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Old 05-10-2016, 10:12 AM   #8
Need_for_speed
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Join Date: Feb 2016
Location: New England
Posts: 296
For the whole story, search on "Mystery problem, limited revs".
Here was the solution:

"PROBLEM SOLVED - In the end, it was the P1502 code that was the problem and the cure. My new Can-Tech OBD II tool showed the P1502 code and below it it said "Fuel Pump Relay End Limit. Porsche Part $11" Seeing this I assumed it was a Fuel Pump Relay code. After changing the fuel pump/sending unit/fuel filter and trying out my new fuel pump relay, I was discouraged so I texted my buddy who is the head mechanic at the Porsche dealership (yeah, tried to do it without him) and he said 1502 was a throttle body error code. Not happy hearing this, I opened my Bentley Service Manual and looked it up.

P1502 - Throttle Jacking Unit Spring Test

I almost crapped my pants. Why the hell did the OBD reader say "Fuel Pump Relay?" I couldn't believe it. I took the TB apart, cleaned it real good, exercised it, put it all back together, and started it up. Very rough idle but I could get it to 2300rpms!! On the right track I said! So I did the EGAS remapping thing where you turn the key to on for a minute and then off for ten seconds and start it. same thing. Then I cleared the code with the OBD reader and started it up.

OMG, it was like a new car. Not only did I have my revs back but after the car got to temperature, there was no flutter in the idle. I was so happy, I took it out and set a personal record for fastest speed on four wheels. 145mph

The throttle body wasn't really THAT dirty so I think I am just going to order a new one and throw it in there so I don't have any issues in the future.

I want to thank everyone who contributed to the effort in getting my baby back to normal. Got 3 days at Watkins Glen August 22nd, 23rd, and 24th. I was starting to sweat a little."
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