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MY SPEEDOMETER IS WAY OFF


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Most of my driving is on local roads so I don't get out on the freeways much. The other day the engine light came on (second time this has happened) so I took the 350 by the local dealer, who I have a great relationship with. The car was running rough and the dealer quickly found that the #4 cylinder ignition coil was bad. This is a common problem in the new 5.0's

 

A couple of days later I was out on the freeway and noticed that the speedometer seemed to be off. The faster I went the more it seemed to be in error. It also seemed that the 350 seemed "tamer" than it had been. The punch just didn't seem to be there, but the car was driving beautifully, just not like the "beast" it should be.

 

I stopped by a local speed and racing shop that had run a Dyno on the 350 for me when I first got it. They were nice enough to check the speedometer on the Dyno and found that at 60mph indicated I was only at 50mph. What was worse at 90mph indicated, I was only doing 75mph. The guy that had run the original Dyno took the 350 for a spin and agreed that it just didn't feel the same.

 

So I talked at length to the Ford dealer to make sure that they didn't reset anything during the coil repair and they assured me that they did not. In fact they knew about the special tune and had contacted Ford engineering the first time the 350 was in for the engine light issue to get the 411 on the GT350 build, so they are aware of the uniqueness.

 

So here's the poser: How can the speedometer lose it's calibration and the "tune" appear to lose it's oomph all at once?

 

It's going back to the dealer on Tuesday and they're going to try and coordinate with SAI and Ford engineering to work things out.

 

Anyone else had any issues like this?

 

John

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do you have the tuner that they used when it was built? if so there is a speedo cal step. it is something like tire circumference gear ratio and something else it can be reflashed with the current tire size configuration

 

 

Nope...all done at SAI.

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John

Sounds the the tune was changed. Have Shelby or ford racing send the tune to your dealer and have the car re-flashed. If they will not help you, buy an sct tuner and contact John Lund. Good luck.

 

 

That's what I thought. Hopefully the dealer and Ford/SAI can get it worked out on Tuesday. I put a call in to Steve Mansell to alert him of the issue and the coming call but haven't heard back yet. My fingers are crossed.

 

Thanks, Tony.

 

John

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Definitely sounds like your car got reflashed. Not only that, but you got reflashed with a stock 5.0, running the stock 3.55 gears....not the 3.73s

 

They may deny it, but it happened and the tech is playing dumb. My guess is he was following the procedure for the TSB 11-3-31, which is a reflash of the pcm for 5.0s built before July 2010 (if your car was build dated before then) because that tsb specifically is issued for cars throwing any misfire code p300-p308. My guess is your car threw p300 and p304, right? Just a hunch....had a similar issue myself. I tried coils and plugs, but my issue ended up being a vacuum leak over the #4 cylinder.

 

Good luck, let me know if my hunch is way off base....:hysterical:

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Definitely sounds like your car got reflashed. Not only that, but you got reflashed with a stock 5.0, running the stock 3.55 gears....not the 3.73s

 

They may deny it, but it happened and the tech is playing dumb. My guess is he was following the procedure for the TSB 11-3-31, which is a reflash of the pcm for 5.0s built before July 2010 (if your car was build dated before then) because that tsb specifically is issued for cars throwing any misfire code p300-p308. My guess is your car threw p300 and p304, right? Just a hunch....had a similar issue myself. I tried coils and plugs, but my issue ended up being a vacuum leak over the #4 cylinder.

 

Good luck, let me know if my hunch is way off base....:hysterical:

 

 

A dealer screw up is usually a pretty good guess... I have a air bag light on all the time on the dash. I’m dreading a dealer visit.

Edited by Torch40
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A dealer screw up is usually a pretty good guess... I have a air bag light on all the time on the dash. I’m dreading a dealer visit.

 

before going to the dealer for your airbag light. check the plastic connectors for both front seats. i would un-snap them, blow some compressed air in them and put it back together. If the connection for the seat airbags is disconnected or not tight, the dash airbag light will come on.

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I had an airbag malfunction also....was lucky though- mine turned to be the passenger dash airbag, and I wanted my signed airbag cover installed, so I got that for free since they had to pull out the airbag anyway!

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before going to the dealer for your airbag light. check the plastic connectors for both front seats. i would un-snap them, blow some compressed air in them and put it back together. If the connection for the seat airbags is disconnected or not tight, the dash airbag light will come on.

 

Thanks, I’ll check that out.

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Definitely sounds like your car got reflashed. Not only that, but you got reflashed with a stock 5.0, running the stock 3.55 gears....not the 3.73s

 

They may deny it, but it happened and the tech is playing dumb. My guess is he was following the procedure for the TSB 11-3-31, which is a reflash of the pcm for 5.0s built before July 2010 (if your car was build dated before then) because that tsb specifically is issued for cars throwing any misfire code p300-p308. My guess is your car threw p300 and p304, right? Just a hunch....had a similar issue myself. I tried coils and plugs, but my issue ended up being a vacuum leak over the #4 cylinder.

 

Good luck, let me know if my hunch is way off base....:hysterical:

 

Warren,

 

Had 2 codes: 304 and 316. No indication that they did any TSB service, just a a stress test and then replaced the coil. Also reset the KAM memory, which I was told was the computer error code memory area to clear the engine light. They only had the car for about 4 hours - which is pretty quick in dealer hours :hysterical:

 

Thanks for the insight.

 

John

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