Anti-Lag System Valve Failure?
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Newbie
Joined: Mar 2019
Posts: 12
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From: Japan
Anti-Lag System Valve Failure?
Hey everyone I’m having an issue with my anti-lag system on my evo 7. I have all the tables set up in ecuflash in rom ID 90550001. For some reason I’m not getting the pops and bangs. I get the pops going just with going off throttle with the negative timing I have set up during low load situations and feathering the gas pedal. I check the solenoid by hooking it up to my boost gauge and I can see when it activates by watching my boost gauge go negative. I pulled the valve off and WD-40’d it to free it up and it seems free to me but does take a lot off effort to open it. I drilled out the banjo bolts to 6mm already as well. The only thing I can think of is the valve is old and just doesn’t open fast enough or enough to do the job. Is the valve a common failure point or should I be looking elsewhere? Thanks for any help.
I think it is working fine and not broken.
I don't remember the names of the 2 versions of antilag, but I'm assuming you have the one that bypasses the throttle. This antilag works like a BOV except it routes fresh air to exhaust manifold. Realize, you have high pressures in the exhaust manifold, so you need to overcome that to get air into manifold.
Going off throttle, your turbo is making boost, so when throttle body closes, cylinder exhausts drop significantly. Turbo was getting good pressure to turn turbine wheel and when volume drops too much, wheel can keep spinning until there is no more pressure. At the same time, your turbo was making boost and then air flow was shut off (throttle plate), so there is pressurized fresh air the needs to go somewhere, so it goes through your antilag into exhaust manifold.
Getting back on throttle is tough to make antilag work. Engine is sucking the air at sane time when turbo is spooling down. So no pressure is available to make antilag work. For this, you need the other antilag that has a air pump to force air into exhaust manifold.
Why is there popping when off throttle? There is fuel that is on runners and on top of valves that evaoprate. When you close throttle plate, air is cut off, but this fuel is still there evaporating that gets into cylinders and doesn't get the oxygen to burn up until it goes into exhaust manifold and reach the antilag air. It burns there to make your popping noise.
This is my opinion/theory.
I don't remember the names of the 2 versions of antilag, but I'm assuming you have the one that bypasses the throttle. This antilag works like a BOV except it routes fresh air to exhaust manifold. Realize, you have high pressures in the exhaust manifold, so you need to overcome that to get air into manifold.
Going off throttle, your turbo is making boost, so when throttle body closes, cylinder exhausts drop significantly. Turbo was getting good pressure to turn turbine wheel and when volume drops too much, wheel can keep spinning until there is no more pressure. At the same time, your turbo was making boost and then air flow was shut off (throttle plate), so there is pressurized fresh air the needs to go somewhere, so it goes through your antilag into exhaust manifold.
Getting back on throttle is tough to make antilag work. Engine is sucking the air at sane time when turbo is spooling down. So no pressure is available to make antilag work. For this, you need the other antilag that has a air pump to force air into exhaust manifold.
Why is there popping when off throttle? There is fuel that is on runners and on top of valves that evaoprate. When you close throttle plate, air is cut off, but this fuel is still there evaporating that gets into cylinders and doesn't get the oxygen to burn up until it goes into exhaust manifold and reach the antilag air. It burns there to make your popping noise.
This is my opinion/theory.
Evolving Member
Joined: Dec 2015
Posts: 469
Likes: 38
From: HWY 9
I think it is working fine and not broken.
I don't remember the names of the 2 versions of antilag, but I'm assuming you have the one that bypasses the throttle. This antilag works like a BOV except it routes fresh air to exhaust manifold. Realize, you have high pressures in the exhaust manifold, so you need to overcome that to get air into manifold.
Going off throttle, your turbo is making boost, so when throttle body closes, cylinder exhausts drop significantly. Turbo was getting good pressure to turn turbine wheel and when volume drops too much, wheel can keep spinning until there is no more pressure. At the same time, your turbo was making boost and then air flow was shut off (throttle plate), so there is pressurized fresh air the needs to go somewhere, so it goes through your antilag into exhaust manifold.
Getting back on throttle is tough to make antilag work. Engine is sucking the air at sane time when turbo is spooling down. So no pressure is available to make antilag work. For this, you need the other antilag that has a air pump to force air into exhaust manifold.
Why is there popping when off throttle? There is fuel that is on runners and on top of valves that evaoprate. When you close throttle plate, air is cut off, but this fuel is still there evaporating that gets into cylinders and doesn't get the oxygen to burn up until it goes into exhaust manifold and reach the antilag air. It burns there to make your popping noise.
This is my opinion/theory.
I don't remember the names of the 2 versions of antilag, but I'm assuming you have the one that bypasses the throttle. This antilag works like a BOV except it routes fresh air to exhaust manifold. Realize, you have high pressures in the exhaust manifold, so you need to overcome that to get air into manifold.
Going off throttle, your turbo is making boost, so when throttle body closes, cylinder exhausts drop significantly. Turbo was getting good pressure to turn turbine wheel and when volume drops too much, wheel can keep spinning until there is no more pressure. At the same time, your turbo was making boost and then air flow was shut off (throttle plate), so there is pressurized fresh air the needs to go somewhere, so it goes through your antilag into exhaust manifold.
Getting back on throttle is tough to make antilag work. Engine is sucking the air at sane time when turbo is spooling down. So no pressure is available to make antilag work. For this, you need the other antilag that has a air pump to force air into exhaust manifold.
Why is there popping when off throttle? There is fuel that is on runners and on top of valves that evaoprate. When you close throttle plate, air is cut off, but this fuel is still there evaporating that gets into cylinders and doesn't get the oxygen to burn up until it goes into exhaust manifold and reach the antilag air. It burns there to make your popping noise.
This is my opinion/theory.
If he's talking about a valve he's probably talking about the EUDM and JDM secondary air ALS. This works by actually pumping air directly into the exhaust manifold as you've mentioned.
OP, you should verify there is flow coming from the pipe that bolts into the manifold. It should bypass air when the solenoid is powered on, so just apply 12v to the solenoid and verify it's not blocked or anything. You will also hear it click when it actuates. No click with direct 12v and you'll probably need a replacement. Do you get popping without the retarded timing in lower cells? If so, it may be working and may just need to bypass more air.