Hey all '86 F150 runs no different with or without SPOUT connector plugged. I'm wondering if the truck advances timing at all, cause it seems pretttty anemic at times. how would you recommend going at this one?

 

Do you have a timing light?

 

D'oh. Good idea - that'd confirm it for sure.

Since there's no change in the way it runs (w/ SPOUT or not), I'm thinking the PCM isn't interpreting it. It has a new ICM & PIP ***'y on it (despite an admittedly tired distributor shaft bearing)

 

Here's one way to diagnose this, as JimsRebel suggests.

1) Go for a short ride to get engine up to normal operating temperature.
2) Park truck, turn engine off.
3) Hook up timing light, disconnect SPOUT, and start truck.
4) Timing light aimed at timing marks should indicate 10 degrees BTD (or whatever advance is listed on your emissions sticker on the radiator shroud.
5) Have an assistant push gas pedal to raise RPMs up to 2000 or so.
6) Timing should not advance at all with SPOUT disconnected.
7) Turn off engine, connect SPOUT, turn engine back on again and check timing. It should be at basal setting (e.g. 10 degrees BTDC).
8) Have assistant increase RPMs to 2000 or so.
9) Timing should advance past 10 degrees when RPMs are increased.

Basically, if there is no advance of timing that concides with increased engine speed when the engine is warmed up, then the computer is not advancing timing like it should.

If so, then a good next thing to do would be to see what problem codes the computer is throwing out.

 

You need to pull the codes if it's true and the computer is not advancing the timing. It should give you a few codes that may point you in the right direction.

P.S. Is this a six cylinder engine with all the smog stuff ripped off it?

 

And here is a good general description of how to retrieve and interpret the computer codes. Your wires and socket for retrieving codes is probably on the passenger side fender in the engine compartment.

Fuel Injection Technical Library » How To Run a Self-Test

 

Galendor - (first, your truck is beautiful.) I wondered what that harness connector was! Geez. That makes sense now, why that's floating around in the engine bay I have the 4.9L with a Carter YFA-1 feedback carb, 1986. I think I'm good with how to pull the codes - this is rudimentary electronic stuff compared to other projects I've taken on. Toughest part will be testing how much patience there is, waiting for these flashes. OBDII is sooo much easier ...

Franklin2 - I hadn't even considered reading what the comp says. Dumb mistake. OBDII is a great tool in diagnosing; EEC IV could serve the same function. All the smog work seems to be intact - I had temporary bypassed vacuum lines in the past, trying to eliminate an intermitent "weak mode" the truck sometimes gets into. The problem was not vacuum related; most things are hooked up fine: EGR, TAB, TAD, but the hot air intake tubing & the choke air warmer tube have rotted off and now run nowhere.

 

You might get a serious trouble code, and that is why the computer has no control over the timing. Something like a code 18(if memory serves) is a serious code where the computer is not getting signals from the distributor module.

 

Wanted to thank you for the input on this matter. I'm curious to crack this problem once and for all; unfortunately I got sick over here and temperatures have majorly dropped, so the prospect of fiddling under that lovely big hood is not as appealing at this time I'll report back when there are new findings though - this truck will live on