how to hook up EGR to weber?

[dlb]

so i've got the hoodscoop on and went for a test drive over the mountain the other day...and the ping remains. so far i have

seafoam'd the engine
switched to cooler plugs
set the timing at stock 5* BTDC
checked for vacuum leaks (the only vacuum lines i have are the two PCV hoses and the vacuum advance)
blocked off all unused ports
adjusted the fuel mixture
wired the warming flap in the exhaust manifold to the 'cool' setting
replaced the heat shield and phenolic spacer

and the ping has remained more or less constant throughout. it's not horrible but it's there when under load. i had no pinging before my friend helped me put the weber on and when we put the weber on, we removed all the emissions stuff. i know petros has mentioned that the EGR's cooling effects are minimal but seeing as i've worked through the above mentioned list, i think it's worth trying now. the only problem is i have no idea how to hook the EGR up--when i look at the diagrams for the emissions set up, almost every vacuum hose is attached to every other vacuum hose via all the metal lines.

so my question is: which components are actually necessary to run the EGR with the weber?

[ARCHINSTL]

Presuming you have the 32/36 - there is a blocked port on the side for the EGR. Mine has a metal cap on it. Dunno if the hole is threaded - maybe just stick a tube in it?
Look at http://www.tercel4wd.com/forums/viewtop ... fic#p44500 (diagram)
and
http://www.tercel4wd.com/forums/viewtop ... low#p44487 deejay1272's last photo.
Tom M.

[dlb]

those are both the same thread tom, was that intentional? although you've given me the idea to actually try hooking the advance up to ported vacuum rather than manifold...

[4wdchico]

OOps!

[4wdchico]

First of all, when you say pinging "under load" do you mean at wide open throttle? If so, a working EGR system will not help as there is not enough manifold vac at WOT to make the system function. A working EGR system will provide the most benefit in reducing ping when lightly accelerating from a steady state cruising condition at highway speeds. Floor it and the EGR system becomes irrelevant. If you still think that having a working EGR system can help, see below.

I'd suggest reading thru the section of the FSM that deals with testing the EGR system a few times. Pay particular attention to page EC-24, I'm assuming that you have a Canada spec car. I would use the TVSV to switch the EGR system on only when the engine is fully warmed. Bad stumbles are the probable result of an active EGR system on a cold motor.

As a minimum you will need an EGR valve, TVSV, EGR vac modulator, a couple of vac T fittings, some vac hose and a check valve. Don't ignore the function of port J on the TVSV, it attaches up high on the stock carb's air horn and serves as a clean air source & release point for the TVSV. So you could use a small gas filter to filter the air in/out of port J to prevent dirt contamination issues if you don't want to get involved with tapping into the upper air horn on the carb or the air filter itself. The ported vac source on your carb can be used to connect to the EGR P port on the vac modulator if it supplies vac just a bit above idle. You will then need a ported vac source a bit above the your existing ported vac point to connect to the EGR vac modulator port R. See page EC-24 illustration 2.

This last bit with the two ported vac sources may seem like a PITA but it will result in an EGR system, if properly implemented, that will start with a small amount of EGR flow at smaller throttle plate openings and then transition to full EGR flow at larger throttle openings. This proportional ramping up of EGR gas flow is key to preventing the classic case of tip in stumble that can can be caused by a malfunctioning EGR system. See notes (1) & (2) in the chart of EGR system behavior at the bottom of page EC-24

[dlb]

4WDC, you're a wizard at emissions controls. it's admirable. here are my questions to you:

when you say

you could use a small gas filter to filter the air in/out of port J

do you mean air filter? like one of those miniature K&N-looking things?

next, what is an air horn? i assumed you just meant air filter till you mentioned that separately. i may have more questions for you regarding ported vacuum points on the weber but i'll see how this goes first. thanks!

[4wdchico]

4WDC, you're a wizard at emissions controls. it's admirable. here are my questions to you:

when you say

you could use a small gas filter to filter the air in/out of port J

do you mean air filter? like one of those miniature K&N-looking things?

next, what is an air horn? i assumed you just meant air filter till you mentioned that separately. i may have more questions for you regarding ported vacuum points on the weber but i'll see how this goes first. thanks!

A small inline fuel filter will function as an acceptable air filter on a vac system . Lots cheaper and easier to adapt than those mini K&N crankcase breather filters. If you really want to get stealthy about it, many car vac systems have mini filter caps on VSV's for this exact purpose. I'm fan of the AC GF453 fuel filter, cheap & high quality pleated paper element with 1/4" barb fitting on each end. Pretty easy to adapt down to 'yota vac line size.

The air horn on a carb is the fresh air intake end of the carb, in this case the top, where the air filter housing is attached.

[danzo]

DLB, if you recall I removed the EGR on my car a few weeks ago and proclaimed the pinging was gone. I spoke too soon, as it slowly but surely came back (even at 0* ignition timing) probably in proportion to the plugs fouling. The car was getting poor gas mileage, about 24 mpg, the motor would 'diesel' when shut off, and the oil was getting fuel-fouled very quickly. You guessed it - running too rich. Also the car was hard to start once warm, which I assume was due to the rich mixture washing the cylinder walls. It would crank excessively until oil could coat the walls and bring the compression back up (in theory).

I didn't notice the oil fouling when I first installed the Weber because the oil was already dirty and in need of a change. But the new oil turned a greyish color and stank of gas after just a couple hundy miles. So I leaned out the mixture as much as I could, which brought the mpg's up to about 30-31. It's still hard to start when warm, but it doesn't diesel anymore. ***Takza just imagine the gas mileage potential here*** The other day I ordered a few smaller main jets which should arrive today or tomorrow. My carb currently has 160's, but I am getting 135 through 150 jets so I can play around and hopefully discover the best combo. Remember my car will use smaller jets than most because it's about 90*F almost everyday, soon to be 100 everyday.

Of course my point in all of this is that your pinging may be due to your car running main jets that are too large. Right now I'm not sure, but if smaller jets work for me maybe you can do the same. I'll let you know what happens.

[4wdchico]

danzo:

Wow, to be pinging with such a fat mixture means that you must have a built up a bunch of combustion chamber deposits since the Weber instal. If this is the case, you could be flirting with preignition also. Yikes, PI is a bad thing. Are you totally sure that you have no vac leaks? Just wondering...

[danzo]

Thanks for the comments 4WDC. I thought carbon deposits due to the richness might have been a source of the pinging so I Sea Foamed 'er for the third time in 2 years. No change. The pinging is not really bad, just slight at light loads and low rpm. I've checked for vac leaks several times using propane and found none, the vac gauge needle is steady and shows the proper vac. Hopefully the new jets will arrive today.

[dlb]

interesting development. i forgot that i had given up on the stock timing thing since it had not stopped the pinging and had left the timing at 10* BTDC. the other night i replaced the dizzy o-ring (the original snapped upon removal, it was so brittle!) so i set the timing back to 5 * BTDC. while i was at it i inspected the vacuum port plugs and found some of them were cracked so i replaced them. didn't think either action would have much, if any, effect but i went for a drive this morning and noticed there was no pinging in usual spots. tested it out by lugging it up a few bigger hills in second, still no pinging. i'll give it a thorough test soon but thought i would mention this in the meantime.

it's unclear what this suggests but i think it's one of three things: one, the vacuum port plugs were leaking; two, the mechanical advance in the dizzy is worn out and over-advances the timing, making 10* BTDC too far when it would be fine on a healthy dizzy; or three, both of these. if i find no ping during my next test i will advance the timing again and see if it was just the leaking plugs the whole time.