charcoal canister and EGR carbon build up fix?

[dlb]

anybody ever have any luck unplugging a clogged charcoal canister or cleaning the carbon build up out of the EGR and its little buddy, the flying saucer vacuum device? i'm just going over all the emissions stuff on the project car and have found these are all clogged (not surprised) and would like to unplug them if possible.

i'll be trying compressed air on the canister in a day or two. is there anything i can soak the EGR in to break down the carbon with? seafoam, i suppose, though it's pretty expensive.

*edit* sorry, i meant to put this in the repair questions forum. can you move it for me, tom? thanks.

[Lil Beast]

Have you try compressed air? Blowing it they other way, I don't know might work! Never attempted before is something I would unplug!

[Petros]

I would think some kind of solvent for the carbon canister would be required, but you do not want to contaminate the carbon. The idea is the carbon absorbs the hydrocarbons from the fuel tank, and than releases them into the intake manifold.

I would think some kind of liquid detergent would be safest, the dish liquid "Dawn" comes to mind. Soak it overnight in soapy water and than wash it out with fresh water several times. You also might try carb cleaner spray, that breaks down gasoline sludge pretty good.

For the EGR you need something more caustic, you get carbon build-up. some kind of acid perhaps, white vinegar comes to mind.

[ARCHINSTL]

Thy wish is my command, Grasshopper.

As to the EGR cleaning - check out Repair Guides for my thread about cleaning the EGR valve that I did in '05 - came out pretty well. I did wind up having to buy a new modulator (aka James Kirk's Enterprise).

As to the canister - I blew it out umpteen times and followed all of the assorted FSM tests, but never did have any idea if it actually worked. Just this year I removed it, though, and just routed the tank-to-canister tube down into the chassis member from where the canister drew air originally. I've not noticed any gassy smells or probs.
Tom M.

[dlb]

yeah, i figure the canister is pretty much a POS but i'll try what peter suggests and see if it works. if not, i'll just vent it as you do, tom. it's not worth too much effort.

i tried searching for EGR cleaning but the search function didn't recognize 'EGR.' i'll browse through the repair guides for it now though.

thanks guys!

[toughtercel]

I remove the EGR from the motor , then you'll notice the hole get smaller from hard carbon stuff , I just use the small srew driver to scrape the stuff out , then some one show me to fill the other end with liquid , ifit hold then it is good EGR valve , if it leak through other end then you have a bad EGR .
As looking for new EGR valve for Canadian brand , is very hard to find and EXSPENSIVE . Amercian model have two end where vacuum hose goes on compare Canadian model has three . I might be wrong .

[ARCHINSTL]

dlb - my thread on EGR valve cleaning - sorry, should have located it earlier: https://tercel4wd.com/forums/viewtopic.php?f=7&t=1496
Tom M.

[dlb]

already found it, thanks though!

[Petros]

My opinion on carbon canister and EGR: both are part of the emissions system but perform very different functions. The fuel tank has to be vented to prevent a vacuum in the tank from building up as the fuel is consumed, however if it is vented to the atmosphere it will allow fuel vapors (unburned hydrocarbons) into the atmosphere. The canister allows venting of the tank by systematically allowing the vapors to be run through the engine. It generally does not affect how the engine performs, it does not harm fuel economy or maximum power output, therefore I have no objection to it. It also is a relatively simple and reliable device, benign in operation and causes no drivablity issues, so it would be my preference to maintain the charcoal canister operation since it helps keep the air clean.

The EGR however is an entirely different device, it feeds exhaust gases into the intake air stream to reduced the amount of oxygen in the air (by using exhaust, it is almost entirely inert gas being fed into the engine). The effect of this is to interfere with combustion by reducing the peak temperatures and pressures during the power stroke. This is supposed to reduce the NOx emissions which form during the combustion process at the elevated temperatures, but this reduces efficiency and reduces fuel economy, and why I hate it. I am not convinced that the reduction in fuel economy actually results in a net reduction in emissions, many engines have passed the federal standards without it (the Toyota 4afe is one of them). when the EGR malfunctions it also causes serious drivablity issues as well, causing knock, ping and all kinds of nastiness to the engine that is not good. So it is my preference to remove it entirely if you can do so without penalty from passing emissions inspections.

[ARCHINSTL]

Interesting reply, Petros...
Vis-à-vis the charcoal canister - last year when I wondered the effect of removing it and simply hooking up the tank return hose to a new fitting in the air cleaner, I received several differing opinions on the efficacy (and safety) of doing this. Since I had no way of determining if the canister worked, despite performing the tests way back when (it passed), and in particular because I'd unhooked/removed all of the emissions stuff when I installed the Weber (and MO eliminated "mature" cars from the emission portion of inspections) - I just removed it for extra working space and routed the tank tube into the chassis member.

As to the EGR removal - I certainly agree with you about its having an effect on driveability. When I revived it back in '05, it - along with MANY other emission thingie "revivals" including a cat - it enabled me to pass the MO standards. The Weber installation and emission component removal was permitted by MO's 2008 removal of the emission test for OF cars from the bi-annual inspection protocol.

I do wonder - with respect - that with one breath you applaud a cleaner atmosphere by retaining the canister and with the next you dismiss whatever emission benefits an operational EGR system may infer.

OT, but - when I replace the exhaust system finally - while I bought the last Bosal in captivity a year-and-a-half ago and have been JB Welding the current system quite successfully! - I presume I will retain the cat but want to remove the air suction stuff for more working area around the drivetrain; so - any probs? I know that CA or Canadian cars do not have this suction device for their cats (CA, in particular, surprised me!).
Tom M.

[4wdchico]

Interesting reply, Petros...
Vis-à-vis the charcoal canister - last year when I wondered the effect of removing it and simply hooking up the tank return hose to a new fitting in the air cleaner, I received several differing opinions on the efficacy (and safety) of doing this. Since I had no way of determining if the canister worked, despite performing the tests way back when (it passed), and in particular because I'd unhooked/removed all of the emissions stuff when I installed the Weber (and MO eliminated "mature" cars from the emission portion of inspections) - I just removed it for extra working space and routed the tank tube into the chassis member.

As to the EGR removal - I certainly agree with you about its having an effect on driveability. When I revived it back in '05, it - along with MANY other emission thingie "revivals" including a cat - it enabled me to pass the MO standards. The Weber installation and emission component removal was permitted by MO's 2008 removal of the emission test for OF cars from the bi-annual inspection protocol.

I do wonder - with respect - that with one breath you applaud a cleaner atmosphere by retaining the canister and with the next you dismiss whatever emission benefits an operational EGR system may infer.

OT, but - when I replace the exhaust system finally - while I bought the last Bosal in captivity a year-and-a-half ago and have been JB Welding the current system quite successfully! - I presume I will retain the cat but want to remove the air suction stuff for more working area around the drivetrain; so - any probs? I know that CA or Canadian cars do not have this suction device for their cats (CA, in particular, surprised me!).
Tom M.

The suction device you are referring to is replaced with a vacuum switched reed valve system that is attached to the front of the air cleaner housing on a CA terc. Both systems supply downstream air to the cat converter to help promote after burn to further reduce emissions.

[dlb]

I remove the EGR from the motor , then you'll notice the hole get smaller from hard carbon stuff , I just use the small srew driver to scrape the stuff out , then some one show me to fill the other end with liquid , ifit hold then it is good EGR valve , if it leak through other end then you have a bad EGR .

in regards to figuring out if your EGR is still good, it's an easy test. it's essentially just a plunger attached to a vacuum-actuated diaphragm so you test it the same way you would your vacuum ignition advance: put a hose on and suck on it. you should hear the diaphragm move. if it holds, it's good. if it doesn't hold or doesn't move at all, it's junk. it's the most easily accessed port on the face of the EGR so you can check without removing it.

i found a mistake in the FSM while testing the EGR vacuum modulator. this only applies to the "canada vehicles wagon m/t & 3A engines" though. on pages EC-24 and -26 the vacuum modulator ports are mislabeled: P and Q are reversed. you can tell by looking at an actual modulator because the ports are labeled on it. i don't know how this affects the testing of the modulator according to the FSM but it seems like it's just a fancy splitter of sorts and i can't imagine much going wrong with it. someone please correct me if i'm wrong.

[Petros]

I do wonder - with respect - that with one breath you applaud a cleaner atmosphere by retaining the canister and with the next you dismiss whatever emission benefits an operational EGR system may infer.

I did not dismiss it. What is considered pollution and how much a car can emit is determined by lobbying, so the picture is not clear if the EGR actually reduces total emissions or not. You tell me, if you can go say 350 miles on the same amount of gasoline, that will only take you 320 miles with an EGR, which car put out less total pollution per mile? Which consumed less resources?

Same thing with ethanol in the gasoline, it is well known it actually puts out more pollution and consumes more resource than burning gasoline. Yet the feds still require us to buy in gasoline, why?

That is all I am saying, the picture is not clear if it is beneficial or not. As for me I am all for limiting pollutions that does not cost fuel economy or engine efficiency to do so. the fuel cut-off solenoid is complicating but beneficial, it will reduce fuel consumption And reduce emission. I like it.

[4wdchico]

I remove the EGR from the motor , then you'll notice the hole get smaller from hard carbon stuff , I just use the small srew driver to scrape the stuff out , then some one show me to fill the other end with liquid , ifit hold then it is good EGR valve , if it leak through other end then you have a bad EGR .

in regards to figuring out if your EGR is still good, it's an easy test. it's essentially just a plunger attached to a vacuum-actuated diaphragm so you test it the same way you would your vacuum ignition advance: put a hose on and suck on it. you should hear the diaphragm move. if it holds, it's good. if it doesn't hold or doesn't move at all, it's junk. it's the most easily accessed port on the face of the EGR so you can check without removing it.

i found a mistake in the FSM while testing the EGR vacuum modulator. this only applies to the "canada vehicles wagon m/t & 3A engines" though. on pages EC-24 and -26 the vacuum modulator ports are mislabeled: P and Q are reversed. you can tell by looking at an actual modulator because the ports are labeled on it. i don't know how this affects the testing of the modulator according to the FSM but it seems like it's just a fancy splitter of sorts and i can't imagine much going wrong with it. someone please correct me if i'm wrong.

DLB, sorry, but I have to disagree on your EGR test statement. The far more common failure mode for an EGR valve is a vac leak of atmospheric air into the intake via a worn pintle shaft/EGR body interface. The EGR valve diaphragm is made from very high quality silicone rubber and can often go the entire life of a car w/o leaking. The previously mentioned vac leak issue is a virtual certainty with high enough miles. Say 150-180k miles for 'yotas of the t4wd's era.

I go into the whole EGR thread issue in detail in my posts in the below linked thread. Function, theory and testing is covered.

https://tercel4wd.com/forums/viewtopic.php?f=4&t=5198

[dlb]

hells bells, i was hoping you were going to chime in on this. i think you must lurk here far more than you post, 4WDC.

that is great info. what i now want to clarify with you is where the vacuum leak is occurring, exactly: you said that the pintle shaft is similar to the stem of a valve, but it doesn't seem like the shaft of the EGR valve would see much wear. i think that between the face of the valve and the body of the EGR is where a leak would occur, due to both physical wear of the two surfaces and carbon buildup on them as well. am i on the right track there?

next question: knowing your savvy nature when it comes to emissions stuff, what have you done in the instance of a leaky EGR? have you bought a new one for $185? if it was leaking due to carbon buildup it could be cleaned up some by applying vacuum to the diaphragm to hold the valve open while you scrape it, albeit blindly. if it's worn out though, you'd be SOL and have to either bypass or replace it--presumably with a brand new one.