You may need to replace your IAC valve.

 

So after re-tracing my steps for 5 hours yesterday afternoon, checking for cracks in vacuum lines, hunting for leaks in the intake manifold, etc, I finally gave up and just decided to drive the truck around to see if it would throw a code. I backed out the driveway with the truck shuddering like it was about to die (and yes, this is after the new plugs + new coils), I put it in gear and drove 2 blocks to a buddy's house to return a tool. Halfway there, I get a wild hair and just decide to go to WOT for a second or 2 to see if I could feel it missing. I go one block and pull up to a stoplight...I have my hand on the shifter thinking I'm going to have to throw it in N to keep it running...but it seemed to be running fine....I go another short block and hit another stop sign, I'm prepared to throw it in N again, but again, it's running fine. I drive the rest of the way to my buddy's house ,and sure enough, when I get there and put the truck in park, it's purring like a kitten! It's running as smooth as it did when new! All I can think of is that maybe I had some dirt in an injector causing the injector to not spray correctly, and when I went to WOT, the increase in fuel pressure and the longer pulse-width perhaps pushed out the dirt?!?!?!? does this seem plausible?? Because, otherwise, I have no real explanation as to how it 'cured' itself.

Thanks
Mark

 

I'm thinking maybe something was in the cylinders after the plug change maybe a piece of carbon and when you went to WOT it blew it out.

Denny

 

Definitely could have been a sticky injector... or like Denny said, a piece of carbon stuck under a valve. Or a valve sticking in it's guide.

 

Actually, it was running poorly both before and after the plug change, so the plug change had nothing to do with it.

 

I'm leaning toward dirty/sticky injector....looks like it's time to run some injector cleaner through the system

 

My brother has a 1999 F350 SD tow truck that had troubles like these. He chose to ignore it until he couldn't use the truck to tow anymore, then bought another 2003 SD with a 7.3 diesel which made him so happy he parked his '99 like an ugly prom date and forgot her. That worked just fine till he rolled the '03 about 6 times driving too fast into a tropical storm last month. About all that survived were him (barely), the diesel, the tranny, and the lift. And the insurance folk have tied his hands processing his claim for a month now, so rather than have the '99 serviced properly, he just had an engine swap done with an '03 V10 engine. Problem solved! Did I mention he whacked his head a bit? XD

So, he asks me to remove the older V10 from the '99 SD truck's bed so he can put his lift back in it and wants me to take it to a rebuilder who'd offered him $250 for it. And because no good deed ever goes unpunished, the rebuilder changed their mind and decided they'd prefer to take it for free. My 1st inclination was to drop it off the tailgate onto his foot. My 2nd inclination was to have my nephews strip the aluminum and scrap it out. But that seems such a waste, and so my 3rd inclination is grabbing hold of me now, and it feels like it could be an expensive one and a HUGE time-suck.

You see, I've not been able to drive my '71 F100 for a good while now and, while I'd been thinking of rebuilding its 390 again (3rd times the charm?), I got to thinking about all that torque goodness of that Triton and wondering what misery it would be to try to shove it where it ought not to go! And I got to wondering about trying to rebuild this beastie. Mind you I've not done an engine swap or even a tune-up, myself, in 15 years.

I don't know what's got into me, into your V10, or into my brother's, but I need to get that beast off the tailgate of my GMC, and I've half a notion of putting it on an engine stand. So, yeah, I *KNOW* I'm absolutely nuts. So, won't you all just please stand in line and share your thoughts with me on just HOW nuts I am? And let me just say neither my rebuild nor my F100 restoration needs to be done in a hurry. I'm convalescing from a long illness, and have nothing but time and foolish thinking and computing to use it up.

What do y'all think I should do? Should I let the nephews have the Triton to take to the tin man? Should I put it on my cob-webbed engine stand? Should I drop the Triton in my brother's front lawn and put my 390 on my engine stand instead? Should I get my head examined, or what? And what might I read to try to regain some shreds of sanity? I don't know why NOW seems the time to take on a few huge projects like this at the same time, but something tells me that FrankenFord must LIVE! XD

Come On, I'm waitin'... Lemme have it! Please SOMEONE talk sense to me!