MarkV

Running Rich Solutions?

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44 minutes ago, MarkV said:

Would a disconnected a/c compressor with lines cause a vacuum leak causing the computer to make up and causing a rich condition? 

 

Good guess but no.

I strongly suggest that you try testing the coolant temperature sensor as both Bloo and I suggested. It could be one or a combination of several different things but  we need to start ruling things out

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Since I don't have magic eye balls that can inspect a car from 1000 miles away I have to guess some things. First guess is, that your mechanic went over the car and verified that everything is to factory specs. Air filter not plugged up, spark plugs good, ignition in good shape, fresh oil change, fuel injection working properly. Your pic of that gadget with the mission hose makes me suspect that something is not working right. I don't know what that thing is or what it does but it is kind of a tip off that something is not right, when you notice parts missing.

 

Now first you or your mechanic has to go over the engine and make sure it is up to spec. I would inspect and replace spark plugs and air filter as a matter of routine. If the plug wires are original I would test them too or just replace them on general principles.

 

With the engine checked over and tuned to the teeth take it on a few long drives. Fill the tank with hi test and add a can of fuel injector cleaner. You may have some old gas in there that is not what it used to be. Run the tank nearly dry then fill up again and add a can of injector cleaner.

 

Run the second tank down, fill it half full, pour in a quart of methyl hydrate (alcohol, you get it at the hardware store). Then go get the emissions test done, make sure the engine is good and hot when you go in, I mean drive around for half an hour so it is fully warmed up.

 

It should pass, if it doesn't there are additives you can use.

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New plugs and wires as a part of the rebuild and air filter. I will run through a tank of gas with additive. Which is the best to use?

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17 hours ago, MarkV said:

Also of note that  I just noticed was the fuel economy meter is now always orange and never turns green. Maybe thats linked? 

 

 confirming the emission test results, the engine is running rich!  While it could be a clogged injector not misting the fuel properly, but that would be give very noticeable engine conditions. 

I am sure there are additives that might work, I myself have never found one.

Edited by John348 (see edit history)

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As I continue to ponder your rich running situation, two things come to mind:

 

1) As part of the 1977 emission controls package, your engine has the A.I.R. system.  The Air Injection Reaction system pumps

     oxygen (~20% of our air) into the exhaust ports.  This helps the combustion process continue after the hot exhaust gases

     have left the cylinders.  I believe it helps reduce HC more than CO or NOx but I don't know.  Making sure this system is working is simple.

 

   Rising up from each exhaust port on both manifolds is a steel manifold.  There is check valve at the top of each manifold.

   The check valve (one way air flow) protects the air pump in case there is a backfire.  Simply disconnect the hose from one

   of the check valves and verify that air is flowing at idle and part throttle. The only time air should not flow is during a high

   vacuum condition (deceleration).  To prevent this flow, there is a vacuum actuated diverter valve which reroutes the pump's air into

   the air cleaner housing.  Extra oxygen during deceleration (when the mixture tends to be richer) can cause backfiring because a richer mixture

   can explode in the very hot exhaust stream.    See the attached image of YOUR passenger side check valve...

 

2) How do you know that at some time in the past, if leaded gasoline was put into the fuel tank.  Granted, the restrictor in the gas tank

     filler neck would have prevented a leaded gas pump nozzle from being inserted but was the car at some point fueled from a jerry can?

     I don't think it took very long to coat the catalyst honeycomb with lead effectively neutering it.  This might be a long shot but... 

 

I read that with the analog FI system, the engine ran so clean that a catalyst wasn't needed to meet 1977 emission standards.  However,

GM chose to install one anyway...

 

Perhaps others can share their thoughts on these two points...

 

You'll find the problem.

 

Paul

 

 

AIR Check Valve 01A.jpg

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You probably also have high HC, hydrocarbons, but that gets reduced by the AIR injection as said above, so by the time it gets out the tailpipe the HC are at a passing level. So the AIR system is doing more to reduce the HC's than it really should have to do.

 

Also if you do have a catalytic converter, install a fresh one. That would help, but ideally you need to get the mixture optimized before putting on a new cat. A cat run on a too-rich engine will go bad much too quickly.

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IMHO fix the car.

 

HC     CO      O2      CO2

50      1.6     0.0      14.1

39      2.0     0.0      14.0

 

WIth HC that low, and 14% CO2, the catalyst is working. Perhaps not as efficiently as it could. The readings ahead of the cat will be higher, and the CO you are looking at AFTER the cat is too high. That is probably 5 or 6 percent (or more) going INTO the cat. That would be a nice full throttle mixture. It is way too rich for idle and cruise in anything remotely modern with reasonable fuel distribution.

 

Kludges like dumping alcohol in the tank never end well, because the original problem still exists. There is no halfway with cars like this. Fix it once and fix it right. It is SO CLOSE.

 

so, IMHO:

 

1) Check the temp sensor the way John348 described.

 

2) Verify it has a 195 degree thermostat in it. Since the work was just done, it should not be too hard to figure out what the part number was. It might even be on the invoice.

 

3) Verify that the vacuum hose to the MAP is not leaky. It needs to fit TIGHT, and not have cracks (look right at the end by the hole for radial cracks) no tape repairs, etc. If it comes off and goes on real easy it is probably too loose.

 

4) The indicator you mentioned that never goes green, Is that like a vacuum gauge? If so, that is indeed a clue. Low vacuum enriches the mixture. It probably does it in a step, and so may not be the problem. If it really should be green normally, then it needs to be sorted. Perhaps a leaky vacuum hose?

 

5) Ignition timing, especially retarded ignition timing, could cause low vacuum. Cars of that era have specific procedures. It can be really easy to get it wrong. The smog sticker might tell how. If not we are going to need the manual.

 

6) Verify that the vacuum hoses are routed correctly, and that there are no loose ones. The amount of vacuum hose I went through back when I was working on cars like this one this is staggering. The cars were only about 10 or 20 years old then. The chances of all of yours being good are about nil.

 

Good luck, you are almost there.

 

Edited by Bloo (see edit history)
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43 minutes ago, mike6024 said:

 

Also if you do have a catalytic converter, install a fresh one. That would help, but ideally you need to get the mixture optimized before putting on a new cat. A cat run on a too-rich engine will go bad much too quickly.

 

Don't do it yet though. The rich mixture combined with the AIR might melt it. Also, I am relatively sure from the numbers that your cat is doing something. It isn't going to take much of a cat to get under those limits once the engine is burning right.

 

The real advantage (since the car is low mileage), is that you probably have one of the old GM cats with the pellets. A modern honeycomb style cat would free up the exhaust and probably give you a little more power.

Edited by Bloo (see edit history)

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As I mentioned in post #4, consider measuring the fuel pressure at the fuel rail. Won't too high a pressure cause more fuel to be injected during the pulse? I don't know.

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The thermostat is #13008 which is 180 degrees and wrong. Obviously we need a 195degree one. Would that send these readings that far off?

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14 minutes ago, MarkV said:

The thermostat is #13008 which is 180 degrees and wrong. Obviously we need a 195degree one. Would that send these readings that far off?

Yes it will.

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I am taking it back over there later this week. Should I have them replace the coolant sensor and egr as preventative?

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The green light is vacuum controlled as the car gets hotter it is more prevalent, so the vacuum must be related to operating temperature right?

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2 hours ago, MarkV said:

I am taking it back over there later this week. Should I have them replace the coolant sensor and egr as preventative?

 

Myself personally I would replace one component at a time, so I am 100% sure what the problem was. Even if you were to test the CTS with the wrong temperature thermostat it might test as being faulty when it is not.  

 

1 hour ago, MarkV said:

The green light is vacuum controlled as the car gets hotter it is more prevalent, so the vacuum must be related to operating temperature right?

 

I am not very familiar with that specific system, but it is very possible that the vacuum is controlled by a temperature controlled ported vacuum switch. Again with an incorrect temperature thermostat it would be affected.   

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At 180 degrees the control unit does not know the car is warmed up. It is most likely still in cold enrichment (fuel injection version of a choke).

 

Edited by Bloo (see edit history)
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You may need new fuel injectors. Fuel injectors when old or dirty can "leak" and also not spray properly. Leaking means they dribble extra fuel when they should not be so that makes for too rich. Not spraying well means they do not atomize the fuel well so fuel and air does not mix well and burn cleanly.

 

Here is a vid showing what bad Bosch fuel injectors look like and why they need replace

 

 

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10 hours ago, mike6024 said:

You may need new fuel injectors. Fuel injectors when old or dirty can "leak" and also not spray properly. Leaking means they dribble extra fuel when they should not be so that makes for too rich. Not spraying well means they do not atomize the fuel well so fuel and air does not mix well and burn cleanly.

 

Here is a vid showing what bad Bosch fuel injectors look like and why they need replace

 

 

Thank you! We did the o rings on the injectors and several were replaced by the previous owner. Once I got it operating to the right temperature yesterday it ran smooth and the economy guage registered green. I have a feeling once the thermostat is replaced all will be good

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Why don't you just fix the things you KNOW are wrong like the thermostat and missing air hose? Inspect and test as necessary to be sure all systems are working correctly and are properly adjusted? There is no point replacing things that are in perfect working order.

 

Then, as the car has been off the road for some time, it would be a good idea to take some long drives to burn off any stale gas and get things working freely. You could toss some fuel injector cleaner in the gas for luck. Any good brand will do.

 

Then you could go back for a retest, with the tank full of fresh gas and maybe some methyl hydrate (alcohol) for luck.

Edited by Rusty_OToole (see edit history)
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