Adding EGR system on non-EGR 1988 740 NA in CA

[xtlicious]

I purchased a 1988 740 from Florida that was originally without EGR. I live in California. Unfortunately all my smog readings were off the charts bad, with a number of remedies recommended and executed including a new CA cat, cleaning the TB, new oxygen sensor, replacing a few very old vacuum lines. After these fixes all readings were excellent EXCEPT NOx. It was still off the charts. It was explained to me that the CA cat doesn't reduce NOx because Volvos sold in CA during that period had an EGR system and mine does not.

This leaves me with two options (though I welcome other options):

1. Purchase a non-CA cat and take my chances that it'll reduce NOx enough (and keep the other readings low, as well). My mechanic told me that he's not willing to do this. This is also not something I'm super-jazzed about after spending $500 doing other fixes.

2. Find a junkyard exhaust manifold that includes the port for the EGR out, and also get the EGR valve.

Questions about above option #2:

a) what else do I need other than such an exhaust manifold and EGR valve (and associated hardline to the EGR valve, I assume)?

b) is this something with semi-capable skills such as myself (brakes, oil changes, tune-ups) can do? Can someone post pictures of the intake vacuum port, intake connection, and/or exhaust connections for me?

Thanks!

[xtlicious]

Lacking any replies over the weekend I went junkyard-diving. I ended up finding a 940 NA from which I extracted the exhaust manifold and intake manifold as well as the hard lines between the two and the EGR. I wasn't certain about the EGR because it has a sensor on it that apparently fed back into the 940's ECU (as well as vacuum-actuated port) AND it looked as old as the car. For reference, the junkyard 940's hard lines exited the exhaust towards the firewall, wrapped around and under the distributor, and under the intake, which is where the EGR valve was. Then there was a hard line from the EGR up to the intake. Apparently that is a little bit different from what was found on early 740 and 240's with non-sensored EGR, as this auction listing shows (http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0310715376). Unlike the junkyard 940 which had a hard line from the EGR valve (under the intake) up to the intake, the EGR valve was actually bolted onto the intake, therefore making it a single hard line from the exhaust to the EGR valve.

It looks like I have few options at this point:
1. Find a used 940 EGR valve and leave the sensor dangling, and install it with the lines I already have
2. Fab my own exhaust line (not sure about finding the right connections with that pipe size) and get an EGR like the one in the eBay auction, above
3. Buy what some auto parts sites are saying is correct for my car, aftermarket part EGV1091, and figure out how to connect it using correct fittings

Hopefully this post will help someone out in the future. I still welcome better ideas...

[jimmy57]

You will need Ignition control module from above brake pedal and I think the Calif fuel injection control module in right kick panel is also needed to be compatible with ignition module. Ignition module runs the EGR valve controller. You will also need the EGR valve vacuum controller from the driver's side inner fender next to engine.
You wiull have to find these parts from a 1988 as 1989 and later use different fuel and injection system and the sensors are ALL different.

First off, is the NOx high on the idle test or the off idle test?
If your harmonic balancer has slipped and the timing marks being used for ignition timing are off then you may have overadvanced timing. This leads to excessive NOx at idle and at higher throttle too.
Simple quick fix is to establish your own top dead center mark. Break the ceramic out of an old spark plug. JB Weld a bolt or some other cutoff piece of rod that extends about one inch from end of spark plug threads into cylinder. THis will be a piston stop. Turn crank gently with socket on crank bolt CW until piston stops on your stop tool. Mark the balancer with chalk or crayon, etc. at the 0 point on timing cover scale. Now turn CCW and do the same. TDC will be the point centered between your marks. Mark this spot and set ignition timing using that mark. To be safe do not set timing at 12 deg BTDC, set it to 8 degrees BTDC. After you pass set it back to 12-14 deg BTDC. Use premium fuel for the testing. An even greater margin would be achieved by using a cooler thermostat in engine or even wedging your t-stat open and then later replacing with new one after test.

Calif catalysts still have NOx catalyst within but the standard was low and EGR was the remedy to assure compliance.

Also be sure your air cleaner housing thermostat is not stuck open. The hose that leads back over to the cover over exhaust manifold goes into chamber in air cleaner box where a door controlled by a thermostat closes fresh air opening and opens the hot air hose side. These are notorious for sticking. Remove the thermostat and use a screw to lock door closed to the hot air hose fitting.

[xtlicious]

First -- I don't plan on making the car's computer EGR-compliant, just adding a mechanical EGR. Looks like non-CA, non-ECU controlled EGR used a wax thermostat through which the vacuum was inhibited until 140 degree coolant temperature. If possible I'll simply add that into the system, along with a stranded sensored (or non-sensored) EGR and I'm done.

BTW, although I have what looks like a sensor in my airbox it is not active. And I don't have the hose you speak of, though I know what you're talking about (my 1993 240 has the over-the-valve cover-and-into-airbox hose off of the exhaust manifold). Amusingly my airbox has the port for such a hose, but it is not drilled out. The only hose my 1988 740 has from the exhaust manifold is the flexible silver one that sucks in air for cold starts, which is extremely important here in Southern California

Regarding your CA cat comment -- perhaps the Volvo factory CA cat had NOx reduction built-in, but the aftermarket ones that aren't $1,000 do not (or very little) regardless of CA's lower-than-usual NOx standards. Therefore they rely on EGR quite a bit. I'll follow-up in a post tonight with the before/after numbers. All of my numbers went from ok (or very bad) to excellent EXCEPT NOx, which remained very bad. And with no driveability or idle issues, and no codes thrown, I'm left to think EGR is the need at this point.

So, to sum up, my 49-state NA 740 in 1988 did not have an EGR, and did not divert any exhaust gases back into the airbox. But it *did* have a heated 3-wire lambda sensor and likely a NOx-reducing cat. I'm converting it to an mechanical EGR car, assuming I can find a place for a wax vacuum-controlling coolant thermostat to feed vacuum to the EGR. I do not want to replace the head in order to add the hardline pipes for the airbox feed nor do I want to change the electronics. I'll be sure to take pictures

[xtlicious]

Also forgot to answer your question -- in CA the NOx is measured at 15mph and 25mph. Both are at about 1700 rpm. It was very high on both (something like 3,000 ppm when it should be in the 200-300 range). I've considered pulling the thermostat as the temperature gauge reading too low doesn't automatically fail the car BUT without the t-stat I'm concerned that the oxygen sensor would not give good enough feedback at low engine temperatures to pass the CO% test.

[jimmy57]

The silver hose to exhaust manifold cover is for hot air, not exhaust. In really cold weather the cold air will hinder mixing of fuel and air and the hose was to give warm air to counteract this. The hot air being available with warm freash air temp will send NOx up drastically.
Your 93 240 has the B230FD engine with Pulsair. Those hoses are used for cold start oxygenation of exhaust to lower cold start hydrocarbon (raw fuel) emissions. The hoses get air from the air cleaner and it is sucked into exhaust through the two check valves. The pressure drop at exhaust valve closing creates enough suction to get the job done without an air pump. No NOx reduction from Pulsair. The hoses have the vacuum shut off to stop the Pulsair function on a warmed up engine.
You have a heated O2 sensor so it will give a reading. Exhaust temp will be great enough for function regardless. Anything you do to cool combustion temp reduces NOx. EGR reduces NOx by making the combustion richer with exhaust encapsulated oxygen removed from availability during combustion, effectively richer but that oxygen is freed post combustion and is available for catalyst function and will be part of the exhaust gas sensed by O2 sensor.

[xtlicious]

Sounds like I need to get rid of the warm air hose (or plug it) and get a low-temp thermostat (or no thermostat). Thanks for the extra info--especially about Pulseair. Wasn't aware of its function at all.