over boosting, backfires CA18DET - Drifting forum

bengravenell · 30-06-2009, 19:58

My s13 with full stainless exhaust and dump valve seems to be reading 1 bar and increasing but when boost comes in it holds back and backfires, if u gradually increase the throttle its fine. i have the dump valve t pieced under the butterfly with the boost gauge t pieced in that, when u rev it up a little, the gauge goes down??? but then on boost driving it just climbs, what is wrong????

the car dont stop like it hit a wall when it holds back more like bunny hops, and pops as if ur out of fuel, where should i put the boost pipe for the boost gauge??

Phoenix · 30-06-2009, 20:26

the main culprits for this are....

overboost, what turbo are you running, boost controller? Intercooler?
Boost leaks - very common with S13 especially if you have been playing around with the engine
Plugs - what type do you have and what gaps are you running?

gsracing · 30-06-2009, 20:35

does the gauge read 0 at idle?then as you push throttle it goes down initially then climbs as you accelerate?if so its plumbed in on the wrong side of the throttle body.

bengravenell · 30-06-2009, 20:38

standard t25 and intercooler ngk plugs but done it before plugs changed, the boost reads 0 on idle then does gown a little then up when it starts to boost

bengravenell · 30-06-2009, 20:46

heres what the previous owner done:
right, heres what ive done, cleaned the afm with white spirit, just fitted new ngk plugs, new fuel filter,checked all coil packs (plugs are same colour)totally bypassed the intercooler. all of this has made no difference,also changed the ecu,the car has 87k miles and is standard.

The nipple under the throttle spring has a t piece to the boost gauge and then after that t piece theres another for the dump valve which u cant here??

Would a chip and adjustable actuator fix this???

bengravenell · 30-06-2009, 21:25

any advice what to look and check?

-WJ- · 01-07-2009, 08:17

does it have a chip of some sort ?

gsracing · 01-07-2009, 16:08

im going to take a wild stab in the dark and say you have fitted the t piece for the dump valve and the boost gauge on the wrong side of the throttle plate.they should be on the inlet manifold side,so that they read vacuum when the throttle is shut.try moving these,or remove the dump valve altogether if easier.leaking dump valves are a pain.

Stavros · 01-07-2009, 16:17

Surely this is obvious whats wrong?

Quote:

Originally Posted by bengravenell

seems to be reading 1 bar and increasing

Its overboosting, 1bar is too much for stock chip and fuel pump quite often and its hitting overboost and cutting out.

Dumpvalve and boost gauge on wrong side of throttle wont be a problem, will stop DV opening when it should, but wouldnt make it open when it shouldnt.

gsracing · 01-07-2009, 17:17

oh yeah,that will cause fuel cut,im still just on about the gauge reading wrong etc and why dv not working.
try turning the boost down and see what happens.to make the dv and gauge work properly do what i said above.

bengravenell · 01-07-2009, 18:06

i want to know whats causing the overboosting, had a play today, got dump valve ok, t pieced to the nipple under throttle spring next to the butterfly and boost gauge t pieced to the back of the inlet on the angled nipple.
Now stills runs the same but on idle i got -0.7bar then goes to 0.9-1bar on boost which is obvious overboosting, i have no chip standard ecu.
on idle is -0.7 ok?

gsracing · 04-07-2009, 22:59

you have an aftermarket exhaust with a larger bore,this will make you experience "boost creep" as you describe. this means you should ideally have a chipped ecu as the boost is reaching outside the limits of its parameters,as suggested on this post a few times. the way around the boost creep is to port the wastegate,but a chip is easier IMO.fairly cheap too.get a horsham developments item.
and as long as the gauge reads in the negative on idle and not at 0 its fine mate yeah.

bengravenell · 05-07-2009, 14:23

got it sorted, split pipe to boost solonoid valve

wheres the best place to t piece the boost gauge and a dump valve???

30-06-2009, 19:58	#1 (permalink)
bengravenell dorifto kingu! Join Date: Dec 2008 Location: kent Posts: 626	over boosting, backfires CA18DET My s13 with full stainless exhaust and dump valve seems to be reading 1 bar and increasing but when boost comes in it holds back and backfires, if u gradually increase the throttle its fine. i have the dump valve t pieced under the butterfly with the boost gauge t pieced in that, when u rev it up a little, the gauge goes down??? but then on boost driving it just climbs, what is wrong???? the car dont stop like it hit a wall when it holds back more like bunny hops, and pops as if ur out of fuel, where should i put the boost pipe for the boost gauge?? Last edited by bengravenell; 30-06-2009 at 21:07.

30-06-2009, 20:26	#2 (permalink)
Phoenix 199 Join Date: Nov 2008 Location: Swansea, South Wales Posts: 1,008	the main culprits for this are.... overboost, what turbo are you running, boost controller? Intercooler? Boost leaks - very common with S13 especially if you have been playing around with the engine Plugs - what type do you have and what gaps are you running? __________________ XBOX 360 Gamertag: PHOEN1XV8

30-06-2009, 20:46	#5 (permalink)
bengravenell dorifto kingu! Join Date: Dec 2008 Location: kent Posts: 626	heres what the previous owner done: right, heres what ive done, cleaned the afm with white spirit, just fitted new ngk plugs, new fuel filter,checked all coil packs (plugs are same colour)totally bypassed the intercooler. all of this has made no difference,also changed the ecu,the car has 87k miles and is standard. The nipple under the throttle spring has a t piece to the boost gauge and then after that t piece theres another for the dump valve which u cant here?? Would a chip and adjustable actuator fix this??? Last edited by bengravenell; 30-06-2009 at 20:56.

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30-06-2009, 20:35	#3 (permalink)
gsracing gripper Join Date: Jun 2009 Posts: 26	does the gauge read 0 at idle?then as you push throttle it goes down initially then climbs as you accelerate?if so its plumbed in on the wrong side of the throttle body.

30-06-2009, 20:38	#4 (permalink)
bengravenell dorifto kingu! Join Date: Dec 2008 Location: kent Posts: 626	standard t25 and intercooler ngk plugs but done it before plugs changed, the boost reads 0 on idle then does gown a little then up when it starts to boost

30-06-2009, 21:25	#6 (permalink)
bengravenell dorifto kingu! Join Date: Dec 2008 Location: kent Posts: 626	any advice what to look and check?

01-07-2009, 08:17	#7 (permalink)
-WJ- Dutch drifter Join Date: Dec 2004 Location: Friesland Posts: 1,360	does it have a chip of some sort ?

01-07-2009, 16:08	#8 (permalink)
gsracing gripper Join Date: Jun 2009 Posts: 26	im going to take a wild stab in the dark and say you have fitted the t piece for the dump valve and the boost gauge on the wrong side of the throttle plate.they should be on the inlet manifold side,so that they read vacuum when the throttle is shut.try moving these,or remove the dump valve altogether if easier.leaking dump valves are a pain.

01-07-2009, 17:17	#10 (permalink)
gsracing gripper Join Date: Jun 2009 Posts: 26	oh yeah,that will cause fuel cut,im still just on about the gauge reading wrong etc and why dv not working. try turning the boost down and see what happens.to make the dv and gauge work properly do what i said above.

01-07-2009, 18:06	#11 (permalink)
bengravenell dorifto kingu! Join Date: Dec 2008 Location: kent Posts: 626	i want to know whats causing the overboosting, had a play today, got dump valve ok, t pieced to the nipple under throttle spring next to the butterfly and boost gauge t pieced to the back of the inlet on the angled nipple. Now stills runs the same but on idle i got -0.7bar then goes to 0.9-1bar on boost which is obvious overboosting, i have no chip standard ecu. on idle is -0.7 ok?

04-07-2009, 22:59	#12 (permalink)
gsracing gripper Join Date: Jun 2009 Posts: 26	you have an aftermarket exhaust with a larger bore,this will make you experience "boost creep" as you describe. this means you should ideally have a chipped ecu as the boost is reaching outside the limits of its parameters,as suggested on this post a few times. the way around the boost creep is to port the wastegate,but a chip is easier IMO.fairly cheap too.get a horsham developments item. and as long as the gauge reads in the negative on idle and not at 0 its fine mate yeah.

05-07-2009, 14:23	#13 (permalink)
bengravenell dorifto kingu! Join Date: Dec 2008 Location: kent Posts: 626	got it sorted, split pipe to boost solonoid valve wheres the best place to t piece the boost gauge and a dump valve???