LUVINMYSS Posted November 16, 2004 Report Share Posted November 16, 2004 I got a tune from Bryan and 2 days after I installed it, the check engine light came on. When I filled the tank up with gas it went off. My check engine light came back on a day after I filled the tank with new gas. I never had this prob before the custome tune. My gas mileage also seems to be extremely low. It's not from my heavy foot either because I'm driving normal to check the miles/gallon since the tune. I'm just barely getting over 12 miles per gallon when I used to get around 14.5 on the stock pcm. Took the truck to Autozone and they said that it was a code 300 (random multiple cylinder misfire). I don't know if any of you have had this code before, but any help would be greatly appreciated. Link to comment Share on other sites More sharing options...
BigTex Posted November 16, 2004 Report Share Posted November 16, 2004 What are your mods? P0300 is usually due to running a larger cam. The cam makes misfires at idle which set off that code. Could also be spark plugs or plug wires. I cant imagine what could be wrong with a tune to make misfires happen on a stock internal truck. Could they tell you what cylinder is having the most misfires? If its a physical problem, your problem cylinder will show the misfires. Your dealership can scan it with a TECH2 if needed. Link to comment Share on other sites More sharing options...
SSminneapolis Posted November 16, 2004 Report Share Posted November 16, 2004 i had that problem after a different custom tune. my problem only came up at high speeds...above 85+...so it came on everyday... i haven't had a problem since i started tuning on my own...i am sure if you contact bryan he can help you out with your problem...he is really good about gettin back to people and helping them out. Link to comment Share on other sites More sharing options...
AWDGM Posted November 16, 2004 Report Share Posted November 16, 2004 Another option is to invest in an Autotap scanner. I have one, awesome tool! It can read, monitor and chart every cylinder individully if you want to watch for missfires. It reads about 100 parameters and you can do datalogging and save them. I ran a datalog on my truck, saved it, and e-mailed it up to Lyndon Wester, he then tweaked my tune based on the readings. I'm sure Brian could do the same. Butch 02 Sierra Denali Link to comment Share on other sites More sharing options...
SSilverad03 Posted November 16, 2004 Report Share Posted November 16, 2004 My SSS just threw a code on me also. I am going to take it to autozone because the dealer said I will have to leave my truck for at least a day . Link to comment Share on other sites More sharing options...
.justin. Posted November 16, 2004 Report Share Posted November 16, 2004 Mine threw a code friday afternoon. It looks like I'll be hitting up Autozone this afternoon. Link to comment Share on other sites More sharing options...
SSplaytoy Posted November 16, 2004 Report Share Posted November 16, 2004 I check mine with the Granatelli, got the same code. It happened right after I put on my Radix. I got new plugs and wires and haven;t seen a problem since....... Link to comment Share on other sites More sharing options...
BigTex Posted November 16, 2004 Report Share Posted November 16, 2004 I suggest EFI Live instead of autotap. I used autotap for years; EFI Live is much better. Link to comment Share on other sites More sharing options...
AWDGM Posted November 16, 2004 Report Share Posted November 16, 2004 I suggest EFI Live instead of autotap. I used autotap for years; EFI Live is much better. <{POST_SNAPBACK}> Thanks Tex, why didn't you tell me that a few months ago!! Butch 02 Sierra Denali Link to comment Share on other sites More sharing options...
davechevyss Posted November 16, 2004 Report Share Posted November 16, 2004 thanks!!!!!!!!!!!!!!!! Link to comment Share on other sites More sharing options...
Krambo Posted November 16, 2004 Report Share Posted November 16, 2004 Misfire codes! My engine light is on more than it is off from the missfire codes! I got to bump up my idle RPM. Link to comment Share on other sites More sharing options...
cokedrvrbjw Posted November 16, 2004 Report Share Posted November 16, 2004 shoulda left it stock... Link to comment Share on other sites More sharing options...
jaydub03ss Posted November 17, 2004 Report Share Posted November 17, 2004 shoulda left it stock... <{POST_SNAPBACK}> NEVER Link to comment Share on other sites More sharing options...
blacktahoe Posted November 24, 2004 Report Share Posted November 24, 2004 I would check your plugs. Pull them and see if they're black. Also, checking codes wont do you any good. It may point you in a direction but wont always solve the problem. A true tech will not only read the code they will look at the data and try to find out what is happening when you're missfireing. You could have a bad connection some where, your o2 sensors might not be reading correctly, you could have an air leak in your manifolds/headers. Check with Bryan and see what he thinks. If you've done any modifications other than the tune there might be a conflit there. At the worst, you can go back to stock very easily by having your computer flashed. I wouldn't do that personally but if you're not out to get big horsepower gains and you're concerned with fuel consuption then stock might be the answer for you. Either that or buy a second car that gets 30 to 40 mpg...then your truck and car will average out to afordable gas milage. The main thing is find out what is important to you. Horsepower which equals money or milage/daily driver equals stock. If you want HP spend the money go to a professional that can do it for you and not give you these headaches. They'll be the ones responsible if anything goes wrong. Nobody at autozone will be able to help you. They try but they're not techs. They can charge a battery for you and they might be able to get you the right part. They're just a parts store. I hope you resolve your problem. Link to comment Share on other sites More sharing options...
BenKey Posted November 25, 2004 Report Share Posted November 25, 2004 Sounds a little odd. Not to say it can't happen, just have never seen it. In all my reflashes of my tune, I have never caused misfires. Plenty of KR, lol, but never misfires. I got them from all of my cam swaps. I also got them from a broke plug. If you have EFILive, you can look at misfires by cylinder. This is how I found out I had a broken plug. I would double check all my plugs, wires, and their connections. Two clicks for coils, one click for plugs. Listen for them. Link to comment Share on other sites More sharing options...
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