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quad 4 backfiring into the intake? by pontiackid86
Started on: 11-12-2013 03:46 PM
Replies: 8 (162 views)
Last post by: cmechmann on 11-12-2013 08:28 PM
pontiackid86
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Report this Post11-12-2013 03:46 PM Click Here to See the Profile for pontiackid86Click Here to Email pontiackid86Send a Private Message to pontiackid86Edit/Delete MessageReply w/QuoteDirect Link to This Post
So today I tried using a little starting fluid on my new fiero and it sounded like it had a little life left in it until a huge fireball erupted through my intake tube and gave me a hell of a time putting it out (no damage to the car wires etc just need a new tube) what would cause this?
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Bloozberry
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Report this Post11-12-2013 03:50 PM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryEdit/Delete MessageReply w/QuoteDirect Link to This Post
First thing I'd check is for proper ignition timing.
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TK
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Report this Post11-12-2013 04:02 PM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by pontiackid86:

So today I tried using a little starting fluid on my new fiero and it sounded like it had a little life left in it until a huge fireball erupted through my intake tube and gave me a hell of a time putting it out (no damage to the car wires etc just need a new tube) what would cause this?


A Quad 4? There isn't any timing to adjust I don't believe. They are coil on a plug and DIS. My first thought it is a cam jumped some teeth and an intake valve is open. An intake valve is open at the wrong time. Bent valve, stuck lifter (pumped up.) Maybe a plug/coil is dead and you are somehow igniting unburnt fuel when the intake valve opens.
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pontiackid86
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Report this Post11-12-2013 04:11 PM Click Here to See the Profile for pontiackid86Click Here to Email pontiackid86Send a Private Message to pontiackid86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by TK:


A Quad 4? There isn't any timing to adjust I don't believe. They are coil on a plug and DIS. My first thought it is a cam jumped some teeth and an intake valve is open. An intake valve is open at the wrong time. Bent valve, stuck lifter (pumped up.) Maybe a plug/coil is dead and you are somehow igniting unburnt fuel when the intake valve opens.


That's what I was thinking, before I bought the car it was overheated, them being aluminum heads don't take to well to that and I think it may have caused some damage, Thankfully the block is iron. I'm going to get a junk yard head to play with this weekend to study with and I know of a rebuilt one in the area that I can reinstall if it comes to that.
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TK
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Report this Post11-12-2013 04:42 PM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by pontiackid86:


That's what I was thinking, before I bought the car it was overheated, them being aluminum heads don't take to well to that and I think it may have caused some damage, Thankfully the block is iron. I'm going to get a junk yard head to play with this weekend to study with and I know of a rebuilt one in the area that I can reinstall if it comes to that.


Have you pulled the cam cover to see if the cam dots line up when you put it on TDC? I had the head off my son's Q4 (95) but that was some years back. I don't remember the details.
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pontiackid86
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Report this Post11-12-2013 05:46 PM Click Here to See the Profile for pontiackid86Click Here to Email pontiackid86Send a Private Message to pontiackid86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by TK:


Have you pulled the cam cover to see if the cam dots line up when you put it on TDC? I had the head off my son's Q4 (95) but that was some years back. I don't remember the details.


planning on doing that this weekend, The Quad 4 head also looks pretty simple to pull as well
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Joseph Upson
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Report this Post11-12-2013 06:47 PM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Back firing into the intake while using starter fluid is very common and has little to do with the motor and more to do with the fact you're using starter fluid. One of the first rules of using that stuff is to be very, very careful, it doesn't take much whether you accept the verbal warning, or experience the consequences. Some guys blew the valve covers off a motor with that stuff. It's dangerous and when I use it I'm as far away from the intake as my arm will stretch.

Do a compression test if you're concerned about the head gasket before you buy a cylinder head.
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racingfortheson
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Report this Post11-12-2013 07:01 PM Click Here to See the Profile for racingforthesonSend a Private Message to racingforthesonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Is that motor an interference motor?
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cmechmann
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Report this Post11-12-2013 08:28 PM Click Here to See the Profile for cmechmannClick Here to Email cmechmannSend a Private Message to cmechmannEdit/Delete MessageReply w/QuoteDirect Link to This Post
Is it an interference engine? Yes
Borrow someones compression gauge, pull the spark plugs, and check. If the valves are damaged that will confirm it.
When you pull the plugs, look at the coil cover, look for blueish discolored marks between the spark plug terminals. That can make it "act" like a bad distributor cap.
To check cam timing.
Remove the drive belt, harmonic balancer and timing cover. There will be be 8mm holes in the timing gears. Bring the engine around by hand till the holes are up(put the balancer bolt back in and use a ratchet). You can either use something long, thin, straight to determine when no. 1 cylinder is at it's top or try to find the small timing mark on the crank gear. It will be small between 2 of the teeth. Line this up with the small line or triangle on the cover behind it. Either way when you do you should be able to take a 8mm dowel pin(or shank end of a 8mm drill bit), install it in the timing gears, and it should push into a 8mm hole in the head behind the gears. May have to move the crank a little back or forth, but no more than 1/2 the distance of the crank gear teeth.
Tend to see these throw off valve timing from worn timing chain guides and weak tensioners than from overheating. However, the heads are prone to crack when overheated.
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