Fourtraxjay Posted May 2, 2011 Report Share Posted May 2, 2011 Hello all. (jeez sorry this is so long, I just don't want to leave out any info) If this is posted in the wrong section sorry. Yes of course I used the search. On this and many other sites for the last few months. I need help resolving po300 codes. I'll try to give those willing to help me out as much info as I can without rambling on. Here is goes: Father passed Feb. 10- My mother gave me his SSS with just under 100k on it. Said drive it home from Fla and its yours. (not the nicest way to receive such a nice gift- I'd rather not have received it, but I absolutely love it.) 2003 bone stock SSS - with just under 100k. My first experience with this truck- driving home from Florida (back to the great white north) At cruise speed. would flash mil every 1/2 to an hour of driving. read code po300. since I was about to swap out a bunch of stuff that would hopefully have resolved this, I didn't really do much about it. This problem has never gone away and is very consistent regardless of fuel choice, weather, etc. At hwy speed (about 75mph) low man press. 'cruising'. I get misfire. Changed plugs and wires. Installed magnacharger. (so all injectors are new, as is the fuel filter, intake gaskets, cleaned stock map, etc) Installed dynatech hi flow cats- magnacharger cat back. (replaced front drivers side O2- because I couldn't get old one out- THE 3 REMAINING 02 are original from what I can tell) No exhaust leaks. The rest of the mods wouldn't really effect po300, but I'll list 'em in case I'm wrong. built tranny, 2600 stall, shift kit, etc. e fan conversion w BB harness, Volant CAI. 160am alternator, boost gauge, or maybe the window tinting is the problem ....hehe etc. I am totally new with EFI live, so bear with me. I logged the cylinder misfires and found #6 to be misfiring way more than others. Swapped coil pack with #4 coil. Misfire remains in #6 (pre dominantly) I do not know what to look for with logged data. I am not looking for a problem with the magnacharger tune, because the problem existed with stock tune/truck. I am looking for a fault somewhere. BUT... I don't know what I'm looking for...... I simply used a pid list that justin at bb emailed me a while ago to prepare for a tune/ log session. Plus the cylinder misfire pids. I have read and read about this. I do not want to change bank 2 o2 sensors on a suspicion. (i don't like the dart board mechanic approach, even though I know sometimes darts must be tossed) with Maggie install, intake gaskets where changed. heads never came off, but I never saw a reason, no signs of bad head gaskets. I read in this post http://www.silveradoss.com/forums/topic/41726-im-missfireing-and-getting-codes/page__p__483107__hl__po300__fromsearch__1 that drive line vibrations can cause po300????? My father had put SSBC oversized rotors on it, and they seem fine. I do not feel any vibration really. Its a truck, with mud snows on it, doesn't drive like a caddy, but its the best driving p/u I've ever owned. I also don't feel any miss in the engine with the misfire count starts hitting. I don't have any reason to think the drive shaft bad either. But I will ask my father's best friend what kind of history the truck had during their weekend escapades under any influences..... haha How accurate are the o2 sensor tests? I know EFI live will 'test them' (actually from what I understand it doesn't test them, it displays the results of the pcm's tests?) Can a bad/ weak/ worn 02 sensor do this? Is there a way to tell short of swapping them left bank to right bank to see if misfire follows o2 sensors? ( someone please tell me this is not necessary, I don't like trying to get those buggers out...haha) I have attempted to attach a log file. I have never done this, please let me know if it does not work. Also the log may be totally useless. Really, I told you, I'm a real efilive noob!!! If someone has a suggestion for other pids to log that may help me please let me know. Any other ideas I am open to. My aim is to get this truck to 12.99 et. My dad and | aways loved the awd gmc syclone back in the 90's and when he got this truck I told him it was time we built our own full size version. I'm almost there, but I want to get rid of thispo300 before I swap the pulley to a 3.0 and hit up Blackbear for a tune. Thanks in advance for any input. Jay MisfireFindmay1B.efi Quote Link to comment Share on other sites More sharing options...
misterp Posted May 2, 2011 Report Share Posted May 2, 2011 ...I am totally new with EFI live, so bear with me. I logged the cylinder misfires and found #6 to be misfiring way more than others. Swapped coil pack with #4 coil. Misfire remains in #6 (pre dominantly) ... Welcome to the forum You are in the right company, and have the right tools to figure out the problem. I would look at your log file, but I do not have that computer with me today so I cannot open it. Can you feel the misfire, or is it unnoticeable? Swapping the #4 & #6 coil was a good idea, I would now swap the #4 & #6 plug wires; then the #4 and #6 spark plugs... Did you install new plug wires & plugs when you installed the blower? Are the front O2 sensors original to the truck (100K+ miles)? Yes they might benefit from replacement but if you see them 'switching' (using/watching the O2 voltage PIDs in EFILive) as you cruise then they are working at least enough to most likely not be contributing to the problem. EFILive questions - what are the LTRIM and STRIM values? Have you thought to clean the MAF sensor? Mr. P. Quote Link to comment Share on other sites More sharing options...
Fourtraxjay Posted May 2, 2011 Author Report Share Posted May 2, 2011 Thanks for the input Mr. P. Here are some answers to your questions. The misfire is not noticable. I only know it is happening when either EFIlive log is telling me its happening, or I see the MIL flashing. Map has been cleaned a few times. no change. Plugs, wires, were new with blower. I already swapped wires. problem stayed with #6. I will try swapping the new plugs around. At least I can have an old school look at them.... but I don't think that will do it. I'll try. Ltft and Stft. Ok I know what they are, and what they do, I have read Greg Banish's book Engine Management Advanced Tuning but I am still confused about reviewing my fuel trims. Are you looking for a average % as a number? My logs for LTFT show them bank 1 and 2 between 5-6% (average). what does that mean? I never logged stft. Is logging how I find out the trims? Or are they stored in the ECU and I have to upload them?? Please correct me if I am wrong. STFT are created by the ECU with driving cycles. They are deleted/ reset with clear engine codes, or battery disconect for long period of time. LTFT are part of the tune? or are these generated by the ECU as well? I have had the battery disconected for extended periods many times while I wrenched on the truck. So the po300 cares less about stft. ? I know stuff was reset because I could tell the adaptive shift was cleared and it shifted differently for 100km's everytime I re connected the battery. Here's a screen shot of my log file that I paused when I saw a spike in cylinder #6 misfire counts. Not sure if it helps or not, at least it made me open a photobucket account. O2 sensors- Bank 1 (drivers side usa right?) front o2 is new, rear original Bank2 (pass side uas right? side I'm having #6 misfire with- Bot sensors original. In the log file. I don't see any obvious problems with oz sensor voltages, but I don't really know what I'm looking at. thanks Jay Quote Link to comment Share on other sites More sharing options...
chpspecial Posted May 2, 2011 Report Share Posted May 2, 2011 Sounds like plugged cats... I don't have my computer with me but these are the symptoms of them. sent from my thunderbolt Quote Link to comment Share on other sites More sharing options...
misterp Posted May 2, 2011 Report Share Posted May 2, 2011 So you are having issues with cylinders #1 and #5 (driver's side), and #6 and #8 (passenger side). STFT = "short term fuel trims", LTFT = "long term fuel trims" - you are already logging LTFT in the pic you posted (PIDs called LONGFT1 & LONGFT2). These are both 'adaptive' values (are not part of the tune configuration) and yes they reset when you disconnect the battery long enough, flash/upload a new tune to the PCM, or command the resetting using EFILive (i.e. "clear fuel trims" function). I think for the minute you can ignore STFT, and concentrate on LTFT; when LTFT is positive, it means the PCM is adding that much more fuel to the cylinder to achieve stoich, when negative it is subtracting that much fuel from the cylinder. Your LTFT's being 5-6% means that after all calculations are said & done, the PCM is *still* having to throw an additional 5-6% more fuel to get a clean burn when in closed-loop. On the face of things, being 5-6% off in fueling isn't awful, ideally you want to be within 1-2%. I would concentrate on the passenger's side, one thing I did when changing spark plugs is that I cracked mine - the crack was hardly noticeable by eye, but caused lots of misfiring due to internal shorting inside the spark plug. You might try swapping the plug from the #4 cylinder to the #6 cylinder, then use EFILive to reset misfire counts, then drive and see if that makes an improvement, or if the missfires suddenly move to #4, in which case you have a bad plug... Also, I highly encourage you to spend $270 on a NGK AFX wideband, and hook it up to EFILive so you can log AFR and we can really see how your tune is doing. Speaking of tune, are you running one of Justin's calibrations in your truck now? Mr. P. Quote Link to comment Share on other sites More sharing options...
misterp Posted May 2, 2011 Report Share Posted May 2, 2011 Sounds like plugged cats... I don't have my computer with me but these are the symptoms of them. ... That didn't even occur to me! Mr. P. Quote Link to comment Share on other sites More sharing options...
Fourtraxjay Posted May 2, 2011 Author Report Share Posted May 2, 2011 (edited) That didn't even occur to me! Mr. P. It occured to me ages ago. While I was running the maggie through the stock cats.... But I installed brand new dynatech hi flow cats about a month after the maggie. That's why I ended up having only 1 new o2 sensor ( couldn't get original out to swap to dynatech cats) so its not cats. I will try swapping plugs tonight, but this is the second set of plugs with the same symtom (although I can't confirm which cylinder was missing when the truck was stock as I didn't have efilive. Should I clear fuel trims before logging again? Or swap plugs, log, clear trims, re-log? Keep in mind I don't think the fuel trims have been cleared since we had a big change in climate here over the last few weeks. (Toronto, Cold, really cold, cold, warm, cold, warm, cold, cold. etc. Now we are finally getting daytime temps in the 60's. Truck may have made its LTFT and STFT when it was below zero. How long do they take to adjust to seasonal weather changes? As for the wideband. Yes I have read all about the virtues of them and how oems are starting to use them. BUT let's slow down a little!!! I'm an struggling to treadwater in the efilive kiddy pool, you want me to jump in head first with a wideband?? Maybe in a little while, when I feel I need one to FURTHER my tune. I am not running justins tune yet. I didn't want to bug him with log files that were potentially corrupted or have him tune a truck with a random misfire. It is the stock Maggie tune. The ony changes I made were to copy paste the trans base pressue table for 1-2 from the stock tune to the maggie tune to soften up the shifts with my built tranny. Oh and I activated the Efans when I installed them. When the day comes for a wideband, I may pick up one of these, as I have worked with this guy on bike stuff and he seems very knowledgable. I can then use the wideband in my bike/ snowmobile projects. http://www.ecotrons....mbda_Meter.html I'll swap plugs and see if it moves. Other than that any other ideas? What would case my fuel trims to be adding 5-6%? If the maggie tune is 'off' would this cause it? Is it a result of a poorly calibrated maf table? Ie. more air is entering then engine than the maf thinks? Jay Edited May 2, 2011 by Fourtraxjay (see edit history) Quote Link to comment Share on other sites More sharing options...
sprayed99 Posted May 3, 2011 Report Share Posted May 3, 2011 It occured to me ages ago. While I was running the maggie through the stock cats.... But I installed brand new dynatech hi flow cats about a month after the maggie. That's why I ended up having only 1 new o2 sensor ( couldn't get original out to swap to dynatech cats) so its not cats. I will try swapping plugs tonight, but this is the second set of plugs with the same symtom (although I can't confirm which cylinder was missing when the truck was stock as I didn't have efilive. Should I clear fuel trims before logging again? Or swap plugs, log, clear trims, re-log? Keep in mind I don't think the fuel trims have been cleared since we had a big change in climate here over the last few weeks. (Toronto, Cold, really cold, cold, warm, cold, warm, cold, cold. etc. Now we are finally getting daytime temps in the 60's. Truck may have made its LTFT and STFT when it was below zero. How long do they take to adjust to seasonal weather changes? As for the wideband. Yes I have read all about the virtues of them and how oems are starting to use them. BUT let's slow down a little!!! I'm an struggling to treadwater in the efilive kiddy pool, you want me to jump in head first with a wideband?? Maybe in a little while, when I feel I need one to FURTHER my tune. I am not running justins tune yet. I didn't want to bug him with log files that were potentially corrupted or have him tune a truck with a random misfire. It is the stock Maggie tune. The ony changes I made were to copy paste the trans base pressue table for 1-2 from the stock tune to the maggie tune to soften up the shifts with my built tranny. Oh and I activated the Efans when I installed them. When the day comes for a wideband, I may pick up one of these, as I have worked with this guy on bike stuff and he seems very knowledgable. I can then use the wideband in my bike/ snowmobile projects. http://www.ecotrons....mbda_Meter.html I'll swap plugs and see if it moves. Other than that any other ideas? What would case my fuel trims to be adding 5-6%? If the maggie tune is 'off' would this cause it? Is it a result of a poorly calibrated maf table? Ie. more air is entering then engine than the maf thinks? Jay The plug issue is very common when people swap them out they crack the body and it causes misfires. The maggie tune isn't off so to speak, but rather not fully refined. The VE table and MAF table are where those numbers can be refined, but you can't get any closer via a mail order tune and 5-6% isnt a big deal at this point. Steve is right on the wideband selection I wouldn't waste any money on anything other than the AFX which uses the NGK sensor and not the crappy bosch sensor. A few other things you need to check. wiring to the coils from the harness. you could have a small damaged section that is causing your P0300. You need to look at more of the mechanics of the truck right now stop worrying so much about the software. The old 02 sensor I would change just because it is a matter of time before it craps out on you at its age. Quote Link to comment Share on other sites More sharing options...
Fourtraxjay Posted May 3, 2011 Author Report Share Posted May 3, 2011 (edited) Thanks retired99. I wasn't really worrying about the software. I was more keen to use it as a tool in order to help diagnos the problem area. The problem was the same when truck was all stock, with stock tune, so I am not blaming the tune. I swapped the plugs out of #6 to see if it followed the plug. It did not. So this means that cylinder 6 has, new injector, new plug wire, new plugs, swapped out stock coil with know good one, new intake manifold gaskets, new exhaust gaskets, cleaned map. My next step will probably be new ox sensors. Perhaps just a swap from bank to bank first to get a positive diagnosis of the issue. Can someone confirm that it is only the front o2 sensors that I should be worried about. Can faulty rear 02's do the same? After that I was going to start looking at the wiring harness under the hood for kinked and possible damaged wires. Before I do all this 2 more questions: NGK plugs vs delco's. I have surfed the web for months and only found 1 reference to ngk's causing a p0300, that went away with installation of delco's.f WHAT SHOULD GAP be??? Can you adjust the gap on these fancy iridium plugs the same way you can one old schoo ones? I never have in the past, as I never need to. My Ngk's are like new. I hate to spend money on plugs because " I read it somewhere on the internet, so it must be true..." Anyone think this is hogwash or worth the price of a set of plugs to test? EfiLive cylinder test- A newbie like me was so excited to use this function when I got the software. Problem is, I updated my EFiLive before I got a chance to use it. I can't find it in the new version, and understand they took it out. I guess I will do it manually. I want to see if #6 is indeed as healthy as the others. I hear no ticking, knocking (other than cold start piston slap of these trucks), valve train noise, etc. I pulled a 13.6 last fall, which I guess is feasible with 1 weak cylinder. So can someone please confirm, that to do this test manually, I simply start logging RPM, then go to DVT control and turn off each cylinder 1 at a time. Ie. start logging, wait 10 secs to steady idle, shut off cylinder 1 for 10 seconds, wait 10 secs for steady idle, shut off cylinder 2 for 10 seconds, etc. Then I just look at the log and see how much the rpm dropped for each corresponding cylinder? :Like it says here: http://forum.efilive.com/showthread.php?14816-Unable-to-find-the-Cylinder-balance-test-in-v7.5 "You have to do it manually likethis: - start logging, - on DVT tab, click each injector disable button one at a time, waiting say 3 seconds between each (as you click an injector disable button, it will enable the previous injector and disable the new one), when you clicked all of them click the enable all button; - stop the log and view it in 3 second slices looking at RPM. " Do I have to increase the idle speed to do this?How using RPM, IAC, or ETC? Can someone please explain those options? mainly RPM? I understand controlling idle by IA(idle air control valve), and ETC(electronic throttle control), but RPM? what does this stand for? Idle is measured in rpm, revolutions per minute, so I don't understand how you control idle using revolutions per minute.... It must stand for something else. thanks Jay Jay Edited May 3, 2011 by Fourtraxjay (see edit history) Quote Link to comment Share on other sites More sharing options...
sprayed99 Posted May 3, 2011 Report Share Posted May 3, 2011 Thanks retired99. I wasn't really worrying about the software. I was more keen to use it as a tool in order to help diagnos the problem area. The problem was the same when truck was all stock, with stock tune, so I am not blaming the tune. I swapped the plugs out of #6 to see if it followed the plug. It did not. So this means that cylinder 6 has, new injector, new plug wire, new plugs, swapped out stock coil with know good one, new intake manifold gaskets, new exhaust gaskets, cleaned map. My next step will probably be new ox sensors. Perhaps just a swap from bank to bank first to get a positive diagnosis of the issue. Can someone confirm that it is only the front o2 sensors that I should be worried about. Can faulty rear 02's do the same? After that I was going to start looking at the wiring harness under the hood for kinked and possible damaged wires. Before I do all this 2 more questions: NGK plugs vs delco's. I have surfed the web for months and only found 1 reference to ngk's causing a p0300, that went away with installation of delco's.f WHAT SHOULD GAP be??? Can you adjust the gap on these fancy iridium plugs the same way you can one old schoo ones? I never have in the past, as I never need to. My Ngk's are like new. I hate to spend money on plugs because " I read it somewhere on the internet, so it must be true..." Anyone think this is hogwash or worth the price of a set of plugs to test? EfiLive cylinder test- A newbie like me was so excited to use this function when I got the software. Problem is, I updated my EFiLive before I got a chance to use it. I can't find it in the new version, and understand they took it out. I guess I will do it manually. I want to see if #6 is indeed as healthy as the others. I hear no ticking, knocking (other than cold start piston slap of these trucks), valve train noise, etc. I pulled a 13.6 last fall, which I guess is feasible with 1 weak cylinder. So can someone please confirm, that to do this test manually, I simply start logging RPM, then go to DVT control and turn off each cylinder 1 at a time. Ie. start logging, wait 10 secs to steady idle, shut off cylinder 1 for 10 seconds, wait 10 secs for steady idle, shut off cylinder 2 for 10 seconds, etc. Then I just look at the log and see how much the rpm dropped for each corresponding cylinder? :Like it says here: http://forum.efilive...ce-test-in-v7.5 "You have to do it manually likethis: - start logging, - on DVT tab, click each injector disable button one at a time, waiting say 3 seconds between each (as you click an injector disable button, it will enable the previous injector and disable the new one), when you clicked all of them click the enable all button; - stop the log and view it in 3 second slices looking at RPM. " Do I have to increase the idle speed to do this?How using RPM, IAC, or ETC? Can someone please explain those options? mainly RPM? I understand controlling idle by IA(idle air control valve), and ETC(electronic throttle control), but RPM? what does this stand for? Idle is measured in rpm, revolutions per minute, so I don't understand how you control idle using revolutions per minute.... It must stand for something else. thanks Jay Jay I do not know the ins and outs of EFI live as I use HPT. The NGK plugs causing this is a joke IMO. Gap them at .035" and run them. I have always used the NGK TR6 plugs on my maggie set ups I have done and never ever had a problem. I however never use the iridium plugs. Cleaned Map? or Maf? there is a difference and you keep refering to MAP and some keep saying MAF. I would go to the wiring first before messing with the software. Quote Link to comment Share on other sites More sharing options...
Fourtraxjay Posted May 3, 2011 Author Report Share Posted May 3, 2011 Yes, sorry I meant Maf not map I'll check wiring, Thanks Jay I do not know the ins and outs of EFI live as I use HPT. The NGK plugs causing this is a joke IMO. Gap them at .035" and run them. I have always used the NGK TR6 plugs on my maggie set ups I have done and never ever had a problem. I however never use the iridium plugs. Cleaned Map? or Maf? there is a difference and you keep refering to MAP and some keep saying MAF. I would go to the wiring first before messing with the software. Quote Link to comment Share on other sites More sharing options...
misterp Posted May 4, 2011 Report Share Posted May 4, 2011 ...The problem was the same when truck was all stock, with stock tune, so I am not blaming the tune. I swapped the plugs out of #6 to see if it followed the plug. It did not. So this means that cylinder 6 has, new injector, new plug wire, new plugs, swapped out stock coil with know good one, new intake manifold gaskets, new exhaust gaskets, cleaned map. At this point I would have to open the GM service manual and see the course of action they recommend. My next step will probably be new ox sensors. Perhaps just a swap from bank to bank first to get a positive diagnosis of the issue. Can someone confirm that it is only the front o2 sensors that I should be worried about. Can faulty rear 02's do the same? You already have a new one on the driver's side; if you are getting a new one, just replace the other old unit on the passenger side. Yes swapping sensors from side-to-side is a good diagnostic experiment, but I am cynical that it will change the situation. The rear O2s are not used for fueling at all, they are there simply to tell the PCM if the cats are fouled - it's only the front O2s that you have to worry about. After that I was going to start looking at the wiring harness under the hood for kinked and possible damaged wires. You never know, there could be a wire with an "iffy" connection or termination at the junction where the coil packs are plugged-in. But it is damned peculiar that these missfire issues are present on both sides of the motor, and it does not seem likely that both coil packs have wiring/connector issues, but hey you never know, maybe somebody at the factory mis-assembled that connection and damaged the little pins inside... WHAT SHOULD GAP be??? 0.33" - 0.35" on forced-induction apps. Use NGK TR6's (they have the correct heat range for forced induction). EfiLive cylinder test- ...Then I just look at the log and see how much the rpm dropped for each corresponding cylinder? Yes, that's exactly what you do. ...Can someone please explain ... RPM? ... I don't understand how you control idle using revolutions per minute.... In these engines, all you have to do is tell the PCM at what RPM you want the motor to idle at (550, 700, 825, etc) and that's it - the PCM will magically make the motor idle at that desired speed by changing fuel mixture, altering ignition timing, increasing/decreasing the throttle (ETC %), and increasing/decreasing the idle air bypass (IAC valve). Mr. P. Quote Link to comment Share on other sites More sharing options...
Fourtraxjay Posted May 29, 2011 Author Report Share Posted May 29, 2011 SOLVED!!! Ok, it has been a while but I just solved this p0300 issue!!! II researched so many forum posts about po300 but most of them never followed up with the eventual solution, so I am finishing off this mystery. Ok after scratching my head thinking it could be a wear issue on a motor with 100,000 miles, I had heard weak valvesprings can cause this. My Mechanic friend asked his GM buddies and they agreed it was a good place to look next. Went for a drive with the Head tech at another reputable dealer and he also agreed that he would look there next to. BUT....... another tech there asked if I had considered gummed up lifters that aren't bleading down fast enough when the misfires begin to occur at 2400rpm (max oil pressure begins). I didn't like this very logical idea. The two techs said go for springs first, if not solved, add tranny fluid to crankcase and run it to try and de sludge it. So thankfully I get dealer cost on the parts. Only $200 for springs, valve stem oil/ shim. (that;s with $60 wasted on new rocker cover "gaskets', which I discover are rubber o-ring types seals that can probably be re used a dozen times? While swapping springs, I wanted to measure the cam lift on all the valves to rule out a worn cam (but come on! this isn't the 80's where cams were rounding off in huge numbers at GM- And its was a roller cam!) I did not measure the lift as I was alone and it would have added some much more time to the job. With springs changed. Misfire counts......... Exactly the same!!!! darn!!! So i sat and thought, I was gonna add tranny fluid to crank to address sludge, but I know this engine is clean, I've had the pan off, the rocker covers off, Looked everywhere when I had top end apart. It had regular oil changes and looked like it. Hell, I'll do the CASE relearn with EFI live just for kicks. All the gm techs said this wouldn't do it, but I argued that the numbers used in CASE are a part of the misfire calc. they agreed but said there is no reason to do it. Well, i thought some more. my father purchased this truck from a dealer as a demo. Who is to say they didn't swap the ecu early in the truck's life and never addressed the case? Well 2 minutes later ZERO MISFIRES ACROSS THE BOARD!!!!!! (at all rpm's!!)) Well as my first real head scratcher for a p0300, I must say I am sofa king proud of myself, even if dumb luck played a role!!! Thanks for the help guys!! Quote Link to comment Share on other sites More sharing options...
chpspecial Posted May 29, 2011 Report Share Posted May 29, 2011 Congrats on the fix. sent from my thunderbolt Quote Link to comment Share on other sites More sharing options...
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