dkcaims

A little background first...

The car is supercharged.
Recently has a new FTC1 (controls 7th injector & retards timing), a PSC1 (signal modifier to accommodate larger injectors, 30lb).
Also installed was a dashdaq monitoring AFR, Fuel Pressure and Boost.

Once everything was wired up and fined tuned the fuel maps, it ran fantastic for the last month, including immediate start-up and idle. WHAT A DIFFERENCE !!!
Note: o2 has been disconnected since tuning and ran great for the last month.
AFR's were consistently 14.2-14.7 at idle and under light load.
AFR's were 11.5-12.0 under full boost.

Just a couple days ago when starting, AFR's were just where the always are at start-up, 14.5-14.7
... but after 15 seconds or so at idle, the AFR's drop to a low of 10.3 and don't go over 11.0 even during a short drive around the block.

What I've checked so far...
Fuel Pressure good
Distributor belt good
Cleaned ISV
Pulled new injectors and had them checked. Thought maybe one or more was stuck open. All checked out fine, re-installed.

Have not checked coils yet. Will do that today.
Vacuum leak somewhere ???

Any thoughts? I'd like to have this resolved before the Porsche Parade.

Thanks
Derek

axl911

Is the rich condition caused by the 7th injector spraying when it's not supposed to?

If the 7th injector is not spraying and the problem is in the 6 injectors, then have you put the car/dme into RoW mode running without an O2 sensor?

As I understand it, in the USA (with o2 sensor) mode, the car will adjust air/fuel to maintain 14.7 at idle and at speed using the o2 sensor readin. However, in the RoW without O2 mode, the car will go on based on a different mapset. If the car is still in the USA mode, then it will be looking for an 02 sensor reading that is not there, and it will probably confuse the heck out of the car. How to put it in the RoW mode, I think there are specific jumpers on the DME wiring harness you have to set. I don't know the specifics.

dkcaims

Hmmm... 7th injector firing when it's not supposed to. I'll check that today. Thanks!
Perhaps the fuel map got corrupted somehow.

As far as the O2 sensor goes, my only thought is why did it run perfectly for the past month with it disconnected? I don't think that's the problem, but won't rule it out.

dkcaims

Pulled the 7th injector... not firing at idle (nor should it)
AFR's creeped down to 10.5 within 30 seconds.
Oh well, it was worth a shot !

axl911

Possible to plug back the o2 sensor to see if that change the AFR at idle? If it does, then you know removing the o2 senssor caused the problem.

Pluggin it back in meant having the o2 sensor in the exhaust tube where it belongs and the electricals hooked back up.

dkcaims

I'll give it a go...

dkcaims

Nope... Started at 14.7 and worked it's way down to 10.5 with O2 connected.
Should I do a DME reset by disconnecting the battery?

Not getting enough spark for complete combustion?
Does this engine have a cold start valve? If so, where is it?

I just checked the coils... runs the same on either coil.

dkcaims

UPDATE...

Someone suggested the Head Temp Sensor.
Can't find my multimeter at the moment though.
I used a jumper on the plug for the head temp sensor going back to the DME and it ran the same as it does connected to the sensor.
The question is... should it? Did I find my problem?

Found the mulitmeter... engine was run for 30 seconds an hour ago and I just now measured the resistance.
It measured .839 ohms.
I'll check it again in a few hours, but I think it should be much higher, correct?

ANYONE... ???

Makmov

15-30c 1.4 - 3.6 Kohms pin 43 & 30
40c 1 - 1.3
80c 250 - 390 ohms

dkcaims

Thanks neighbor !
Best measured from DME plug then?

Makmov

that is what Porsche says if you do not get a good read there then they say test the sensor itself. That way you know if its wiring issue or a bad sensor.

However, the fault error creats a cold start LEAN issue. not generally a rich one. I am not sure if your piggyback box is tapping that value for something or not.

I am availble if you can't figure it out. I might be able to stop up and take a look at if for you.

dkcaims

OK...thanks
I'll do both and compare.
Any other thoughts as to what might be the cause of the rich mixture?

Makmov

I will have to ponder that since you have some other things going on with the supercharger.

Let me think about it a bit and I will get back to you.

Are you using both O2 sensors. One wide band for the guage and the factory one together?

dkcaims

The wide band for the DashDaq and the stock narrow band has been disconnected since I'm able to create custom fuel maps.
Ran fantastic for over a month with it disconnected using the custom fuel map.
Reconnected the narrow band O2 just to see if improved, but it ran the same (10.5 AFR)
Odd though... starts immediately, idles smoothly at 800rpm and 14.7 AFR then after 10 seconds it creeps down to 10.5 as if the DME starts receiving a signal from a sensor and starts to adjust things. (just a guess)

Makmov

where is the wideband sensor located? On a charged application it should be 36 inches away from the port or turbo otherwise they don't last long.

Does the sensor test good?

What kind of sensor is it?