High idle , creeps up when driving
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Instructor
Joined: Oct 2014
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From: Steinbach
High idle , creeps up when driving
So my 88 l98 is having idle problems, more so when it warms up.
It starts at 1000, settles to around 800 but after I drive it , goes up to 1200-1300 rpm
I did the iac reset and adjusted tps to .54
I can get it to idle at 550 with the reset procedure as per Lars notes. But after plugging in the iac it goes back to high rpm
I've cleaned the tb and timing is 6' , I did being the timing down as it was at 14 but it did do the same thing before. Regardless of timing. New to this car as I've had it only since October and want to drive it now the weather is warm
Thx for any suggestions
It starts at 1000, settles to around 800 but after I drive it , goes up to 1200-1300 rpm
I did the iac reset and adjusted tps to .54
I can get it to idle at 550 with the reset procedure as per Lars notes. But after plugging in the iac it goes back to high rpm
I've cleaned the tb and timing is 6' , I did being the timing down as it was at 14 but it did do the same thing before. Regardless of timing. New to this car as I've had it only since October and want to drive it now the weather is warm
Thx for any suggestions
Race Director
Joined: Mar 2015
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So my 88 l98 is having idle problems, more so when it warms up.
It starts at 1000, settles to around 800 but after I drive it , goes up to 1200-1300 rpm
I did the iac reset and adjusted tps to .54
I can get it to idle at 550 with the reset procedure as per Lars notes. But after plugging in the iac it goes back to high rpm
I've cleaned the tb and timing is 6' , I did being the timing down as it was at 14 but it did do the same thing before. Regardless of timing. New to this car as I've had it only since October and want to drive it now the weather is warm
Thx for any suggestions
It starts at 1000, settles to around 800 but after I drive it , goes up to 1200-1300 rpm
I did the iac reset and adjusted tps to .54
I can get it to idle at 550 with the reset procedure as per Lars notes. But after plugging in the iac it goes back to high rpm
I've cleaned the tb and timing is 6' , I did being the timing down as it was at 14 but it did do the same thing before. Regardless of timing. New to this car as I've had it only since October and want to drive it now the weather is warm
Thx for any suggestions
Instructor
Joined: Jul 2014
Posts: 125
Likes: 14
From: Southern NE OH
Thread Starter
Instructor
Joined: Oct 2014
Posts: 162
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From: Steinbach
Thx for suggestions, but wouldn't it be doing it all the time if it's a vac leak? Say it idles at 1400 when warm...I can shut it off and start it right back up and it will idle at 750-800
Instructor
Joined: Jul 2014
Posts: 125
Likes: 14
From: Southern NE OH
That is exactly how mine behaves. Besides, it's cheap and easy to check for vacuum leaks.
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and also, you might be finding that as parts expand ever so little with heat, the vacumn hole gets a bit bigger. which explains why its worse after its heated up.
Instructor
Joined: Feb 2014
Posts: 145
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From: Dunkirk Md
Mine was doing the same thing, I visually inspected and verified each vacuum line. I found many leaks, buy a roll of vacuum line and follow the diagram. There should be a vac dia under the hood. mine is in the front left corner next to the radiator
Safety Car
Joined: Jan 2014
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From: Poughkeepsie New York
In checking your vacuum lines take a look at your vacuum check valve. They get brittle from the heat. I had one that developed several small holes at the neck where the vacuum line slid on. Also checking your runner and plenum bolts is a good idea.
Last edited by Dt86; Apr 14, 2015 at 12:26 PM.
Instructor
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From: Dunkirk Md
Does you ac/heat work? I mean a lot of air coming from the vents?
Thread Starter
Instructor
Joined: Oct 2014
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From: Steinbach
Hey, so I found a hose by my blower fan off and now my vents are blowing air, which I didn't have before. I used a half can of carb/intake cleaner and could not find any leaks. My vac gauge reads 21 off the plenum. It was idling at around 1000 in the garage.
Think I'll take the TB off later once it cools down and take a look at the iac.
Any other ideas?
Think I'll take the TB off later once it cools down and take a look at the iac.
Any other ideas?
Thread Starter
Instructor
Joined: Oct 2014
Posts: 162
Likes: 1
From: Steinbach
Ok thought I had it licked today. I bought a new iac, cleaned the tb up really good put it together, set it using procedure for idle and tps . Was working great. Then I get an error 33 code. I check it out as its a maf code, then realize I had not plugged it in. I plug it in and bang I'm back at idle of 13-14 again. With it unplugged I get 700. What's going on? No code plugged in yet idle is super high, unplugged it idles nice and low.