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Got my fiero running, but now the engine is making popcorn popping noises.... by 1985FieroGT
Started on: 09-30-2003 10:32 PM
Replies: 8
Last post by: Doug85GT on 10-02-2003 12:41 PM
1985FieroGT
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Report this Post09-30-2003 10:32 PM Click Here to See the Profile for 1985FieroGTClick Here to Email 1985FieroGTSend a Private Message to 1985FieroGTDirect Link to This Post
Ok, the 2.8 is finally running in my 84, after I hooked up the fuel injectors. Now after fixing a vacumme leak, my engine is now making popping noises, like if someone is making popcorn, not full out, but like, pop, de pop, pop, pop, de pop, something like that, and its not the exhaust I think and its not backfiring. Is it a rod maybe?

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Proud owner of a Bright Red 1993 Grand Prix SE, 3.1 V6, 4 speed on the floor, fully loaded, very nice

In Progress Restoration/and attempt of a 1984 SE, to be powered by a 2.8 V6.

1984 SE converted with 86 GT parts being parted out, pm me with requests.

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Phaeton
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Report this Post09-30-2003 11:30 PM Click Here to See the Profile for PhaetonSend a Private Message to PhaetonDirect Link to This Post
Possibly the injector harness is intermittant? Or has a mechanical pressure gauge been hooked up while engine is running?
I like being first response, it allows me to guess the easy stuff first. I have not followed the history of your swap so do not know where you are at, so don't get mad if I seem to patronize. The four cylinder fuel pump won't feed the injectors on the six. It sounds like a fuel mix problem to me (that's one out of eight thousand) so more vacuum leak somewhere is still very possible. Hope it turns out simple.
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1985FieroGT
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Report this Post10-01-2003 10:03 AM Click Here to See the Profile for 1985FieroGTClick Here to Email 1985FieroGTSend a Private Message to 1985FieroGTDirect Link to This Post
fuel pump's been replaced with a v6 delco, maybe its the catalytic convertor?
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Indiana_resto_guy
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Report this Post10-01-2003 10:34 AM Click Here to See the Profile for Indiana_resto_guyClick Here to Email Indiana_resto_guySend a Private Message to Indiana_resto_guyDirect Link to This Post
Check for exhaust leaks and insure that your timing is correct @10*BTC. Done a compression check to look for a leaking valve (lash adjustment?).
Just a few common things, a bad rod will sound like someone knocking on the door.
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GT40 Kit 3.8 SC
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Report this Post10-01-2003 12:09 PM Click Here to See the Profile for GT40 Kit 3.8 SCClick Here to Email GT40 Kit 3.8 SCSend a Private Message to GT40 Kit 3.8 SCDirect Link to This Post
The old chevy 283's used to pop like that through the carb when the cam was wiped out. Pull the air cleaner hose off and take a ride to see if it gets louder. Hope it doesn't!
Kevin

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85 Fiero-based ASPP GT-40 MarkII. 3800 S/C, Auto, Held suspension all around with 2" drop spindles and sport fr. end. RCC bump-steer correction. Mr. Mike's interior.

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1985FieroGT
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Report this Post10-01-2003 09:58 PM Click Here to See the Profile for 1985FieroGTClick Here to Email 1985FieroGTSend a Private Message to 1985FieroGTDirect Link to This Post
I'm pretty sure I got my timing reset, I moved it back and forth finding the best area the engine likes to run in, and it idles at about 1200-1500 rpm's. I did think I heard about the cat making popcorn popping noises when it was bad? Of course this cat's only got 50,000 miles on it from 86.
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Indiana_resto_guy
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Report this Post10-02-2003 10:21 AM Click Here to See the Profile for Indiana_resto_guyClick Here to Email Indiana_resto_guySend a Private Message to Indiana_resto_guyDirect Link to This Post
 
quote
Originally posted by 1985FieroGT:

I'm pretty sure I got my timing reset, I moved it back and forth finding the best area the engine likes to run in, and it idles at about 1200-1500 rpm's. I did think I heard about the cat making popcorn popping noises when it was bad? Of course this cat's only got 50,000 miles on it from 86.

So you set the timming by ear?
Use a light to get it in the rest of the way.
Sounds more like an exhaust leak, check the rear header for cracks. Leaks at the "Y" pipe and other connections of the exhaust.

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1985FieroGT
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Report this Post10-02-2003 12:18 PM Click Here to See the Profile for 1985FieroGTClick Here to Email 1985FieroGTSend a Private Message to 1985FieroGTDirect Link to This Post
It does have a crack on the weld on the 5th cylinder, the exhaust manifold by the trunk wall. About an inch through the weld.
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Doug85GT
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Report this Post10-02-2003 12:41 PM Click Here to See the Profile for Doug85GTSend a Private Message to Doug85GTDirect Link to This Post
 
quote
Originally posted by 1985FieroGT:

It does have a crack on the weld on the 5th cylinder, the exhaust manifold by the trunk wall. About an inch through the weld.


You just found the source of the popping. Good luck removing that exhaust manifold.

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