NoTransistors

I ask because, years ago, I removed much of the A.I.R. injection system. I set it up so that the pump dumps into the cat. I removed the solenoids from the diverter valve, and simply connected a vacuum line directly to the valve to eliminate backfires. The air rails were removed and plugged.
Two months ago, I removed everything else, believing that the dyno test would no longer be necessary.

Wrongo!!!!!!!
Last month, the car refused to pass stringent AND STILL REQUIRED NYC sniffer tests
Got the sticker a different way, but decided to put things back.

Today, I ran a new copper tube from cat to valve, and put everything back
Had to find new electric plugs for the diverter valve. Had to find the clipped wire ends in the motor harness, and connect my new wires.The manual shows what color wires to use.

The Question Is: Why does the computer divert air into the little black muffler for extended periods. It still does divert into either the air rails or the cat, but it seem to do neither for way too long. The manual says that the computer may do this for a second or two during low vacuum "or other situations", but vacuum is far from low.

Could it be the MAP sensor erratically reporting low vacuum?
I did not short out the harness wires, so I don't believe it is the computer, but some of you may understand this better.

Kindly help.

Seth

jv9999

iTrader: (1)

Air only gets pumped into the CAT for a short while at startup, then diverts. You don't want air pumping in there all the time as it will burn out the CAT. Plugging the manifold tubes is going to cause a higher reading, but will usually still pass. Is your EGR still working? What were the numbers when you failed?

That copper tube probably isn't going to last long. Copper work hardens and cracks when subjected to vibration.

rgarcia63

Mine diverts to atmosphere until the engine starts then "not diverted" but switched to the ports for the majority of the first 6 minutes of engine run time the rest to the cat. From then on it only diverts to atmosphere on deceleration..

NoTransistors

As for the copper tubing, we will have to see.
For some time, I had a pipe made out of copper sweat-piping and several sweat fittings. Worked for years. Why was it there? Because I trashed the original chromed pipe years ago, way before the dyno tests were required.

I didn't take enough notice of the emission quantities, to make it stick in my head. Haven't a clue what they were.
The E.G.R. roughens idle when manually manipulated. The E.G.R. solenoid works, and I cleaned out the port in the manifold, when it was off for gasket replacement about three years ago. I will need to test the valve with the break bleeding tool.

Every bit of plumbing and wiring is now back in place.

Mr. Garcia states that the pump air diverts into the atmosphere only upon deceleration, only after the engine warms.
The diverter valve is set up to divert upon deceleration. It uses manifold vacuum to function in this manner. That is is a fact, BUT is it possible or probable that the computer uses the MAP sensor to sense deceleration, where upon both electric valves on the dirverter-valve are deactivated to permit the pump to temporarily bleed into the air?
This would then point to a fault in the MAP sensor.
I am looking for the simplest reason for the prolonged bleeding into the air.

What do you think about my thoughts on the subject?

Seth

rgarcia63

With my TPI not possible there's no MAP.

NoTransistors

Your engine must have some form of vacuum sensor. We both know that spark requirments change with load conditions. Unless you have an old-fashioned distributor in a non-factory setup.

My MAP sensor has actually been referred to by a different name. Not exactly MAP, but that alternative type of sensor.

Seth

rgarcia63

Mass Air Flow sensor (MAF.)

BluFBdy

iTrader: (1)

i dont think his carbed motor is running MAF

naf

iTrader: (7)

MAP = VAC sensor for the carb'd motors.

It's very unlikely your VAC has gone bad, though not impossible. A failing VAC should throw a code. I also suspect that were it's readings to be sporadic enough to cause diverter malfunction you'd also experience other symptoms, like converter un-lock, rich/lean, pinging, etc.

Can't help much more on the proper behavior of the diverter. I finally yanked it out of my 85 last Summer when I discovered many of the pipes were corroded through from the inside. It was less effort to remove than to try to fix.

Confuzed1

iTrader: (4)

Your CAT is most likely bad, or your engine wasn't warmed up fully. I had mine bypassed, meaning I had the hose going straight from the pump to the air connection on the CAT. I passed the sniffer and dyno thing with flying colors, and I had removed my divertor valve all together.

The diverter valve only sends air to the exhaust manifold for a short time until the engine warms up, then it "diverts" all the air to the CAT after the engine and exhaust warms up. I think the TVS tower where your vacuum lines hook up in the T-stat allow vacuum to pass after the coolant is warmed up and allows vacuum to your diverter valve, but I'm not positive. But it basically shifts the air about the same time the ECM goes into closed loop.

NoTransistors

The car did pass inspection last year, with the pump simply connected to the cat, and the diverter valve used only to avoid backfires.
If a cat can go bad from receiving pumped air 100% of the time [from JV9999's response], then it may be bad, but it would be still be nice to solve the vents-into-the-air-way-too-often problem.

O.K., I do appreciate your input.
If anyone comes up with more insight, please throw it this way.

Seth

Confuzed1

iTrader: (4)

Ok....straight out of my Haynes manual. "1. The AIR system helps reduce hydrocarbons and carbon monoxide levles in the exhaust by injecting air into the exhaust ports of each cylinder during COLD engine operation or directly into the catalytic converter during normal operation."

So- the CAT should be receiving air to it close to 100% of the time anyway. I could really only see the CAT failing if you took a bunch of short trips in the car and allowed raw unburned hydrocarbons to really build up in it. But I'd think that if you ran the car for a while it would rejuvinate itself for the most part after burning it off for a while. Again, mine passed with flying colors for 4 years with just the air going to the cat. If yours is backfiring when sending air to the manifold, it's probably running way rich.

1st line in paragraph under "Checking" -" Because of the ECM's influence on this system, it is difficult for the home mechanic to make a proper diagnosis."

I've done the check as per the manual, and it's not easy. I do understand how it's supposed to work however. It was a piece of junk out of the factory.

Vader

Open Loop Mode - A.I.R. output ported to the manifold distribution tubes.

Closed Loop Mode - A.I.R. output ported to the center chamber of the dual bed cat converter.

Decel - A.I.R. output dumped to the atmosphere (muffler).

The ECM determines whether the control mode is Open- or Closed-Loop. When in decel (higher than about 1,100 RPM, TPS voltage lower than 0.63, and in Closed Loop Mode) the AIR is diverted to prevent afterfire and/or cat converter overheating from excessive oxygen/light-off.

Hack the ECM program and it's all there to be viewed. The parameters may change slightly from year to year, and binary to binary, but the basic scheme is the same.

Confuzed1

iTrader: (4)

Hey Vader! Thought you quit posting...haven't heard from you in a while! So is that info out of the service manual?

My cheap Haynes manual doesn't mention TPS voltage at all. It only shows ways to check the individual components of the system (Pump,check valve,air management valve,deceleration valve) using vacuum gage and a vacuum pump.
But I'll stick to my guns, that system sucks.

NoTransistors

I borrowed an unused Map sensor from a friend today. Same exact unit as in my car. Computer still dumps air pump into muffler too often.

And no backfiring, ever, to answer your question.

I had a 1977 440 New Yorker Brougham Coupe that always blew mufflers, until I swapped the Carter for a huge Holley and the computer distributor for a Mallory. This was before dyno emissions testing. That car was incredible. But I digress.


So, if the 'puter thinks that the TPS is in the right spot, it will shut off all air injection.
It is either one of very few sensors or the computer, unless the distributor also sends some info out.
Does this mean I should check the 2 year old TPS?
Something is making the thing think we are decelerating.

Food for continued thought.

Thanks for the info you have already offered.

Seth

Kevin91Z

iTrader: (1)

That doesnt give you the priviledge of removing it though. Its required equipment by federal law on a street vehicle in all 50 states. It cleans up the air better than not having it does, and that is the point.

NoTransistors

Because you helped me solve this problem.
I inferred from what you said, that the 'puter is seeing a condition [closed-throttle deceleration] that simply is not there.
Well, guess what? The TPS voltage was 1/3rd of a volt rather than specified 1/2 volt. The adjustment screw had moved.As soon as I got it adjusted to spec, the diverter opened up to the cat.

Thank You for the insight.

Furthermore, I wondered why the mixture solenoid's dwell hardly budged when I pulled vacuum hoses. Well, there is a major vacuum leak in the canister control valve [the thing with all those nipples].

So, that valve's control hose is temporarily blocked off, and all is well.

Idle is smoother than it has been in years.
The exhaust smells like fine French perfume.

One more thing. I should order a new cannister control valve, as well as the T.V.S. for that valve [also trashed]. Anyone know part #s?

And finally, I have a problem with the EGR solenoid valve clicking on and off rapidly. I recall that this used to occur in the past, when the engine went into closed loop. Had been silent for the duration of these just-resolved issues. Just reared its noisy head again. I just remembered-----one problem mentioned by the dyno machine was high NOx.

Is the valve supposed to do that?

Seth