**i will paypal $100.00 to the person that figures this out!***

[firefly9r68]

ok i have started another thread with my issues. but i am starting another because people dont look st thread more than once alot of times, and also i will PAYPAL 100.00 to whom ever figures this out!. i will go down the list of what all i have done and look at and changed. Im out of ideas and so are many of my normal contacts that help figure out bugs when i cant.

CAR: 2005 corvette
MODS
427 lsx
trick flow heads
direct port Nitrous with window switch
twin turbos
no maf
2 bar GM map
CAM
235/231 .620 .617
on a 115 LSA
INT before 2 after 52
EXH before 50 after 0
lobe lift .365/.363

ok car ran perfect when we pulled it into the shop. what we changed:
Direct port nitrous kit
new cam
2 bar SD tune.


car will start now and idle. but its running like it is on 4 CYL.
i have changed the map to another new one to make sure it was right.
i have checked to make sure that all the coil packs were on the right cyl, all the inj harnes were on the right one. all rockers are TQ right and rockers are on correct, 02's are on the right side, all grounds are on, the MAP plus has 5 volts and ground like it should. i have checked everything i can think of to check. Here is the one weird thing:

just noticed today. the back of the intake gets ungodly hot after only a few mins of running. with a temp gun it was 200+* but only on the back runners. pulled the whole thing down to make sure there was no stuck valve or rocker installed wrong making the exh come back into the intake and i can see nothing of the sort. car runs like crap and smells of fuel bad out the exh also. i have adjusted the VE way up and way down and that does nothing to help me. also my MAP reads in the 90's at idle or if i am on the gas reving it up it never changes a whole lot.

so any ideas

[firefly9r68]

here is a short scan and the old tune i was trying ran the same on this one. and the map setting are right now so disregard this post but here is the tune attached

http://www.hptuners.com/forum/showthread.php?t=25799

[firefly9r68]

only the BACK of the intake gets ho also! the front is under 100*

[firefly9r68]

after two weeks of fighting with it and then making this post i may have just figured it out, but i wont know till i get it all back together later this week most likely. i want to keep this thread open though to shoot out ideas though just incase!

[ayousef]

we had a car do the exact same thing, turns out it had a bad spec cam, incorrect grind or something, and that one or two pushrods were slightly bent, and it happened after a cam swap as well.

Our problem was a little worse, two runners on the intake manifold melted from exhaust reversion, and one side used to get hotter than the other, obvious as the manifolds get slightly orang'ish at idle!

try putting back the old cam, and check the pushrods

[firefly9r68]

i have changed 100's of cams and never had this happen to me, i found out what it was.
the #8 rocker arm wasnt moving. i though that was really weird on a new cam. so pulled it off and the valve was pushed all the way down. OMG i was scared then, though that the piston could have hit the valve. well what was so weird was turning the engine over all would move but that one. what i still cant figure out is how it was holding the valve open. how was the lifter UP??? took the rocker off and turned the motor over and the pushrod moved fine...at that point i was very confused. put it all back together and rocker moved fine and wasnt holding hte valve open any more....i dont know how the lifter was stuck up like that and was holding the valve open but it was and that has been the issue this whole fricken time!


now i just have to figure out how to get my scanner to graph over 105 KPA so i can start tuning. does someone have a SD HISTO for tuning 2 bar?

[angrygoat]

Try this one out Stephen

[Andy@A&A]

i have changed 100's of cams and never had this happen to me, i found out what it was.
the #8 rocker arm wasnt moving. i though that was really weird on a new cam. so pulled it off and the valve was pushed all the way down. OMG i was scared then, though that the piston could have hit the valve. well what was so weird was turning the engine over all would move but that one. what i still cant figure out is how it was holding the valve open. how was the lifter UP??? took the rocker off and turned the motor over and the pushrod moved fine...at that point i was very confused. put it all back together and rocker moved fine and wasnt holding hte valve open any more....i dont know how the lifter was stuck up like that and was holding the valve open but it was and that has been the issue this whole fricken time!


now i just have to figure out how to get my scanner to graph over 105 KPA so i can start tuning. does someone have a SD HISTO for tuning 2 bar?

If something was physically stuck and has "unstuck" you'd better figure out what it was. It's likely to have at least some small amount of damage, or a clearance issue that will come back and bite you. Don't take a chance until you are sure about what it was and are positive it caused no damage.
A valve can't stay open, overcoming the valve spring, without something serious going on. Also, if the valve was open, the rocker had to be making a horrendous amount of clatter. I'd be shocked if the valve wasn't bent.
Something like this can become real expensive, real fast.
I may be a page or two behind some of you guys on tuning, but I do know engines. They just don't fix themselves.
Call me if you need help with it.

[BBA]

I'm guessing the lifter was not in the guide.

[firefly9r68]

If something was physically stuck and has "unstuck" you'd better figure out what it was. It's likely to have at least some small amount of damage, or a clearance issue that will come back and bite you. Don't take a chance until you are sure about what it was and are positive it caused no damage.
A valve can't stay open, overcoming the valve spring, without something serious going on. Also, if the valve was open, the rocker had to be making a horrendous amount of clatter. I'd be shocked if the valve wasn't bent.
Something like this can become real expensive, real fast.
I may be a page or two behind some of you guys on tuning, but I do know engines. They just don't fix themselves.
Call me if you need help with it.

yea i know totally cough me off guard when i found this. did a comp check on that CYL and its good so no bent valve, and car runs smooth as glass......the lifter must have somehow gotten stuck in the guide when i did the cam swap.....stupid LSX blocks and there special guides i bet

[gtautoparts]

yea i know totally cough me off guard when i found this. did a comp check on that CYL and its good so no bent valve, and car runs smooth as glass......the lifter must have somehow gotten stuck in the guide when i did the cam swap.....stupid LSX blocks and there special guides i bet

More than likely the push rod was on the lifter guide and not the lifter. I would check real close and make sure the guide is not damaged enough to allow the lifter to turn.