LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

New tune up and now high idle

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Old Sep 26, 2012 | 08:38 AM
  #16  
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Re: New tune up and now high idle

New O2 sensor is already installed and there is no change really as far as the idle goes.
Old Sep 26, 2012 | 09:13 AM
  #17  
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Re: New tune up and now high idle

Do you have a way to get the codes?
Old Sep 26, 2012 | 10:11 AM
  #18  
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Re: New tune up and now high idle

I can take it to the garage, but thats 30 bucks a trip. I tried to jumper the connector for the code reader but I couldn't get it to work. I got a single flash from the MIL. Which I have heard that means the PCM is bad. If there is truth to that, I don't know for sure but that is just what I've heard.
Old Sep 26, 2012 | 02:08 PM
  #19  
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Re: New tune up and now high idle

Don't think that works on a 95 computer. If you have no other way to get them read for free, then for thirty bucks it is money well spent. You are really at a stand still and the code might solve it immediately!
Old Sep 26, 2012 | 02:51 PM
  #20  
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Re: New tune up and now high idle

oh I know its money well spent, I worked in a garage for years, but I'm just to the point to where it's starting to add up right now. I may just have to let it sit for a while until I can get back around to working on it. Nothing has changed since it first started. Even though I've replaced the parts that the original codes were from. So I'm just stabbing in the dark so to speak. Even with a code reader it's not helped so far. Its starting to get frustrating when you can't figure it out as I'm sure you all know.
Old Oct 3, 2012 | 02:59 PM
  #21  
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Re: New tune up and now high idle

Recent update. Ok so I have still been messing with this thing and I think I finally have found the idle problem. I pulled the CTS and replaced it. No change. Well I had a TPS that I had bought and I couldn't get to the screws. So I pulled the throttle body off and looked at it. It was a little nasty so I cleaned it up somewhat before putting the TPS on. I also noted that the gasket on the top of the throttle body was raised up a little bit. I had sprayed that gasket with carb cleaner trying to find the vacuum leak but didn't find one there. I pulled that top cap and the gasket had a small slit in it right behind one of the screws. I made myself a new gasket and reinstalled it. And would you know what? Its idling at about 800 now. So I'm thinking it was that little slit pulling in more air. Or at least thats what I'm going with. Now I was testing it on the road and of course it had to just die when I downshifted to turn around. I popped the clutch and it came back to life but it had that nice little MIL on again. I'm beginning to hate that red light. I guess I'm off to the garage to check codes again. BUt on the up side, the idle is fixed for now. Thanks guys for all your suggestions and help.
Old Oct 7, 2012 | 02:52 PM
  #22  
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Re: New tune up and now high idle

Well I thought I had the gremlins worked out of it. Now its got the "I'm going to throw an itermittent code" syndrome. Went and scanned it and no codes, drove it home and it was fine. Cranked it up to leave and engine immediately dies. Tried it again and it cranks but now has a code. Doesn't seem to affect the running. Idles like it should then runs fine. Drive it to the gas station. Fuel up and crank it again. No code. Runs great. Drove to my destination, then on the way home, it started to miss and cut out and threw a code. I was trying to get it to the next exit off the interstate. It decided to clear up but the code was still there. So I guess it's back to the garage in the morning to have it scanned AGAIN. It's one of the codes that will turn the fan on, so it does narrow it down a tiny bit at least. Any thoughts of what might be intermittent like this???
Old Oct 7, 2012 | 09:07 PM
  #23  
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Re: New tune up and now high idle

Not sure what codes don't get stored for a certain length of time. Assumed they all would show for a while even if the light went out.

Last edited by mrmint69; Oct 7, 2012 at 09:09 PM. Reason: spelling
Old Oct 8, 2012 | 05:32 AM
  #24  
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Re: New tune up and now high idle

No point in speculating really.

Perhaps it's time for you to invest in a scantool. It's something everyone should have. This is why.
Old Oct 8, 2012 | 12:52 PM
  #25  
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Re: New tune up and now high idle

Yeah, I used to work at a garage and had access to a scan tool. But the guy is gone now. Also, I never really had any problems out of the motor. This is the first problem I've had in the 6 years I've owned it. So a scan tool is on the horizon I believe. So I guess its off to the garage to pay for it now. I'll let you guys know what I find.
Old Oct 8, 2012 | 04:50 PM
  #26  
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Re: New tune up and now high idle

Scanning software is free. All you need is a cable.
Old Oct 10, 2012 | 10:21 AM
  #27  
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Re: New tune up and now high idle

Ok, Took the vehicle and had the codes read. Popped up a DTC36 High resolution pulse code. This is an itermittent problem. Didn't have the MIL on this morning when I left. Got to the garage and checked it. There it was. Cleared it and within about a minute of starting it, it showed back up. One other thing I noticed is now my radiator has a little leak and it had blown a little antifreeze up on the motor. Do you think these two are related by chance? Maybe the antifreeze is getting into one of the connections possibly and causing it to code? Or on the new distributor cap? Radiator is getting pulled and attempted to get fixed for sure.
Old Oct 10, 2012 | 02:12 PM
  #28  
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Re: New tune up and now high idle

Originally Posted by LT1Jeepin
Ok, Took the vehicle and had the codes read. Popped up a DTC36 High resolution pulse code. This is an itermittent problem. Didn't have the MIL on this morning when I left. Got to the garage and checked it. There it was. Cleared it and within about a minute of starting it, it showed back up. One other thing I noticed is now my radiator has a little leak and it had blown a little antifreeze up on the motor. Do you think these two are related by chance? Maybe the antifreeze is getting into one of the connections possibly and causing it to code? Or on the new distributor cap? Radiator is getting pulled and attempted to get fixed for sure.
A DTC36 isn't supposed to cause an engine shut down or erratic idle. I imagine it could have been caused when the engine dies and the PCM is expecting the his res signal.

The problem you describe could be caused by a messed up distributor cap...messed up as in soaked with antifreeeze. Unfortunately I can't think of an effective fix other than replacing the distributor cap. Antifreeze really does a number on the dielectric property of plastics....
Old Oct 11, 2012 | 02:53 PM
  #29  
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Re: New tune up and now high idle

It idles fine. Thats not the problem anymore. The problem is when its been run a little bit, and the you turn it off. You can crank it back up after a little while and it will die immediately. Thats when it throws the check engine light. After that it runs fine but it's got that code. Thats why I'm wondering if its the antifreeze from the radiator thats sprung a leak and dousing the cap maybe.
Old Oct 11, 2012 | 03:18 PM
  #30  
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Re: New tune up and now high idle

Originally Posted by LT1Jeepin
It idles fine. Thats not the problem anymore. The problem is when its been run a little bit, and the you turn it off. You can crank it back up after a little while and it will die immediately. Thats when it throws the check engine light. After that it runs fine but it's got that code. Thats why I'm wondering if its the antifreeze from the radiator thats sprung a leak and dousing the cap maybe.
LOL..reread my post. I said that the DTC isn't going to cause rough idle or engine shutdown. I did, in fact, realize that the idle situation was resolved.

As I stated, antifreeze messes with the dielectric properties of the plastic in the distributor cap. It is very possible that it could be the cause of your random shut down and difficulty restarting.

Try soaking the distributoer cap with WD-40 to displace the moisture to see if that helps. It may or may not. If it does the solution is to repalce the cap....



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