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Running issues. I'm out of ideas


MGTS

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Rotor was fine. 

So when I disconnected the mixture solenoid, it (surprise) changed the mixture. I have to compensate by opening the throttle a bit more, so instead of it taking on fuel from the idle mixture, it was taking fuel form the venturi 

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This is for one of the plugs to the emission control box. My "E" wire does not ground, "A" does. Could I bridge "E" to "A" to obtain ground? Or just run a slice from "E" to ground?
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I suppose you could.

 

 

On 2/22/2021 at 4:43 PM, MGTS said:

Rotor was fine. 

So when I disconnected the mixture solenoid, it (surprise) changed the mixture. I have to compensate by opening the throttle a bit more, so instead of it taking on fuel from the idle mixture, it was taking fuel form the venturi 

 

If drawing fuel from the primary then the idle is way too high. When the idle cut solenoid turns off with the key it should immediately stall form lack of fuel.

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So I got the mixture solenoid replaced and it runs great. It stumbles off of idle. I'm fairly sure it's the accelerator pump. The plunger is new, but it doesn't seem to slide up and down inside the chamber easily. Most of actuation is just from the integrated, I think they call it a damper spring, built into the plunger

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I replaced the plunger and it's running better, but it hesitates off of idle. If I don't feather the throttle just right, it will die. Any ideas?

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Xpx5kbG.jpg

 

Is the throttle valve switch set properly? Should be closed at idle. If not opening the ECU thinks you are at idle.

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Is the idle mixture screw uncovered? From the factory they are set then an aluminum plug covers it so you can't mess with it.

 

LjGaCgo.jpg

 

Mixture could be fine tuned slightly on the rich side at idle. You would want to turn it back leaner for emissions testing.

 

Try turning the idle up to 800 or 850.

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It passed!! 
I know how to lean-drop the idle, but screwing in the mixture screw all the way doesn't make the engine stop running. On my Land Cruiser, if you turn the mixture all the way in, the engine dies. I currently have the idle set to the FSM 700. I will try pumping it up

 

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Usually turning in the mixture screw will make the mixture so lean it will quit.

 

Well a pass is a pass.

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Congrats on passing! where you at in California? i'm about to go get a smog done next week or the week after. fingers crossed, i'm hoping it passes. do yourself a favor and put the Weber on like i'm going to after it passes. just keep all the old stuff to swap back over. makes for a fun weekend switching stuff back and forth haha.

 

Hoping i can pass with the Sentra mixture solenoid i found out that i have. Also when whoever repaced that solenoid on that carburetor, someone had the bright idea to drill it out, leaving a hole above it creating a lean issue. i have a rubber vacuum cap in there right now i'm going to epoxy in to seal it up good.

 

LMAO nevermind i see you are in the bay area. i'm other side of the Altamont

Edited by A guy named Rick
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20 hours ago, 720_Jeff said:

MGTS, if you can, post a copy of your emissions test.  Interesting to see how it actually tested out.

 

 

I second that. If i pass, I'll post mine too. See who's cleaner haha.

 

I do wonder if all that water i was getting in the cylinders before doing the intake gasket maybe steam cleaned the engine and catalytic convertor. it was just water... and rust

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On 3/31/2021 at 1:46 PM, 720_Jeff said:

MGTS, if you can, post a copy of your emissions test.  Interesting to see how it actually tested out.

 

 

When I did the test, It was with a brand new cat, literally 1 hour after it was installed 

 

Smog.jpg

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On 4/3/2021 at 10:30 AM, MGTS said:

When I did the test, It was with a brand new cat, literally 1 hour after it was installed 

 

Smog.jpg

 

Which Cat did you buy/use?  Those numbers seem to be insanely low!

 

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It also helps to have a recent tune up, have the EGR valve working, probably an oil change, and have the engine well warmed up. I've heard that dumping a gallon of alcohol into half a tank helps. This would lean out the mixture in a carbureted engine and it might run cleaner. I would only try this after a fail.

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3 hours ago, datzenmike said:

It also helps to have a recent tune up, have the EGR valve working, probably an oil change, and have the engine well warmed up. I've heard that dumping a gallon of alcohol into half a tank helps. This would lean out the mixture in a carbureted engine and it might run cleaner. I would only try this after a fail.

Great point!  Thankfully mine has been passing, I'm sure there's always room for improvement.

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The truck stumbles quite a lot off idle. I need to give it a lot of throttle so make sure it doesn't die. I found the EGR was the main problem. I disconnected and plugged the line. It's now really smooth off idle, but now it pings bad at higher RPM. Thoughts?

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Timing at 3 degrees with an idle of 700?

 

There should be no EGR at idle and perhaps just slightly above idle. Is the EGR hose connected to the correct ported vacuum source??? Looks like there are 3 sources. EGR should be connected to the middle of the three.

 

Is there a crack or hole in the pipe from the EGR to the exhaust manifold?

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Yep 3 degrees and 700. No EGR at idle, but it kicks on pretty much as soon as I put it under any load. I have the CA base model with no accessories. I only have the advance and EGR port. They are all routed correctly. I will check the pipe. I replaced the EGR to intake gasket

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 Well, if it idles then the EGR is closing properly. The E in EGR has to be exhaust which has almost no oxygen in it and is inert. If there is a leak in the pipe oxygen will alter the air /fuel mixture and lean it out.

 

Also is there not a BPT (back pressure transducer) between the EGR and the ported vacuum signal. I think it varies the amount of EGR by using exhaust pressure as an indicator of load.

 

I have an '84 FSM and it clearly has 3 ported vacuum sources on the carburetor.... perhaps the '83 did not

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Yea I have a CA model. So I completely disconnected the advance and the EGR/canister lines and set timing to 10 degrees and it runs a lot better. I'm going to see what my mileage is like on the next fill-up
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You'll have to try it with the vacuum advance connected. You'll see that you get better mileage with than without.

 

Yes, I see there are only 2 ports on the CA '83. The '84 has 3 and the EGR has it's own port.

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