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sensor problem? Your diagnosis

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Old 09-25-2014 | 10:55 AM
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Question sensor problem? Your diagnosis

I got this in an email from my co owner last night
"The car started stalling when pushing the gas pedal to the floor. At one point, at idle the engine was surging but would not accelerate."

Any thoughts? We will tear into it tomorrow night. Hoping to DE it Sunday.

TIA
My first guesses are crank position sensor or connections to MAF. This is the Rogue 944S test mule back to stock.
Old 09-25-2014 | 11:23 AM
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Originally Posted by Tom R.
I got this in an email from my co owner last night "The car started stalling when pushing the gas pedal to the floor. At one point, at idle the engine was surging but would not accelerate." Any thoughts? We will tear into it tomorrow night. Hoping to DE it Sunday. TIA My first guesses are crank position sensor or connections to MAF. This is the Rogue 944S test mule back to stock.
The Maf was a plug in affair, and the car is back to stock in every way, no splices were done to make that Maf work. Check the wiring to the hall sensor which was messed with by a PO and the afm which was also opened up by the PO. By PO I mean not me btw, I mean the guy I bought it from. Maybe check the tps as well, I cleaned it when I had the intake off and verified its operation and adjustment at the time, but it could still be a problem.
Old 09-25-2014 | 11:55 AM
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Thanks Chris. I know its back to stock, and nothing was spliced.

I haven't updated my signature and needed to ID the model, and brag aboug it's provenance as the Rogue mule.
Old 09-25-2014 | 12:17 PM
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Could be the AFM track is worn. Easiest way to check the AFM wiring is to just unplug it completely and see if they behavior changes. I don't think it would be the position sensor since that would prevent the engine from running at all. Another possibility is that the exhaust is blocked, usually in the catalytic converter.
Old 09-26-2014 | 01:15 AM
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Im gonna pick up an O2 sensor, swap DMEs, and check the other stuff. Any other ideas?
Old 09-26-2014 | 02:50 AM
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it doesn't sound like O2 or MAF to me, it sounds more like a vac leak or a disconnected/defective fuel press regulator
Old 09-26-2014 | 10:29 AM
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check the water temp sensor for the dme as well.
Old 09-26-2014 | 03:10 PM
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Without seeing the car yet, im starting to think bad gas. I added 2 gal of $9.49 a gallon 100 octane at the track so we could get the last runs in and have enough to make it to the local Sinclair.

I was at the track helping a friend at the vintage race last month and he was running awesome until he tanked up with the 110 octane not for street gas. He was flying around the track when all of a sudden the car missed, etc. and it sounded like the symptoms my co owner described.

Im gonna add some dry gas, fresh gas if not already done, etc. check all of the above, and see what happens.
Old 09-26-2014 | 05:22 PM
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Maybe speed sensor starting to go bad?
Old 09-26-2014 | 06:37 PM
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My car is doing this, tapped the TPS and got myself home.
Old 09-27-2014 | 01:12 AM
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I replaced the O2 sensor in the car when I purchased it, I had bought a new Bosch universal for my 924s about 6 months before it was hit and I transferred it over when I bought the 944S
Old 09-27-2014 | 01:24 AM
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Originally Posted by Arominus
I replaced the O2 sensor in the car when I purchased it, I had bought a new Bosch universal for my 924s about 6 months before it was hit and I transferred it over when I bought the 944S
thanks chris. got the boot today.
should be fun tomorrow tracking this stall down.
Old 09-27-2014 | 12:16 PM
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Originally Posted by Tom R.
thanks chris. got the boot today. should be fun tomorrow tracking this stall down.
I never replaced the fpr,it might be worth getting a fuel pressure gauge on it to see how it acts. The injectors where cleaned at witchhunter last year, I replaced all of the vac hoses under the intake too, so that shouldn't be an issue.

Last edited by Arominus; 09-27-2014 at 02:35 PM.
Old 09-27-2014 | 12:51 PM
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Why do i think its bad gas
Old 09-27-2014 | 02:35 PM
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Originally Posted by Tom R.
Why do i think its bad gas
drain the tank and refill if it's not super full right now, you'll know pretty quick then.


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