Hi guys, I have a '99 cab (996) that ran perfectly fine till my battery went dead. The car only has 38K miles. Battery went dead, I bought
a new one (Optima Red top) & installed it. After installing it, the car will no turn over and start up. I turn the key & the engine cranks... and
cranks and cranks. I checked for spark... it's getting spark. I checked for fuel... it's getting fuel out of the back of the fuel filter (closest to
engine). I haven't checked fuel pressure yet. A friend has a ODB reader... it threw a P1691.

Has anyone else had a car unable to start, and throwing a P1691 code?

As mentioned above... it cranks & cranks without wanting to give that "I'm getting gas & spark" sound... as if it's ready to cough spit & sputter till it starts up.

Any ideas? I can't imagine that putting a new battery in the car would cause this to happen. But it (coincidentally?) happened.

 

Have not had any of these issues however I believe the code is for the check engine light. How they may be related escapes me. Hopefully some experienced people will chime in.

P1691 Check Engine Malfunction Indication Light (MIL) - Open Circuit

 

Manual car? Perhaps it thinks the clutch isn't in...
Ignition switch going south creates some strange issues also.

 

It is a Tiptronic car, so no clutch. Ignition switch seems to be OK.

 

I think I've also ready it can be the Check Engine light. But I can't imagine the car not starting because of that. I also read, that on Boxsters, the P1691 can mean you might have gauge cluster wiring issue. Or a pinched harness somewhere.

 

Kind of a long shot but consider disconnecting the battery and leaving it disconnected a while before you reconnect it.

Be sure you turn off the key and remove the key from the ignition.

Be sure you follow the proper battery disconnect procedure and you follow the proper battery connect procedure.

Be sure you obtain the radio code -- if applicable -- *before* you disconnect the battery.

The above is a long winded way of suggesting you reset the DME.

Also, an engine will likely crank just fine but if the battery is a bit too low there will not be enough volts to cause a spark. The electrical field in the coil isn't powerful enough and when it collapses when the power is cut there is no spark generated.

The battery is new. Is if fully charged?

 

GOOD IDEAS! The battery is fully charged. So that's good. I've disconnected that battery when I know the car is going to sit for a few weeks. But I didn't know there is a certain procedure to connecting that battery again. What is the procedure?

 

Procedure is described in the owner's manual somewhere near page 218.

 

might be a long shot as well, but have you checked your fuses?

 

jhbrennan pointed you to the section in the owners manual. I would prefer you go by that rather than have me type it in.

I might make a mistake.

Generally the key wants to be off, all electrical loads off, and the battery leads connected in the right order and this is very important, connected to the right battery posts. Get this step wrong and....

After you connect the battery there are things that probably need attention. The owners manual should have a section on what you do after you connect the battery.

These include entering the radio code, setting the window limits, and calibrating the e-Gas.

DME fueling/ignition adaptions are lost but the DME will adapt again as you drive the car and there is no real need to do anything special.

 

It may be possible your immobilizer is on the alarm state. Did you already disarm and rearm and disarm again, paying close attention to the door locks to make sure the alarm has gotten a signal from the key fob? When you first reconnect the battery, you usually have to turn the alarm off.

 

I have a felling that might have something to do with it (now that you mention it). My passenger door won't lock or unlock (with the key or button on dash).
Wonder why that door is not locking? I guess that would be a place to start. If the cars is mobilizing itself because it thinks something is not "right", it makes sense to me.

 

Hehe... My owners manual only has 208 pages. but found the battery info toward the end of the manual.
Really it's telling you to remove the positive cable first, then the neg. (when removing/disconnecting battery.
When reconnecting it, positive 1st, then the negative. Pretty simple.

 

OK... the BIG mystery! I bypassed the fuel pump relay (with home-made wire) just like shown how to do on Rennlist (I think that's where I
saw it). With that "bypass wire" I have the "buzzing" of the fuel pump. It's definitely ON. Try to start the car however, and it just cranks &
cranks.

NEXT: I installed a brand new Porsche fuel pump relay (in case my old one was bad) and I DON'T hear the "buzzing" of the pump when the
key is turned to that 1st position! Strange. I'm thinking I should hear that pump buzzing/priming.

NOW... something strange also I noticed with my car: And not sure if it has anything to do with the car NOT starting/ turning over, BUT...
the passenger door WILL NOT lock. So I'm thinking maybe the cars alarm/immobilizer won't allow it to start up?

Has anyone experienced a car NOT wanting to start when a door lock is NOT locking? Seems pretty drastic to stop a car from starting just
because a door lock won't work. But you never know...

My next mission is taking of that passenger door panel and see if the electric wires fell off somehow.

Has anyone experienced anything like this?
Thanks much!!! ;o)
Nick

 

Was the car armed by chance when your battery went dead? It could be a combo of the immobilizer being armed and the replacement of the battery retriggering the armed status due to your faulty passenger door lock circuit.

One way to see if your car is armed is to keep one door or center console lid open and try to arm it and see if you get some beeps. Another way is to trigger one of its sensors, like the shock or tilt sensor(forgot which one the 996 has off the top). Also make sure your alarm horn is actually hooked up in the drivers side under the cowl. You can test that with a 12v source if you're not sure on the working condition.

Other coincidental failures could be the clutch or ignition switches but doubtful as you said it was running fine before the battery swap.