I decided to resurrect some information on EGR timers I posted at dodgetalk.com a while ago. With the increasing number of new members, this might be of some use when it comes to demystifying the purpose of one of those potted metal cans on the firewall...
This was from 3 messages I posted... I've rolled them all together here:
Being bored (-namely it's too breezy outside to be fun to work on the van...) I did a bit of research on some of the other EGR Delay Timers, and I found that they are becoming much less common! Take note of this if you need one: AC Delco has *completely discontinued* them, (I called to verify this) and Standard Motor Parts only still produces their EGT3. (I called them too!) It looks like KEM has discontinued several of them as well!!
Working on antique vehicles makes me feel old sometimes...
Since I have two timers on hand I decided to see what their delay times were. My various manuals claimed the idea with the EGR Delay Timer & CTS system is to prevent the EGR system (which includes the evaporative canister system) from operating until the air charge (the air fuel mixture in the intake manifold) temperature reaches 60 degrees, and to delay an additional 60 seconds after the air charge temperature does exceed 60 degrees. (In cold weather they figure on the air cleaner's Heated Inlet Air System to eventually stabilize the air charge temperature at around 100 degrees once the engine's exhaust manifold has warmed up sufficiently.)
I set up a bench power supply and wiring to simulate the CTS and EGR solenoid, and found that my Mopar 4111181 is a 90 second timer. This is equivalent to a Mopar 4111481, and the SMP EGT3 and KEM 173-603. These are the Red or Gray colored units.
My Mopar 4111180 is a 60 second delay unit. It is orange colored. These appear to no longer be in aftermarket production. The good news is that the connector and wiring is identical to the 90 second units, so a 90 second delay timer could be used as a drop-in replacement - giving you a slight additional delay before the EGR kicks in.
I don't have one of the 4111179 timers (black colored) to test, so I don't know it's delay time yet. If I find one I'll post the results.
As a further public service, I'll add the only diagram I've *ever* found for the correct and complete Emission wiring of my van - a 1981 Dodge Ram B250 Custom Sportsman 6400 GVW maxi van with 318 & 2bbl carb. It also applies to the 4 bbl version, and the 360 4bbl. The Haynes and Chiltons diagrams aren't even close, and even adjacent year Dodge service manuals don't have this exact diagram.
Oh, BTW - I found it is necessary to test these EGR Delay Timers with a load which approximates the EGR solenoid resistance. I used a 30 ohm resistor. Without the load they won't toggle their output.
Another rainy day here... I finally got my hands on a black 411179, and I found it's delay time is 35 seconds.
These EGR delay timer's purpose is to keep the EGR valve from opening for a period of time after starting the engine, to give the engine a little time to warm up so it won't stall as easily.
So, if passing emissions are an issue for you, I'd think the 35 second delay 411179 is your baby. If the engine is hard to keep running immediately after starting, probably the 60 second 411180, or the 90 second 411181 or 411481 is the ticket.
BTW, these are practically obsolete *now*!
After much runaround and several canceled orders I finally got one from KEM, (which interestingly had the Chrysler insignia on it...) and the invoice stated "Available until stock exhausted". Take that as notice that if you need a new one this is probably your very last chance. In short order they will all be boneyard only parts.
I've seen these timers in Dodge vans, pickups, and Ramchargers, as well as cars like the Omni & Aries, which all used EGR systems, up to the entry of the Electronic Spark Control computer on the scene. Since many of our most treasured vintage vans are from the pre-computer era, I wanted to get this information out so that no fellow Vanners would be surprised by yet another non-available part situation, or baffled by what to do if they need a substitute for these poorly documented parts.
I also got a green 3874129 out of a 1977 Dodge van a while back, but I haven't tested it yet. One of these days...