Title: Backfiring under full boost
Post by: muzzyd on September 09, 2004, 01:34:39 PM
Post by: muzzyd on September 09, 2004, 01:34:39 PM
I had this problem before when flooring the rx it would backfire loads and the power would go. I took it for a long drive with virtually no signs of it doing this, but as soon as I got back near home it started up again, car scared of being stopped? Seriously though I used RF102 (102 octance stuff) for the first part of the journey and then just optimax for the second to see if it was the fuel. But it would overtake fine.
It has a single air filter, pan racing ecu, running 1.2bar of boost, large FMIC with hard pipe kit. I have recently changed the fuel filter/plugs/oil/manifold gasket (as was blowing). It is fine until around 4500rpms onwards.
I had suspected the cold and boost spikes? Also noticed when hot the boost gauge does not read more than 1bar. Is it possible that the car is overboosting when cold? Havent had a chance to check out the problem personally yet but what should I look for this weekend?
Car was fine each time I drove it in the summer months when the engine was hot with the high octane fuel.
Any suggestions?
It has a single air filter, pan racing ecu, running 1.2bar of boost, large FMIC with hard pipe kit. I have recently changed the fuel filter/plugs/oil/manifold gasket (as was blowing). It is fine until around 4500rpms onwards.
I had suspected the cold and boost spikes? Also noticed when hot the boost gauge does not read more than 1bar. Is it possible that the car is overboosting when cold? Havent had a chance to check out the problem personally yet but what should I look for this weekend?
Car was fine each time I drove it in the summer months when the engine was hot with the high octane fuel.
Any suggestions?
Title: Backfiring under full boost
Post by: maximtaylor on September 09, 2004, 01:43:20 PM
Post by: maximtaylor on September 09, 2004, 01:43:20 PM
You\'re hitting boost cut.
You either need to lower boost or raise the boost cut threshold.
Max
You either need to lower boost or raise the boost cut threshold.
Max
Title: Backfiring under full boost
Post by: scooby_si on September 09, 2004, 06:16:18 PM
Post by: scooby_si on September 09, 2004, 06:16:18 PM
Jessus ECU means nowt to me but if you haven\'t got any uprated fueling mods, pump injectors &/or such like then as i understand it you could be soon visiting rebuildville. Dont think standard rotaries like having boost up\'d & again as i understand it anything over 1 bar is not cunning!!!!
Si
Si
Title: Backfiring under full boost
Post by: muzzyd on September 10, 2004, 01:23:57 PM
Post by: muzzyd on September 10, 2004, 01:23:57 PM
Can lowering the boost be done by adjusting anything manually
or does this mean another visit to a garage?
Kinda hoping rebuildville isnt that close as I havent covered 24000miles yet and I havent started saving for that :(
or does this mean another visit to a garage?
Kinda hoping rebuildville isnt that close as I havent covered 24000miles yet and I havent started saving for that :(
Title: Backfiring under full boost
Post by: davefrith on September 10, 2004, 01:29:29 PM
Post by: davefrith on September 10, 2004, 01:29:29 PM
1.2 bar will kill it fairly quickly I would think
With no extra fueling, std injectors ??!!!
With no extra fueling, std injectors ??!!!
Title: Backfiring under full boost
Post by: kevint on September 10, 2004, 01:31:16 PM
Post by: kevint on September 10, 2004, 01:31:16 PM
QuoteOriginally posted by muzzyd
Can lowering the boost be done by adjusting anything manually
Fully adjustable by the pedal under your right foot ;)
Kevin
Title: Manual boost control
Post by: eatmyrx7dust on September 11, 2004, 04:46:53 PM
Post by: eatmyrx7dust on September 11, 2004, 04:46:53 PM
You can manually adjust boost down by enlarging the pill which is located in the vacuum hose that feeds the waste gate actuator.
Or you can remove the pill and replace withneedle valve.
This pill can be used to remove boost spikes etc.
If interested, I can find a drawing or something !!!
The pill is located underneath the air pump are of engine bay !
Or you can remove the pill and replace withneedle valve.
This pill can be used to remove boost spikes etc.
If interested, I can find a drawing or something !!!
The pill is located underneath the air pump are of engine bay !
Title: Backfiring under full boost
Post by: muzzyd on September 12, 2004, 09:29:11 PM
Post by: muzzyd on September 12, 2004, 09:29:11 PM
dave not sure on the set up yet of the rx, just know its been boosting at that since i got it and nearly doing this but not as bad, a long run this weekend sorted out until under full boost in 3rd/4th
you right kev, lighter right foot needed :)
eatmyrx7dust Would be cool if you can get a drawing
you right kev, lighter right foot needed :)
eatmyrx7dust Would be cool if you can get a drawing
Title: Backfiring under full boost
Post by: K1HKS arse on September 12, 2004, 11:03:19 PM
Post by: K1HKS arse on September 12, 2004, 11:03:19 PM
Standard map sensor is 2 bar, 1 bar vac,1 bar boost.They spike/cut at around 1.2 bar which will feel like complete loss of power for a brief second.Only way around that is to change the map sensor to a 3 bar one.
Reason why you have less boost when warm so not reaching boost cut is to do with intake charge temps,have you ever noticed when you have driven car on a cold day its seems to go better even though you havent changed anything?
I would say imo that your hitting boost cut as mentioned earlier and that your a lucky man not to have killed the engine yet.At that amount of boost on a stock fuel system it must be so lean under full load,egt temps must be close to 900c.I would again imo ease of till you can get the fuel system sorted.Panspeed ecu is a remapped unit right not remappable?Have you got any sort of boost controller,would assume not?
I would fit electronic boost controller(lower boost level) and AIC(Additional inj controller),get 2 550cc primary inj,put them in the inlet tract to sort the fueling or better still get remappable ecu(e.g.Power FC),bigger secondary inj,rolling road and a remap.Power FC is better option but more expensive,you will still need to get a boost controller of some sort.
Regards
Gary
Reason why you have less boost when warm so not reaching boost cut is to do with intake charge temps,have you ever noticed when you have driven car on a cold day its seems to go better even though you havent changed anything?
I would say imo that your hitting boost cut as mentioned earlier and that your a lucky man not to have killed the engine yet.At that amount of boost on a stock fuel system it must be so lean under full load,egt temps must be close to 900c.I would again imo ease of till you can get the fuel system sorted.Panspeed ecu is a remapped unit right not remappable?Have you got any sort of boost controller,would assume not?
I would fit electronic boost controller(lower boost level) and AIC(Additional inj controller),get 2 550cc primary inj,put them in the inlet tract to sort the fueling or better still get remappable ecu(e.g.Power FC),bigger secondary inj,rolling road and a remap.Power FC is better option but more expensive,you will still need to get a boost controller of some sort.
Regards
Gary
Title: Backfiring under full boost
Post by: muzzyd on September 13, 2004, 11:12:12 AM
Post by: muzzyd on September 13, 2004, 11:12:12 AM
Your right Gary my ecu isnt remappable, although a mate noticed when it starts this backfiring thing there are loads of flames out the rear. Think I will look into a boost controller, problem is in my neck of the woods no1 to fit the thing or if they attempt it they take a long time.
Although I had to get the ECU replaced to get it through the mot/SVA as it was running so rich. So I am not sure if it is running that lean under full boost, the other thing is that when it was waiting for the testing someone mentioned they suspected it had larger injectors due to the fuelling. I am a little bit confused as not too technical with the engine set up yet :confused:
Although I had to get the ECU replaced to get it through the mot/SVA as it was running so rich. So I am not sure if it is running that lean under full boost, the other thing is that when it was waiting for the testing someone mentioned they suspected it had larger injectors due to the fuelling. I am a little bit confused as not too technical with the engine set up yet :confused:
Title: Backfiring under full boost
Post by: davefrith on September 13, 2004, 11:14:00 AM
Post by: davefrith on September 13, 2004, 11:14:00 AM
From whats been said you need to take it to a special with a AFR meter asap
Title: Backfiring under full boost
Post by: muzzyd on September 13, 2004, 01:09:44 PM
Post by: muzzyd on September 13, 2004, 01:09:44 PM
Dave, what should the results be with an AFR read out? I assume this will show the airflow ratio to fuelling?
Title: Backfiring under full boost
Post by: davefrith on September 13, 2004, 02:45:13 PM
Post by: davefrith on September 13, 2004, 02:45:13 PM
I am not sure on the resdings mate, I suggest you ring the nearest specialist to you
Boost spiking will destroy the engine fairly quickly
Boost spiking will destroy the engine fairly quickly
Title: Backfiring under full boost
Post by: K1HKS arse on September 13, 2004, 07:40:32 PM
Post by: K1HKS arse on September 13, 2004, 07:40:32 PM
Starts backfiring after heavy run?What colour are the flames - blue,orange?Air pump removed?
Most non remappable ecu\'s will not control bigger inj,fuel curve is altered by increasing inj duty.Maybe you can buy ecu\'s which cater for larger inj but they would have to come with the ecu as a package.I have never heard of one but you never know.
Do you know where secondary injectors are situated?If yes go and look,they should be burgandy/red colour around top where inj plug connects.
We need to establish exactly what you have got first to get a better understanding of what is required.If you are planning future mods,more power then a mappable ecu is a must.
Where are you based?Do you have a rolling road nearby?If you do a simple power run on the dyno connected to analyser will tell you how car is fuelling/running.
Let me know
Gary
Most non remappable ecu\'s will not control bigger inj,fuel curve is altered by increasing inj duty.Maybe you can buy ecu\'s which cater for larger inj but they would have to come with the ecu as a package.I have never heard of one but you never know.
Do you know where secondary injectors are situated?If yes go and look,they should be burgandy/red colour around top where inj plug connects.
We need to establish exactly what you have got first to get a better understanding of what is required.If you are planning future mods,more power then a mappable ecu is a must.
Where are you based?Do you have a rolling road nearby?If you do a simple power run on the dyno connected to analyser will tell you how car is fuelling/running.
Let me know
Gary
Title: Backfiring under full boost
Post by: muzzyd on September 13, 2004, 07:54:20 PM
Post by: muzzyd on September 13, 2004, 07:54:20 PM
Nearest rolling road is approx 40miles away, not sure how to get at the injectors but i do have a manual. There is not anyone up here that will actually fit or work on the car unless they have detailed instructions or a point of contact.
Willing to travel to sort out the prob so I dropped WGT Auots an email earlier.
The flames were blue but with a hint of orange, from what my mate was saying.
I only use the car/have access to it at weekends so will be checking it out next weekend. Are the injectors easy to get at?
Willing to travel to sort out the prob so I dropped WGT Auots an email earlier.
The flames were blue but with a hint of orange, from what my mate was saying.
I only use the car/have access to it at weekends so will be checking it out next weekend. Are the injectors easy to get at?
Title: Backfiring under full boost
Post by: bnaellis on September 13, 2004, 08:53:49 PM
Post by: bnaellis on September 13, 2004, 08:53:49 PM
May sound silly but vheck the batter terminal connections aren\'t loose, it causes the same symptoms.
rgds
rgds
Title: Backfiring under full boost
Post by: muzzyd on September 13, 2004, 10:25:53 PM
Post by: muzzyd on September 13, 2004, 10:25:53 PM
Hey Brian thanks I will check this too.
Hows things?
Hows things?
Title: Backfiring under full boost
Post by: Gerry M on September 13, 2004, 11:55:09 PM
Post by: Gerry M on September 13, 2004, 11:55:09 PM
Muzz the car still up north??..........you could try neil ellis at foyers
Title: Backfiring under full boost
Post by: muzzyd on September 14, 2004, 10:48:23 AM
Post by: muzzyd on September 14, 2004, 10:48:23 AM
QuoteOriginally posted by Gerry M
Muzz the car still up north??..........you could try neil ellis at foyers
Thats exactly the guy I was meaning, cheers gerry couldnt remember fo rthe life of me his name.:)
Title: Backfiring under full boost
Post by: Gerry M on September 14, 2004, 12:29:33 PM
Post by: Gerry M on September 14, 2004, 12:29:33 PM
//www.thetuningshop.co.uk
takes forever to reply to emails phone would be best. dont know what hes like with rotarys, but seemed ok when I used him for my imp
takes forever to reply to emails phone would be best. dont know what hes like with rotarys, but seemed ok when I used him for my imp
Title: Backfiring under full boost
Post by: muzzyd on September 14, 2004, 01:02:07 PM
Post by: muzzyd on September 14, 2004, 01:02:07 PM
I have heard he got mixed reports, but I will stick with a rotary specialist for a diagnosis right now. If it just needs checked on a rr\'d i will pop it along there.
Still got your impreza gerry?
Still got your impreza gerry?
Title: Backfiring under full boost
Post by: Gerry M on September 14, 2004, 02:25:22 PM
Post by: Gerry M on September 14, 2004, 02:25:22 PM
I\'ve heard mixed reports since, but the imp( hillman not subaru) had been tuned there before i got it so made sense to take it somewhere it was known. Theres always ricky gauld in huntly. only subaru i\'ve had was a legacy estate non turbo now rusting on my drive