Today i went by bills house and he fixed the low idle problem with the edge. He messed around with my PCM for a while trying to figure out why my engine would idle so low (low 400's) after being accelerated. He tryed a number of things until he put my stock tune back on my truck and found out that it had nothing to do with the edge. The engine idled low even with the stock tune. He popped the hood and took the air box off the trottle body and he found the culprit of all of our problems (people with edges that have low idle). It was a bunch of carbon build up in the throttle body. He took the throttle body off and cleaned it and the problem vanished. I was so happy and im sure alot of you guys with my problem will be to. All you have to do is unplug two wires from the throttle body and remove four 8mm screws. Get some carb cleaner and clean it up. It is a real quick fix. He told me that the PCM cannot adjust to the carbon build up after the edge erases the old tune and puts a new one in. So basically all you have to do to remedy the problem is to clean the carbon off your throttle body. Bill is sure a great guy. He took his evening to work on my truck while his wife and kids where home. Bill is one of the nicest and most intelligent person i have ever met. He took some pictures of my throttle body and he said he would post them soon and he can probably explain everything better then me. Sorry for such a long post i am just really happy!

Trent Kammerer

 

Bill Are You Busy? I Need Something Worked On If You Have Chance!

 

First, thanks to Trent for coming by and giving me an opportunity to finally nail down the cause of this issue. I have had complaints about this a couple times and am really pleased to find that it was very simple to resolve.

Now... You know, it's funny that we get so caught up in this age of computer and electronics that we forget some of the most basic mechanical concepts. Every once in a while I do that and I need a good healthy jolt to snap me back into reality. Today was one of those occasions!

In an effort to resolve a "Low Idle" issue, I had Trent bring his truck by so I could run through some test calibrations. I started by updating his unit to the latest versions and then programmed his truck. All worked smoothly as I would expect. (Bite your tongue ) Truck started and ran, but it seemed a tad rough on idle. A tap of the throttle and the idle would drop to around 400 RPM and then slowly climb back up to the 650 range. This was consistent and would do it in neutral, drive, a/c on, or a/c off. Strange...

I broke the cardinal rule of diagnostics by not immediately checking to see if the problem occurred when running stock and instead started making some changes to the calibration. Well, after several times of reprogramming the PCM with no luck, it finally hit me to program back to stock and see if it still ahd the problem. Lo' and behold, it did. You'd think that being a mechanic for as long as I had, I'd have known sooner. Well, the light bulb finally popped on and I popped the hood to check the throttle. You guessed it, it was a mess. Cleaned it up and all is well now.

I have now added a FAQ to the website pertaining to this issue. You can find it at

http://www.powerhungryperformance.com/faqs.htm#idle

Before...


After...


The following are also direct links to the hi-res images of the throttle body...

http://remote.powerhungryperformance...rty_clsd_1.jpg
http://remote.powerhungryperformance...rty_open_1.jpg
http://remote.powerhungryperformance...rty_edge_1.jpg
http://remote.powerhungryperformance...ean_clsd_1.jpg
http://remote.powerhungryperformance...ean_open_1.jpg

I won't repost the FAQ here, but rest assured it is a good read.

Hope this helps.

Bill

 

Tony... Call me. I'm up.

 

How many miles are on that T/B? Is it a 5.4 or 4.6? What year truck?

 

It is a '04 4.6L with something like 62K on the clock.

 

Yea, It is a 04' 4.6L with 63,300. Thanks so much bill!

 

Awesome Bill! You are a great help to this site and me!

 

For those of you out there that are slightly curious about the state of your throttle bodies' carbon build-up (I know that I was). Consider this: I have a 2005 4.6 with 48,000 miles on it. I thought, 'eh there probably isn't that much build-up on my throttle body.' But, my curiosity, (combined with an excessive amount of free time ) caused me to tear into things and see what it looked like. WOW, i was surprised! There was quite a bit of build-up on the throttle plate and the intake body. I did have an idle issue with my truck as well, however until reading this thread, I was convinced i could live with it. Welp, about an hour later, after a thorough cleaning, with the T/B reinstalled, i started the engine. PERFECT! idles strong, just like it should. Thanks guys for such an informative discussion on a simple problem that would have otherwise been overlooked by many!

 

04 ford van-5.4-troyer 93 tuning since day 1-exclusively sunoco or chevron fuel-75 k miles-amsoil pi evry 5 k miles-i had my tb off other day-looked nothing like this-i'd say tuning and fuels used had something to do with all your carbon buildup-phil

 

I fail to see what tuning and/or fuel would have to do with anything. The fuel injector sprays directly on top of the intake valves and vacuum would prevent any atomized fuel from traversing the intake manifold to any significant degree. And, unless the tuning in the truck is so bad that it is causes backfiring, again you’re going to be hard pressed to find a valid reason for it being the cause of buildup on the throttle. Fuel is definitely a consideration as far as valve buildup, but that is a whole other world of problems.

With that said, I have generally found this problem to be prevalent specifically to the 4.6L. A couple days ago I was going over an '04 5.4L with about 60K on the clock and it exhibited a fair amount of carbon buildup but it was nothing close to what I have seen on the 4.6L. The back of the 5.4L TB was comparatively quite clean with buildup only around the edge of the throttle plate. 20 minutes, a couple spritzes of carb cleaner, and the truck idled smoother and had a noticeable improvement in light throttle response.

The reason the 4.6L has such a problem has to do with the shape of the intake manifold and the location of the main vacuum port (which is located directly behind the throttle body). Any particulates (including oily residues) that may be drawn through the vacuum port, particularly at closed throttle when vacuum is very high, end up exiting the port and slamming directly onto the back of the throttle plate. That combined with any ultra-fine particulates that seep past the air filter can cause enough buildup to actually change the shape of the throttle bore causing rough or unstable idle.

Buildup used to be a much bigger problem back in the days of carburetors and TBI units because the fuel droplets would adhere to the throttle bore and throttle plates and then extremely small dirt particles would then stick to the fuel residues. Waaaaay back in the day, it used to be that we would do a throttle body cleaning any time we did a fuel injection service or tune-up. You can’t even begin to imagine some of buildup. Throttles so nasty that they would actually stick closed. Now with port fuel injection, fuel-based buildup is pretty much removed from the equation and throttles are much, much cleaner.

Fortunately, TBs are fairly easy to check. One clamp on the 4.6L or five 10mm bolts on a 5.4L. Grab a flashlight and give it a peek. The bore should be smooth, although it may be black. If you can open the throttle and feel a ridge or lip on the throttle bore, it's time for a good cleaning.

Enjoy.

Bill

 

I know this is an old post but thought I would bring it back. I think its good information. I too am having the low idle. I pulled the throttle body off to look at mine and it was scary. My tuck only has 37,500 miles and it was covered something terrible. I cleaned it and installed it back on. I will post back tomorrow if this corrected anything. That is of course when I get back from the morning fishing trip.

 

Don't apologize. It's good information and easily forgotten. Let us know what happens.

- Jack

 

Well I am thrilled to say that this has apparently solved my issue of the low idle I would get when coming to a stop. Glad I seen this thread because I gaurantee I would have ended up taking the edge off my truck. There is no way I would have ever guessed this was the problem. For anyone else having this type of issue with their edge. I would do this before any other diagnostics.

 

I've noticed idle in the 400s from downshifts, but not in park or neutral, but I bet it wouldn't hurt to take mine out and clean it, 04 5.4 with 76k. Whats the safest proceedures for this? Just carb cleaner and a cloth?