Link2603 Posted November 4, 2011 Report Share Posted November 4, 2011 I recently did a cam, head and stall upgrade on my truck. I get it done and give it to my friend so he can tune it. Well a couple of days past and he calls me and tells me i have a cylinder down. The truck is throwing code p0300 and when i did the old spray water on a header test sure enough that cylinder is difinitely missing. So i go down there and pick up the truck and bring it back so i can figure out what was going on. My friend told me that he switched the spark plug from 7 to 1 with no change. Then he switch wires from 7 to 1 with no change. Then he switched coils with still no change. He then began looking for a vacume leak which he couldn't find any. Well when i get back to my house I do everything that he did just to double check which i come up with the same results. i then spent a couple of hours looking for a vacume leak which i couldnt find one. I then switched injectors from 7 to 1 and that didnt do anything. I then decided to do a compression test on the cylinders. These were my results # 1 185 # 2 185 # 3 180 # 4 185 # 5 180 # 6 180 # 7 180 # 8 185 I did a cat delete awhile back ago so i dont have any 02 sensors. I did have it tuned after i did that. He is exactly all my mods on my truck to date: Fast 102mm intake, 102mm TB, X Link, headers, Cai, Yank pt 3600, 799 heads, 160 t-stat, 44lbs injectors, comp 275, 918 springs. I dont know what i should do next. Should i take off my head on that side and investagate. Do you guys think this might be a tuning issue so my friend isnt any expert but he does have experience with tuning. I just dont know what the next step is. Any help would be appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
BlueAKSSS Posted November 4, 2011 Report Share Posted November 4, 2011 (edited) Is P0300 the only code coming up? I know when you tune for a cam sometimes the pcm will pickup a misfire when there isn't one and throw that code from what I've heard. Also you say you don't have any O2 sensors at all??? That could be your problem right there, you at least need the front O2 sensors installed to make your truck run right at all. Most likely there nothing wrong with the head since you have compression. Anyways hope that helps. *Edit also check to make sure your injector is firing, I assume you changed to aftermarket injectors with the fast intake. When you pull the plug is it wet with fuel after the trucks been running? Edited November 4, 2011 by Matt* (see edit history) Quote Link to comment Share on other sites More sharing options...
Link2603 Posted November 4, 2011 Author Report Share Posted November 4, 2011 Is P0300 the only code coming up? I know when you tune for a cam sometimes the pcm will pickup a misfire when there isn't one and throw that code from what I've heard. Also you say you don't have any O2 sensors at all??? That could be your problem right there, you at least need the front O2 sensors installed to make your truck run right at all. Most likely there nothing wrong with the head since you have compression. Anyways hope that helps. *Edit also check to make sure your injector is firing, I assume you changed to aftermarket injectors with the fast intake. When you pull the plug is it wet with fuel after the trucks been running? Im sorry im not 100% that sure the front o2 sensors were removed since the headers were put on before i got the truck. So i will have to check. I did not see fuel on the spark plug. The plug came out black. Andyes that is the only code the truck is throwing but you can tell its miss. Quote Link to comment Share on other sites More sharing options...
Cramer Posted November 4, 2011 Report Share Posted November 4, 2011 Check your coil wires and injector wires and plugs. Might have a broken wire or bad connection. Quote Link to comment Share on other sites More sharing options...
Krambo Posted November 4, 2011 Report Share Posted November 4, 2011 So you are confident that only one cylinder is misfiring with a P0300 code? Curious what changes were made to tune for the cam. What are the cam specs? Quote Link to comment Share on other sites More sharing options...
Link2603 Posted November 4, 2011 Author Report Share Posted November 4, 2011 I use the water test and the other header pipes to the other cylinders are red hot. Now am i sure that there missing every now and then no. I replaced all wires and plugs when i changed cams. I plugged up one injector to the wire that went to the cylinder that is missinh and i felt it pulsating. Quote Link to comment Share on other sites More sharing options...
Link2603 Posted November 4, 2011 Author Report Share Posted November 4, 2011 (edited) Cam specs are 222/224 .566/.568 112 lsa its a comp xr275hr. I would of thought it would of thrown p0307 Edited November 4, 2011 by Link2603 (see edit history) Quote Link to comment Share on other sites More sharing options...
Krambo Posted November 4, 2011 Report Share Posted November 4, 2011 Cam specs are 222/224 .566/.568 112 lsa its a comp xr275hr. I would of thought it would of thrown p0307 With the info you supplied, I would look to your friends laptop to help figure it out. You said #7 plug is black...how about the rest? Your friend doing the tuning should be able to run a log (logging misfires per cylinder) and tell you immediately if number 7 is the issue. While logging misfire parameters, keep an eye on the STFT/LTFT and see what they do when it goes into closed loop (idle better or worse, fuel trims increase or decrease etc.). With a P0300 and only a P0300, I would assume other cylinders are at fault as well not just #7. A heavy rich condition (kind of makes sense with the black #7 plug) will do this as well as not adjusting the misfire event relationships in the tune file for the cam. Of course physical issues can still be at play here. Was the cam installed advanced or retarded at all? Are the plugs new, what brand and heat range, what gap? Is your friend using HPT by any chance? I can forward a few diagnostic configurations that could help in this situation if so. You will figure it out! Quote Link to comment Share on other sites More sharing options...
Link2603 Posted November 4, 2011 Author Report Share Posted November 4, 2011 The cam was not advance or retarted at all. The plugs are brand new acdelco 41-110 set at .041. I did not set the gap. What is the recommened gap? I think i read somewhere .030 was the new recommened gap. As soon as my friend calls me back i ll know what program he is using Quote Link to comment Share on other sites More sharing options...
Link2603 Posted November 4, 2011 Author Report Share Posted November 4, 2011 Is P0300 the only code coming up? I know when you tune for a cam sometimes the pcm will pickup a misfire when there isn't one and throw that code from what I've heard. Also you say you don't have any O2 sensors at all??? That could be your problem right there, you at least need the front O2 sensors installed to make your truck run right at all. Most likely there nothing wrong with the head since you have compression. Anyways hope that helps. *Edit also check to make sure your injector is firing, I assume you changed to aftermarket injectors with the fast intake. When you pull the plug is it wet with fuel after the trucks been running? I looked undet my truck and saw that the two o2 sensora before the whwre the cats would be are there but NOT plugged in. Both of the wires are cut so i cant hook them up. I instlles the cam so i know they were cut and the truck was tuned before i got it. Quote Link to comment Share on other sites More sharing options...
desrtrat Posted November 4, 2011 Report Share Posted November 4, 2011 The cam was not advance or retarted at all. The plugs are brand new acdelco 41-110 set at .041. I did not set the gap. What is the recommened gap? I think i read somewhere .030 was the new recommened gap. As soon as my friend calls me back i ll know what program he is using the plugs are pre. gaped from the factory at .040 use the .040 gap.. good luck Quote Link to comment Share on other sites More sharing options...
zippy Posted November 6, 2011 Report Share Posted November 6, 2011 It sounds like a great build, but I'd have to wonder what tuner would go after a p0300 code with a cam of that type. That cam has alot of overlap and is on a 112 LSA. If your tune is done right you can check for a missfire by locking the converter 100% and manually select a high load gear which will bring on a missfire if it's there. I would never chase a p0300 code with a cam like that though. I'm not saying you don't have a missfire, but you need to make sure the crank relearn was done and the tune is as complete as possible before you chase a missfire. You have way too much money on that nice of a build to chase that problem. I would also change your plugs. With the compression that high you'll want a colder plug such as a TR6 or if you want to run iridiums, buy the LS9 plugs. (I have the part number written down at work). That is seriously a bad ass build, I hope your tuner will be able to get you all you want out of it. I hope you're gonna run that truck, it is gonna f'ing fly. Quote Link to comment Share on other sites More sharing options...
Link2603 Posted November 7, 2011 Author Report Share Posted November 7, 2011 It sounds like a great build, but I'd have to wonder what tuner would go after a p0300 code with a cam of that type. That cam has alot of overlap and is on a 112 LSA. If your tune is done right you can check for a missfire by locking the converter 100% and manually select a high load gear which will bring on a missfire if it's there. I would never chase a p0300 code with a cam like that though. I'm not saying you don't have a missfire, but you need to make sure the crank relearn was done and the tune is as complete as possible before you chase a missfire. You have way too much money on that nice of a build to chase that problem. I would also change your plugs. With the compression that high you'll want a colder plug such as a TR6 or if you want to run iridiums, buy the LS9 plugs. (I have the part number written down at work). That is seriously a bad ass build, I hope your tuner will be able to get you all you want out of it. I hope you're gonna run that truck, it is gonna f'ing fly. Thanks for the great info and yes im am planning to run it as soon as i get past tgis little speed bump Quote Link to comment Share on other sites More sharing options...
Link2603 Posted November 13, 2011 Author Report Share Posted November 13, 2011 (edited) Hey i got everything worked out. Matt it was because my 02 sensors where not hooked up. Found a guy and he got it all worked out. We took off the front drive shaft and it made 387 to the ground so im happy with the results. Thanks everyone for the help Edited November 13, 2011 by Link2603 (see edit history) Quote Link to comment Share on other sites More sharing options...
zippy Posted November 13, 2011 Report Share Posted November 13, 2011 That doesn't make any sense since tuning is performed in open loop. Good to hear you have the problem worked out. Quote Link to comment Share on other sites More sharing options...
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