5.0L General DiscussionThis section is for non-tech specific information pertaining to 5.0L Mustangs.
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Pulled the upper intake off, and replaced a bunch of vacuum lines. (PCV line, MAP sensor line, line coming off the front going to the charcoal canister, and all the other lines under the plenum) Replaced the small 90 degree line going into the charcoal canister, and while the upper was off and out of the way I replaced the two heater hoses and the small water hose that used to go through the EGR spacer. Now it just reconnects to the hard line on the lower intake, since I have the Accufab EGR delete spacer. Also while it was apart I replaced the PCV valve and grommet. The grommet had hardened and I doubt it was sealing really well.
The car had a small water leak at the thermostat housing so I took that apart and replaced the thermostat, and put a new gasket in it.
Well, I started it up, and it now idles a WHOLE lot better. Not sure what the culprit was since I fixed so many things at once, but at least it idles without dying now. It still surges every now and then, and will idle high for a few seconds, but not near as bad as before. It got so bad that it wouldn't idle unless I held the RPMs around 1000.
I'm thinking of replacing the MAP sensor, does anybody think that it might be at least contributing in a small way to the weird idle and surging issue?
Regarding the water leak, the housing was still leaking after I put it together, so I pulled that apart again and put another new gasket on it. (I don't think I had the thermostat seated properly) I put some Permatex on it to hold it all together, and I'll put it back on tomorrow.
All in all I'm happy again, now I can actually drive it again.
Foxbody experts, let me know what you think about if it's worth replacing the MAP sensor or not. I've read that they can contribute to idle issues.
run a koeo/koer test and it'll let you know if the map sensor is bad
Thanks. Since there's no check engine light, how does that work? Do you have to hook it up to a scanner? Sorry, been out of the fox game for a while.
I fixed the water leak. I made a stupid rookie mistake previously. I'm not a noob at wrenching, but it's been a while since I had anything to work on, so I keep making dumb mistakes! LOL
When I put permatex on the thermostat housing the first time, I went around the main large opening, but didn't put any around the bypass hole. This time I did it right, and it actually sealed. Duh.
I took it for a test drive today and it's running great. No water leaks, no stuttering on acceleration, and it idles fairly normal now. When it first fires up from being cold, it will rev high for a few seconds, then it drops down and idles great, no surging.
You can take the MAP sensor off and clean it out real good and see if that helps any. Otherwise just replace it. It's 28 years old. All of those sensors including the TPS will need to be replaced at some point. Some of the first things I replace on the old 5.0's is the TPS, MAP, temp sensor, spark plugs, wires, cap, rotor, 180* thermostat... you get the jist. Most of those things it sounds like you've already tended to. Most of those things are cheap fixes. You can also check the voltage coming out of your TPS to make sure it is adjusted correctly. You know there is an adjustment on it right? Gotta love it.
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