P0642 code comes up when coasting

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, Olds 98 91-96, Buick Lesabres and Park Avenue 91-96. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.
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krissondors
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Joined: Sun Mar 30, 2014 4:35 pm
Year and Trim: 1995 SSEi

P0642 code comes up when coasting

Post by krissondors »

Hi everyone, new to the place. I recently bought a 95 ssei and I love it. Needs some tlc but its nice. So I have my ses light come on and the car drives great BUT I am only getting about 2# of boost. I bought it off my friend and before the light came on it was hitting around 7#. Anyway, the code is p0642 which is quad module 1. Im 90% sure its the tcc circuit because the code only comes on when coasting. I replaced all four solenoids and still no luck. I have alldata and on demand and I did all the tests I could without the tech 2. Any ideas what I can be? Thanks!
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J Wikoff
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Re: P0642 code comes up when coasting

Post by J Wikoff »

Is that similar behavior to a bad egr?
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krissondors
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Posts: 3
Joined: Sun Mar 30, 2014 4:35 pm
Year and Trim: 1995 SSEi

Re: P0642 code comes up when coasting

Post by krissondors »

J Wikoff wrote:Is that similar behavior to a bad egr?
As far as I understand, EGR has nothing to do with it
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PopaTim
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Re: P0642 code comes up when coasting

Post by PopaTim »

try another PCM. 94 & 95 are notorious for pcm's going bad.
krissondors
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Joined: Sun Mar 30, 2014 4:35 pm
Year and Trim: 1995 SSEi

Re: P0642 code comes up when coasting

Post by krissondors »

PopaTim wrote:try another PCM. 94 & 95 are notorious for pcm's going bad.
That's what my suspension is. If I had one handy I'd do it but seems like a expensive test. Im going to purchase a tech 2 at some point so if I dont find the problem by the problem by then hopefully ill figure it out
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