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Discussion Starter · #1 ·
Wondering if anyone else has this happen. When I'm driving my 2004 Mustang 4.6L and have the RPM above 2600, if I engage the clutch and don't downshift before the RPM's drop down, the engine will kill. Say I'm leaving the interstate and my cars @ 3000 RPM, if I was to hold the clutch in, the car will kill. If I downshift right away (normally I do) it does just fine. Its been this way ever since i've had the car, and learned to deal with it, but sometimes it catches me off guard. I've never had this happen to any other manual car I've driven.
Is this normal for the 4.6L?:scratchchin
 

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Have you replaced or at least cleaned the IAC? I'm surprised you've learned to live with all this time. You may want to clean the MAF while you're at it. Check all connections at the MAF, IAC, TPS and everything else. But I have a sneaky suspicion a new IAC will take care of it.
 

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Discussion Starter · #3 ·
do you think that might relate to hard starting say, I stop and get gas, then start up and engine struggles a bit to get going? I only have 23K on the motor/car, so these problems seem odd.
 

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Possibly, one thing for sure is you definitely have a problem. Are you throwing any codes?
 

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Discussion Starter · #5 ·
You know, I just ordered an SCT X3 tuner this past week and should have it soon. I thought I would try running a diagnostics test with it. My Check engine light isn't on or anything.I will ckeck the IAC and MAF in the meantime. It sure would be nice to get rid of that damn stall. I sure have sharpened my shifting techniques though.
 

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you can run diagnostics with nothing in the car. ford built a system into the car so that you can figure it out. give me a second to find the link that shows you how to do it. it also does a lot of cool stuff with your odometer like a digital tach, mph, kph, voltage, oil pressure etc...
 

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Discussion Starter · #10 ·
That is too sweet. Ford rocks just because of that feature, and I never knew it existed before your info. Thanks:bigthumbsup I checked the engine diagnostic code and it said NONE. If I can get a chance to drive it today, maybe I'll leave at the diagnostic feature and let the car do it's stall thing. Maybe a code will pop up then.
I did just all wiring harness and the IAC and MAF, and all looked good. Proper voltage present at each. Car still stalls unfortunately.
 

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Discussion Starter · #12 ·
After checking through the connections and sensor last night, the only things I noticed was the water exit tubes from my shaker hood were routed very poorly. The place that installed it ran them so the water pretty much dumped/exited on top of some wiring harnesses in a couple spots, so I rerouted those, just to prevent possible future damage. I ran that diagnostic code reading on the Gage today, but couldn't get my car to stall. I thought tightening the loose intake tubing might have fixed it, but that seemed way to easy. Anyways,
Later today, I was going down a hill, the rpm's were at 2600, so I pushed and held the clutch in (to see if it would stall out, but wouldn't normally do this). The rpms dropped (like they should) but kept going down till the engine died. There were not any engine codes that came up unfortunatly, so I'm still stumped.
Is there anything else you guys think it could be, and anything I should be watching for on the digital gauge menus?
P.S. Sorry for the long comments, but just want to give you all I know about the problem:D
 

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You didn't say if you cleaned or replaced the IAC. I don't think a bad IAC is going to throw a code. Pull it out and spray the crap out it with brake cleaner. Drive it as you normally would and see if it still cuts out. Cleaning will get some extra mileage out it but you'll eventually have to replace it.
 

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Discussion Starter · #14 ·
I did detach the IAC but I read in this mustang manual I have to be careful of spraying anything in it, because it is and electrical component. Brake clean does dry fast so I wouldn't think it could hurt anything, since its not connected while cleaning it. Now I wish I would have sprayed it with cleaner (like you said to start with) since its a real pain in the ass to get at with the shaker hood. Oh well, You think I should really flush that sucker out though huh?
 

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Discussion Starter · #16 ·
Today I removed the IAC valve and cleaned it out. The IAC didn't have much build-up in the valve body or the spool, but it does look cleaner now. I took the car out for a test drive and unfortunately it still does the same thing. I got going down a hill and was in 3rd gear @ 2600rpm, pushed the clutch in and shifted to 4th, but left the clutch in to see if the engine would die, and it did. Its almost like it pauses at 500rpm for a split second, and then drops down to zero. The car has very low miles and everything i've removed so far has looked pretty clean. Do you guys have any other ideas what this might be? Maybe a computer issue?
 

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Discussion Starter · #17 ·
Thanks you guys for all the help..You definitely got me further than I would have gotten. I originally was going to post this under the 4.6L tech section but goofed up, so I 'm going to start a new there, since it is more of a technical support problem. If you have any other suggestions, please leave them under the new post.
Thanks Again Guys:)
 

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Discussion Starter · #18 ·
gnats02 , I still haven't figured anything out. I've been researching this on my own as well but just can't quite pi it down. I can seem to prevent it from happening though. The one other thing I was think (if not a defective IAC) is the EGR. I read that a certain flow through this valve can cause the engine to stall.
 

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Discussion Starter · #19 ·
Today my car displayed the dtc code 5284. Any ideas if this might be part of the problem?
 
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