My idle went all wonky a couple of months ago....Nothing bad, it would just sit at 1100 or so in park after warming up. Unfortunately, my trusted multimeter up and died so I just left it as I only drive the car only once every couple of weeks or so now anyway. Fast forward to this week. Got a day off with NOTHING to do. Unhook battery, let sit, pull out IAC and clean it, clean throttle body (it was BAD. Lots of idle time), reinstall IAC, perform Proper base idle reset. Hooray! 850 in park, 780 in drive.
I walk away and 4 hours later, with the car stone cold, I start it up again. PERFECTION. Awesome.
Next day Leaving for work. 2:15 PM. Running like on startup. Bucking, cranky, cantankerous....
I had to give it a bit of gas to keep it from stalling from park into drive.... WTF?
I drive it to work. It's fine in traffic under a load and at a light in drive. I get to work and put her in park. Perfect idle.
Drive home is flawless after sitting for 8 1/2 hours with a perfect cold start (around 25 degrees faranheit that night). Next day same thing. Perfect.
Proof positive my car is cursed as I've been saying for years now.
So.....Anyone else have any intermittent anomalies that appear when there is no explanation other than voodoo or witchcraft?
short answer,, yes
you can pull codes or pull your hair out but chasing these problems like this have always lead me down the road of pointless hair pulling epesodes.
so....... i ignore most little things till something breaks. Broke stuff is easy to find.
Yeah mine would act similar to the point I was going to a carb with the 331 but I think I may have found the answer just prior to yanking the old 5.0...
I believe it was the PCV valve, as after the hose blew off and I then plugged the line, idle was better with a blown head gasket than than it had ever been prior... I may be all wet, but with new MAF, 30Lb inj and Eldebrock intake included with that 306 I bought I'm gonna try the EFI one more time... If I can't get a handle on it this time, I'll yank it all and go carb...
Something that reportedly helps a surging idle is reduce the IAC opening(make your own gasket), so if the ECM calls for max air, the idle won't go above a predetermined level...
BTW the PCV valves for smaller engines have less CFM than V8 types, I figure in my case if I still have problems I'll go with one that has less flow or maybe use open breathers...
How has it been since then? From that post, you had a bad idle when you went to work, and then two restarts that were okay. I'd definitely give the ECM a week or so of *varied* driving conditions and styles to accumulate the collection of false readings to ignore, as well as any other data storage it does.
I've owned 5 EFI 5.0's at this point, and they all have tended toward a higher idle when unloaded once they're warmed up. It seems to take anywhere from 1 to 5 minutes of just sitting there idling for it to come back down from 1000-1100 to 800 or so where it belongs. I chalk THAT one up to whatever routine is built into the software.
I don't know how these systems compare to modern EFI...all I do know is that my Crown Vic pretty much idled and ran like a new car, my '87 Grand Marquis I now have does the same. How refreshing. Why? Because it hasn't been modified yet. :) That's gotta be where you run into trouble. Someone that actually tunes a PROM for your ECM, and who knows the software well, can probably modify some parameters to make up for modifications done to the engine. We all know how terrible the throttle response is on an S.O. engine compared to, say, a Trick Flow top end setup with a 70mm throttle body. Very snappy. And so you basically turned up the gain on a (relatively speaking) overdamped control system. The engine responds slowly and surely to the inputs of open/closed IAC. Now, with high-flow everything, it makes a the same opening and the RPM jumps beyond anything it expected. It will learn to make more gentle, smaller adjustments because of the quick response, but until then it'll fall into a seemingly never-ending oscillating loop.
This is where you need someone who really knows the EEC-IV well, and I guarantee (well almost guarantee) that there will be parameters for seemingly trivial settings like "how quickly to ramp up the rate at which the IAC opens/closes". What Tom described is technically this, just a physical mod, not a computer parameter. Your mileage WILL vary, as they say.
My red cougar has the IAC unplugged. I do this because of the high idle, and because I don't really love the fact that on a cold startup, the engine zooms to 2 grand and sits there. I'd like it more gentle. Below 50 degrees, I have to sit there and help it idle for a couple minutes like it's freakin' carbureted. In the summer? Not a problem. Just starts and idles like a.....warmed up carbed car :hick:
At SOME POINT (lmao) I'll get that and the black car professionally tuned. I guess Mustang Magic on LI is supposed to do OBD-I Ford and do it well...?
every once in a while my car idles a bit funky. I always figured its cause I jumped the nss since the 94 up t-5's don't have a nss.
I've already put about 50 miles total on it since. Half of it was non-stop highway with light traffic where I could vary engine load and speed at will.
I had that happen a few years back. Cold startup would go high idle then come down to normal in a few seconds and then after driving for a while it would hang at 1200....
Nothing wrong then either.... Reset the idle and went away.....
Interesting..... I may look into that. I don't know if i'd trust cork or paper though. Maybe sandwich a piece of aluminum in there and measure up holes that would amount to half of the area of the originals in place. Put a stock gasket on each side of it for sealing. Done.
Owning a Mustang website has helped me contact wise down here. When you come down, tell him Paul from L.I. Stangs says hello.
I haven't seen him in a bit. I'll have to spin by.
Will do. By the way there are "IAC block-off plates" sold, I know someone makes an aluminum one, and they reduce the size of the opening. So no worrying about a gasket coming apart lol.
My car is erratic as hell. I figure its a lot due to its age and the fact I've changed a lot of things on it. I don't drive it in cold weather at all, but back when I did it would idle all over the place.
Car's been sitting in my driveway since this cold snap/shiznitty weather started right after the New Year. Snow, drop 20 degrees repeat......yay. It warmed up to a blistery 35 yesterday. Figured I'd start the cat up (if the battery wasn't dead). Cranked right up. High idle for about a minute. Settled right down to 750 and stayed there without me having to play with the throttle or anything.
Awesome.
Question but are you setting the idle with the stock digital tachometer? I found out it's way off. I set the idle on my Thunderbird with a tach/dwell meter to 750 rpm in park, hot idle. The factory tachometer has 5 bars illuminated at that engine speed (800-1000 rpm), with the 6th one sometimes coming on. Two separate tach/dwell meters verified the 750 rpm idle. You probably didn't do that but just a thought. BTW at that idle speed in park the engine in my Thunderbird makes right about 17" of vacuum. Not bad for the setup.
My Mark VII is having some odd idle issues in the cold. When started it will settle to a 700-750 rpm idle in park. Drive it around (idle in drive 625 rpm), warm the thing up, and then park the car and the idle wants to stay at 900 rpm, hot. Shut the car off and turn it back on and it goes to the normal 700 rpm idle. Blip the throttle and it sticks at 900 rpm again. It gets code 11 both with KOEO and KOER and has 18" of vacuum at the normal 700 rpm idle and almost 21 when it sticks at 900+rpm. Stupid car.
I just idle it down till it barely runs, then I plug the iac back in. no need to set it to a particular speed in my opinion.
Pulled the dash apart yesterday. My digital clock decided it didn't want to show me the time anymore and it was forever the same date. I put another in from my stash. Problem solved. While I was at it, I decided to pull my cluster as the turn signal indicators both went within a couple of days of one another. I pull the bulbs and they are both clearly burned out. I install new ones, button everything up, and go meet a few friends. They still don't work..... I decide I'll mess with it at some other time as all the exterior lights are working properly. On the way home the indicators worked.....
Haunted car...
They built '57 Plymouths in same factory(AKA Christine).... Yeah that's BS :hick:
Mostly shiznitty connections on the plugs to PC connections and socket to PC...
Dissemble it and use a pencil eraser to clean all connections, wipe lightly with electrical contact cleaner... For the sockets bend the contact arms slightly toward the foil trace to insure contact(be sure to clean traces)... Over the years the arms compress and/or dig a trough in the foil connection...
Tom, I rubbed the contacts with a microfiber and and bent the arms. It was just weird that they decided to not work for a drive and are now working. Just took her out to the store and back without issue.