Reduced Engine Power - limted to 11mph

[BobX]

First nice weekend of the year, I went to start my 2000 Boxster w/ only 20K miles on it. Battery was completely dead so I put a jump on it. It took several tries but it eventually started. Ran rough but as expected because several attempts of starting loaded it with fuel. I went to back out of garage and the vehicle stumbled. I went to take a nice easy drive around to clean out the excess fuel and I couldn't go past 11mph. Not in first gear or in second gear. Engine runs smoothly, no misfire, no CEL, but it's just limited like the engine controls is in some protection/valet mode. I figured 11mph is 20kph so it is controlling to that speed. Like I said, no check engine light and the vehicle runs relatively smoothly, to 11 mph. At idle, it will run smoothly at 1000rpm then dip below and run rough and keeps cycling that way. Anyone seen an issue like this? Thanks for your help.

[Paul]

You need to reset your egas.

Turn car off

Turn ignition on (Do not start) (DO NOT TOUCH THE GAS PEDAL during this procedure)

Wait about a minute (you'll hear the throttle motor run in the engine compartment)

Turn key off for at least 30 seconds.

Start car and see if it's fixed.

[BobX]

Thanks for the suggestion, Paul. I tried what you posted and after sitting for several minutes (4 to 5) I never heard the throttle motor. I'm guessing your suggestion has something to do with the electronic throttle control and learning minimum position (accelerator pedal or throttle blade?). Regardless, I tried a couple times and could not fix it. Any other suggestions would be appreciated. I even tried disconnecting the battery for several hours. Thanks.

[Paul]

Time to check for faults in the DME.

[Steve Tinker]

Did you fully charge the battery (over 12 hrs on a charger) before trying to reset the e-gas?
If you try what Paul suggests without a fully charged battery (~ 12.6 v at the terminals) you are wasting your time as the DME is very voltage sensitive....

[jmatta]

Time for a new battery...buy a maintainer while you're at it. You can't let these cars sit and drain the battery...causes all sorts of problems, as you're finding out.

[BobX]

Thanks for all of the help, guys. How do I check the codes on DME, Paul? Is that different from engine trouble codes? I've had the battery charged and still not getting any success. I still do not hear the throttle body motor. Does it matter if I have the hood up or have the battery charger hooked up? Does the boxster have a hood switch?

[Paul]

Where are you located?

[Paul]

The DME is one of several computers that can post codes.



Here's some eGas codes:

[BobX]

Thanks Paul. I live in Ann Arbor, MI. These are p codes so they should illuminate the check engine light, no? Do you think my pedal sensor has failed? what does egas learn do? learn the minimum position?

[Paul]

As you can see from the displays:

Lamp off



Any time the battery is disconnected, the eGAS off throttle settings must be relearned.

[BobX]

Well, the check engine light finally came on. I still cannot "learn the egas". I even tried disconnecting battery just to see if I can get it to learn. No success. I'm going to try to pull codes next. Is there a history of sensor failure in these cars? I did try to crank the engine with a low battery, but I can't imagine that failing accelerator pedal sensors. Anyone know what else I can try before taking it in?

[Paul]

Status please.

[BobX]

Finally got a code reader hooked up and saw a P1502 Pending. When I clear codes while the vehicle is running, the car runs like there is nothing wrong. Reading codes after clear codes, there are no faults active or pending. But on the following start, it will go back into reduced power mode and have P1502 Pending. Based on what I've learned so far, it won't learn "egas" and it is failing some throttle code during key up. However, I think it's failing falsely as once the code is cleared, the vehicle runs flawlessly. Not really sure what to do at this point. And thanks for the followup, Paul.
Any help would be appreciated.

Robert

[Jager]

What is the voltage reading on your battery when the car is not running?

[Paul]

Just to rule this out, check the intake plumbing from the air cleaner to the MAF to the throttle body for air leaks.

[urban_legend]

If you could use some help or a referral to a good indy p-car shop just PM me.

The sad part of MI is good Boxster weather is flying by.

[jhandy]

so the way I understand the problem is that the car is stuck in "limp home mode".

there is a electric throttle valve switch on the side of the throttle body. It may be loose or a poor connection, or maybe failed altogether.

unless you charged the battery while it was still connected to the car, I cant see how the charging of the battery could have damaged the switch. May be coincidence.
looks like a square with two nuts on each wing, and a plug in the bottom.
If you know how to use a multimeter, you may be able to test it.


2000 Porsche Boxster F6-2.7L
Vehicle Level Powertrain Management Computers and Control Systems Testing and Inspection Diagnostic
Trouble Code Tests and Associated Procedures P Code Charts P1502
P1502 Notes P1502
412 Throttle Jacking Unit, Spring Test - Above Limit

Function
The position of the throttle is controlled by a digital position controller which emits a pulse-width-modulated (PWM) duty cycle and a direction bit.
After the output stage has been deactivated, the throttle is brought into emergency air position by means of two springs. This return of the throttle must take place within a certain time. If this time is exceeded, a fault is stored in the memory.

Diagnosis conditions
Ignition on (approx.30 sec. )
Stationary vehicle
Engine not running
Engine temperature> 5 °C
Intake air temperature> 5 °C




In any case, part number 99660611600. 4$ from china, 97$ generic replacement, 161$ from porsche.

[BobX]

I don't think its a low voltage issue as I've fully charged the batter using a trickle charger. The vehicle starts up fine now. But I set the fault at most key ups. As for intake blockage I don't thinkin should set s P1502 based on the description. Based on what I read above, the throttle is not returning to default position fast enough during a learn. After i clear codes while vehicle.is running, everything runs great. I even monitor the throttle position using the scan tool and it reads likely values. I guess I will try to replace the aforementioned part and see hoe it goes. Thanks for all the suggestions.

[Jager]

I'm really curious to know what the voltage is while the car is not running. It's possible to start the car with lower than optimal voltage. Then when the car starts the alternator kicks-in and provides higher, more than sufficient, voltage. Do you have a volt meter?