Ok…I need some help. This is a long one but I’m putting all the little details incase I missed something during all of this and because I know the systems all work together.



Backstory: I have a 2000 TL. For years it’s leaked oil & I always thought it was the oil pan just never dealt with it. In 2017 I got in an accident, did damage, patched up the car to be able to drive it, ended up getting a new car in Feb 2018, so my TL sat until 2023 (only being driven once in a blue moon if at all) when damage was fully repaired & my husband starting driving it as his daily driver. In the beginning of 2024, the oil leak got bad enough that is was “running” onto the exhaust & causing a terrible smell. Finally decided to deal with it & for the first time since I bought the car (in 2013), I let a mechanic/shop work on it (previously I have done all of the work to it). Terrible idea. They charged us way too much, replaced the oil pan & replaced the oil filter housing gasket. After getting the car back the 2nd time & it still leaking oil, we took it to a different shop. That shop told me they couldn’t pinpoint the oil leak but they were pretty sure it was coming from the timing chain… 🙄 so needless to say, I was done taking it to shops & decided to fix it myself as I have done all the work before & I have the dealership service manual.



So beginning of August, I started figuring it out. Come to find out it was the oil pump “gasket” leaking. I also found the power steering pump leaking, the high pressure line for the power steering leaking a very small amount & the drivers side axle seal leaking. So I tore it down, resealed the oil pump with genuine Hondabond & put everything back together with new gaskets/o-rings. Found that the 1st shop had just lopped on the RTV on the new oil pan so I cleaned it all off & did it properly. I put a new power steering pump in & a new high pressure line (what a b****). Also did the drivers side axle seal.



When I originally reinstalled the used timing belt, I lined up my marks that I had made on it but stupidly forgot to line up the rear camshaft to TDC & I was off 2 teeth. When I fired it up the first time after all the work, it ran like crap. I immediately knew the timing was off so I undid it & could not for the life of me get it lined up correctly so I ended up getting a brand new timing belt, power steering belt & AC belt & putting them on. I only ran it for a minute or so with the timing belt misaligned. Once all the new belts were on, fired it up & there was a ticking that wasn’t there before & while letting it idle for a few mins to check for leaks, it would start jumping the RPMs up & down. Thinking the IACV was clogged or not working properly, I removed it & put a new one on. Still had the same issue & after going over every single hose, I found a tiny vacuum line that I had forgot to reattach. Ended up thoroughly cleaning the original IACV & putting it back on & everything was fine.



I was still concerned about the ticking so I decided to do a valve adjustment. So I did the valve adjustment, new spark plugs (NGK Laser Platinum plugs - gapped correctly), new valve cover gaskets, new tube seals, new rubber grommets, new plenum & intake manifold gaskets & new throttle body gaskets. I did save & use the old coil packs (I marked them with what cylinder they came out of & put them back accordingly). I thoroughly cleaned every part & got any “gunk” out (mainly from the plenum). I torqued every bolt & nut to spec & just overall double checked my work.



My husband drove it to back & forth to work for 3 days (roughly 180 miles) & on the third day, I happened to notice a mass amount of fluid drips on our garage floor, so much fluid on the underside of the motor & body that I honestly couldn’t tell where it was coming from. Finally narrowed it down to being ATF but not 100% sure where exactly it was coming from. Honestly, at this point, it was one thing after another & I ended up just leaving it parked for a month or so cause I needed a break. Finally got the motivation to work on it again & figure it out, I put UV fluid in the ATF, drove it 10 miles, got it home, jacked it up & found the axle seal (the one I already replaced) leaking. Long story short, ended up getting a new axle shaft, new set ring, new axle seal & genuine Honda spline grease & was able to get it in all the way & put back together.



After all of this & because I know the car like the back of my hand, I told my husband that I was going to drive it for a week (I only drive about 10 miles a day) to verify everything is good before he drives it again (he drives 60 miles a day). Last week, I drove it Monday with no issues, Tuesday with no issues, Wednesday to work was fine but on my way home about 5 mins after leaving work, it started to shutter & felt like it was misfiring, the CEL light came on & was flashing, I immediately plugged in my OBDII scanner & got code P1399 “misfire in any cylinder” but no other codes & specifically no code for what cylinder was misfiring. I’ve also dealt with misfires before & it didn’t seem to shutter as bad as when I had a misfire before so I was a bit confused. I just wanted to get it home so after pulling into a parking lot & popping the hood to check for anything obvious & taking a quick look underneath & not seeing anything, I pulled out & headed home driving really cautiously. I had called my husband to give him a heads up incase I need towed home. Drove another 5 mins & got to a stoplight & then I smelled a terrible smell. Gut feeling wasn’t good & I didn’t want to ruin anything so I pulled over into a parking lot. Let it idle while I popped the hood & was searching for anything, most obvious fluid everywhere or something. Didn’t see anything so I shut it off & closed the hood. Called my husband to come flat tow me home. He had to get dinner paused, the kids loaded up & the dogs dealt with so it took him a little bit. While I was waiting I went & popped the hood again & this time a plume of white smoke came from between the firewall & the motor. Went to the passenger side & laid on the ground & thick white smoke was pouring from the catalytic converter. Husband ended up getting to me, flat towing me home & we pushed the car into our garage.



At this point, I’m really over this car but there is no way in hell I am giving up now. So after doing research & reading forums on here, I was convinced it was a bad catalytic converter. I got a new one (Magnaflow 27402) & installed it over the weekend. I did notice that the O2 sensor in the cat was white on the tip. Cleared the codes, fired it up & got a P1399, a cylinder 2 misfire, a cylinder 5 misfire & a random misfire codes. Shut it off, put a used (from a parts TL I had but new to this TL) coil pack in cylinder 2, cleared the codes & fired it up. It ran great! My husband drove it through our neighborhood (maybe a mile or 2) & then came back home.



I drove it Monday & Tuesday with no issues. I needed my car (not the TL) yesterday so my husband drove the TL to work. He got to work & said everything was fine & it ran great. On his way home shortly after leaving work, he was on the highway & it started shuttering again. He got off the highway & got to a parking lot. He ran the codes & again a P1399. He was much further from home & I was not able to go home & get his truck to go flat tow him home so he used our AAA & got towed by a standard tow truck, not a flat bed. I dealt with our kids & dogs & then I had a work event. Before I got home, he fired up the car & just backed it into our garage for me. When I got home, he told me the power steering whined when he just slightly turned the wheel to straighten out the car while backing it into the garage. I wanted to flip the car around so that the exhaust was going straight out of the garage while I did a coil pack test. So I pulled the TL out & flipped it around & put it back in the garage. It shuttered & flashed the CEL the entire time but the power steering was also whining like crazy. After getting it nosed into the garage I let it run while I pulled each connector one at a time on the coil packs. I didn’t go in any specific order but the order I did was cylinder #6 - no change, #5 - no change, #4 - no change, #2 - change, #1 - change, #3 - change. I was severely confused so I went back & pulled the connecter on #4 - now a change, #5 - now a change & #6 - no change still. So shut it off, grabbed another used coil pack & put it in cylinder #6. When I went to clear the code, there was a P1399, a random misfire, and codes for misfires in cylinders 2-6. Originally those codes didn’t show up hence why I did the coil pack test. So I cleared all the codes, fired it up & it runs great for the moment.



At this point, I am waiting for the other shoe to drop & this to happen all over again. After reading more forums on here, I have tested the battery (12.23 with the car off, dips to low 10s when cranking & then jumps up to 14s while running) & with the car off, I pulled #13 fuse for the clock (& ECU) on the passenger side & kept it out for about a minute before putting it back in.



A few things to note, I have a sound system, aftermarket deck, all 4 aftermarket door speakers, 4-channel amp for door speakers, 2 subs (stock sub is completely removed) & a mono-block for the subs. I also have an aftermarket alarm with remote start. I have lights in all 4 footwells. My battery is a Fullriver FT825-34 from 8/20. The battery cables terminals no longer tighten around the posts on my battery to get a snug fit. I currently have them zip tied down to get a better connection…I know, I know not my proudest moment but this car got put on the back burner for quite a few years & now I’m trying to get it running & not leaking anything but something new keeps happening. Also, when I was driving it last week & got the P1399 code & this week my husband was driving it & got the code, we had both been listening to music with the subs turned up.



If you made it this far, thank you! I have read probably hundreds of the forums on here & I’m just at my whits end. I have read everything from battery issues to coil pack issue to fuel rail issues to ECU issues. I’m trying to start small & cheaper & then work up to the bigger stuff. Any ideas, comments, questions, fixes…would be very much so welcomed!

Below is live data from my scanner that I took last week Tuesday, incase that helps at all.

 

Misfires can be a PIA.

I had purchased a used SC'ed 2003 CL-S automatic back in late 2019. When I received it I found that it would consistently throw a P0305 and some other random cylinder misfire upon a cold start, every time I drove it. No noticeable hesitation while idling or driving, no oil burning from the exhaust.

I'd clear the codes (ScanGaugeII) and they would not return, during driving; however, if I parked the car a short while (to shop at a store) and then restarted, P0305 & other random cylinder code would reappear. Clear the codes and none would return during driving & no other problems.

In short, initially, I removed all the go-fast parts (as a COVID project ), changed the original timing belt and returned the car to stock using a factory airbox / filter from a salvage yard CL-S. The salvage air box was 'well worn' & had the rear plastic hold down 'ring' on the opposite side of the hold down screws broken off and was not a tight fit in that corner. Reset the ecu, performed the idle relearn procedure & went for a drive.
Same drill with the appearance of P0305 / random cylinder misfire code.

I replaced all the spark plugs & COP's, along with the #5 cylinder fuel injector, reset the ecu, performed the idle relearn procedure, went for a drive and found no joy, lol.

As a result, I thought if I was going to have this 'issue' to contend with, going forward, I was going to let the engine 'breath' a little easier, in the mean time, and purchased a cheap Chinese ebay CIA and installed it. Reset the ecu, performed the idle relearn procedure & went for a drive.
Same drill with the appearance of P0305 / random cylinder misfire code.

Drove the car many many months and 'put-up' with the annoying P0305 issue. As an experiment, having run out of ideas (should have done a compression & leak down tests, oh well) / options at the time, I found a cheap OEM 17245-PGE-A00 Air Cleaner Lower Case for sale and purchased it. Just figured I'd remove the CIA and go back to stock and sell the CIA.
Installed the new air cleaner lower case with the stock filter. Mind you, since this air cleaner lower case was new OEM it had an intact rear plastic hold down 'ring' on the opposite side of the hold down screws. Reset the ecu, performed the idle relearn procedure & went for a drive.


No P0305, or any others thrown by the ecu!
I sh!t you not, lol! I could not believe it.
Finally as a result, I was able to get enough 'code free' drive cycles on the car to set the emission system readiness codes and the car will now consistently 'cold' start and 'hot' start without throwing any DTC's, it has been this way now for a couple+ years.

With that all said about my random misfire adventure, maybe give these battery post shims a try to improve the terminal connections in helping with your situation??
Perhaps a fluctuating inconsistent 'wonky' battery connection is having an indirect effect on the cars ECU??