Plugs, Cap, Rotor, Wires replaced, truck really liked the plugs as stated above! But we are not out of the woods yet.
Timing, I checked the timing with the SPOUT disconnected, it is about 9 degrees BTDC, I left it there. After reading that the pulley can turn on the harmonic balancer, I took a lot of time to verify that the timing mark was correct. I verified that it was on the compression stroke on #1. I used a small wooden dowel, marking it with a pencil, while turning the crank with a wrench, there seems to be about 4 degrees at the top where the piston does not move much at all. I feel that the timing mark is properly oriented to #1 TDC.

So, I then looked at the timing with the SPOUT connector installed, and at warm idle, the timing moves around a lot, jumping back and forth, the engine is idling well, about 675 RPM (truck tach). There might be an intermittent miss, but with the timing jumping around like that, I am not surprised. If I throttle up to maybe 800 RPM, the timing really smooths out, and holds steady. It is interesting, not like vacuum controlled distributor advance.
I was curious, so I checked the TPS voltage and it was 1.07VDC, so I loosened the screws, and moved it a little (thats all it would go) and it has a range of 1.02 to 1.07 VDC, I left it at 1.02.
Reading around on the forums, I see that some people say that it should be down in the 0.8 VDC range at throttle closed idle, Thoughts, Comments? I am the original owner of this truck, and the throttle stop screw has never been touched. I inspected the throttle body, and the throttle plates seem to be about perfectly closed when the throttle is on the stop screw,

It still has the famous stumble on opening the throttle off idle, I have considered the EGR washer with the 1/8th hole in it, or the restrictor plate with the 1/8" hole in it.. comments appreciated.

I am also Planning the exhaust gasket repair, even though the leak does not show itself with the engine not under load (I need a dyno)(or automatic transmission).
With the exhaust gasket will be all new intake gaskets, and clean the intake manifold, throttle body, etc. Injectors still a question, I like the idea of the newer ones with the 4 holes, just not sure which ones to get.. I hear the originals are Bosch. Any suggestions on a specific part number, or place to get them?

Thank you

 

Don't worry about the exact TPS setting. As long as it's near 1.0 volt and goes steadily up through the range of motion, it's fine.

I sourced my injectors from the junkyard off a '95 4.9. I just gave them an external cleaning and inspection, deeming them good to go as-is. Just looking on-line it looks like the Ford part# is F1ZE-B4C; Bosch part# is 10465 or 822-11112.

 

When Vinny and others were helping me, I just put a penny (had read about it) in the EGR hole. Easy to do and blocked it perfectly. Got everything going good and decided to remove it which I did with no ill effects. Some just leave it. On the timing, with the spout out mine is set at the large notch 10* BTDC. That is what is recommended. I know some run theirs up to 14*. If you didn't loosen the distributor you might do that and see if you can adjust it to what it likes and eliminate the stumble??? That will be base timing. When you put the spout back it will move as it is then computer controlled. Sandy

 

Unless I'm remembering incorrectly, the EGR shouldn't be opening during that phase. It should only be opening at a cruise throttle setting.

start the truck and goose the throttle with your hand (in Park), and see if the EGR valve is opening when you apply throttle. You'll quickly be able to see if that's your problem.

Part 4 -How to Test the Ford EGR Valve EGR Vacuum Solenoid, DPFE Sensor - Troubleshooting guide for EGR system

 

Brad:
Thank you for that information, and numbers, and advice, I appreciate it.
Rob

 

Sandy:
Thank you for the reply, the Penny is a good Idea, I was/am confused and blurted out too quickly about the EGR, as LATECH says, and we all know, the EGR does not open at idle, or even when just starting out, it opens later while mid throttle in 5th gear and causes problems then,,,
I will try advancing the timing for the base timing, the computer really runs that timing all around, and pretty far advanced for no load on the engine, I saw up to 26 plus degrees BTDC, with just me playing with it, but I will try advancing.
This problem I am having can be described in carburetor terms like the accelerator pump is not working, when the throttle is opened from idle, the engine just sort of boggs, then takes off OK. I put a vacuum gauge on the manifold tonight, and opening the throttle from idle, the vacuum drops way off, like 22 to 10, and the engine boggs, then as soon as the vacuum has recovered, the engine runs fine.
Rob

 

latechbanjo: Your memory is fine, the EGR does not open at idle, or even just above, I must had a brain fart...I put a vacuum gauge on the EGR tonight, and revved the engine, the gauge bounced a little, like possible the solenoid may be leaking, but it did not seem like it was enough to open the EGR valve. I also tried revving with the EGR disconnected, no difference on the bogg/stumble. As I told Sandy above, it could be described in carburetor terms as the accelerator pump not working, goose it, engine boggs, then it "catches up" and away we go. Any idea when/how the AIR system is supposed to route/waste air? It seems to be routing air even during idle, but maybe supposed to be, seems to run better with AIR system off...
Thank you, Rob

 

My EGR Solenoid did have a vacuum leak in it. Not sure how much trouble it caused, but replaced it anyway. The AIR systems vary with model. My 1994 4.9 doesn't have a TAD, and the secondary air is dumped straight in to the exhaust.

When I first bought my truck, the stumble was noticeable. I seem to remember a few vacuum leaks in odd places that cleared it up a bit. My guesses with a stumble are going to be timing, vacuum leaks, TPS, fuel pressure, MAP.

I know you said there was no CEL, but have you checked for stored codes in the ECM?

 

latechbanjo:
Good Call, weird, now I have a code 114, ACT our of range, Perfect, that's easy, we'll see if that helps!!
Problem is, where the heck can I get a Motorcraft IAT sensor these days?

Thank you

 

Did you warm up the engine before running the KOEO tests and stored code (CM) display?

If not, you triggered a false error code.

 

rla2005:
It was warm, but not freshly warm, after arriving home, I went inside, had some food, etc, then went back out and pulled the codes, the engine was warm, but I guess the intake manifold was cold already, we are below freezing now, I tried again tonight with the engine cold, and got both IAT, and ECT codes, RATS, I knew that was too easy. Thank you for pointing that out.
You guys are great, you keep me on my toes, and make me think. Thank you.
I am reading the Ford Fuel Injection & Electronic Engine Control Book, by Charles Probst... I hope to be helping to give answers someday. In the meantime, I am learning a lot from the truck, you guys, and the book. I do feel my truck needs new exhaust gaskets because of a tick tick tick on acceleration or under heavy load. I am working on clearing a place large enough in my shop to get the truck in. Maybe while I am doing the gasket project, I will repair some crazy vacuum leaks, or find something else.
In the meantime I will post anything that comes along.
Thanks again.