1987 bonneville le 3.8 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-24-2006, 02:26 PM   #1
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Default 1987 bonneville le 3.8

Hi...this is my first post here...

I have a few problems with my 87 le...

1) Harmonic balancer went on me (any advice on changing these?)

2) Does anyone know the location of the high side and low side service ports on the a/c? any tips as far as recharging a/c?

3) Whenever I switch to "defrost" at idle, my revs jump up to 1500.....I was getting a 33 error code, but thats been gone for a while....sometimes revs will jump up at a stoplight (which is somewhat disturbing).....I think it'* a vaccuum problem, but I can't locate it....

Thanks
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Old 05-24-2006, 06:13 PM   #2
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Welcome to the club!
1. They come off easier if you use an impact wrench. Don't disturb the crank position sensor. Use a new key. I paid just under $100 for a new one. Money well spent. It was actually the reason I got the car so cheap, the previous owner thought the engine was trashed. The difference is amazing.
2. On my Pontiac, low is up by the fire wall, high is down by the battery. If you aren't familiar enough with AC to know the difference, it'* best to have it done by a pro. Trust me, you won't save money by "learning" how on your own car. You'll want to have it changed over to R134 because they don't make R12 any more. If you find some, it'* not worth the price or the fine if you get caught using it without a HVACR license.
3. Just a guess on this one. The AC compressor kicks on when using the defrost setting, so I'm thinking maybe there is a high idle solenoid that bumps the idle up a notch so it won't die. Like I said, just a guess.
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Old 05-25-2006, 02:17 AM   #3
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thanks....

I picked up a new balancer today..(came with a new key)...looks like it won't be too big an issue to swap out...(I love that removable splash panel)

I have done AC before just couldn't find the high side port to save my life...figured I'd err on the side of caution and ask before hooking up a can to the wrong port (boom)...going to be using Redtech 12a in this system (don't need a license for this), and I know someone who can empty the system for me (legally)...I'll let you know how the 12a works....

I didn't realize the AC kicked in when you hit defrost...somehow that seems kinda counter productive doesn't it? (lol)....I'll keep searching on this...there seems to be a bit of a "hiss" when you flip it to defrost as well, that'* what made me think it was vaccuum initially...gotta get the balancer on before I can test anything anyway.
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Old 05-25-2006, 03:16 AM   #4
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The AC kicks in during defrost to remove the moisture from the air. This prevents the film of water on the inside when you are thawing the outside.

Esentially you are drying the air then heating it up.
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Old 05-25-2006, 09:34 AM   #5
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So does anyone know if there actually is a selenoid in this picture that would bump up the idle? This was a bit of a problem last winter when it hit -30 C...
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Old 05-25-2006, 12:26 PM   #6
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The idle is controlled by the idle air control solenoid. When the throttle is closed the solenoid opens a small port that allows air to bybass the throttle. This is how the idle rpm is controlled. This is only during closed throttle. It also needs to see the correct signal from the throttle position sensor to help control idle.

I would start by cleaning the IAC valve and checking the setting of the TPS.
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Old 05-25-2006, 12:39 PM   #7
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The A/C will definitely kick in on defrost for the reasons stated above. If your system is low on refrigerant, it will cycle more often too.

As far as hpw many rpms the idle will increase during A/C cycle, I don't know that but it doesn't sound too out of line to me.

I would look into that hissing sound a bit more. It is possible that you also have a vacuum leak, especially in a car with the years yours does. The rubber vacuum hoses and vacuum line connectors are likely to be old, brittle, and possibly cracked. A full visual and tactile inspection of all vacuum lines and connections should be part of your 20 year tune up, lol.
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Old 05-25-2006, 12:40 PM   #8
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Quote:
Originally Posted by myfirstbonnie
The idle is controlled by the idle air control solenoid. When the throttle is closed the solenoid opens a small port that allows air to bybass the throttle. This is how the idle rpm is controlled. This is only during closed throttle. It also needs to see the correct signal from the throttle position sensor to help control idle.

I would start by cleaning the IAC valve and checking the setting of the TPS.
I would pull and clean the TB... Make sure you can get the plastic coolant line connectors for the TB tho... They usually break... Also do like mentioned above and clean the tip of the IAC, in the 87 the IAC will unscrew... Checking the TPS is also a good idea...

If all of these 3 items are good, then you idle should be smooth even when its cold

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Old 05-25-2006, 07:19 PM   #9
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The temperature is in the high 90s F here, where are you that you need defrost in the summer?
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Old 05-25-2006, 09:58 PM   #10
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I'm in Canada where it'* cold all year round...lol....actually it was about +30 C today, so not warm by Arizona standards, but we're getting close to summer weather....

Actually I just have it in my shop right now for the balancer, so figured I'd try and fix a couple of other probs at the same time. (20 year tune up..lol)

This car does have over 300,000 Km on it, so ya, I could see TPS, IAS, etc. needing a bit of "love"...I think I'll be driving this puppy for quite a while yet. Everything else seems to be pretty good yet...needs a bit of work on the trans, but nothing I can't do my myself at home.

It is low on refrigerant as well...good suggestion...that'* why I was asking about the service ports earlier...once I get it back together I'll go get it purged and then charge it with R12a and try that...
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