Hyundai tucson 2008 2L FWD p0304 missfirr

Maintenance/Repairs
21

Thanks continuing with searching

22

The compression you mentioned is pretty decent so that is not a worry.

Injector spray patterns and volume can be checked but it takes an expensive test rig to do this. The only other option would be to build one. Itā€™s doable but really not worth the effort for someone working only on their own car.

For what itā€™s worth, every injector has a tiny and very fine screen in it to keep debris out of the pintle and seat area. Debris means that which is not caught by the sock in the fuel tank or the fuel filter.
When injectors are remanufactured they are often reverse flushed; meaning fluid pressure is used to force debris off of the screen and back out the way it came.

Something else to consider. This is very rare but I have seen it a few times over the years and that is new plugs right out of the box which misfire and in one incident would not fire at all.

23

Thank you for you time I really appreciate it.So my plan is to swap the injectors e.g. 4th with 3rd to see if my code goes from p0304 to p0303 as next step.I am doing that along with oil change and vvt sensor replacement.i guess thatā€™s the most cheap and guaranteed way to see if it is the injector on 4th cylinder that causes the issue right?I mean after I checked my self with that sound trick I mentioned above that all four are getting powered Wich they do

24

Just went for the oil change and the mechanic did a compression test to all 4 cylinders and said 2 and 4 where at 70 pounds !!! So heā€™s said the rigs are probably worn out and he throued a little bit of oil in them and said the pressure went up to 190 so that tells him itā€™s the rigs.While the other mechanic from the same shop measured the pressure on the 4th cylinder over 170 pounds two months ago.Can they worn out so fast? I am buying the compression gauge to measure all 4 my self as I donā€™t know what to believe and who to trust.By the way if he is true is it safe for me to drive the car till the engine lasts or die on me? I donā€™t want to spend 2000-3000 $ to rebuild or replace an engine in that old car that I brought it for 2500

25

Safe to drive, yes. Will be a bit weak, but yes.

Not a bad idea to check compression yourself.

There are chemicals, like Restore, available at auto parta stores that can help a bit. Wonā€™t fix it but will help performance.

26

Once again thank you man you teach me things I never heard of.I am reading that the ametech restore engine and oil is very good.have you ever used it? Do I just throw it in the oil? I am reading itā€™s a savior and it can maintain the wear out at least and improve performance.

27

I have never used Restore but I hear good things about it.

Good luck, hope it helps.

28

i ll try it tomorrow.One question if you know.The sell it on canadian tire too and it says 8-cylinder treatment and if you choose from the drop down menu 4-cylinder its the same product but less ml . i am assuming the 8-cylinder is the same product but more of it as you have more cylinder but still can be used e.g. half a can for a 4-cylinder

29

I have used this product, and like you I noticed the fact that on a per-mL basis, the 8-cylinder bottle is cheaper than the 4-cylinder bottle. Like you, I had the idea to use half of the 8-cylinder bottle in my 4-cylinder engine, and save the other half for the next oil change. Unfortunately, the product reacts with air, and when it comes time to use the other half-bottle, the Restore has discolored and smells different from a freshly opened bottle.

BTW, to get the maximum benefit from this product, and to avoid the risk of engine sludging, you should always do an oil and oil filter change, and then add Restore to the new oil. Never add Restore to oil that has already been in the engine for a while.

30

thanks for sharing your expirience.Just changed the oil today 12 dec 2020 with the filter.So you are saying its good to be used to a 4 cylinder engine still but whatever remains in the can its waisted after a while?

31

By the way about the compression test.Is the 8:1 to 10:1 presure (betwwen 117.6 to 147 psi) ok for a cylinder ? with no more than 10% diference between the cylinders?Also what is the difference between cold and warm engine compression test?

32

First you said the numbers were said to be 170ish or so from memory. If the memory is faulty and the latest numbers are correct then the engine is near the end. When it gets that bad a warm and cold compression test is not going to make enough of a difference to mean anything at all and the odds of a Miracle In A Can working are near zero IMO when numbers are way down in the double digits.

I do not know how the last guy checked the compression but here is how Iā€™ve always done it. I own 5 compression testers and whenever a cylinder shows a problem I do a followup with another tester just to verify the first. You, in theory, should not need to do this since you have been given bad news and are about to do a followup with a new tester.

33

well i just did the compression test to a warm engine after driving about 30 klm in highway.The results are dryā€“>180-178-178-179 4th to 1st cylinder wet(2-3 drips of engine oilā€“> 181 179 178 180. What is going on? can the little oil that the mechanic dropped in made that difference and balanced everything?check engine light is still of after driving about 70-80 klm.Spark plugs where looikng clean and good shape all 4 of them.p.s. i did the test with a bran new compression tester kit from canadian tire about 35$ but even if the tester is a little of set still all 4 are close to numbers that is good right? i ll do the test after a week or too to see any changes or if the check engine light comes on again

34

Any guides or tips how to check my coil pack without replacing it with a new one? i mean i have new spark plugs and cables and the only thing my mechanic did for the coil pack is swap it place to see if the code will transfer to another cylinder.But at this point i dont know what to trust so i would be more reliefed if i check it my self

35

Check engine light came on again this morning.Here is a pic of 4th cylinder head I took with a bore scope in August when the check engine light starting to be persisting and tried a fuel/cylinder cleaner bg44k.20200827_2002058
Could carbon build up cause missfire? Can a head cylinder be replaced without take the engine down?

36

I will try a compression test at cold engine tommorow noon and let you know guys see if the are any changes

37

The 170 and 180 compression numbers are decent for a 13 year old car and those would not cause a misfire. I donā€™t see enough of an issue with carbon that it would be a problem and I donā€™t think a cold compression test is going to make much difference at all.

That piston top looks pretty gnarly; especially around the edges. The possibilities I could see for that would really not apply. That would be advanced timing or an EGR fault as I do not think that your car has either one.
One viable possibility could be a knock sensor issue which is causing the timing to not be electronically retarded when needed.
Other possibilities could be an intake air leak into that particular cylinder or possibly engine coolant entering the combustion chamber although engine coolant can often scrub the piston top clean.

How physically noticeable is the engine miss and just to clarify; is the CEL flashing?

38

Thanks once again for your response.The CEL is not flashing.I can feel it a little slow in acceleration on a hill if I donā€™t have the boost from the flat area before or let say in a hill with 20-30 degree angle it needs a lower gear to go up.As for the missfire I donā€™t hear any backfires any stal or other hesitation.Maybe smooth vibrations on idle but nothing crazy.Also 2 things : since I bought it the coolant hasnā€™t dropped a bit from the max line neither I had to fill engine oil because it dropped from max line both stayed max the hole time.No other noticable fluid leaks either on the engine or on my parking floor

39

Also some higher rpm around 1200 on cold start till it gets in operating temp

40

Good stuff man learning a lot.Just checking the knock sensor operating and troubleshooting.I d like to check my self if both coil pack and knocking sensor are working.Also my mechanic said once itā€™s piston rigs probably there was no point of replacing the intake vvt solenoid Wich I had with me.A bad vvt solenoid can cause bad timing and misfire right? So so far I should replace the intake vvt solenoid and check with a multimeter the coil pack and the knocking sensor