Tune-up???
#1
02-17-2011 | 05:30 PM
Thread Starter
|
Junior Member
Joined: Feb 2011
Posts: 1
Tune-up???
Tune-UP???
I have a mazdaSpeed 3 with about 75,000 and I have cobb intake hks blowoff and I have my car boosted to about 21psi and I have rear engine mount I was wondering what else cheap is worth getting for it. and I need help I have never had a Tune-Up and does anyone know a recomended milage for that also I have backfire sometimes when shifting at like 4 or 5 rpm could this mean I need new sparkplugs.
#2
02-18-2011 | 06:38 AM
Super Moderator
Joined: May 2006
Posts: 1,526
From:
yeah you might need colder plugs. check out this thread for similar discussion with people who actually sound like they know what they're talking about (unlike me) http://www.mazdaspeeders.com/index.php?topic=139404.0
#3
02-18-2011 | 07:11 AM
Senior Member
Joined: Nov 2008
Posts: 2,726
From: southern New Hampshire
Situations such as this are very difficult to diagnose over the internet. With that said, before I write any more, I need to state some assumptions and a given:
The OP stated that the engine was “overboosted”, and that it would “backfire” when shifting in the four to five thousand RPM range. I’m thinking there’s a pretty good chance that the overboost is simply pushing raw/unburned intake charge through the combustion chamber and right out into the exhaust header/manifold (where things is kinda hot). It seems logical to me that the instant the driver lifts off the throttle for the shift, the ECU shuts off the fuel flow to the cylinders, and given the latent boost in the intake, pure air then makes its way through the combustion and mixes with the raw unburned fuel in the exhaust system and then detonates at some opportune moment (such as when shifting in the four to five thousand RPM range).
If my assumptions are correct, and if my theory regarding the whys and hows of the backfire are also correct, then no amount of changing the spark plugs (regardless of temperature range) will fix the problem.
- Assumption: the "backfire" the OP wrote about is issuing forth through the exhaust and not the intake
- Assumption: the subject has been recalibrated to run a richer mixture than what came from the factory
- Given: the Mazda engineers have programmed in at least some valve overlap when they designed the engine
The OP stated that the engine was “overboosted”, and that it would “backfire” when shifting in the four to five thousand RPM range. I’m thinking there’s a pretty good chance that the overboost is simply pushing raw/unburned intake charge through the combustion chamber and right out into the exhaust header/manifold (where things is kinda hot). It seems logical to me that the instant the driver lifts off the throttle for the shift, the ECU shuts off the fuel flow to the cylinders, and given the latent boost in the intake, pure air then makes its way through the combustion and mixes with the raw unburned fuel in the exhaust system and then detonates at some opportune moment (such as when shifting in the four to five thousand RPM range).
If my assumptions are correct, and if my theory regarding the whys and hows of the backfire are also correct, then no amount of changing the spark plugs (regardless of temperature range) will fix the problem.
#4
02-19-2011 | 01:49 PM
Senior Member
Joined: Jan 2006
Posts: 3,183
From: Aberdeen, MD
Id go with a set of NGK plugs o.e spec or one step colder. (check your stock plugs first, if there black then replace with one step colder)
If your really backfiring as in shooting flames out of your exhaust then your car is dumping too much fuel, the accessport would give you the proper tune needed to stop that and if i were you my next upgrade would be the downpipe.
Also you bought the wrong car if you think something is gonna be cheap aftermarket or o.e, the "cheap" parts are the mounts and bov everything else 150+
If your really backfiring as in shooting flames out of your exhaust then your car is dumping too much fuel, the accessport would give you the proper tune needed to stop that and if i were you my next upgrade would be the downpipe.
Also you bought the wrong car if you think something is gonna be cheap aftermarket or o.e, the "cheap" parts are the mounts and bov everything else 150+
Last edited by Tracker; 02-19-2011 at 01:54 PM.
Thread
Thread Starter
Forum
Replies
Last Post
