So the problem is on a 95 LT1 w 6 speed bone stock other then a K&N filter. Just days after picking it up she had the idle jump up to 1100-1200 & hold. 1st thought was a vac. leak & I did find a cracked connector that I replaced. But that didn't do anything for bringing the idle down. Next was going after the idle air motor. Sure enough it was totally bound up. So I order the new one. Yes, it's the P code car so it was the more expensive choice. Anyway, I replace the idle motor & sure enough I fire it up and it drops back to normal So I take it for a 20 minn. drive and everything is golden. I stop for fuel & make it about another 10minn I come to a stop and she's idling 9-1000. Next stop she's back @ 1100-1200 and holding
I love this car! & the last thing I wish to do is cause any damage digging into something I know nothing about. My 1st thought at this point is what ever that motor is controlling is gummed up & sticking.
So, am I correct that it could be dirty & sticking? If so whats the safe way to clean it out? If am wrong & there's nothing that can get hung up where should I look next?
Also, no the car does not run rough or feel down on power in any way, shape, or form. It just wont drop the idle into the normal range. Other then that it's running normal & has never had a code or warning lamp pop on.
Thank you in advance
Jeff

 

recheck the iac, see if its been fried again

 

Thank you for the reply. The 1st IAC that I pulled look to be the stock unit & the reason I called that one bad it because the plunger was frozen in place. This one is free and moves rather easy. How do you go about bench testing an IAC motor ?

 

there's some good tech info in the sticky's, and venders like mid america also have tips and testers.

 

If its a high mile car, the throttle body can wear out. The hole for the throttle shaft gets sloppy and the throttle blades dont get full return to idle.

 

Shes @ 70,XXX well cared for miles. Not sure if play or slop can be felt. But everything feels normal without any play. It's just odd to me that when the IAC was replaced she acted normal for around a half hour. I would think if it was throttle body the new IAC wouldn't have made a difference.

 

Check the throttle position sensor. It might have gone out of adjustment or is just bad.

Here is how you test it. You will have to get a multimeter and a set of terminal connectors. Basically, you push one of the flat connectors behind the connector and test the voltage. You can do it with the key in the ON position and the motor off. That way your not going WOT in neutral. .45 Volts to about 4.5 volts. Once you test closed to open with the car off, start it up and test it. Try to do it when the problem is occurring AND when the idle is normal if you can get it there. Play around with the throttle cable. Let it snap shut and even put a little pressure towards closed to see if you can get it idling correctly.

 

Thank You! I will be testing the TPS today.

 

You can not adjust the TPS on a 95.

 

this sounds like it.

Tap the throttle, and see if it idles down. If that doesnt work, go out and manually push the throttle body closed.

If this does not work, then its time to look at the IAC.

Mike

 

Very true, but that doesn't mean it can't go out of adjustment. It is adjusted during manufacturing, but sealed up after that. All it is is a variable resistor. All it takes is one section of the spool to get a little overheated. A tiny piece of dirt or lint contaminant on the conductor during manufacturing can cause a burn. That can change the whole dynamic of the coil.

 

Just an update. I wish I knew exactly what it was that was causing the high idle. But I pulled the IAC once again & shot the inside of the TB with a healthy dose of TB cleaner, let it dry for a few & reinstalled the IAC. Fired it up & she returned to a normal idle. So I filled the tank along with adding some injector cleaner & hit the interstate. Set the cruse at 75 mph and relaxed for about 1.5 hours. Pulled off for a rest and THANK GOODNESS shes good as new. Only I just wish I knew just what it was that caused the problem to start with.
Thank you everyone!

 

bad gas?

 

I hear ya, problems that "disappear" make me just a little nervous, especially an intermittent. For what it's worth, you can check whether the TB is leaking air if and when the problem recurs- remove the air inlet and seal off the two bores ONLY, not the IAC passage. The idle should be normal. If you then remove the tape , or whatever you used, the idle should not change. If it does, the bores are leaking. (But, this is not likely on a 70K mile car.) You may have a vaccuum leak caused by a loose or slightly cracked hose that only leaks when in a certain position. With the car idling, touch all the vaccuum hoses lightly, see if you can cause the idle to change.

 

I don't think it was bad fuel. The problem that started this whole thing was a frozen IAC. Only once I changed out the bad unit the symptom returned. Personally, I think what ever valve system the IAC is controlling was dirty & sticking.

 

Thanks for the tips. I truly do fear problems that go away & still leave me wondering just what it was in the 1st place. I drive my cars for a living & the last thing I want is a gremlin just waiting too strike 200 miles out in the middle of nowhere.
I put the update in when I was at the half way point of tonight's drive. I figured if I was going to get results from a fuel system cleaner I better go for a drive. So I went to Tulsa for dinner. Jumped on the interstate, set the cruise around 75-80, & logged about 240 interstate miles. So far it's perfect. But I am using it for work tomorrow & that will be the true test. I have just shy of 600 miles up & down the eastern OK AR border. Basically running the twisty back roads in the foothills of the Ozark mountains down to the Texas border @ 300 miles & making a u-turn. So my fingers are crossed it's an issue free day.

 

MAP sensor?
I don't think the intake temp sensor could cause this kind of thing. The again, it could still be that the intake valve was getting stuck open. Something just got in the way.

 

So yesterday was 600 miles & today another 300 and shes running like it should. Thank Goodness & thank you all for the input/help.

 

I know you think you've fixed it with TB cleaner, but once the lube properties of it (the cleaner) wear off, you might be back to the high idle again. If it "kicks down", like an older carbed engine, then that's the problem. I'm shooting the inside pivot points with white grease every other month on my '96 until I feel flush enough to spring for a new or rebuilt TB.

 

Thank you, I will hit the TB with some lube since I cleaned it. Only I am not exactly (high) miles yet @ 70,XXX. So I don't think it was anything in that part of the TB.
Yes, I pulled the intake tube and cleaned inside the TB early on before going after the IAC. But it was when I pulled the new IAC and cleaned inside that part of the TB that it cleared up. I think it was gummed up hard where the IAC seats & that burned out the factory unit. She spent more time sitting then anything with the PO. I was looking over the records & found that I have driven more miles in the last 2 days then it had seen since 2009. So thing where bound to be a bit sticky from sitting.