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88 Cabriolet, idle issues.
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Square73
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PostPosted: Tue Jul 08, 2014 6:05 am    Post subject: 88 Cabriolet, idle issues. Reply with quote

Just picked up an 88 Cabriolet, 5 speed with CIS fool injection. 2 things, related or maybe not.
1. One of the Idle Boost Valves has one green wire going to it and the other has both wires connected. A pic of the wires would help me track down what goes where. Bently and the internet haven't got me anywhere.

2. It's very hard to start / keep running, when cold. When it finally warms up and will idle on it's own, it's at 1500 rpm or so. It started out around 2500 RPM and I backed the idle screw off and it's down to 1500. I've read that can be the Auxillary Air Valve. Is there a way to test it on the car ?

Otherwise, it runs very well, has plenty of power for what it is.

Thanks,
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ps2375
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PostPosted: Tue Jul 08, 2014 6:57 am    Post subject: Reply with quote

I would check for vacuum leaks at the injectors and anywhere else. And Bently should have the diagrams you need to figure out what goes where. Aux Air Valve should be open when cold and closed when hot (assuming you should know that) but pull it off and look at it, then put some heat to it and watch it close. Also check that 5th injector is passing fuel on cold cranking. That gets it's power from thermo sw.
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kamzcab86
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PostPosted: Tue Jul 08, 2014 12:18 pm    Post subject: Re: 88 Cabriolet, idle issues. Reply with quote

Square73 wrote:
1. One of the Idle Boost Valves has one green wire going to it and the other has both wires connected. A pic of the wires would help me track down what goes where.


Black valve is the standard boost valve. It has two wires (black, and brown/black) that disappear into the wiring abyss.

White valve is for A/C. Green wire goes to a connector where it splits off and goes to the compressor. Brown wire goes to the cold start valve mounting bolt.

Square73 wrote:
2. It's very hard to start / keep running, when cold. When it finally warms up and will idle on it's own, it's at 1500 rpm or so. It started out around 2500 RPM and I backed the idle screw off and it's down to 1500. I've read that can be the Auxillary Air Valve. Is there a way to test it on the car ?


Based on this:

Square73 wrote:
Bently and the internet haven't got me anywhere.


...you have the Bentley Service Manual for this car? If so, turn to page 5-27 for testing the AAR (aux air regulator). Continue on to the next page for testing the idle boost valves (one or both could be stuck open, or the relay for the black one could be faulty).

You'll want to go to http://www.cabby-info.com/fuel.htm#CIS . And, I highly recommend that you go to http://www.cabby-info.com/cis.htm and perform everything outlined on that page, including the tests (and potential adjustments) in the PDF documents.
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Square73
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PostPosted: Wed Jul 09, 2014 5:42 am    Post subject: Reply with quote

ps2375, I checked for leaks with starting fluid, seems to rev up when I spray the intake manifold at the block ( new gasket(s) time).

kamzcab86, Thanks for the info, I'll get the wires hooked up correctly and see what's what. Then I'll start running the tests in the Bentley.

Any time I buy a car, first thing I do is get a Bentley manual for it, seems to end up cheaper that way.
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