Need your brains! 3.8 SC - TCCoA Forums
 
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post #1 of 10 (permalink) Old 12-01-2011, 04:44 AM Thread Starter
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Exclamation Need your brains! 3.8 SC

I need your brains on this one. A 93 SC with a brand new engine. After assembly and installation the car has had 1 probelm. Fires up when cold great. After roughly 20 seconds it starts to miss mildly with a rough idle. Moments later you gotta keep it running by light reving, its get so bad with some popping, you gotta shut her off. Now, you turn the key it will fire back up running rough. I noticed that once it has any heat in it at all it runs terrible, cold its ok.

I have pulled the timing cover and checked the crank/cam timing. I have pulled the cam sensor and used the cam sensor tool to insure that all is aligned. THe cam sensor originally wasn't causing it to run with a different firing order. All that has been fixed and its how it should be. I replaced the Ignition control module as the last one tested bad.

If the crank sensor was bad the tach wouldn't work, it does work. Im about ready to burn it down! A real money pit!

Any help is appriciated!

Thanks, Jake
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post #2 of 10 (permalink) Old 12-01-2011, 05:38 AM
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Possibly a bad or poorly grounded DIS module would be my guess.

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post #3 of 10 (permalink) Old 12-01-2011, 09:54 AM
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Make sure your plug wires are correct. Alot of time the 4 and 6 get mixed up at the coil pack.

Looking at coil pack from the bumper side

1___2___3
5___6___4

Engine order from bumper

3____6
2____5
1____4
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post #4 of 10 (permalink) Old 12-03-2011, 02:27 PM
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^^^This is definitely something to think about. I have done it myself a couple of times, lol. It does pop back through the intake some too when crosswired. If that doesnt get it, I would start watching data and codes with a scanner to help point in some sort of direction, lol.

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post #5 of 10 (permalink) Old 12-03-2011, 02:35 PM
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Only runs bad when warmed up? Would that be a "closed loop" issue? Like faulty O2 sensor, maybe?

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post #6 of 10 (permalink) Old 12-06-2011, 07:42 PM
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is the maf clean?

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post #7 of 10 (permalink) Old 12-06-2011, 07:44 PM
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I would look at the maf or IAC but it it probably a vac leak, getting the tubes sealed up on those is difficult what did you seal them with? Did you use a spanner wrench on them or something else?
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post #8 of 10 (permalink) Old 01-10-2012, 01:04 AM Thread Starter
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Originally Posted by Smkn600ctd View Post
is the maf clean?
yeah its been cleaned with sensor cleaner twice
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post #9 of 10 (permalink) Old 01-10-2012, 01:23 AM Thread Starter
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Possibly a bad or poorly grounded DIS module would be my guess.
The Plugs were all bad. I put a new set in. They all had grounded out when tested? Not too sure why they did that, how the link on all 6 had made contact inside the ceramic. The new plugs fixed the probelm, it ran fine.

I drove it for the first time since 04. Made it home and all was well. Fixed a couple other loose ends and was pretty happy that it was on its feet, finally.

I'm ready to take it for a spin and it wouldn's start. I observed similar symptoms as before but this time the tach dropped for second while it was running. I immediately unplugged the cam sensor and it fired up and ran fine.

I went and bought a new sensor and installed it. Nothing changed with it so i unhooked the new sensor and it started. It will only start with the sensor unhooked sometimes. When it does it shakes and sounds like its missing running really rich.

I took all the new plugs out and cleaned them very well. replaced them ensuring the firing order was correct and nothing changed.

Do you think the crank sensor is bad? Maybe a bad coil causing a weak spark? No vacuum leaks seen or heard?

One minute its a-ok then it falls on its face.

Thanks
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post #10 of 10 (permalink) Old 01-18-2012, 03:44 PM
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Quote:
Originally Posted by Jakey50 View Post
The Plugs were all bad. I put a new set in. They all had grounded out when tested? Not too sure why they did that, how the link on all 6 had made contact inside the ceramic. The new plugs fixed the probelm, it ran fine.

I drove it for the first time since 04. Made it home and all was well. Fixed a couple other loose ends and was pretty happy that it was on its feet, finally.

I'm ready to take it for a spin and it wouldn's start. I observed similar symptoms as before but this time the tach dropped for second while it was running. I immediately unplugged the cam sensor and it fired up and ran fine.

I went and bought a new sensor and installed it. Nothing changed with it so i unhooked the new sensor and it started. It will only start with the sensor unhooked sometimes. When it does it shakes and sounds like its missing running really rich.

I took all the new plugs out and cleaned them very well. replaced them ensuring the firing order was correct and nothing changed.

Do you think the crank sensor is bad? Maybe a bad coil causing a weak spark? No vacuum leaks seen or heard?

One minute its a-ok then it falls on its face.

Thanks
Sounds like the cam sensor syncro stalk is installed wrong.

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