Old Blue - 1984 XL Flareside

Jim,

No worries!  I understand.

I get it is a different vehicle than my drive-by-wire turbo Accord. I agree where you are coming from. The roughness is ok.

It’s not in the video because sometimes it is worse than others, but if I hold the throttle there, I can stall the engine semi-reliably.

Basically, I don’t want to risk stalling because I didn’t punch it when trying to gently pull away from a stop.

And it’s not really about me as much but my son. He’s wanting to drive the truck, but he’s 16 and I don’t want him stalling it in traffic etc (if I can help it)

This is all more about optimization and striving for that last one or two percent making it as good as I can.

Im very much a shadetree mechanic and have never liked driving automatics (except in stop & go traffic)

If it were a drag car with a C6 bogging out of the hole I would say change the converter for one with a higher stall, but this is a street vehicle with an AOD so linkage adjustment is critical to longevity and I wouldn't mess with adjustment.
.... Mostly because I know I could do more harm than good.  

It might be worth checking the TV rod for proper adjustment.
I can only assume that it's been off and on a bunch of times if you've been working on the carburetor.

If I'm way off base hopefully someone like Bill will correct me.

Back to something else I mentioned earlier, EGR valve, if it opens too far as the throttle is opened, it will cause a severe lean condition, to the point of probably stalling the engine. It will be more noticeable on easy throttle opening as the accelerator pump shot is very slight under those conditions.

Your EGR control system is the same style that was used through the 1986 302 engines, there are two solenoid valves, a vacuum and a vent and they control the EGR by alternating to open it the desired amount. I imagine it is the same criteria the 1985/86 EFI 302s use, somewhere around 1.05-1.10 volts on the TPS sensor, the EEC commands the EGR to open, assuming the other criteria (engine temp etc. are met) the EGR solenoids may chatter when this occurs as they are balancing the EEC command against the EGR position sensor signal. EGR position is called EVP for Egr Valve Position and is a 1-5 volt range.

I would try disconnection the EGR vacuum hose, plug it and repeat the light throttle test. If the engine comes up smoothly, then the EGR system is the culprit. Check the EGR vent valve filter, if it is dirty and maybe clogged it will not release the vacuum quickly when the vent solenoid opens.

Thanks Bill, I tried that awhile back, but that was before I fixed a couple of the vacuum leaks. I will try that again. I feel there are multiple variables in play.

Regarding what Jim said about the TV rod - I did measure the pressure and it is higher than it should be in park.  It's around 15PSI if I recall correctly.

With Jim's comment about the torque converter engaging being the potential source of the change in sound/rougher idle, could that be a potential cause of the overall behavior?

It's on my list to take it to a transmission shop and get it adjusted at the transmission itself.  The screw on the carb is basically backed all the way out already.

I only meant to say that the roughness seems to occur as the torque converter starts to load the engine.
Definitely understand what you say about multiple variables.

I also disagree with your carburetor guy being dismissive of EGR. It has its purpose and was perhaps the only solution available to the auto industry at the time.
Taking it out of the equation (for testing) could prove helpful.

I don't really know if this stumble is due to fuel mixture, timing, weak spark or whatever...

having checked as much as possible so far. I like the earlier suggestion about the timing chain test.  I usually consider them worn out by 150k (my own decision based on my results). even when I replace with a good double roller I can still find more slack then I like at 150k. I have had many ask why I do this if it's still "running good". because I want it to keep running good! I put a lot of miles on some of these trucks/vans. one I put 408k on a 5.0 that only got timing chains and plugs/wires. do you have an idea of the mileage on your engine? it can be hard with the odometers in these trucks. after 100k it's a guess or an honesty issue. I find "low mileage" trucks every day. "original miles" even

Thanks Mat, yep, that one is on the list to do.  I worked on the interior this weekend, it is nearly done.  I'll post pictures hopefully next weekend.

The truck has 308000 miles on it total, but the engine was rebuilt at 265000, so since the rebuild it has ~43000 miles.  Hopefully the test comes out OK - I'll be kind of upset if it doesn't!

Chris

if you find excess slack at 43k then something aint right. But if the test shows slack, then it is what it is. replace the chain.

I'm way overdue on replying after doing the timing chain test.  I'm still going to do it, but after stepping away from the problem, I am almost thinking it isn't an engine problem at all.  I mean it still can be I suppose, but hear me out:

This behavior only happens when the truck is in gear.  In park or neutral, I can rev it all day with ZERO stumble/hesitation.

Could something be wrong with the transmission, or more specifically the torque converter?  When it engages, perhaps it's engaging too early etc?  The shift behavior is good, smooth, etc.  But the "only in drive" thing seems like a clue.

Just a thought.  I'll post project updates in another post...

Testing for timing chain slack/slap takes 5 min and a single tool (deep 15/16 on a breaker bar)

Diagnosis is about methodically eliminating potential problems (at least without something like OBD-II)

Before fretting about an inaccessible thing like the torque converter maybe do the test in less time than you've devoted considering the fluid coupling?

No arguments on your position, Jim. .  Might as well do it so it can fall off the list of possibilities.  I'm getting ready to tear some stuff down and I'll make it a point to do this at that time.  I have just been procrastinating lately and have been focusing on just enjoying the truck before I take the bed off and work on the frame/rear end. (I'm going to start that next week)

I'm sorry Chris. I certainly didn't mean to come off as argumentative.  

Bill's procedure is simple, and perhaps enlightening.
I too hope you can enjoy your truck before you dig in.  

Hi Jim,

Oh no, I didn't take it that way at all.  I understand where you are coming from, and it's good advice!  Keep It Simple, Stupid! (me, haha)  Don't worry.

I just ran out to the garage to do it, and the socket is too short or my extension is too long - so I just ordered a extension set where there are some shorter ones.  I'll try again tomorrow!

Deep impact socket has always worked for me, but your front pulley/dress may be deeper than I'm used to.

Didn't mean to offer poor advice or trivialize the process.

All good!  The extension I had made things too long so I couldn't even put the socket over the nut without hitting the radiator with the wrench

If you decide you're going to remove your timing case pull the radiator entirely.
No chance of damage and you can get the alternator pivot out easily.

Yep, will do if that ends up being the case (gosh I hope not)

So, I thought I'd catch everyone up over the past few months:

Code 31/33 is intermittent on KOER.  No KOEO or Continuous codes. Need to look at wiring back to EEC again for shorts and missing insulation at very rear of engine (its really hard to get to).

Put new ACC Carpet (Code 833, Ocean Blue) in

LMC door panels (painted with SEM to Dark Harbor Blue)

Installed Coverlay map pockets.

Replaced instrument cluster lens

Some pictures of the interior:

Set Radio EQ via app and USB key (FAT32). Much better now!  EQ was flat.  Raised bass and treble.

 

Replaced the rest of the rubber vacuum lines/fittings with silicone hoses (4mm ID).

Replaced fuel sender with LILAND GLOBAL SUFD36 after looking at the one purchased from RockAuto. (They look to be the same)  The existing sender went bad due to gas being inside the brass float.  I bent the arm slightly down so the gauge reads a little higher than the actual amount in the tank (to give more reserve).  It reads way past full, and doesn’t go down for a very long time.  After putting the sender in, I refilled the tank and got a strong odor of gas and noted gas on the top of the tank.  The ring wasn’t tightened all the way.  I bought the Spectra FG75A also - will try that one next.  

Bought the rest of the material necessary for painting rear portion of frame.

 

Looking good, Chris!

On the gas, I had trouble getting that ring to seal on Big Blue.  But with some lube and patience I finally got it and there's now no leak.  Good luck.  

But what radio do you have which allowed you to use an app to adjust it?  Jim and I have Sony radios that allow that, but yours looks like it is stock from this distance.

Your interior does look great, Chris!
Is that the printed speaker patch that Gary designed?

As for my Sony radio, I'm no fan of the app and had to uninstall it from my phone to keep my sanity.
... I'll admit to being technically challenged.  

I have a Lilland midship tank from RA.
Seems high quality.
** and it looks like I'll be getting a rear soon!
I just filled up and my truck is dripping!  
Its a pita with my receiver hitch but I'm in no position to pull the bed.