trying to figure out a trouble code po301 cylinder 1 missfire coils good

What is your question?

want to know if the only way to check the plug and wires and fuel injector is to take off the plenium(intake) cant even see the fuel injectors on cylinders 1-3-5 or pluges, my issue is hesatation which comes and goes but getting worse please help 2004 hyundai xg 350 l

karenflackad812b in Brooklyn NY

Jul 18, 2017

2 Replies

Popular Answer

pushrodon Jul 18, 2017

Plenum removal is required to access bank # 1 cylinders .. Recommend: compression test, IF ok then replacement of spark plugs - fuel injectors and ignition coils at same time on that cylinder bank using 'quality' parts! .. Vehicle is getting old & tired - It's just time to spend some money on it! https://repairpal.com/repair-shops

karenflackad812bon Jul 18, 2017

to my knowledge their are only three coils on this engine coil pack one controls cylinders 2&1 coil two middle controls cylinders 4&3 and cylinders 5&6 are controlled bye the last coil,the cylinders facing the firewall are 1-3-5 front off engine are 2-4-6 and also the engine responce improves with speed dont think compression is the problem do you think maybe an intake leak or bad sensor could be a problem???? and yes i thank you for the info on the plenium will check wires and plug but if # one coil is bad wouldnt it affect cylinders 2 & 1 ???

pushrodon Jul 18, 2017

I think the plug wires are permanently attached to the coils .. SO - it is highly recommended to replace all, otherwise inaccessible, items while intake plenum is removed > this is including a compression test! .. It is also a good idea to have a 'professional' scan test performed, with engine performance protocol, prior to working on the vehicle... As a side note > Compression problems are more pronounced at low engine rpms! Good luck with it! â–ªï¸https://repairpal.com/repair-shopsâ–ªï¸

karenflackad812bon Jul 19, 2017

Thanks for your help

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casey40510on Jul 18, 2017

Hello, I'm sure pushrod will have more info, but the coilpack may or may not affect 1 and 2. If you want to check the coil easily, just swap the "1-2" coilpack for the "4-3" coilpack, and see if the misfire moves to cylinder 3 or 4 (P0303 or P0304). If it does not move, swap the plug wire for 1 and 3 (or whichever plug wire is the same length as "1". If the misfire still does not move to another cylinder, coil and wires are fine. At that point, get a squirt bottle that does a fine mist of water, and when the engine is warm, spray it near the #1 cylinder (all over) and see if the tone of the engine changes. This will test if there is an open air vacuum leak. The reason he said compression is because misfire at idle only can be indicative of a loss of compression in a cylinder

karenflackad812bon Jul 18, 2017

thank so much for the info it is a crazy issue sometimes at idle its fine sometimes you feel the ,, engine shake and the rpms go down then come back up, i will try all these suggestions and i appreciate all the help,one last question does the plenium have a gasket or is it permatex and got to say not looking forward to all this lol thanks again

casey40510on Jul 18, 2017

No problem, it shouldn't be that bad. The plenum and intake manifold have a total of three gaskets. Upper and lower

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