86LT1
03-28-2011, 05:38 PM
Ok so heres the issue, and what I've done so far...
When I start the car it sounds like it has a big aggressive cam in it, very choppy, the cam is only an LT4hot. When idleing in the garage you can tell the car is running very rich because in a couple min. your eyes will be watering and you can smell it. I havent had a chance to have this car properly tuned yet for different reasons but it has a mail order on it for now and it should be running better than this even with a stock tune. When the motor was built we did a compression check and every cylinder checked out fine. The optispark is an MSD (new), and the wires are super conductor MSDs (new). The plugs are NGK TR55's, gapped to w/e the book says (forget right now/been in the car) Injectors are 30# SVO red tops (new). Short run down of whats going on and what I have ignition/fuel wise.
Next I took some notes on what the car did while idleing. At cold start all the header tubes started to heat up, but not evenly. I waited 5 minutes and took some temp reading with my gun. #1 actually heated up the quickest, but as you'll see didnt matter.
@ idle around 900rpms after 5min. - cylinders #1- 103F / #3- 240F / #5- 505F / #7- 570F even cylinders #2- 650F / #4- 773F / #6- 690F / #8- 560F.
... all these temps flucuated while i was hitting it with the gun so these were average temps of the header tube.
now to me some of these cylinders dont seem like they're firing at all, or misfiring sometimes? esp. cylinder 1 and 3. And why are they all different? should they run at the same temp, or close to??
ok... so after that test I then reved the motor up from my TB, held it at the rev point and took some more readings. Some temps changed pretty drastically;
#1- 450F #3- 450F #5- 660F (these were the most drastic changes from all the cylinders that i noticed, again round about temps.)
Last I unplugged the MAP sensor because I heard that it defaults the computer back to stock settings? Not sure if true or not but at this point i figured it couldnt hurt to try. At this point temps didnt change much from the first readings I took :-/
Now I havent done anything yet but my first thoughts are to 1, change the spark plugs because there is a good chance that they could be fouled from the very rich air/fuel mixture i have going right now-but that wont fix my problem?. 2nd was to check the fuel injectors (i forget how this is done but i've seen it on the internet before, i just gotta look again) but they are brand new and buy the smell i dont think they are not firing. And third I thought about getting another computer and going for the dyno tune? Just starting fresh and changing out the plugs. This would be the most expensive option but if the other ways don't work I'm not sure what else to do. I just can't figure out what is going on with this right now, or where to start. Another observation I had made was when i took it out yesterday I noticed that it feels like its running choppy at some points when im going slower, but at others when I down shift and really get on it, it screams like a bat outta hell. Feels very powerful and solid, and like i said sometimes it doesnt feel like that.? or could it just be reved so high at that point I cant tell if its missing? UGH! haha Does this mean anything? Thanks for all the help guys and if you need anymore info on anything I'll try to help you out the best I can.
When I start the car it sounds like it has a big aggressive cam in it, very choppy, the cam is only an LT4hot. When idleing in the garage you can tell the car is running very rich because in a couple min. your eyes will be watering and you can smell it. I havent had a chance to have this car properly tuned yet for different reasons but it has a mail order on it for now and it should be running better than this even with a stock tune. When the motor was built we did a compression check and every cylinder checked out fine. The optispark is an MSD (new), and the wires are super conductor MSDs (new). The plugs are NGK TR55's, gapped to w/e the book says (forget right now/been in the car) Injectors are 30# SVO red tops (new). Short run down of whats going on and what I have ignition/fuel wise.
Next I took some notes on what the car did while idleing. At cold start all the header tubes started to heat up, but not evenly. I waited 5 minutes and took some temp reading with my gun. #1 actually heated up the quickest, but as you'll see didnt matter.
@ idle around 900rpms after 5min. - cylinders #1- 103F / #3- 240F / #5- 505F / #7- 570F even cylinders #2- 650F / #4- 773F / #6- 690F / #8- 560F.
... all these temps flucuated while i was hitting it with the gun so these were average temps of the header tube.
now to me some of these cylinders dont seem like they're firing at all, or misfiring sometimes? esp. cylinder 1 and 3. And why are they all different? should they run at the same temp, or close to??
ok... so after that test I then reved the motor up from my TB, held it at the rev point and took some more readings. Some temps changed pretty drastically;
#1- 450F #3- 450F #5- 660F (these were the most drastic changes from all the cylinders that i noticed, again round about temps.)
Last I unplugged the MAP sensor because I heard that it defaults the computer back to stock settings? Not sure if true or not but at this point i figured it couldnt hurt to try. At this point temps didnt change much from the first readings I took :-/
Now I havent done anything yet but my first thoughts are to 1, change the spark plugs because there is a good chance that they could be fouled from the very rich air/fuel mixture i have going right now-but that wont fix my problem?. 2nd was to check the fuel injectors (i forget how this is done but i've seen it on the internet before, i just gotta look again) but they are brand new and buy the smell i dont think they are not firing. And third I thought about getting another computer and going for the dyno tune? Just starting fresh and changing out the plugs. This would be the most expensive option but if the other ways don't work I'm not sure what else to do. I just can't figure out what is going on with this right now, or where to start. Another observation I had made was when i took it out yesterday I noticed that it feels like its running choppy at some points when im going slower, but at others when I down shift and really get on it, it screams like a bat outta hell. Feels very powerful and solid, and like i said sometimes it doesnt feel like that.? or could it just be reved so high at that point I cant tell if its missing? UGH! haha Does this mean anything? Thanks for all the help guys and if you need anymore info on anything I'll try to help you out the best I can.