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Bad Oil Pressure Switch or Actual Low Oil Pressure? Please Help!

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Bad Oil Pressure Switch or Actual Low Oil Pressure? Please Help!

Old 07-07-2011, 11:08 AM
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1998Slow 'Stang
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Default Bad Oil Pressure Switch or Actual Low Oil Pressure? Please Help!

So, I've done a lot of searching on my problem here, with no one sharing the EXACT same symptoms as my car. I know the oil pressure switch on my 98 GT is just that, a switch, gauge reads low <6 psi and normal >6 PSI. But, when i'm driving its fine, then when I come to a stop with the AC on, the idle wants to drop low (550-650 RPM) instead of the 1000 RPM it normally idles at. That is going by the inaccurate stock Tach btw.

When the idle drops low like this, it feels like its going to stall and thats when the oil pressure "gauge" starts jumping bak and fourth between High and Low. Its like a fast flicker/bounce, not a slow/steady rise. I just changed the oil last week, put in Castrol GTX 5W-30 and ran seafoam in the oil before that. When I changed the seafoamed oil it had a little bit of black greasy chunks in it. Is it possible that one is stuck in the switch and not allowing for a good "reading?"

Its a manual btw, this is with the car in neutral and the clutch disengaged towards the last 5 MPh of a stop, and just after coming to a full stop.

This JUST started yesterday, never seen anything like this other than when it overheats (only happened twice, never got "hot enough" to crack the heads) This really has me worried, any help would be GREAT! I hope you could understand all that, seeing as how I'm typing this in more or less a state of panic.
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Old 07-07-2011, 01:37 PM
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It sounds as though the idle air control valve is not working as it should--also it is normal, and not good, to have the idle so low that the oil pressure "flickers".

To check the IAC disconnect the electrical connector with the engine hot and idling--the idle speed should drop, and perhaps stall--if it stays the same then the IAC is bad...
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Old 07-08-2011, 12:38 PM
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Thanks for the speedy response, it's been raining a lot down here, and I havent had a chance to drive anywhere to get the car warmed up. I'll test as soon as I can and probably be back with a deeper problem. Ha.......
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Old 07-08-2011, 09:04 PM
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Originally Posted by cliffyk View Post
It sounds as though the idle air control valve is not working as it should--also it is normal, and not good, to have the idle so low that the oil pressure "flickers".

To check the IAC disconnect the electrical connector with the engine hot and idling--the idle speed should drop, and perhaps stall--if it stays the same then the IAC is bad...
Well, took it out and got it really warmed up (donuts and a burnout in the Kmart parking lot ). Anyway, I pull the harness off the IAC and it stayed running.....like crap but it wouldnt die. So, now that we know that it is shot, would it hurt to spray it with some carb cleaner to delay buying a new one.....for the time being anyway. I don't have the money for one right now. (poor college student )
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Old 07-08-2011, 09:14 PM
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Originally Posted by 1998Slow 'Stang View Post
Well, took it out and got it really warmed up (donuts and a burnout in the Kmart parking lot ). Anyway, I pull the harness off the IAC and it stayed running.....like crap but it wouldnt die. So, now that we know that it is shot, would it hurt to spray it with some carb cleaner to delay buying a new one.....for the time being anyway. I don't have the money for one right now. (poor college student )
It won't hurt--however Ford makes it clear in the shop manual that:

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Old 07-08-2011, 11:32 PM
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Originally Posted by cliffyk View Post
It won't hurt--however Ford makes it clear in the shop manual that:

......Yeah, I'm aware, I've seen many of your other posts as well as Paladinmicro.com (your site?) Anywho, I don't see how it could hurt either. Will a house brand unit from the autoparts store of my choice, or should I look for a Motorcraft one (doesn't seem like the smart choice as that is OE to my understanding....which fails........easily)? Well, correct me if I'm wrong again. Thanks for your help Cliff
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Old 07-09-2011, 07:00 AM
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Originally Posted by 1998Slow 'Stang View Post
......Yeah, I'm aware, I've seen many of your other posts as well as Paladinmicro.com (your site?) Anywho, I don't see how it could hurt either. Will a house brand unit from the autoparts store of my choice, or should I look for a Motorcraft one (doesn't seem like the smart choice as that is OE to my understanding....which fails........easily)? Well, correct me if I'm wrong again. Thanks for your help Cliff
I said it won't hurt, it likely will not do any good either.

I have been running a Wells (Autozone) IAC for over two years and 43k miles with no problems. In fact as I said in another thread I have been using national chain replacement parts ever since there have been national chain store--I.e. over 30 years--and have never once (except for the real cheap bottom end plug wires) found them to be lacking in any way.

It is silly for those who do so to assert that Advance, Autozone, Pep Boys, etc. deliberately purchase and sell sub-standard parts so that they can **** off their customers--and how is that you suppose they have manage to survive and flourish for 30+ years doing that?

Additionally, most of the replacement parts they sell are made by OEM manufacturers--Wells, Dorman, Remy, Echlin, et al are all OEM suppliers (and rebuilders).
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Old 07-09-2011, 07:41 AM
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Originally Posted by cliffyk View Post
I said it won't hurt, it likely will not do any good either.
I didn't mean to sound like I didn't read your whole post their man, I saw, and I was agreeing. No hostility needed.

Thanks for the info though, I'll be going to my "FLAPS" for one asap
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Old 07-09-2011, 10:52 AM
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I didn't mean any hostility...
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Old 07-09-2011, 04:53 PM
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Originally Posted by cliffyk View Post
I didn't mean any hostility...
Must have misread your reply, my mistake man
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