Rough Idle Crap (1 Viewer)

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Both are being Primed over to me from my friends over at Amazon.

In the meanwhile, I look forward to trying the propane vacuum test, with a friendly fire extinguisher by my side.
Propane is easy. Your not lighting the torch. Should be fine. Carb spray IS way less stressful tho.
 
Did you disconnect the brake booster hose when you did the exhaust? Major vac there.

Voltage looks low on the dash picture too. Did you replace the block to firewall ground ?

Still think you need to check the EGR, by using a spare piece of longish vac hose.

Idle till warm, and put a piece of vac hose on the tophat. Suck quickly on the end, it should almost stall. Do a few times, and listen for rocks rattling down the pipe. this will last a couple years, then have to do it again. If no change, it may be welded open on a rock, and will have to replace.

EGR or no EGR?

Vacuum test steps (with video)

Did not disconnect the brake booster or touch it.

Block to firewall ground? Not sure what that is, but does not sound familiar. Is this the ground that is connected to the intake manifold? I didn't replace that.

I am interested in this EGR check you are talking about. I did do some slight cleaning of the EGR , but it was not as thorough as suggested in the post you link to. I also did not fully disassemble it from the EGR Valve, only enough to get it off from the exhaust manifold and the intake. I did replace the EGR Inlet Gasket and cleaned up the EGR Valve's long tube.

When I took it off of the exhaust, I never saw a small ferrule ball sleeve. But the truck was working fine before I started all of this work, I had just taken it into Mudrak for a grand worth of work.


Appreciate all the inputs Mudders!

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Love that red hose! So vibrant!
Block to firewall ground?
Just a 10” or black wire w/ yellow stripe which grounds the side of the block near the back passenger side to the firewall. Engine has a handful of wire grounds.
 
Attempted the propane with the watchful eye of my brother work a fire extinguisher. Did not notice any big differences in idle.

Also did not set the truck on fire, which is a huge bonus .

Thinking this might be a timing issue now.

Updates to follow .
 
Although I received the timing light over the weekend, I could not break away from Father's Day or the other familial duties.

Tonight however, I was able to hook up the nifty vacuum gauge to the intake.

Here is what I see.

It looks like my engine is holding very steady at 16 Hg. The gauge says on the bezel that this is indicative of late timing.

Since I did the propane test on Friday and did not find any leaks, I am tempted to say that ignition timing is the culprit.

Thank you to everyone for the input.

Now that I have the timing strobe, I am a little curious about how I will make this work. I've read through a few different threads on ignition tuning. The little window above the starter motor is damn hard to see and barely possible to find, next to the the side cover.

This will have to be my next trick, as I attempt to turn the distributor and get a better handle on the ignition timing. Part of me thinks it would be easier to just rotate the distributor, keep the vacuum gauge on until I see the vacuum move into the 21-25 Hg range. Any harm trying that? Or am I just being really lazy?

Onward and upward. More to follow :)

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Go for it. I think I’ve read someone on here turns the distributor for the best vacuum reading, then back it off 1 in hg.
 
Any harm trying that? Or am I just being really lazy?
Nope. Timing lights with digital tach output are fairly new. Prior to that all they had was inductive lights and before... exactly as you said. Your ear and your sense of touch to feel the RPMs.
The window is prob covered w/, grease. It’s about 1.5”x1.5” and is held on w/ one bolt in the upper most edge. If you can feel it, loosen it and the cover pivots up toward the passenger side (I think) allowing you to see the marks on the flywheel inside.
 
Tuesday night update - I feel like I had a breakthrough tonight! :rofl:

First, I hooked up the new Innova timing light after inserting a paperclip in the diagnosis box.

After 10 minutes of rough idling, the truck was hovering around 1,050 - 1,100 RPM.

I tried my darndest to look in the small flywheel window to see the large diameter circle ( which would indicate 7 degrees). But I couldn't get my head in there and didn't feel like taking apart the air intake.

So I decided to hook up the vacuum gauge to the intake manifold. Starting pressure was around 16 Hg.


Next, I loosened the distributor bolt.

I twisted counter-clockwise and the engine abruptly died.

Thus I put it back to its original position and restarted the engine.

I started to rotate the distributor clockwise and the engine started to sound so much better. I got as far as I could go with the distributor before the bolt would not allow any more movement.

At this point the engine sounded pretty near normal.

The vacuum gauge went from the low of 16 to a new standard of 20 Hg.

One thing that stood out was that despite the engine now holding vacuum at 20 Hg, the idle stayed put at around 750.

I attempted to rotate the Idle Bolt on the Throttle Body ( I think on the FJ60s it was called the golden screw). This only accelerated the idle, so I put the screw back to its original position. No luck getting the idle to go down.

I decided to drive around the neighborhood ( up some steep hills) and the truck performed great.

Since I had not had the truck working this well in months, I took it on the freeway. Power was there. At any stop light or stop sign, the truck would gleefully idle at around 750-800.

On the freeway at 67 mph, the RPM is hovering around 2,300. Does this seem about right? I realize this depends on altitude ( sea level), size of tires ( 31"), weight of vehicle, etc ( no extra crap just yet - all stock).

By the time I got home it was idling at around 750 give or take (pictures below).

Question: At this point, is it just a fine-tuning of the distributor's position - or would it appear no need to adjust further?

If I already maxxed out the distributor's range. Does it make sense to take it out, reposition it by a tooth and then try this clockwise/counterclockwise turning again?

I guess I am trying to figure out if my new base for idle RPMs at 750 sounds about right or if the 20 Hg vacuum indicate that I still have more work to do in tuning the engine.

Appreciate everyone's input and help.

Lastly, might have to get an aviator's mirror so I can actually see inside the flywheel window. There is no cover, it must have fallen off at some point. SOR has a used OEM one for $27. Debating if its worth the cost.

Images

1. Dash while sitting in driveway after driving for 30 minutes
2. Tach and Speedo at Freeway speed
3. Tach while in Park in driveway immediately after I rotated the distributor

Thanks,
Sawdust

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I’ll get you a photo as soon as I can. The viewing window isn’t where I think your looking... follow the white dowel I’m holding to the bolt that retains the little plate cover on the bellhouse.

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Inside the window on my photo you can see a little white line. I added white out to the pointer as well as white out on the BB and TDC (which you can’t see in that photo).
 
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Also if you maxed the diz bolt then I’d have to assume someone had pulled the diz at one point and it’s a tooth or so off. Boltshouod not need to be advancedfully and if it is thenyou ‘should’ be getting some hardcore pinging.
At 67mpg typically the rpms would be about 3k. Best rpm range for a 60 would be about 2500 to 2800. In mine at 70 is just about 3k.
And 750 is a great idle to maintain at, these trucks tho can run at 600/650 new are now 30 years old. And if your at sea level, 20 on the vac gauge is near perfect. Last I checked mine it was at 21, on a rebuilt head and in CT (sea level).
 
FYI, photos at freeway speed... funny thot I was the only jackass that did that.
 
Lol Felicity!
 
Here’s the thing @hygge - I can’t remember if you got under the truck and painted the bb and TDC mark with anything. If you haven’t, you won’t be able to see the line and circle. With the window exposed that Felicity pointed out and your light pointed at it, you can use the little advance button (the up arrow) to advance the light, eventually you’ll see the TDC mark appear in the window. When it’s on the pointer, look to see where your advance is set to. Like @NeverGiveUpYota said, 20” and 750 is good, especially if it’s pulling strong and not pinging or knocking.

My distributor maxes out also, the reason, I believe, is because the FSM says to put the distributor in when the truck is at TDC. I think most people on this site put the distributor in with it at 7 deg before TDC. Then the distributor will be fairly centered when it’s timed correctly. When I figured that out I felt my timing was fine at the max position and didn’t change it. But I will next time I pull it.

What the mud consensus? Felicity?
 
Not sure other than by the book. I’ve recurved my own and when I reinstalled I tried to set it to the sharpie marks I’d added before pulling. But it just didn’t work... the gear that locks into the oil pump is curved, helix something or other so WAY easy to have it off a tooth or two is also WAY easy.
I finally did it by the book, no clue on the 7* degree way, I just went by TDC and the FSM and I’m fairly confident it’s right now because at my idle of 650ish my diz bolt is nearly centered.
It’s taken me awhile to realize, by the book is way better than by what I think is a good way.
 
FYI, I can be way thick skulled, born blond doesn’t help... BB (before TDC) I take it is 7* correct? Interesting theory to set it there initially. Guess the folks who’ve guided me never mentioned that one.
 
@NeverGiveUpYota @evilorgoodtwin i will have to give a second look to check in on that bolt for the viewing window cover.

I also never painted BB , TDC or the pointer. However, in previous image earlier in the thread, you can see what I think is the window and the pointer.

Is the best way to get to the TDC and BB marks by using a wrench on the crank bolt? I know this is in the he FSM.

To answer an earlier comment, yes the dizzy was removed. I took it out so I could replace the side cover (push rod) gasket. When I did this I attempted to mark the position of the rotor with a paint pen. I had some trouble getting it to align correctly while also seating properly during the reinstall. It would make sense that this is why I am now maxxing out the dizzy with the retaining bolt. When I pulled the dizzy the bolt was about center.

I will sit on it for the next little bit on whether to go back, pull the dizzy and reseat it. If I go this route, I’ll most likely start the process all over again and try and do the timing per FSM. Where I am at right now seems pretty solid, like 95- 99% sure I am all good.

Appreciate the inputs folks!

Once I have this all set, I can get to work on the AC conversion. I bought an R-134 kit Andy need to get the old lines vacuumed and recharged for the summer.
 
Best way is to pull the cover underneath the truck to expose the flywheel. Pull the plugs and you should be able to turn it by hand to get a visual of the marks.
 
Or just have a socket and ratchet on the alt bolt and turn it toward the driver side then get under and check. Might take a few partial turns to get the marks where you can see them from underneath.
 
Are you referring to number 34 in the image?

Couldn’t find an image that was specific to the 89’ SOR only shows image up to an 87.

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Yes. I think the bolts are all 12 or
14mm. Might be 8 altogether.
 

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