2k pm burst on start...

Denisefwd93 · Nov 13, 2018

Now that it's cold out its back again do I need to go for a third IAC?
arrrg!..
everything else is fine it runs smooth the Ping stopped since I cleaned the MAF no codes since I had the oxygen sensor replaced etc. don't have a vacuum gauge yet but the new brake booster holds vacuum when engine is off for a while.

Denisefwd93 · Nov 13, 2018

Bump I really get tired of fixing things 2 and 3 times

Bgunner · Nov 13, 2018

Because this is a new thread could you be so kind to give us a rundown of the issue? I haven't read your old thread involving this and I'm sure others might not remember everything either.

From reading the headline I gather, when cold, as soon as she starts it jumps to 2k RPM's?

Denisefwd93 · Nov 13, 2018

Exactly what's happening, I'm on, I've actually lost count, how many times I've switched back to the original IAC, a new IAC, that I returned and picked up another which is on there now, I guess I'm going to have to get hitachi or motorcraft replacement,

Bgunner · Nov 13, 2018

Now are you sure this is not just the high idle? Does it come down after a period of time and act normal after?

My 3.0 hits about 1800 RPM high idle when started but drops back down after the engine warms for a short time. This is normal for an engine to do when the weather gets cold.

Denisefwd93 · Nov 13, 2018

I just don't actually know, but I don't think it's a good to rev an engine that high when it's cold, even though it drops right down after.

It bugs me that my other truck the 4.0 had the same advance Auto parts IAC and it never high revved on startup.

rangerenthiusiast · Nov 13, 2018

I had the same (or a very similar) problem. I have a thread on it here somewhere, with some suggestions that others left me, if you want to check it out.

Seems like a tremendous number of people with Rangers (and probably BIIs) on here have high initial idle issues. And I concur that the way mine was racing during warm up was definitely not normal or good for an engine. It was also doing it when it was warm out, so cold was not a factor. Replacing the original Motorcraft IAC with a Hitcachi one from Advance did diddly squat, so I’m not really sold on the IAC fix. Then again, others one here have stated that they went through 3 IAC units before landing on one that fixed the issue.

To me, it seems utterly bizarre that so many of any one part would fail time-and-time again right out of the box (unless they’re all coming from China, in which case, I’m surprised that any ever work). Similarly, I can’t begin to comprehend how all stock and aftermarket Ford pumps would whine, though ppl on here swear they do. I don’t get it. Anyway, sorry to ramble. Just wanted to let you know that you’re not the only one and that a Hitachi IAC isn’t a slam dunk.

My truck has been sitting in the garage all summer and fall, coming out only occasionally to be worked on (I can barely squeeze it in there because the structure is essentially a cinder block shed). Oddly, now that I’m not driving it around, there seems to be no idle issue anymore. Guaranteed, if I finish working on it and put it back on the road, the issue will return. Guaranteed.

Here are the threads I mentioned above, in case there is any advice from others there that’s helpful. As I remember, RonD had some good tips on troubleshooting:

https://therangerstation.com/forums/showthread.php?t=176685

https://therangerstation.com/forums/showthread.php?t=176156

Denisefwd93 · Nov 13, 2018

They are a very simple device it's just a solenoid with a slide that has a gasket that goes between two ports I know how to check them out with an ohm meter. When unplugged the idle drops. There is a lot of discussion about vacuum leaks under the manifold causing additional vacuum leak so I guess I need to get it vacuumed age but this truck runs really really good even better than the other one except for that scary high idle when it starts up

Vincenthdfan · Nov 14, 2018

Don't forget to check the inside of your throttle body for wear.

Everyone told me that couldn't cause it, but guess what...I changed mine and my problem went away.

Mine had a pronounced groove on one side which would allow butterfly to shift to that grooved side, allowing more air to bypass butterfly valve, resulting in faster than normal idle.

I did all the lower intake smoke checks etc prior to this fix looking for air leaks and found none.

I had the exact same 2,000 rpm rev when I replaced my IAC with an aftermarket one too...I re-installed my original motorcraft one and that problem went away as well.

Uncle Gump · Nov 14, 2018

Every ranger I've owned with a 4.0L has Flared RPMS on a cold start.

When I say Flare... It's momentary... about a second. Then it settles

I believe if you had a vacuum leak... idle RPMS would be high in general

I'm headed out later and will check to what RPM it Flares and settles

Uncle Gump · Nov 14, 2018

Sat two days with temps in the teens/20's...

Rolled over... fired up... 2k and started dropping immediately... settled at 1500... then went to 1100.

Bgunner · Nov 14, 2018

Denisefwd93, If yours does what Uncle Gump's does this is normal when cold. The ECU richens the mixture to help with starting, when cold, then leans it out as it warms up. Here in MA. when the temps stay low, single digits or below my ranger will hit the 1800ish rpm mark then level out at 1500 till warm enough, about 3-5 mins max, to drop to 1100 and eventually the 800ish warm idle. This happens to all vehicles, carburated and injected. This is basically the fuel injection system acting like a choke flap on a carburetor. Since there is no choke flap on an injected motor the system just adds more fuel to cause the rich mixture.

If you are worried about lubrication issues during the cold starts you can use the clear flooded mode. How to activate it can vary but one of these two ways will work:

1. turn key to the run position, push and hold the throttle to teh floor and crank. This will turn off the injectors but will allow the engine to crank to pump oil through the motor before starting.

2. push and hold the throttle to the floor then turn the key to the start position and let her crank.

My 94 3.0 motor requires the first to activate the clear flooded motor function.

Denisefwd93 · Nov 15, 2018

Yes I know about holding the pedal down to clear and crank. I can begrudgingly accept a high idle on startup, but I don't like it, and I'll never like it, it just goes against everything I was ever taught about reving cold engines!

2k pm burst on start...

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