P1635
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Instructor
Joined: Nov 2011
Posts: 181
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From: Franklin Square NY
P1635
So I got this code before changing my pcm, changed my pcm, pcm was tuned wrong but he code was gone.
Got pcm back after being tuned correctly and i get the p1635 code.
Pulled the plug on the A/C sensor got 2.3 volts
pulled the plug on the map sensor got 2.3 volts
pulled the plug on the oil pressure sensor get 5.00 to 5.05 volts
with the oil pressure sensor unplugged the a/c and map read 5 volts.
Is it safe to assume that it is the oil pressure sensor causing the issue? (also getting weird readings switching back and forth between 0 and 40 with car running)
Also idk if this makes a difference but i had to pull the fuel pump fuse for in order to turn the key (so i don't get gas every where)
Also the first time i got the p1635 code a coil pack was grounding out to the engine block so i assumed that the pcm went bad (bad assumption) is it possible both went bad or i should have checked that first.
Got pcm back after being tuned correctly and i get the p1635 code.
Pulled the plug on the A/C sensor got 2.3 volts
pulled the plug on the map sensor got 2.3 volts
pulled the plug on the oil pressure sensor get 5.00 to 5.05 volts
with the oil pressure sensor unplugged the a/c and map read 5 volts.
Is it safe to assume that it is the oil pressure sensor causing the issue? (also getting weird readings switching back and forth between 0 and 40 with car running)
Also idk if this makes a difference but i had to pull the fuel pump fuse for in order to turn the key (so i don't get gas every where)
Also the first time i got the p1635 code a coil pack was grounding out to the engine block so i assumed that the pcm went bad (bad assumption) is it possible both went bad or i should have checked that first.
Last edited by robert1989; Jul 26, 2018 at 09:27 PM.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,310
Likes: 3,924
From: Cape Coral, Florida
Yes, the oil pressure sensor was pulling down your 5 volt ref. That's exactly how you troubleshoot that !!...good job !!...don't know what you mean that you had to pull the fuel pump fuse and not getting gas everywhere. A bad coil pack wouldn't require a PCM change...yes, bad assumption !!
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
Likes: 1
From: Franklin Square NY
Yes, the oil pressure sensor was pulling down your 5 volt ref. That's exactly how you troubleshoot that !!...good job !!...don't know what you mean that you had to pull the fuel pump fuse and not getting gas everywhere. A bad coil pack wouldn't require a PCM change...yes, bad assumption !!
yet another issue.
The idle surges now i'm thinking it is the reuse of the paper style pro comp intake manifold gasket. I'm guessing i should change this before changing the MAF. Also the MAF is only about 30 miles old but is reading down to 2.56 and not giving a steady reading. When unplugged it runs normal.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,310
Likes: 3,924
From: Cape Coral, Florida
low and behold i now have 2 good pcms
yet another issue.
The idle surges now i'm thinking it is the reuse of the paper style pro comp intake manifold gasket. I'm guessing i should change this before changing the MAF. Also the MAF is only about 30 miles old but is reading down to 2.56 and not giving a steady reading. When unplugged it runs normal.
yet another issue.
The idle surges now i'm thinking it is the reuse of the paper style pro comp intake manifold gasket. I'm guessing i should change this before changing the MAF. Also the MAF is only about 30 miles old but is reading down to 2.56 and not giving a steady reading. When unplugged it runs normal.
Last edited by C5 Diag; Jul 27, 2018 at 05:55 PM.
Thread Starter
Instructor
Joined: Nov 2011
Posts: 181
Likes: 1
From: Franklin Square NY
The MAF is not throwing any codes but was changed a few months ago when it did. almost 2 days later i ended up with the 1635 code ( I was in the middle of moving to NC so i towed the car on a trailer to NC from NY). Yea now i get the surge goes away when i unplug it.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,310
Likes: 3,924
From: Cape Coral, Florida
If the surging goes away when you unplug the MAF you most likely need a MAF sensor...I prefer looking at grams/second or frequency when diagnosing a bad MAF. But an issue oscilloscope waveform is the gold standard !!
