I'd start looking for vacuum leaks. Or one big one. You might have to pull the intake and check the gaskets.
2004 mustang throwing 8 different codes accelerates on its own and high idle
I bought this 2004 3.9 mustang automatic about a month ago. When I bought it, the car would have trouble stopping. When I slowed down to a stop it would jump up in rpm’s and try to accelerate before coming to a stop. Recently the car had started revving itself up to 3500-4000 in park and staying there. When thrown in drive or reverse the car starts to accelerate on its own and I’m barely able to stop it. Ran the codes and I’m getting P0161, P0135, P0141, P0155 (all O2 sensors), P0507, P0443, P0446, and P0403. I have already replaced the IAC and cleaned the throttle body after purchasing the car. I’m hoping one or two things are causing the others to throw codes because I’m not trying to replace every single sensor on this thing right away. Anybody had anything similar
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I’ve checked some vacuum lines and they seems fine from what I can tell. The #8 fuse was blown throwing all the codes. I replaced it and still the high idle. The weird part is that when I disconnect the battery, the high idle fixes itself for a moment but then right back to the high idle almost telling me it’s a sensor issue. Also explaining the blown fuse. Just don’t know whatI'd start looking for vacuum leaks. Or one big one. You might have to pull the intake and check the gaskets.
Check the egr valve and for vacuum leaks ,, a cheap old way to check for vacuum leaks is buy a cigar blow a good puff of smoke into a hose I’d start at a hose by the intake and watch for the cigar smoke to leak out you might need to try from different spots / vacuum hoses but if there’s a leak you’ll see it ..
Just in case engine not running when using the cigar idea for vacuum leak check … I’m not trying to insult you , I bet you knew that but there are some out there who don’t ..
Nah you good, I have it running when checking for any vacuum leaks lol. I’ll have to try the cigar idea I know you can smoke test it with a kit but it’s kinda pricey. But do you think a vacuum leak could cause THAT high idle. I’ve had vacuum leaks on many other vehicles and it just causes it to idle 1500-2000Just in case engine not running when using the cigar idea for vacuum leak check … I’m not trying to insult you , I bet you knew that but there are some out there who don’t ..
Idle air control , sometimes they need resetting there’s a process on it too or it will make the car idle higher if not set or properly functioning I know this I went through it .. was a pain in the ass… if you have a decent scan tool it will show current idle Rpm’s and the (remedes) it’s the idle speed the cars pcm has set it’s usually 700-900 rpm range but may very on the vehicle. The idle air if not functioning properly will cause higher rpm like 1200-1500 rpm . And the scan tool can show the values of the idle air & if it’s not set or not functioning it can mess up the idle.. my car idled at 1250 but it threw a code for the idle air so I knew the problem. Try unplugging the idle air when running see if the idle drops to almost a stall or around 450 rpm’s it can tell you if it’s working or not .
There’s information out there on resetting the idle air id do a search or look on YouTube for it there’s a few videos out on it .. Hope this helps you I had to do quite a bit of research myself but it ended up working with my cars situation..
Thanks! I put a new one on it a couple weeks ago. Just tried it and unplugging the IAC did bring down the idle lower to like 1000. How do you reset itIdle air control , sometimes they need resetting there’s a process on it too or it will make the car idle higher if not set or properly functioning I know this I went through it .. was a pain in the ass… if you have a decent scan tool it will show current idle Rpm’s and the (remedes) it’s the idle speed the cars pcm has set it’s usually 700-900 rpm range but may very on the vehicle. The idle air if not functioning properly will cause higher rpm like 1200-1500 rpm . And the scan tool can show the values of the idle air & if it’s not set or not functioning it can mess up the idle.. my car idled at 1250 but it threw a code for the idle air so I knew the problem. Try unplugging the idle air when running see if the idle drops to almost a stall or around 450 rpm’s it can tell you if it’s working or not .
Okay thanks!!There’s information out there on resetting the idle air id do a search or look on YouTube for it there’s a few videos out on it .. Hope this helps you I had to do quite a bit of research myself but it ended up working with my cars situation..
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