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Author Topic: back fire exhaust popping  (Read 5199 times)

October 01, 2007, 03:09:00 pm

gibber

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back fire exhaust popping
« on: October 01, 2007, 03:09:00 pm »
Im running an AAZ in my caddy, so far it has, GTD injectors, GTD boost pin fitted , 1.6 turbo, guv mod, GTD intercooler, and pump turned right up, free flow exhaust and filter ect.

It runs great and slips the 4 puck clutch.

But if I gave it all, from the line, in 3rd I get a miss fire out of the exhaust.
A real good popping, if I let off slightly then floor it again its fine, then similar again in 4th if the clutch is still holding on.

I cant work out how a diesel can miss fire like that. sounds like an anti-lag kit.

any ideas guys?
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Reply #1October 01, 2007, 03:32:09 pm

jtanguay

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back fire exhaust popping
« Reply #1 on: October 01, 2007, 03:32:09 pm »
some drunk douchebag poured gasoline into the oil filler on an argo.  we managed to drain the oil, and put fresh oil in, run it, and repeat once more.  the air filter sponge was full of the gas/oil mixture... it was disgusting!  it ran like a champ after the 'flush' but everytime we turned it off, there was a loud POP out of the exhaust (about 1-2 seconds after shutdown)

i'm not sure if that helps you any... just thought i'd share a story  :lol: is there much blowby in this motor? what type of oil are you using? free flowing exhaust but not straight pipe?

sounds like you're having fun with that beast :)
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Reply #2October 02, 2007, 06:27:24 am

gibber

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back fire exhaust popping
« Reply #2 on: October 02, 2007, 06:27:24 am »
Yep interesting story, but no help at all to me!
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Reply #3October 02, 2007, 02:04:09 pm

Mark(The Miser)UK

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back fire exhaust popping
« Reply #3 on: October 02, 2007, 02:04:09 pm »
Could it be a leaking exhaust valve?
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Mark-The-Miser-UK

"There's nothing like driving past a bonfire and then realising; its my car on fire!"

I'm not here to help... I'm here to Pro-Volke"

Be like meeee: drive a Quantum TD
 ...The best work-horse after the cart...
Reply #4October 02, 2007, 02:28:09 pm

Baxter

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back fire exhaust popping
« Reply #4 on: October 02, 2007, 02:28:09 pm »
Delivery valves?
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Reply #5October 02, 2007, 02:43:05 pm

andy2

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back fire exhaust popping
« Reply #5 on: October 02, 2007, 02:43:05 pm »
I've run into a similar problem only worse,it ended up being the valve guides that were made too tight for the valve stem.Some manufactures make them too tight on the inside Diameter and when the exhaust temp rises then the stem will seize and hold the valve open a bit causing a missfire/popping noise and I my case it actually stalled the engine :shock:.After I let it cool of a bit I could then restart and they would free up again.This only really happens to modded engines that have tight guides!!
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Reply #6October 03, 2007, 07:51:16 am

gibber

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back fire exhaust popping
« Reply #6 on: October 03, 2007, 07:51:16 am »
Quote from: "andy2"
I've run into a similar problem only worse,it ended up being the valve guides that were made too tight for the valve stem.Some manufactures make them too tight on the inside Diameter and when the exhaust temp rises then the stem will seize and hold the valve open a bit causing a missfire/popping noise and I my case it actually stalled the engine :shock:.After I let it cool of a bit I could then restart and they would free up again.This only really happens to modded engines that have tight guides!!


I dont think that is my problem.
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Reply #7October 04, 2007, 03:05:10 am

Mark(The Miser)UK

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back fire exhaust popping
« Reply #7 on: October 04, 2007, 03:05:10 am »
Maybe it's just that you are supplying too much fuel for the turbo to supply air for.
 Do you have a spare injector to rotate round until change is felt? :idea:
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Mark-The-Miser-UK

"There's nothing like driving past a bonfire and then realising; its my car on fire!"

I'm not here to help... I'm here to Pro-Volke"

Be like meeee: drive a Quantum TD
 ...The best work-horse after the cart...
Reply #8October 04, 2007, 03:50:03 am

gibber

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back fire exhaust popping
« Reply #8 on: October 04, 2007, 03:50:03 am »
Quote from: "Mark(The Miser)UK"
Maybe it's just that you are supplying too much fuel for the turbo to supply air for.
 Do you have a spare injector to rotate round until change is felt? :idea:


Why only at mid revs then?

If you back off the power a bit wen it does it, the problem clear and it will rev right to the top again.
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Reply #9October 04, 2007, 10:13:15 am

gibber

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back fire exhaust popping
« Reply #9 on: October 04, 2007, 10:13:15 am »
Does no one have an answer for me?  :cry:
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Reply #10October 04, 2007, 04:33:45 pm

Mark(The Miser)UK

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back fire exhaust popping
« Reply #10 on: October 04, 2007, 04:33:45 pm »
Quote from: "gibber"
Does no one have an answer for me?  :cry:


People do have answers but just not the one you like :wink:

If it happens as you say only mid revs after 'flooring it'; surely that could be because of excess fuel which takes longer to burn as it has reached into the manifold and is not under compression then the revs pick up and turbo catches up and all is well. It's plausible anyhow :shock:
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Mark-The-Miser-UK

"There's nothing like driving past a bonfire and then realising; its my car on fire!"

I'm not here to help... I'm here to Pro-Volke"

Be like meeee: drive a Quantum TD
 ...The best work-horse after the cart...
Reply #11October 04, 2007, 07:44:57 pm

andy2

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back fire exhaust popping
« Reply #11 on: October 04, 2007, 07:44:57 pm »
Is the crank gear ok? The AAZ is known to have issues there.If the crank to cam timing is not correct you can have valves hitting pistons causing issues as described!The only way to confirm that there is no problem is to remove the crank gear for inspection.Have you checked the belt timing?
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Reply #12October 04, 2007, 08:04:12 pm

Tintin

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back fire exhaust popping
« Reply #12 on: October 04, 2007, 08:04:12 pm »
The only time that having back fire with a big cloud of black/grey smoke it's when preceding seized a 12mm head pump,  or and at ridiculous too high RPM with 11mm.
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Reply #13October 05, 2007, 03:10:08 am

gibber

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back fire exhaust popping
« Reply #13 on: October 05, 2007, 03:10:08 am »
Quote from: "Mark(The Miser)UK"

People do have answers but just not the one you like :wink:

If it happens as you say only mid revs after 'flooring it'; surely that could be because of excess fuel which takes longer to burn as it has reached into the manifold and is not under compression then the revs pick up and turbo catches up and all is well. It's plausible anyhow :shock:


It happens at mid revs if it has been floored from low revs, as it climbs up the rev range, at mid revs point I get a hessitation with a loud exhaust popping, if I let off the power slightly the problem clears and it will continue to climb up the revs.

The boost needle does not move at the point off popping, but the boost gauge is out of range so I can acuratly say what boost I am running
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Reply #14October 05, 2007, 03:11:31 am

gibber

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back fire exhaust popping
« Reply #14 on: October 05, 2007, 03:11:31 am »
Quote from: "andy2"
Is the crank gear ok? The AAZ is known to have issues there.If the crank to cam timing is not correct you can have valves hitting pistons causing issues as described!The only way to confirm that there is no problem is to remove the crank gear for inspection.Have you checked the belt timing?


Timing belt, gear and bolt have all been changed recently. Keyway showed no wear.
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