up but i guess i read wrong. maybe i was too tired or something i'll take your word for it.. were just gonna clear the egr port first. he also has a ripped motor mount passenger side.. probably from the engine shaking very weirdly..

 

It's really annoying because it happens so randomly. If it were a bent valve or something, it should ALWAYS happen. I'm starting with all the spark plugs, then coils. EGR/throttlebody have been cleaned.... valves adjusted 15k ago, CAI cleaned and reoiled. Can anyone thing of anything else? Sensors that would throw a missfire code (o2 would throw an o2 code but maybe MAP sensor or crank sensor?) Also I had someone clean the throttlebody when I had the Plenium spacer installed. Is that the same thing as cleaning the IVAC? I tried to search it but found no D.I.Y's for it........

 

ok my friend said his dad brought it to a shop and they changed the fuel injectors and it fixed it.. lets see..

 

A heavy dose of seafoam at 2oz per 1 gallon gas or 1 can in 1/4 tank of gas, will clean the injectors like magic. Always try that, and a can in the intake vac line when dealing with misses.
The EGR port gets carbony buildup really bad and the tiny holes need to be cleaned out.
See the DIY section for Thermoblock spacer install w/ EGR cleaning
Do not put old plugs in! If they are recent the seafoam wont hurt them at all, and doing the all important burn off drive afterwards cuts down on the CEL and other wierdness

 

I had a similar problem w/ cyl 4, 5, and 6 misfire. I had the luxury of having a scan tool and the misfire was happening during idleing when engine cold. First I rotated spark plugs and coils, but that didn't fix it.

Then I took a guess on the egr valve being cracked open a bit during idle (supposed to be closed) and replaced it. While I was in there sprayed some TB cleaner in the egr port, clean the TB, and IACV. So far no CEL for about a week now.

 

What kind or car do you have?

 

Does the IACV(or IVAC) come out with the tb? It seems like it would be my problem. I'm changing all the plugs tommorrow(denso irradiums @ $15 a plug ) so first Imma buy 3 cans of seafoam, do one in the gas tank and 2 thru the vaccum lines. Everytime I seafoam it the CEL /VSA's light comes on immediately.

 

Yes a o2 if bad enough to throw a code would throw a O2 code, but if its not reading right or failed we have seen them cause a misfire code. There are many things that can cause it.

 

Taking the EGR off and spraying cleaner in was a quick cleaning but not a total cleaning of the ports that get clogged in the first place.
The only way to get them totally is remove the intake manifold and spray spray spray. Acura method places manifold in a solvent tank, running thru each opening of the manifold to get it spotless again.
Check the DIY- Installed Thermoblock spacer and EGR cleaning
The IAC Idle Air Control is attached to the Throttle Body assembly- when thats off, you flip it over and see the screws. Clean it with carb spray-throttle body cleaner

Dont buy the Denso PLugs- what a $$ ripoff
NGK Iridium IX or NGK Platinum if thats what they have- 7 bucks each, and outlast outplay outwit the denso

 

Swapped out the plugs(I was running rich by the looks of the plugs but It may be from all the seafoams 7+ times) also cleaned out the IVAC and it's more responsive...... We'll see if it solves the problem

 

Update... driving about a week now with no missfire codes...

 

I had the misfire codes as well, 02 TL-S, and it ended up being the #2 cylinder injector that was bad. If you haven't looked at that.

 

^How'd you know that? Did it throw a specific code?

 

Headhunter: Were you getting *random* misfire ie. more than in one cylinder? I think it's unlikely that 1 injector would cause misfire in the other cylinders.

 

It doesnt but our cars are very sensitive and the ECU will often thro a multiple misfire code when its just one cyl

 

on the subject of injectors, is there an upgrade(3g tl-s or odyssey injectors)? i plan to go s/c and want to get around 350whp

 

hi guys, has anyone had misfiring from all the cylinders,
i had codes.po300,PO301,02,03,04,05,06.
i tried reseting it but it came back on the next day.....
iddle is low when i start the car, but it become normal when it start driving,....

 

running the SC from what i read there isnt much need unless you really start to go all out with the HBP. I suggest you take some time reading the SC threads on the CL side. You can buy expensive injectors but from what i read im not sure its needed. Maybe pick up a set of S2K injectors.

 

Soo are you looking for a answer?

Buy new plugs. and reset. if it comes back buy one new coil pack and start at 1 cyl. Replace it reset the ecu again and see if it comes back. If it does take off and go to the next cyl. Repeat till you find the one thats bad. (on our cars very often just 1 will cause the multiple misfire like you have)

 

I give up............. Had to turn down the s/c sale because my missfire codes came back.. damn i was good for 2 weeks I think my engine's wearing down because I burn oil like crazy. I'm gonna change the coil packs but that's my last straw... Here comes 3G TL-S