fire coming through the throttle body.....
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Launching!
Joined: Feb 2009
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fire coming through the throttle body..... I was having what i thought was opti spark problems, but when i put a new opti and tried to crank it, fire came from through the intake from the throttle body. I pulled the vavle cover off and had a bent push rod, and the rocker was completely off. anyone have any idea as to why it would be shooting flamed from the intake??? It cant be timing becuse it has a wideband tune on it, and a new opti. so right now my car will turn but not crank up. so at this point in really clueless as to what else it could be....any suggestions??
You need to find out why you have a bent pushrod. The very least you should do is test the spring on that valve to see if it is good. If it isn't then you should have the rest tested. You need to find out what caused that bent pushrod. More than likely it's bent from the lifter being tossed off the lobe and/or the piston coming into contact with the valve.
When you installed the opti was there any resistance?
When you installed the opti was there any resistance?
I would put money on your valve lash being off. Sadly I had this same problem. Your valve lash is most likely too tight causing the valve to hang open. That allows the combustion charge to come back into the intake. I didn't have actual flames shoot out (kudos for that should be crazy to see) but i could hear it igniting in the intake and hammering the back of the throttle body blade. That it is also the most likely cause of your broken push rod. Happened to me twice until I found out the proper process of doing it.
Did you recently install the cc503? Either way, I would double check it all the way around.
Did you recently install the cc503? Either way, I would double check it all the way around.
I would put money on your valve lash being off. Sadly I had this same problem. Your valve lash is most likely too tight causing the valve to hang open. That allows the combustion charge to come back into the intake. I didn't have actual flames shoot out (kudos for that should be crazy to see) but i could hear it igniting in the intake and hammering the back of the throttle body blade. That it is also the most likely cause of your broken push rod. Happened to me twice until I found out the proper process of doing it.
Did you recently install the cc503? Either way, I would double check it all the way around.
Did you recently install the cc503? Either way, I would double check it all the way around.
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Verdad Gallardo Neither did I. But the reason they broke was because the valve lash was way too tight. Just running melling replacements from autozone and its still running strong. Now that I have it close to spec they're holding up fine. I would just double check it. Why not, It's free. Just a suggestion... take it or leave it.
Also, I don't think its possible to get the opti timing wrong on a 95 (correct me if I'm wrong) but it is possible that the opti was tightened down incorrectly and it is caught at an angle. I believe there was a thread about someone who had their opti hang up on the timing cover when he installed it. Or the pigtail plug on the top of the opti is not in all the way.
Also, I don't think its possible to get the opti timing wrong on a 95 (correct me if I'm wrong) but it is possible that the opti was tightened down incorrectly and it is caught at an angle. I believe there was a thread about someone who had their opti hang up on the timing cover when he installed it. Or the pigtail plug on the top of the opti is not in all the way.
Last edited by projekt70chevelle; Dec 12, 2009 at 10:37 AM.
I aligned the pin like 3 different times swaping between 2 different optis. It was at night and dark so I'm gonna take a better look at it today but I'm prity sure its on there right. Is it possible that the car didn't want to start and back firing from the throttle body because we had 1 rr and pushrod off the engine and trying to start it w/ 15 rr. When my 93 had a bad lifter I remember pulling the 1 rr off and the engine was still run.
Depends, if it was on the exhaust valve, then it would not allow the combustion charge to leave the cylinder forcing it back into the intake when the valve opened, while simultaneously adding more fuel to the mixture. Not a good combination. I would not deliberately run it with one of the valve stuck close, can lead to more problems.
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Joined: Dec 2008
Posts: 4,147
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From: Little Rock, AR
Neither did I. But the reason they broke was because the valve lash was way too tight. Just running melling replacements from autozone and its still running strong. Now that I have it close to spec they're holding up fine. I would just double check it. Why not, It's free. Just a suggestion... take it or leave it.
Also, I don't think its possible to get the opti timing wrong on a 95 (correct me if I'm wrong) but it is possible that the opti was tightened down incorrectly and it is caught at an angle. I believe there was a thread about someone who had their opti hang up on the timing cover when he installed it. Or the pigtail plug on the top of the opti is not in all the way.
Also, I don't think its possible to get the opti timing wrong on a 95 (correct me if I'm wrong) but it is possible that the opti was tightened down incorrectly and it is caught at an angle. I believe there was a thread about someone who had their opti hang up on the timing cover when he installed it. Or the pigtail plug on the top of the opti is not in all the way.
Really? I thought that it had designated holes for the dowel pin and the cam bolts (or at least that's how I remember mine being set up). Either way, I guess if you try hard enough, you can do anything wrong lol.
So at this time I am going to assume that the back firing came from the trying to start the car on 15 rr but I dont think that would explain the car not starting. I'm gonna try to take pics and post them up and get some more input later.
Can a bad Cap&Rottor cause incorrect timing and in doing so cause backfire from the intake as well?
Last edited by sepno77; Dec 12, 2009 at 12:26 PM.
TECH Veteran
Joined: Dec 2008
Posts: 4,147
Likes: 62
From: Little Rock, AR
http://shbox.com/1/opti_back.jpg
It does have a correct hole to put the dowel pin in. That does not mean you can't fudge it up (proven time and time again by folks).
http://shbox.com/1/opti_back.jpg
http://shbox.com/1/opti_back.jpg
op* I would pull it back off and verify the pin is in the right hole. It should slide in with no resistance, if you have to "push" it on it's not right!
I'm not to familier w/ this year opti. is the dowl pin suppose to be long enouph to reach the opti or just the reach the cam sprocket. In this car it just reaches the cam sprocket and the 3 cam bolts is what turns the opti.
Can a bad Cap&Rottor cause incorrect timing and in doing so cause backfire from the intake as well?
Can a bad Cap&Rottor cause incorrect timing and in doing so cause backfire from the intake as well?
First thing I would do is get the rocker on there and check your valve lash all the way around (IIRC there is a clear step by step on shbox's website). I say this for the simple fact that the opti was most likely not the problem to begin with, although it is possible there is an issue with the unit you installed or the way you installed it. Once you get the rocker on there then see if it will start. If it will crank but wont start, check your connections all the way around. And make sure you got spark and fuel. If it cranks and is still backfiring (assuming you have the valve lash as close to perfect as possible) check plug wire placement on the opti to make sure you don't have a couple swapped. Swapped wires could cause this too because it does inadvertently change your timing in a way. Make sure the opti is flush against the timing cover. Also look around for vacuum leaks.
If you cant find anything, then start to consider issues with the opti. Good rule of thumb is to start with the free stuff before you start condemning something pricey like the cap and rotor. Not to mention the opti is one of the longer repair processes for the motor. Doing the valves and checking everything else is relatively quick compared to an opti swap. Especially since you just put a new one on there. It is highly unlikely for one to fail that quickly.
Again, these are just suggestions, take it or leave it. I learned my lesson overtime, taking the opti off nearly 10 times over the years, condemning it before properly checking everything else. As well as doing my valves 4 or 5 times after my CC503 install before I finally learned to do it properly. But keep us updated and let us know what you find...
I'm not to familier w/ this year opti. is the dowl pin suppose to be long enouph to reach the opti or just the reach the cam sprocket. In this car it just reaches the cam sprocket and the 3 cam bolts is what turns the opti.
Can a bad Cap&Rottor cause incorrect timing and in doing so cause backfire from the intake as well?
Can a bad Cap&Rottor cause incorrect timing and in doing so cause backfire from the intake as well?
the cam dowel needs to be long enough to reach the opti slot on the back. If it isnt long enough then that could be an issue. the bolts dont turn it. why it would backfire if the dowel isnt long enough to reach the opti if that is the case i dont know.... and get the rocker on!!
you need to verify correct dowel pin length and go from there. Its very important!