86 with very high idle
Thread Starter
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
86 with very high idle
This problem relates to my dad's 86 LPE 383. It likes to idle at 1400->1900 RPM most of the time and will occasionally drop down to 8-900. It is also prone to stalling when taking off from a stop. It takes some careful clutch work to get it moving. It is not chuckin' codes and seems to run OK otherwise.
I've followed the manual in setting the minimum idle. The TPS is set correctly. It has new plugs, wires(found a burnt one), cap and rotor. The TB is a new ASM 58mm so it is clean.
Anyone got any ideas on where to start looking?
Thanks!
Dale
I've followed the manual in setting the minimum idle. The TPS is set correctly. It has new plugs, wires(found a burnt one), cap and rotor. The TB is a new ASM 58mm so it is clean.
Anyone got any ideas on where to start looking?
Thanks!
Dale
Racer
Joined: Jun 2002
Posts: 411
Likes: 0
From: Palm City FL
Re: 86 with very high idle (Professor)
My 86 had a similiar problem. It turned out to be a cracked vacuum line on
the EGR valve. The car would only idle high when the computer told the EGR to open...
Good luck!
the EGR valve. The car would only idle high when the computer told the EGR to open...
Good luck!
Drifting
Joined: May 2001
Posts: 1,295
Likes: 2
From: Surprise Arizona
Re: 86 with very high idle (Professor)
Vacuum leaks. Look for vacuum leaks. Hoses, gaskets, intake manifold to head, etc. That is the first thing to look for if you have an unexplained high idle. One way is to go around the gaskets with a propane torch. When the propane gets sucked in the idle will change. Just be careful not to blow yourself up! The other (hillbilly) method is with a water hose. When the water gets sucked in the idle will change. Safer for you. Just dont let it suck in to much water. Once you find and fix the leak re check the TPS adjustment.
Somone else may have a high tech way but those two have worked for me.
Somone else may have a high tech way but those two have worked for me.
Heel & Toe
Joined: Jun 2003
Posts: 23
Likes: 0
From: Columbus MS
Re: 86 with very high idle (First C4)
I don't know with a 383, but my guess is it should be around 6-700. Another thought is that you're delivering too much fuel. I've had a very similar situation and had to switch to smaller injectors. Do the spark plugs had abnormal carbon build-up, if so I might check into that.
Thread Starter
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
Re: 86 with very high idle (Twanster2000)
I found a broken rubber vac line running near the evap can. It is fixed but I have not had a chance to test out the car. I should now by tonight.
All of the plugs looked consistent and normal.
When setting the minimum idle via the book method, I was only able to get it down to 650 or so, any lower and it wouldn't run.
I'll report back in a few hours. :cheers:
Thanks!
All of the plugs looked consistent and normal.
When setting the minimum idle via the book method, I was only able to get it down to 650 or so, any lower and it wouldn't run.
I'll report back in a few hours. :cheers:
Thanks!
Melting Slicks
Joined: Jul 2003
Posts: 2,384
Likes: 124
From: Reno/Sparks Nevada
Re: 86 with very high idle (Professor)
My '85 was surging recently and the idle was erratic, sometimes it would idle right. Checked my TPS and it was set a .54 volts. Left the digital meter on while idling and noticed the voltage fluctuating between .54 and .90 +. I replaced the TPS tonight and it seems to be idling at around 6200 in neutral and in the low 5000s when in gear. Try checking the TPS voltage while the engine is running. It was $33 for a new one.
:cool:
:cool:
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Thread Starter
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
Re: 86 with very high idle (First C4)
Well the car is running a bit better with the vac line repaired. It is a bit easier to launch and the idle will occasionally drop down to normal. We need to go over the rest of the vac system and then look at the gaskets.
The TPS might also need attention, I will take a look at the output while running once to see if it is acting funky.
Unfortunately, we cannot get to it right away due to problems with a different car :mad
Thanks for the help so far! I'll report back when I can.
Dale
The TPS might also need attention, I will take a look at the output while running once to see if it is acting funky.
Unfortunately, we cannot get to it right away due to problems with a different car :mad
Thanks for the help so far! I'll report back when I can.
Dale
Advanced
Joined: Sep 2003
Posts: 50
Likes: 0
From: Tinley Park IL
Re: 86 with very high idle (MrRenoman)
it seems to be idling at around 6200 in neutral and in the low 5000s when in gear.
:cool: [/QUOTE]
Now that's a real high idle.
The book says to adjust the idle to 400-450 with the IAC disconnected. I adjusted down to 500. Then reconnect IAC with ign off, the result was an idle of 800-700 and an in gear idle of 600-500. I may readjust the idle again tomorrow. TPS should be near .557 ( I think book not handy) +- .075.
:cool: [/QUOTE]
Now that's a real high idle.
The book says to adjust the idle to 400-450 with the IAC disconnected. I adjusted down to 500. Then reconnect IAC with ign off, the result was an idle of 800-700 and an in gear idle of 600-500. I may readjust the idle again tomorrow. TPS should be near .557 ( I think book not handy) +- .075.
