i know similar issues have been posted many times in the past, and I have been lurking and researching on this forum and on google but can't seem to narrow it down and any inputs or advices will be greatly appreciated before quick to tell me that I should do my research.. Thank you

My car is 2004 TL 6speed with 160k miles. Purchased few months ago and it was fine although cel came out occasionally but went away. I was told it was CAT related but wasn't urgent so I let it be.

This one night tried to start a car, it hesitated a bit. It cranked about 2times and paused as in went completely silent though key was turned in fully, then resumed to crank 2-3 times before car started. This keeps happening till today, and I noticed that it only occurs from cold start or cars been turned off for few hours. I am suspecting this fuel rail/ injector problem.

A few days later, noticed CEL came on and started flashing on highway going approx 60 but flashing paused but cel stayed on as I slowed down.

I brought it it to mechanic, and he changed cylinder 4 & 6 coils, he inspected all spark plugs but looked good. I personally did bad coil check by unplugging wires to each cylinder while car is running to check any changes in idle, no problems found. I haven't cleaned EGR yet they can't be the reason why car hesitates to start sometimes..

Code I have is p0300 -p0306/ random misfire and for all of each cylinder..

please help, I'm about to pull my hairs out, after spending $220 at mechanic already for shit I could've done but didn't fix this issue is driving me nuts!!!

 

Since you mention the car is MT, there is a good chance that some one might over rev the motor in the past causing a bent valve. This also will give you flashing CEL.

 

1, Check fuel pressure
2. Check your primary cats, they could be clogged
3. Bent valves, leakdown test and compression test

 

sounds like bent valves!!

have the mechanic run a leak down test and then for shits and giggles, a compression test.

 

Thanks for the replies guys, I think my car is fixed. *knock on wood*

I forgot to mention that this problem emerged since I put seafoam thru throttle body. I brought it to a different mechanic in the area for diagnostics. Told him everything I knew about the car and including injecting seafoams he told me drive WOT on highway since I havent done that after seafoam treatment. 2 days after, CEL and misfire is GONEE.

For those looking for an answer for misfiring /cel especially after seafoam treatment, YOU MUST DO IT WHEN THE ENGINE IS AT OPERATING TEMPERATURE AND DRIVE WOT TO COMBUST SEAFOAM IN YOUR ENGINE.

I had a friend revved the engine to 1.5 - 2k RPM while injecting, but I havent driven much after that. I was told by the mechanic that you can't 'Hydrolock' your engine from putting too much seafoam in your engine. I am not sure that's true? be free to chime in if you know anything..

I am also looking to change fuel injectors/rail and do valve adjustment soon just for precaution.. perks of buying a 10yr old used car. Anyways car seems to be running smoother and getting MPG.. I will revive this thread if problem comes back again.. hopefully never lol

 

FORGOT TO UPDATE THIS... It turns out the culprit was fuel pump located underneath the carpet in the trunk. If anyone experiences the same issues that I've had, have your mechanic check fuel pump as well.