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1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 04-06-2008, 08:57 PM   #1
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Default High Idle

Well it appears that I am experiencing a high idle. It was very occasional at first, and only recently has become increasingly common, almost to where it happens everytime I turn on the ignition.

The car will start just fine, but will soon begin to idle higher and higher until the RPMs reach nearly 1.5 or above, then they just feel as if they are increasing farther. If I shift into gear (reverse or drive) they generally drop, but if I allow the car to idle with these increased rpms in drive, i will be idling over 15 mph. It'* ridiculous. After a minute or two of DRIVING they will drop to the normal 750-800ish that they should be, and the car will be fine. It'* just annoying because I have to be on the BRAKES to keep at parking-lot speed limits.

I thought maybe it has something to do with the IAC. I cleaned the MAF when I first got the car, and the PCV didn't seem dirty, though I will replace it if these problems keep occurring.
I tried to pull codes a minute or two ago but it flashed Code 12 over and over again, indicating (according to techinfo) that there were no stored codes. When it first began occuring, I could shut down the engine and restart, and it would most likely not start again. Recently it'* done it more and more often. Seems it may have gotten worse after the accident with the deer the other night, but I can't imagine that would mess with anything, especially for as little damage as it did. (http://www.bonnevilleclub.com/forum/...ic.php?t=96486)

My plans if this keeps occuring firstly is to replace the PCV, but I'm not sure what I could do beyond that and cleaning the throttle body. I am going to re-clean the MAF before it gets dark tonight. My main concern is for the transmission, not the engine. If I shift from Reverse to Drive while experiencing this, the RPMs can often get near 2000, producing an almost-neutral bombing BUMP. I want to fix this before I end up with more costly problems. Ideas?
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Old 04-06-2008, 09:25 PM   #2
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You have a vacuum leak. Inspect all connections and lines carefully. If you don't find the obvious, use a can of carb cleaner at idle, gently spraying on each connection until the idle changes from the extra fuel to combust (leaking vac lines suck it in and combust it).
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Old 04-06-2008, 09:31 PM   #3
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Thanks again will! Any specific areas I should check? I was looking into seafoam earlier today, so I saw that my model has a few choice lines near the throttlebody that I'll check, and one near the PCV. Any more likely culprits? I'll have to check it tomorrow afternoon in the daylight. Our hood lamp is a joke.

Could this leak also cause the whine under 20mph? I know vacuum lines can cause a whistle, but my car has whined under 20 mph since I got it. I never minded really, just curious.
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Old 04-06-2008, 09:40 PM   #4
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Where to start?

ALL of them. Follow every single one from the source. Including at the brake booster, the vapor recovery canister under your airbox, your shift modulator on the trans, the vacuum accumulator between the wiper motor and maxifuse relay cover, and any and all other lines including your fpr, etc.

Also spray around the base of the UIM/LIM. Same effect. If you have a whistling noise, replace your PCV while you're at it, and make sure the o-ring(*) are properly installed.
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Old 04-07-2008, 11:06 PM   #5
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Well I checked all of them that I could think of several times over, and I couldn't seem to find a change in RPM. I did, however, find the pattern for this ever-accelerating engine.

Upon starting, I'd hear a tick, then it would sound as if a fan kicked on or something, then it would tick off. As it ticks off, the RPMs raise slightly. A few seconds later it will tick, then tick after a second and they will raise again slightly. It goes in steps, but if I rev the engine once to ~2.5/3k RPMs, it will drop to the normal 700-800.

Also, driving home today, I briefly got an SES light for the first time. It went off about a second later. I was trying to reproduce it by going slow again and it did pop back on for about a second. Due to this, I decided to check for codes once more, and I got this

Code 21 - Throttle Position Sensor Circuit ( Signal Voltage High )

So... I know that the 1993 does not have an adjustable TPS, and now that I have a way of solving this, it doesn't seem like it will be much of an issue, but any suggestions or other things I should be concerned about if this continues?
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Old 04-07-2008, 11:09 PM   #6
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A TPS can cause idle issues. I'd start there. But before you replace it, make sure it'* connected securely with a clean connection.

The ticking associated with your idle could very well be your evap purge. That'* the round canister below your airbox. On your 93, the solenoid to purge is on the canister itself. If your idle changes as it clicks (the solenoid can be heard better on cold mornings), you may very well have a vacuum leak in that system. Between the solenoid and the intake manifold.
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Old 04-08-2008, 09:46 AM   #7
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Quote:
Originally Posted by bad.moshi
Upon starting, I'd hear a tick, then it would sound as if a fan kicked on or something, then it would tick off. As it ticks off, the RPMs raise slightly. A few seconds later it will tick, then tick after a second and they will raise again slightly. It goes in steps, but if I rev the engine once to ~2.5/3k RPMs, it will drop to the normal 700-800.
My 93 has that same tick, etc., w/slight change in idle speed. On mine it is the AC compressor kicking in and out. I think it is using cold, dry air on the defrost.

Also, on that TPS, I've had to replace a couple. The first replacement part from Autozone only lasted 2 yrs and VERY few miles. Have one from NAPA in there now.
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Old 04-08-2008, 11:30 AM   #8
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I had a TPS from AZ fail as well. NAPA only for me.
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Old 04-08-2008, 06:17 PM   #9
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Is this likely something to get worse as it progresses? Seeing as I can get it to stop raising RPMs at startup now, should I still replace this ASAP?

(College student, kinda tight on cash as it is, especially with this recent deer incident)

I appreciate all your guys' help. Willwren you ought to just run a full bonneshop! Both of your cars are amazing, and from what I've read it seems like a lot of handywork, but they're definitely showing it!
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Old 04-08-2008, 09:07 PM   #10
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There'* a test you can run, but it requires a volt-ohm meter.
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