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Old 02-02-2013, 01:24 PM   #1
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Posts: 16
Backfire - Diagnostic Port

Help- So we sold the house and hit the trail from Calgary Alberta and are currently in Ft. Myers Fla.
I have a 96 Classic 36’ with the P30 454 gas engine.
On our trip we have:
- new rubber
- new right side exhaust manifold gasket
- new plug wires (after one melted)
- new fuel filter

Other than that odds and ends. I have one issue now I cannot seem to solve. The engine backfires quite a bit. No a huge backfire but I am pretty sure it is in the exhaust system . When I press accelerator she goes, but lots of continuous back fires.
I have had it in twice to different garages and they both wanted to plug in their diagnostic tool. Trouble was we cannot find it! Does anyone know where the female end of the diagnostic tool is on this unit? We have looked high and low and cannot find it. I wonder if it is behind the in-dash TV? Is it under the hood? Does it have one?

Any help would be muchly appreciated. My fuel consumption has increased markedly. Some people have told me it could be the gas here in Florida but I want to be sure.
Thanks in advance!

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Old 02-02-2013, 02:08 PM   #2
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1993 21' Sovereign
Colfax , North Carolina
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The firing order is 1-8-4-3-6-5-7-2. Check that before doing anything else, you may well have two plug wires crossed.

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Old 02-02-2013, 05:42 PM   #3
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2011 34' Classic
Westchester Cty.NY , / Miami FL
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you should also check under the distributor rotor for corrosion or arcing. they can actually burn through the center or the rotor and arc to the distributor shaft.
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Old 02-03-2013, 07:44 AM   #4
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1992 36' Land Yacht
Grayson , Georgia
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Posts: 1,313
Backfiring through the exhaust could indicate an exhaust leak and possibly running rich as well. Backfiring through the intake usually means lean.

I feel your pain on trying to find the ODBII connector. I'm still trying to find my fuse box on my 92 LY.
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Old 02-03-2013, 08:11 AM   #5
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Missing OBD port

Thanks to everyone who responded. I am going to grab a flashlight and look for it today. Not sure what I am looking for but will continue to search on the internet. Will call airstream in the morning if I cannot find it.
Thanks again. Think we might go to the Florida airstream rally in a couple of weeks so if you plan on attending let me know and we can break bread.

Thanks again
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Old 02-03-2013, 08:13 AM   #6

2003 25' Classic
Zanadude Nebula , Milky Way
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Question question.....

Start with the most recent...was the melted wire the original diagnosis for the mis-fire?

Melted wire, new replacement=rong firing order. the SES light on? Rough at idle?

All the scan tool will tell is that you have a P0300 misfire code. (if in fact it is a MF)

Idle drop test....pull one wire at a time from the cap @ idle, note changes. Loosen wires before starting.

...check dist cap for carbon tracks, replace cap & rotor if needed.

"We are all here on earth to help others; what on earth the others are here for I don't know."
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Old 02-07-2013, 08:27 PM   #7
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1987 34.5' Airstream 345
Hendersonville , North Carolina
Join Date: Jan 2004
Posts: 88
While you're at it, check for vacuum leaks! Not sure if your rig has a distributor with vacuum advance, but if it does then it's worth ensuring that the hose is securely attached with no cracks in the rubber. Poor vacuum = improper distributor advance under load = poor performance, backfiring, increased gas consumption. Also, check/replace the fuel filters (one near the fuel tank, one in-line along the right side). Ours was backfiring through the exhaust because of a failed auxiliary fuel pump, not sure if yours has one of those.

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