cam swap trouble
04-01-2010, 10:20 PM
#1
cam swap trouble dot to dot, degreed & still f'cked up. Car has very little power. airflow is about half of what it should be (logged airflow w/tuning software). Seems like it's off 180 degrees, but, don't know how. TDC cyl 1 @ start of intake stroke.
04-02-2010, 10:52 AM
#3
No such thing as being off 180 degrees. (Says Matt of TSP and he of course is correct lol.)
https://ls1tech.com/forums/13092390-post14.html
Look elsewhere. Are you getting any codes? Make sure all the grounds (in back of the cylinder heads) and electrical connections are good.
Sometimes you'll blow the sensor fuse and that alone will bring about a combination of codes and the car will run like poo.
GL
https://ls1tech.com/forums/13092390-post14.html
Look elsewhere. Are you getting any codes? Make sure all the grounds (in back of the cylinder heads) and electrical connections are good.
Sometimes you'll blow the sensor fuse and that alone will bring about a combination of codes and the car will run like poo.
GL
04-02-2010, 04:15 PM
#4
No such thing as being off 180 degrees. (Says Matt of TSP and he of course is correct lol.)
https://ls1tech.com/forums/13092390-post14.html
Look elsewhere. Are you getting any codes? Make sure all the grounds (in back of the cylinder heads) and electrical connections are good.
Sometimes you'll blow the sensor fuse and that alone will bring about a combination of codes and the car will run like poo.
GL
https://ls1tech.com/forums/13092390-post14.html
Look elsewhere. Are you getting any codes? Make sure all the grounds (in back of the cylinder heads) and electrical connections are good.
Sometimes you'll blow the sensor fuse and that alone will bring about a combination of codes and the car will run like poo.
GL
Thanks for the reply,
Am glad to hear that it can't be 180* off. The symptoms are acting like it is (logged 1/2 of the airflow that it should be & no power while driving) & I have installed 3 different cams & a rebuilt short block trying to figure it out. Am just too aggravated & ignorant to find it. I'll swap the cam sensor & check the fuse. As noted, same issue 3 times & the third install was cam set up w/ engine out of car & on a stand. Will search more electrical, as well.
04-02-2010, 08:43 PM
#5
Found 15A fuse blown in under hood electrical center 2. Fuse feeds MAF, rear brake switch, bank 2 sensor 1 O2 sensor. Did have an O2 code, but have had trouble w/ that one in the past & don't rely on them for fueling. Will post once the fuse has been replaced. Don't know if it, by itself is the root of the problem.
04-02-2010, 09:27 PM
#6
In the 4 stroke cycle there are 2 TDCs in 720 degrees of crankshaft rotation. The end of the exhaust stroke(merges with the start of intake stroke) is one TDC. The end of the compression stroke(merges with the start of the combustion stroke) is the other. The cam DOT only reaches 6 O'clock once in 720 degrees of crankshaft rotation because it turns at 1/2 crank speed, but the crank DOT passes 12 O'clock twice. The crank and cam don't know that each other even exists before the chain is installed. This is an arranged marriage that takes place when the timing chain is put in place. This is the very first time the crank and cam meet in their entire lives. Before the chain was installed they were total strangers. So before the chain is installed stokes don't even exist. When you install the timing chain big things begin to happen. If you install the chain when BOTH sprocket DOTs are at 12 O'clock they will soon be at DOT to DOT(cam 6 O'clock and crank 12 O'clock) when the crank is turned 360 degrees or the cam is turned 180 degrees. There isn't much room for error if you have it DOT to DOT.
04-03-2010, 12:09 AM
#7
Found 15A fuse blown in under hood electrical center 2. Fuse feeds MAF, rear brake switch, bank 2 sensor 1 O2 sensor. Did have an O2 code, but have had trouble w/ that one in the past & don't rely on them for fueling. Will post once the fuse has been replaced. Don't know if it, by itself is the root of the problem.
No feedback from the MAF or O2 sensors, PCM is in Open loop, I think they call it.
Last edited by ShevrolayZ28; 04-03-2010 at 12:17 AM.
Trending Topics
04-03-2010, 05:17 PM
#8
In the 4 stroke cycle there are 2 TDCs in 720 degrees of crankshaft rotation. The end of the exhaust stroke(merges with the start of intake stroke) is one TDC. The end of the compression stroke(merges with the start of the combustion stroke) is the other. The cam DOT only reaches 6 O'clock once in 720 degrees of crankshaft rotation because it turns at 1/2 crank speed, but the crank DOT passes 12 O'clock twice. The crank and cam don't know that each other even exists before the chain is installed. This is an arranged marriage that takes place when the timing chain is put in place. This is the very first time the crank and cam meet in their entire lives. Before the chain was installed they were total strangers. So before the chain is installed stokes don't even exist. When you install the timing chain big things begin to happen. If you install the chain when BOTH sprocket DOTs are at 12 O'clock they will soon be at DOT to DOT(cam 6 O'clock and crank 12 O'clock) when the crank is turned 360 degrees or the cam is turned 180 degrees. There isn't much room for error if you have it DOT to DOT.
Yah, I kinda saw that while turning the crank to check the postions during the engine stand cam install. It just didn't sink in. Good description & thank-you. Looks like a I pulled the engine & installed my spare short block over a simple electricla issue. Not simple to me, but, simple in that it may be fuse related. Since the problem ocurred during the initial cam install, I got stuck in "it's gotta be a mechanical issue w/ the install," & never considered an electrical issue because of the lack of codes.
Yah, well unfortuneately I was wrong. Schematics are poor quality & I missread the current rating of the fuse in that circuit. The brake switch, MAF & O2 sensor are protected by a 20A fuse, not the 15A that I miss-noted last night. So the MAF, brake switch, O2 fuse was not blown. Spent more time looking & found a second blown 15A fuse. From my schematic, it looks like the (1) fuse is related to the evaporative emissions system; vent valve & purge solenoid (these are disconnected & not used. Should not matter unless the PCM wants feedback). The second 15A fuse I'm not sure about. There are several fuses under the hood that aren't on my schematic. From what is on the schematic, the second fuse could be the PCM ign fuse or a bank 1 or bank 2 fuel injector fuse. Best guess is that it's the bank 2 injector fuse. However, would expect a missfire code...........we will see once I test the car.
Thanks for the continued support. Hope that the fuses are the problem.
04-14-2010, 08:10 PM
#9
Car is fixed. It was one or even both of the blown 15A fuses. One was for the bank 2 injector circuit. As soon as I started the car could hear the difference & then see the heat from the bank 2 header burning off crud from the short block swap.
Thanks for the help
Thanks for the help
04-15-2010, 11:13 AM
#13
Yah, it did. Long story short; last October, the crank pulley bolt came loose causing us to have to tow her home. Just my luck, this happened a day or two before my first new cam arrived. The fuses blew as a result of the pulley issue; I am pretty sure. Figured, I'd just re-install a pulley w/ the cam swap & that would be it. So, the next several months (over the Winter) of cam swaps & triple checking the cam set-ups (degreeing...etc.) were nothing more than practice because it was the blown fuses that blew w/ the pulley that were the issue.
Car is going into its' 8th year since built & I'm still learning all of the time. Obviously, electrical stuff is my biggest weakness. That's why I keep a Thank-you to LS1Tech in my signature. You guys are the reason that the "Munster" stays on the road. Whether it's me getting in my own way or it's an actual problem, can count on LS1Tech to help me get it straight.
