throttle problems

94droptop · Feb 9, 2018

1999 b3000 with the flex engine. I have a few problems. I have replaced the IAC and it has newer motorcraft plugs and wires. First problem I have is sometimes when I am coming to a stop, disengage the clutch and coast the idle drops to 400-500rpms and the truck seems like it wants to die. even makes the oil pressure gauge flicker.
Second problem is if im running down the road, doesnt seem to matter what gear, if I let off the gas there is normally a 1 second delay before the engine actually stops pulling. Ive also had it where the engine will seem to keep pulling/maintaining speed up to 5 seconds after i have completely let off the throttle.

Changed the Iac, checked for vac leaks, getting ready to install a new pcv, fuel filter, and clean the throttle body. Ill report back with those.

melanie · Apr 6, 2018

What was the issue?

Sent from my iPhone using Tapatalk

rangerenthiusiast · Apr 7, 2018

I know this is almost definitely not the problem, but is it possible that your throttle cable and/or it’s bracket is binding up or bent?

cbxer55 · Apr 8, 2018

New IAC means absolutely nothing. My Ranger 3.0 eats them for lunch, especially the Made In Mejico POS parts from Vato Zone. And the NAPA parts are not much better, also made in Mejico POS parts. However, once I decided to get Vato Zone's premium IAC, made in Japan by Hitachi, haven't had another issue with them in over two years.

I've bought one, put it on, and taken it back the next day, defective. More than once. Same with the IAC on my Lightning. Took three of them, and buying the premium part, before I stopped having IAC issues.

rangerenthiusiast · Apr 9, 2018

cbxer55 said:
New IAC means absolutely nothing. My Ranger 3.0 eats them for lunch, especially the Made In Mejico POS parts from Vato Zone. And the NAPA parts are not much better, also made in Mejico POS parts. However, once I decided to get Vato Zone's premium IAC, made in Japan by Hitachi, haven't had another issue with them in over two years.

I've bought one, put it on, and taken it back the next day, defective. More than once. Same with the IAC on my Lightning. Took three of them, and buying the premium part, before I stopped having IAC issues.

I’m curious about several things here. First is how you managed to get a parts store to take an IAC back, since none of them (especially AutoZone and Advance) ever want to take back an electrical component for any reason.

Second is how you managed to determine that they were defective. A continuity test perhaps? I ask because I’ve been having a problem with a racing idle in my ’92 Ranger that’s proving difficult to diagnose. The MAF was replaced (for unrelated reasons) and the truck has had a racing idle since I bought it (anywhere between 1100 and 1700 RPMS). As a result, the auto trans also had to try to kick down through several gears at the last minute when coming to a stop. I unhooked the IAC for a few days, during which she idled much better (anywhere from 750-900 RPMS) and the gear kicking down issue stopped altogether. But after two days, the check engine light came on and once or twice, it almost sounded like she might stall.

In the meantime, I had ordered the Hitachi brand IAC from Advance for about $46. It was new, not rebuilt, and surprisingly enough, was made in the USA. Since hooking it up two days ago, the idle is now back up to around 1100 RPMs and never really drops below that, though it does bounce slightly. I can tell that it’s too high, but have no way to really judge if the IAC is defective. I would think that the computer would have adjusted to it by now, if it was going to. Any insights are appreciated.

Thanks.

cbxer55 · Apr 9, 2018

The ones from Vato Zone that are made in mejico have a one year warranty, correct? They didn't take them back, they exchanged them for new ones. When I went for the Hitachi part, they took it back and charged me for the extra money it costed.

I don't really know how to tell you to diagnose them. I just know that they cause a bad idle when they're going, and in the case of the Lightning, it causes a weird mooing sound, likely caused by the IAC being mounted on top of the supercharger, and the plenum it's mounted on acting like an echo chamber. And also, every time I changed one, the idle got better for awhile, before going to crap again.

When the original equipment IAC went out on my Lightning, the idle would fluctuate between 500 and 1200 rpm's. I put a new one in from Vato Zone, and it was okay for about one month, then started the fluctuating again along with the moo cow sound. Swapped it for a new one, it lasted about one week. Swapped it for the Hitachi part and it's been good for 8 years now.

The Hitachi parts may be made in the US. I was just assuming they were made in Japan since it is a Japanese company. I'll go look at the box in my garage later, I still have it.

rangerenthiusiast · Apr 9, 2018

Hey, cbxer.

I actually bought it from Advance Autoparts, but yeah, it has a one year warrantee. A little over half the price of Rotorcraft, which I would have preferred, but I have too many parts to replace on this truck and needed to save a few bucks.

If you’re curious, you can view them here: https://shop.advanceautoparts.com/p/hitachi-idle-air-control-valve-abv0033/10594937-P?searchTerm=IAC. Does this look like the one you bought? Because it doesn’t appear to be a premium model or anything, so maybe Hitachi makes different grades of the same part?

I never actually checked the box, but when I pulled the part out, it clearly had “Made in USA” stamped on it. My jaw dropped. A “woo-hoo!” may have also been uttered. lol

I’m still surprised that AZ did the exchanges without a whole lot of BS. Usually, once you buy an electrical part, they don’t want it coming back.

adsm08 · Apr 9, 2018

cbxer55 said:
New IAC means absolutely nothing. My Ranger 3.0 eats them for lunch, especially the Made In Mejico POS parts from Vato Zone. And the NAPA parts are not much better, also made in Mejico POS parts. However, once I decided to get Vato Zone's premium IAC, made in Japan by Hitachi, haven't had another issue with them in over two years.

I've bought one, put it on, and taken it back the next day, defective. More than once. Same with the IAC on my Lightning. Took three of them, and buying the premium part, before I stopped having IAC issues.

IACs create EMF. The good ones have a diode to keep it from getting back to the PCM. That's probably why you go through the cheap ones so quickly.

rangerenthiusiast · Apr 9, 2018

adsm08 said:
IACs create EMF. The good ones have a diode to keep it from getting back to the PCM. That's probably why you go through the cheap ones so quickly.

Greaaaaaaaaaaat. And how does one go about finding if there’s a diode in a given unit?

cbxer55 · Apr 9, 2018

adsm08 said:
IACs create EMF. The good ones have a diode to keep it from getting back to the PCM. That's probably why you go through the cheap ones so quickly.

That I didn't know, glad it's actually something worthwhile then. Wasn't real sure why the good ones are better than the bad, other than they seem to last longher for sure.

EMF. Electro Magnetic Frequency? Electro Magnetic Field? Google search says the latter.

cbxer55 · Apr 9, 2018

rangerenthiusiast said:
Hey, cbxer.

I actually bought it from Advance Autoparts, but yeah, it has a one year warrantee. A little over half the price of Rotorcraft, which I would have preferred, but I have too many parts to replace on this truck and needed to save a few bucks.

If you’re curious, you can view them here: https://shop.advanceautoparts.com/p/hitachi-idle-air-control-valve-abv0033/10594937-P?searchTerm=IAC. Does this look like the one you bought? Because it doesn’t appear to be a premium model or anything, so maybe Hitachi makes different grades of the same part?

I never actually checked the box, but when I pulled the part out, it clearly had “Made in USA” stamped on it. My jaw dropped. A “woo-hoo!” may have also been uttered. lol

I’m still surprised that AZ did the exchanges without a whole lot of BS. Usually, once you buy an electrical part, they don’t want it coming back.

Well, I mean if you bring it back for an exchange within the one year, what are they going to do? Tell you NO, **** off and die! I would hope not. All the ones I've had to exchange were pretty quick after the purchase, or previous exchange. And yes, I have had them go bad after the one year, to which I just tossed it in the round-open-top container and bought another. That gets old fast! :annoyed:

I will have to look at mine again. It's one of the few that I've put on and not had to pay any attention to for several years, amazingly. :shok:

cbxer55 · Apr 23, 2018

The IAC on my truck, a Hitachi premium part from Vato Zone, has a sticker on the top that says "Made In Japan".

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