So I finally have my new 6 speed in my car... new problem is that it has a random misfire which I assume to be an ignition coil, but the car also has an issue where it will stall if i give it light throttle ex. rev from idle to 2-3k, but if I give it a good rev like from idle to 4k it won't stall but it does drop to around 600 or so rpms sometimes and come back to idle. It doesnt do it if I come to an almost stop in gear or take it out of gear without throttle. ONLY when giving light throttle. I do have a CEL for the misfire, its random across all cylinders, I dont remember the code so I'll have to add it later. I've had a couple very small backfires (just enough to notice) and a couple fits where it misses for a good 1/2 to full second.... Any ideas??

 

Valve adjust?

 

It could be possible. I was told the engine has around 100-120k miles but it doesn't sound like it needs an adjustment for the most part

 

check for a vacuum leak..

how old are the plugs in the car ?

post up the cel code..

 

I'm not sure how old they are because I've only had the car for about a month now. But I think I figured it out, two of the ignition coils are bad and I have the replacements coming by Friday. It misses REALLY bad at idle, like the car rocking back and forth bad... So hopefully after I replace those it will be fine! I will also check for vacuum leaks, but idle isnt bad, it just misses and stalls easily.

 

bad coils will make your car sound n run terrible at idle....

keep us updated after the coil replacement..

 

Will do, it definitely doesn't sound very nice... Almost like a cam without being tuned lol, my thinking is since the idle is already weak because of the horrible missing that when I give it some throttle it just dies because it can't keep a decent rpm. But at higher rpm it doesn't die after letting it go down to idle... So I guess I will just have to see.

 

So I just installed the two new Ignition Coils. It fixed the rough idle for the most part, got rid of the misfire on all cylinders but now I just have one single code, P1399. Looked around and apparently its a random misfire code... But now I'm not getting the codes for each cylinder having misfires, I'm not sure where else to look atm for that issue.

 

on my cls 6 i was hunting for that p1339 code for a long min.... thought it was a plugged egr issues..

this was my fix..

 

That is kind of a common thing. Random misfires that may not even show a bad idle. I get it on freeway acceleration sometimes.

Its been posted around here a lot, bad fuel injector/s.

 

So I'm back again after a bit, driving around trying to learn my car a little more, the car almost never catches idle on its own with A/C on. When A/C is off the car always catches its own idle when its warmed all the way up. You guys are saying injectors, so I might try that but could it possibly be the TPS?

 

I don't think it's injectors. I would remove the front plugs and check their condition. That's easy and takes 5 minutes. If the car is new to you, I'd remove the intake manifold and clean all the EGR ports. Get 2 cans of carb cleaner and scrub it all out, wash clean. If the plugs look old, put new ones in and don't cheap out on them.

 

Yeah I'm definitely not planning on cheaping out on my spark plugs... Do not wanna figure out what happens then, the main reason I haven't replaced all my plugs yet is because they're like 14 bucks a pop at Autozone but my motor probably needs'em, its at probably around 130k

I've replaced two ignition coils and it didn't do a whole lot, I replaced the first and second ones on the front of the engine. I'll try cleaning all of the EGR ports and see what happens. Thanks for the info!

 

Pull those plugs and post pics!

 

Okay back from the dead again, I recently replaced all 6 spark plugs with some cheapo ones because I have a 3.5 build on the way, (I'll post about that when its in the works) and the car does run smoother... BUT I do still have that pesky p1399 code and on the torque app it says wheel speed sensor, but apparently for our cars its a misfire, I can tell the engine still misses a bit but not nearly as bad or much as with the old plugs, beginning to think I should buy a couple more coil packs and see if that helps...

 

do you have a 3.5 already? steal some coils from that.

 

Dont yet have the 3.5, Im gonna be picking it up next month... Otherwise I would definitely do that.

 

Primary O2 sensor? Make sure it's a Denso. It wouldn't be wasted money since I'd be a good idea for the 3.5 anyways.

 

I know my downstream O2 sensor is bad from when I did my headers last week and the cable got a little mangled... Ive since bought a new one but it was a cheapo just to make do. I'll have to get a denso one and see where that goes

 

I've heard many people with issues when they had anything other than a Denso primary O2

 

Pretty sure my primary is stock but the car does have like 220k on it so maybe it's time for a replacement anyways. Is the secondary a big issue?

 

No secondary only reads the cat.

 

Alright, I'll have to go ahead and order that. I'll report back what happens!

 

So back again
This is starting to get tiring
Replaced the TPS and Primary O2 sensor and still the same issue, weird thing with the TPS though is that at first it didn't want to idle correctly then eventually fixed itself. Still shuts off when the A/C is on. Odd thing is when I make a sharpish turn and give the car gas it acts like its losing fuel pressure, maybe this is a fuel issue?