1992 Olds 88 Royale Cold start issues (FYI)

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fallenknight73
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Joined: Sat Dec 07, 2013 5:44 pm

1992 Olds 88 Royale Cold start issues (FYI)

Unread post by fallenknight73 » Sat Dec 07, 2013 5:54 pm

Being a bit of a BYM, I have tracked down what seems to be my issue with cold starts. I still have to test this fix, but I am about to and will post about it when I am done.
Like others my car suddenly started with cold start issues. I replaced the IAT, flushed, tune up, oil change. Computer at first kept giving me IAT codes. Well one day i shorted the IAT with some wire just to make it seem like it was 100+ air temp to the computer, I got a new error. I do not remember the exact code but it has to do with the ECT. It sends a reading to the computer of -40 below 0 at temps of 32 and below. This causes the computer to increase the fuel to the engine, aka it floods out. I am going to disconnect the ECT and short it to see if I continue to have problems. If not I will report this. Now I will not assume that it is the sensor causing the reading as it could be a faulty computer as well. Further testing will see.

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TerryAuto
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Joined: Fri Dec 11, 2009 8:48 pm

Re: 1992 Olds 88 Royale Cold start issues (FYI)

Unread post by TerryAuto » Sun Dec 08, 2013 10:35 pm

Yes, a reading of -40 degrees on the coolant temp sensor will surely cause a rich condition and hard start on your Oldsmobile. Most likely a bad sensor other than the PCM. It gets to a point and then goes full cold. The IAT and ECT share a wire I believe, so I would move around the wiring harnesses while watching the sensor data to make sure it does not have a wiring problem.

fallenknight73
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Joined: Sat Dec 07, 2013 5:44 pm

Re: 1992 Olds 88 Royale Cold start issues (FYI)

Unread post by fallenknight73 » Sun Dec 08, 2013 10:46 pm

Well shorting it did not work, did a system reset and brought it back up with IAT and ECT disconnected. Same problem. Any other ideas aside from the ECM?

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TerryAuto
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Re: 1992 Olds 88 Royale Cold start issues (FYI)

Unread post by TerryAuto » Mon Dec 09, 2013 11:58 pm

Well, having those sensors disconnected and having the same problem is not really a good test. You may have just induced a problem that acts the same as you are having. The sensor need to be plugged in and reading correctly to properly diagnose the problem. Shorting a sensor makes it go full one way or the other- neither is accurate to actual temps so that can cause problems.

You say it started all of a sudden- I would check for a leaking fuel pressure regulator and also do a fuel sample to see if you have water in it, and also an alcohol test.

fallenknight73
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Joined: Sat Dec 07, 2013 5:44 pm

Re: 1992 Olds 88 Royale Cold start issues (FYI)

Unread post by fallenknight73 » Sun Jan 05, 2014 9:05 pm

Sensors and pcm replaced and it is still flooding out in cold temps. I am starting to think it is the pressure regulator. Any good tips on what the pressure should be at the rail for my car? I know the test is with the key on but engine off, but I am not sure of the reading I should get. No more pcm codes due to temp sensors either btw.

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carriedi
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Re: 1992 Olds 88 Royale Cold start issues (FYI)

Unread post by carriedi » Mon Jan 06, 2014 9:22 pm

3.8L should be 40 to 47 psi
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