stokes Posted December 1, 2014 Report Share Posted December 1, 2014 I've always gotten excellent advice here,so I'm back with another question.Engine is running rough.Service engine warning is flashing.Scan tool shows "P0304 CYL 4 Misfire detected" When I check the freeze frame it shows "Fuel SYS1 OL-Fault" and "Fuel SYS2 OL-Fault?" I'm thinking bad fuel injector on cylinder #4 Am I on the right track? Thanks in advance for any help. Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted December 2, 2014 Report Share Posted December 2, 2014 OL-Fault, indicates the PCM is commanding open-loop due to a system fault; what do the onboard diagnostics show when you check codes? Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
stokes Posted December 2, 2014 Author Report Share Posted December 2, 2014 The only current code is P0300.History codes are C1225, C1228, B1004, B1009, P0463, P1617, P1633, U1016, U1132. Link to comment Share on other sites More sharing options...
KHE Posted December 2, 2014 Report Share Posted December 2, 2014 What is the three letter code in front of the codes you posted? I know P0300 should be PCM P0300 but what about the others? Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Logan Posted December 2, 2014 Report Share Posted December 2, 2014 If the service lamp is flashing...the misfire is bad enough to damage the catalytic converter. I am a little confused..."scan tool shows PO304" and "The only current code is PO300" Most scan tools will only show a PO300 on a 2000-2003. You then need a better scan tool or a GM Tech2 to show which exact cylinder is missing. I suspect a bad coil pack and bet the fuel injector is fine. Picture shows a GM Tech2 displaying a misfire. #4 is on the front bank of the engine. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
stokes Posted December 2, 2014 Author Report Share Posted December 2, 2014 I went directly to the scan tool to check.It showed P0304 Cylinder 4 misfire detected.That is the only code the scan tool shows.When Bruce asked about the OBD codes I went back and checked and the only current code was P0300 it didnt show P0304.Not sure offhand what the 3 letter codes were before the codes.I believe the "B" codes were AMP,I'll have to check tomorrow. I originally thought it might be something with the coils,I had a similar problem that turned out to be a cracked boot on one of the coils.I didnt have the scan tool at that time so I dont know what the codes were then.When I saw the "Fuel SYS1 and 2 OL-fault I thought the fuel injector. Link to comment Share on other sites More sharing options...
KHE Posted December 2, 2014 Report Share Posted December 2, 2014 Access the codes from the onboard system on the car. Here is how to access the onboard diagnostics in the Deville – It will work for the 2000-2005 model years: With the key in the run position or the engine running (it makes no difference), simultaneously press and hold the ON/OFF and INFO UP buttons on the dash to the right of the speedometer and above the gearshift lever. The system will go through a segment check and then you will see ALL? on the driver information sensor (DIC). To operate the diagnostics, the following buttons are used: ON/OFF = Yes INFO RESET = No INFO UP/DN is the toggle to between systems To exit the diagnostics, repeatedly press the INFO RESET button or turn the ignition to OFF. Any codes will be displayed on the DIC (driver information center) as CURRENT or HISTORY. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
stokes Posted December 2, 2014 Author Report Share Posted December 2, 2014 Okay,heres where I'm at today.Had no time to mess with the car today,but I did buy four new spark plug boot caps and I will install them tomorrow.I had a similar problem in the past,engine stumbling,misfire,P0300 on the DIC.I took it to a mechanic and it turned out to be a dry,cracked boot plug on one of the rear cylinders.At the time he told me it could either be the coil pack or a boot.I got lucky.He only changed the 4 on the back of the engine,so I'm going on the premis that the front boot caps are bad.My scan tool indicates cylinder #4 which is on the front,is misfiring.I figure even if its a bad coil,the boots will need to be replaced as well anyway.So if it works,it will be a $30 repair,if I have to change the ignition coil pack,its $30 I had to spend anyway.Anything special I should be aware of when removing the coil pack?I know there is a grounding spring and insulator to watch for. Is that part going to fall out when I lift the cassette?Or is it left in the engine when Ipull the pack? Link to comment Share on other sites More sharing options...
stokes Posted December 3, 2014 Author Report Share Posted December 3, 2014 Changed out the four spark plug boots,no good.Its off to the mechanic,waiting for a call back from him. Link to comment Share on other sites More sharing options...
KHE Posted December 4, 2014 Report Share Posted December 4, 2014 The next step in the troubleshooting process would have been to swap the coil cassettes and see if the misfire moved to cylinder #5 If it did, that would indicate that the coil cassette that was on the front (and is now on the rear bank) is bad. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
stokes Posted December 4, 2014 Author Report Share Posted December 4, 2014 Thats what I thought but I wasnt sure if the cassettes were interchangeable.When I looked at the parts at rockauto they are two different parts for the front and back so I didnt think they were.I'm limited to what I can do at this point,physically.Just got over hand surgery and had surgery on my shoulder a couple weeks ago and am having an MRI tomorrow to see if I need surgery on the elbow.All from a motorcycle crash last October.I have to take it to the mechanic tomorrow after the MRI.Hope its just the coil or fuel injector and nothing worse. Link to comment Share on other sites More sharing options...
KHE Posted December 4, 2014 Report Share Posted December 4, 2014 The reason the part nos. are different is the colors of the coils - I think the front one is silver or grey and the rear one is black. It is strictly cosmetic - the internals are the same. It is similar to the front cam cover is silver and the rear one is black. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
stokes Posted December 4, 2014 Author Report Share Posted December 4, 2014 Went to the mechanic,he confirmed it was the coil,no charge,I tipped him $40.Went and got the coil and all is well again. Link to comment Share on other sites More sharing options...
Logan Posted December 4, 2014 Report Share Posted December 4, 2014 There are 4 coils per coil pack. They were used from 2000 to 2003. Any of the 4 can go bad as they are each a individual coil. The front and rear are identical except for color. One silver...one black. The coils packs are expensive when needed....can fail at any time...and hard to find at midnight on a rainy Saturday night. I used to carry a tested used coil pack in the trunk for just this type of situation. Turns a 10 day issue into a 20 minute road side repair. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
stokes Posted December 5, 2014 Author Report Share Posted December 5, 2014 Yeah,its just cosmetic and they charge about $15 more for the black one.I dont quite get the "cosmetic" thing,even with the hood open you cant see it.Guess which one is going on the back if it goes south? Link to comment Share on other sites More sharing options...
KHE Posted December 5, 2014 Report Share Posted December 5, 2014 Yeah,its just cosmetic and they charge about $15 more for the black one.I dont quite get the "cosmetic" thing,even with the hood open you cant see it.Guess which one is going on the back if it goes south? I would have thought the silver/grey one would have been the higher cost part... Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Logan Posted December 5, 2014 Report Share Posted December 5, 2014 The coils packs are such a unique part...I recommend keeping a tested spare in the trunk. They are very reliable. That said..if one does fail it's very handy having a spare one nearby. Kinda like years ago...some of us would carry a spare GM HEI ignition module in the glove box. Very handy to have at certain times.. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
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