Failed Emissions with a Volvo 1988 740 GLE Non-Turbo in MD!!

Hello,

This is a follow up post to the following thread.

http://groups.google.com/group/alt....nk=gst&q=Volvo+1988+740+GLE+Non-Turbo&rnum=1#
[I was telling the story of my car and my fears of failing the
Emissions test].

I have just failed it after I have changed oil, spark plugs [Bosh
Platinum Plus plugs] and with the correct Air Mass Meter. One thing to
note, the idiot tester drove the car on the trademill without the
overdrive engaged. I told them but they just didn't understand what I
was talking about I don't know if this would have affected the
test. I doubt it since it failed with double the allowed limits of
NOx.

The car failed only on the NOx category but passed fine in the CO and
HC with nice margins. I have changed almost all what should be
routinely replaced. Rotor, Cap, O2 sensor is only about a year old
with less than 10K on it. Flame Trap and hoses changed with the O2
sensor.

The only remaining item on my list is the AirBox Thermostat [AutoZone
and Advance Auto Parts doesn't even know what I am talking about].

Now, the EGR valve comes to picture as the major player in NOx from my
research of as to how it works. I do have a Haynes manual for my volvo
but I can't find any mention of an EGR valve anywhere. The valve is
pretty expensive new $200-$250. I am thinking to go to a U-Pull it
yard and get a couple to try. My only problem is that I don't know
exactly how it looks or where is located in the car. I would
appreciate any help in that regard.

Pictures of where is it or description as to where is it exactly would
be greatly appreciated. Thanks a million.

Note: I really thankful for the Volvo help you guys have given to me
in the past. The car's mileage has gotten better after I had used the
correct Bosh AMM with xxxxxx007 but still below the EPA estimated
numbers for the old tests but somewhat okay with the new test
procedure results.


Thanks.


-- Hameed.

 

Try backing off the timing a bit, that should lower the NOX.

 

I just passed California smog with barely discernible levels of NOX.
My pre-test tune up consisted of new plugs and wires, one can of
BG-44K in the gas tank, change the oil and filter immediately after
the BG-44K was used up, and clean the air filter. I checked my flame
trap, too, but it was pretty clean.

 

Any info about the EGR valve?

Also, I am having a symptom that is starting to become clearer now:

The car would start in a very high idle rpm around 2000 RPM or a
little lower and when put in gear sometimes it just dies but starts
back again right away. Is that the knock sensor?

I am afraid this will get worth.

I love this car and I have till July 25th to get it to pass the
emissions. I read at the swedishbricks that the BG-44K was correlated
to failing CATs by Volvo and they asked people not to use such things,
any truth to that?


--Hameed.

 

I'm pretty sure this car doesn't have EGR, that seems to be mostly a
domestic car hack to get around antiquated engine designs, I mostly saw
it in late carbureted cars.

The idle issue sounds like a vacuum leak to me, definitely not a knock
sensor. Bad knock sensor will cause the engine to ping under high load,
particularly at low RPM on hot days. Sounds like someone going pink pink
pink on the engine block with a hammer. If you ever hear this, lay off
the gas immediately.

 

Correct, in 1988 there was no EGR. It came back on California models in
the early '90s. Retarding the timing a few degrees will lower NOx (as
suggested), as would running the engine at a lower speed (i.e. using
overdrive). Also, my uncle had good results with using Goodwrench (yes,
from GM) top end cleaner. This removed carbon buildup in the combustion
chamber, removing hot spots and reducing combustion pressures.

However, my guess is a new cat is needed - the part of the cat that
reduces NOx is separate from the oxidation part (that promotes burning
of CO and HC) and usually fails first.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Correct, in 1988 there was no EGR. It came back on California models in

Can you explain a bit more what do you mean by retarding the timing?

The idiot who did my Emissions test when he engaged the Auto
Transmission stick and accidently had hit the overdrive switch. I saw
the sign on the panel and I tried to alert the guy but they just
didn't understand. So I am not sure if I really failed because the car
was bad or because of that.

How can I be sure that the CAT did really fail?

 

You adjust the angle of the distributor as to back off the ignition
timing, ie move it closer to TDC. That car may be new enough to use a
crank sensor instead in which case you can't adjust the timing, my '87
uses a distributor sensor but it was right around that time they changed.

Even during a time when I had no cat at all, I still didn't fail the NOX
test so something else is wrong.

 

Assuming you're talking about your turbo, turbos have lower compression,
so they can get away with a bad or missing cat regarding NOx, especially
if the timing is retarded.

To the original poster: The only way to know if the cat is the problem
is to make sure everything else is OK, or test by substitution.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

My mom's '86 245 hasn't had a cat in years, the innards crumbled to
dust. Ironically the emissions check on that comes back cleaner than my
turbo with a cat. Go figure.

 

You'll have less detonation, pinging, knocking, whatever you want to
call it, and consequently lower NOx with the overdrive disengaged.
I'm assuming when you hit the switch, it disengages the overdrive so
that's a good thing.
We've even gone as far as run my '83 245 in second gear to stop it from
knocking. As long it will stay in the RPM range, it's a legal test.

Minor things that will help lower NOx:
Make sure the car is completely warmed up.
The entire drive train.
Run it hard at highway speeds (up hills, if you have any) for a ½ hour
or so to get _all_ the lubes warm and flowing.
The motor is going to cool down while you wait in line for your test.
That's ok, a cooler engine makes less NOx.

Overfill the (drive) tires. You can run them 5-10 lbs over max for the
test. They'll roll easier...

Good premium gas. Don't use whatever you used last time...

If you've used any fuel treatments, run a full tank of untreated gas
through it before you test.

 

If it's knocking then something is wrong. A naturally aspirated 240
should run just fine on ordinary 87 octane gasoline.

 

The OP didn't mention his 740 was knocking. That's just one thing that
can cause high NOx.
If you're referring to my 240, it runs fine on regular (with the knock
generator bypassed.) Otherwise it rattles and even with premium it won't
pass smog...
The second gear thing was before I wised up.
My HC's were surprisingly high this last check. I can't help but wonder
if the new flame trap had something to do with that?
I'm sure if I put a new engine harness in it and did the injectors, it
would run better... one of my projects this spring.

 

Knock generator? You mean detector? Is it bypassed as in shorted across,
or simply unplugged? It's possible the ignition box is bad and causing
the timing to go full advance, or it could be the knock sensor itself or
perhaps the wiring harness. I do believe there's a load signal from the
ignition box to the ECU. If the wiring harness is deteriorating that's
certainly the place to start.

 

Knock generator= Volvo/Chrysler ignition control unit. Plug the vacuum line.

 

And possibly end up with this: http://www.viatrack.ca/Misc/16VBREATHER.jpg




Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

My dad used to switch over to premium gasoline when it came time for
inspection. Worked every time back in the '70's.