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General => Lounge => Topic started by: Masejoer on August 09, 2010, 12:32:22 PM

Title: Bad speed sensor = backfiring? (Not cat/bird related)
Post by: Masejoer on August 09, 2010, 12:32:22 PM
I'm curious if someone could explain this to me as it's confusing. A co-worker had some backfiring under load in a Dodge Caravan and the solution ended up being a replacement output speed sensor that I assume heads back up into the ECU. In what ways would a speed sensor be used for managing spark timing? I've just NO clue how a bad speed sensor would cause ANY vehicle to have ignition timing issues.

Crank sensors I can understand but vehicle speed sensors (or whatever Dodge calls them)?!
Title: Bad speed sensor = backfiring? (Not cat/bird related)
Post by: jpc647 on August 09, 2010, 12:34:52 PM
I get an error code related to my vehicle speed sensor, I don't have backfiring though.
Title: Bad speed sensor = backfiring? (Not cat/bird related)
Post by: Masejoer on August 09, 2010, 01:31:14 PM
Oh, not that it matters, but the vehicle didn't throw a code for a bad vss, or any codes actually. Replacing it fixed the backfiring under load. It makes no sense to me.
Title: Bad speed sensor = backfiring? (Not cat/bird related)
Post by: Cougar8775 on August 09, 2010, 01:56:19 PM
makes no sense at all. the vss does not control timing or have any matter in it. But it does control abs, cruse, and obviously the speedo. But not timing. unless it was back feeding in some way?
Title: Bad speed sensor = backfiring? (Not cat/bird related)
Post by: Masejoer on August 09, 2010, 11:18:27 PM
Yeah - I just don't believe a second of it. I've never known of any ecu that would base ANYTHING off of the speed sensor. Vehicle's a 1996 Dodge Caravan - I don't think those even have a crank position sensor so I doubt it could be mixed up with that although supposedly the sensor IS on the transaxle or something.

I was just curious if I was crazy. Either I'm not or I'm not alone - either way, I feel better.