On my recently aquired 2006 TL. It idles poorly and sometimes stalls. Under heavy acceleration there's a noticeable valve chatter around 4k. It still has excellent power under acceleration. It has a misfire in cylinder 2. It throws no codes and has none stored. I have narrowed it down to weak spark in said cylinder. I have swapped coils and still a weak spark in the cylinder. The plug looks fine, the egr ports look fine, the throttle body is clean. What would cause one cylinder to have weak spark even with known good coils plugged in??

 

Possibly a bad ground at said coil pack or bad spark plug, or needs valve adjustment.

 

Take a compression test

 

I appreciate the replies. Thank you for that. In my experience a misadjusted valve and/or low compression usually doesn't cause a low spark condition at the coil. These are definite problems that should be addressed if they were present but I'm almost positive they aren't causing the problem I'm having at the moment.

 

that's why its called a test.
rule it out, please.

 

Swapping is good, "looking fine" not so good. Have you tried swapping plugs by chance.?

 

How can you be sure it's "valve chatter" that you are hearing?

How do you know that if there are no codes?

How do you determine what defines a "weak spark"?

How many miles on the car? auto or 6MT?

Have you check the passenger side carpet for wetness?

Have you checked all plugs for proper torque?

 

not sure how you diagnosed the spark. but if you're absolutely sure that it's the spark, swap plug and coil with different cylinders.

 

How do you know if it's misfiring on 2 if there is no code? Foul plug? Flashing CEL?

how many miles on the car? Running premium fuel? Are you also running low on oil? Check that oil level.

 

because he doesnt want to test the car,

 

You're a funny man.
I performed a power balance test to determine which cylinder was giving me trouble. I do not need a check engine light to determine that the engine has a misfire. I will do a compression test today and report back with the results. I know there is a weak spark because I used a spark tester to measure the spark on the front 3 cylinders and the middle cylinder has a noticeably weaker spark.
I know that it's valve chatter that I am hearing because I am familiar enough with engine sounds and am not exactly inexperienced with them.

 

The front middle cylinder is #5, not #2....

 

If you know everything already, what are you looking to ask in this thread?


so much for "need help"

 

If it's not the coil or plug then replace ECM/PCM. Unless it's a connection or grounding problem.

 

I gotta say:

1. If there's no MIL, no flashing MIL and no codes, it's not misfiring.
2. #5 is notorious for the loose spark plug issue. It's possible the chatter you heard was the fact that the plug is/was loose.
3. You also could have water in the ECM. Again, check the ECM for water stains/corrosion and also check the passenger side carpet for any signs of wetness.

 

^this

Also, is water in the ECM a common problem or something?

 

Tip: Put a diaper on the ECM/PCM if it keeps wetting it self. Lol

I'm sure Pampers or Depends will work, depends on your preference or it's age I suppose. If you want a snug fit try Snuggles. Lol, puns intended.

 

Yeah, water in/on the ECM from the A/C drain tube getting plugged has happened several times. The water backs up in the evaporator area and then spills over and drips down onto the passenger side carpet and the ECM...

It usually results in melted/fried coil packs.

 

Not sure how my comment gave you the impression that I thought I "know everything already". I'm also curious as to why I'm having to defend myself. I thought that the children were on vw vortex. I guess some of them decided to buy some Acuras. Anywho, the compression test was a straight 195 psi across the board. I'm going to do a leak down test this week to rule out valve issues. I appreciate all those with helpful, non-angsty teenager comments.

 

Well, you sure don't know which cylinder is which

 

True. But I was corrected and I appreciate it. I'm not sure how your comment is relevant or helpful but thanks. I guess?

 

HEY! I'm 26...


We have had our fair share of people asking questions, disregard all answers, and then "figured it out". Your posts were leading down that path. Once bitten, twice shy.

Maybe you've done most of what we've assumed you haven't done but don't actually write it out in your post thus leading us to presume you're not properly diagnosing, in which case: you know what you're doing when it comes to cars yet your writing leaves much to desire.


At the end of the day, we're trying to help you here, but you're our eyes and ears and hands. You have to help us help you too

 

Understood and well said. Thank you for being straight up. I looked further into it today and it is unequivocally a spark issue in the #5 cylinder. I hooked the spark tester up and it has zero spark at idle. Once the accelerator is pressed to slightly above idle the spark starts up and is very strong. I'm thinking it could be a problem with the crankshaft position sensor or the pick up wheel. This explains why the car screams when accelerating but wants to almost die when idling. What do you all think?

 

Ok. For those who may have the same problem I had, I have solved the misfire issue. Yes, regardless of what others have said in this thread and despite their false conviction, it is possible to have a misfire without a check engine light. My timing was off by three teeth. I took the belt off, lined up the timing marks and put the belt back on. You will need a bench vice and small allen key, drill bit, or other small price of metal to press the tensioner in. The timing being off caused the misfire. I appreciate all those who tried to be helpful and at least acted their age. I might not have known what cylinder number I was talking about and may have disregarded some advice that I knew was not facing the right direction but I never acted with the childish candor that I don't even expect out of my 6 year old nephew.

 

Who did your TB change?

 

I bought the car with this problem from the original owner (I'm in the car business). I am assuming, since the timing belt looks new that whoever did the service royally screwed it up. I don't know who did it but it cost me nothing to fix it thank goodness.