Anybody know how much exhaust pressure is in the egr pipe when engine reved? specifically the pressure in the small tube that goes from egr valve to bpt valve? I cant feel any pressure with my finger and it is not lifting the bpt valve. not sure if it is low pressure or if bpt valve is weak. if i blow in bpt valve where exhaust goes it works.
second problem is that the ecu is telling the egr solenoid to keep egr valve closed when egr should be open. car is warmed up and the ecu is reading normal coolant temperatures. the only thing i can think of is that the crank angle sensor is defective or ?
Any egr experts?
Re: Any egr experts?
Well I know that the exhaust back pressure should be less than 2 psi, anything over can cause driveability issues. With that said I dont think you would be able to feel any noticeable amount of preasure at the transducer(bpt). Transducer is used to switch open with back pressure and supply a determined vacuum, based on btp diaphram position, to the egr valve. There is also an egr solenoid that is controlled by the ecu that allows vacuum to be supplied to the egr and btp when certain criteria are met (usually at cruise speeds, never at idle). Make sure you have vacuum to the egr and btp by jumping the egr solenoid while engine is running. Also, turn the engine on and use a vacuum pump on the egr valve, applying about 15in.hg and verify it works and is flowing exhaust to the engine. Fully open it should want to or just stall. Transducers or common for carbon blockage, so look at the btp and verify no blockage in the tubes. If the egr works ok i would start with a btp and vlean the egr passages to the engine/manifold.
Good luck,
Eric - Veracity Automotive/Racing
Good luck,
Eric - Veracity Automotive/Racing
Last edited by rivera01 on Mon Jun 28, 2010 2:59 pm, edited 1 time in total.
Re: Any egr experts?
thanks for intelligent answer. if I blow in tranducer the egr system operates. just dont know if the backpressure is low or if tranducer is too weak. the tube going to tranducer and its port on the egr are clear. cut the thing off and stuck welding rod in. if i plug the tranducer tube with my finger, no pressure builds ups.
for some reason, the ecu is telling the egr to stay closed at all time even when I rev engine. I have to unplug the ecu signal to get vacuum. if i dont solve the computer problem, car is going to junk yard.
for some reason, the ecu is telling the egr to stay closed at all time even when I rev engine. I have to unplug the ecu signal to get vacuum. if i dont solve the computer problem, car is going to junk yard.
Re: Any egr experts?
Ok, do you have a check engine light on? If so, do you have a code. Also, I am assuming we are talking about a KA engine, right?
The ecu will not acutate the egr solenoid(this supplys vacuum to the btp and egr valve) at idle, if the engine isn't at normal operating temperture or if the engine is overheating, If it did then the engine would run poorly or stall.
The ecu uses inputs from the throttle postition sensor, engine coolant temp. sensor, CAS and MAF. If you can, verify they are in proper working order.
Vacuum to the solenoid is only supplied to the solenoid when the throttle is partially open, never at wide open throttle or closed(idle). The solenoid is normally open and closed when the ecu grounds it. Take off the solenoid and blow through it, you should be able to blow straight through it. Next, jumper the solenoid and blow in it, you shouldn't be able to. If it checks ok reattach it, it is ok.
Next, verify coolant temp is at noraml operating temp and is working correctly. Afterwards, check the ecu is able to signal it on and off by disconnecting solenoid and attaching a test light in series across the solenoid connector (make sure it is secured good, you're going to have to drive it). Remove the hood or rig the test light so you can see it while driving. watch for the test light to turn on and off under various conditions. If it does, ecu is ok.
If those are ok, unplug solenoid valve and verify vacuum is reaching the btp. Do this by unplugging the vacuum hose going to the btp from the solenoid (not egr valve), start the engine and run it off idle. place your finger over the vacuum hose opening and see if it sucks on your finger. If it does, you are ok up to the btp, reattach everything.
Next, remove the vacuum hose on the btp going to the egr valve. *The btp vents vacuum to atmosphere when no back pressure is present in the btp. Check to see if you have a large vacuum at the btp outlet while running engine slightly off idle. If you do, then the btp diaphram may be stuck closed. Run the engine at about 2500 RPM and verify vacuum at the outlet side of the btp is greater than than last test. If it is good, btp ok. If you dont have vacuum or vacuum increase, then the btp is most likely leaking internally at the diaphram or stuck closed and needs replaced.
Backpressure to btp may be weak due to clogged passeges in exhaust. Take a vacuum pump and attach to the exhaust tube going to the btp. Apply vacuum to it. It should not hold any vacuum, if it does the passage is restricted and needs cleaned. Easier check is to disconnect btp from exhaust, turn engine on and run it at 1000+ rpm. You should have a lot of exhaust discharge at that pipe.
If all that is ok, retest egr valve as stated in previous post.
Good luck,
Eric - Veracity Automotive/Racing
The ecu will not acutate the egr solenoid(this supplys vacuum to the btp and egr valve) at idle, if the engine isn't at normal operating temperture or if the engine is overheating, If it did then the engine would run poorly or stall.
The ecu uses inputs from the throttle postition sensor, engine coolant temp. sensor, CAS and MAF. If you can, verify they are in proper working order.
Vacuum to the solenoid is only supplied to the solenoid when the throttle is partially open, never at wide open throttle or closed(idle). The solenoid is normally open and closed when the ecu grounds it. Take off the solenoid and blow through it, you should be able to blow straight through it. Next, jumper the solenoid and blow in it, you shouldn't be able to. If it checks ok reattach it, it is ok.
Next, verify coolant temp is at noraml operating temp and is working correctly. Afterwards, check the ecu is able to signal it on and off by disconnecting solenoid and attaching a test light in series across the solenoid connector (make sure it is secured good, you're going to have to drive it). Remove the hood or rig the test light so you can see it while driving. watch for the test light to turn on and off under various conditions. If it does, ecu is ok.
If those are ok, unplug solenoid valve and verify vacuum is reaching the btp. Do this by unplugging the vacuum hose going to the btp from the solenoid (not egr valve), start the engine and run it off idle. place your finger over the vacuum hose opening and see if it sucks on your finger. If it does, you are ok up to the btp, reattach everything.
Next, remove the vacuum hose on the btp going to the egr valve. *The btp vents vacuum to atmosphere when no back pressure is present in the btp. Check to see if you have a large vacuum at the btp outlet while running engine slightly off idle. If you do, then the btp diaphram may be stuck closed. Run the engine at about 2500 RPM and verify vacuum at the outlet side of the btp is greater than than last test. If it is good, btp ok. If you dont have vacuum or vacuum increase, then the btp is most likely leaking internally at the diaphram or stuck closed and needs replaced.
Backpressure to btp may be weak due to clogged passeges in exhaust. Take a vacuum pump and attach to the exhaust tube going to the btp. Apply vacuum to it. It should not hold any vacuum, if it does the passage is restricted and needs cleaned. Easier check is to disconnect btp from exhaust, turn engine on and run it at 1000+ rpm. You should have a lot of exhaust discharge at that pipe.
If all that is ok, retest egr valve as stated in previous post.
Good luck,
Eric - Veracity Automotive/Racing
Re: Any egr experts?
Great answer. I just substituted in a new ecu and the ecu is now turning the egr system on but I still have to blow in the bpt valve where the exhaust is supposed to go in. The bpt exhaust tube holds no vacuum whatsoever but if I blow in the tube its like blowing into a closed system. theres no exhaust noise from bpt tube and nothing seems to be coming out. as i said , if i block with my finger , no pressure builds up. to get the bpt valve to work manually, I have to blow reasonalby hard. you'd definitely feel the air flow at that pressure.
Re: Any egr experts?
Well as long as you made sure the btp is recieivng and is able to supply vacuum to the egr valve, then I would blow compressed air through the bpt exhaust tube and listen for it to exit the tail pipe. The bpt should share the same exhaust tube with the egr or splice off it. If it does try removing the egr valve and blow compressed air through the bpt tube and see if it exits at the egr valve tube. It is probably mostly restricted, but not completly (this may be why vacuum won't hold). Try cleaning the tube for the btp, to me it sounds like it is restricted.
Re: Any egr experts?
the bpt tube is cut off. and i can stick a welding rod right into the egr valve. last yr the egr had half strength. might be the new cat is not clogged up enough or it could be that i dripped a ton of solder into egr tube last yr when i mended it. the bpt valve does leak quite a bit so i may as well get new one.
Re: Any egr experts?
drilled hole in egr pipe around where I soldered it together. nice flow of gas coming out. wire goes all the way up to egr so only place it could be blocked is entrance to egr. didnt think egr was blocked because when I manually open the egr valve the car bogs but i guess that could just be air entering.
Re: Any egr experts?
drilled another hole close to egr valve. lots of back pressure coming out. wire goes right into egr valve. however, compressed air going in pipe hole does not come out bpt orifice. the compressed air did frost the bpt stub and carb cleaner did spit out. not sure if that is just the carb cleaner reacting to the drop in temperature.