Fault Code P1691
05-17-2004, 12:36 PM
#1
Race Car
Thread Starter
Fault Code P1691
I keep getting this fault code (every time I drive the car). I reset it and the next time I start the car...it comes right back. If anyone has any ideas, I would appreciate guidance.
Thanks
Thanks
05-17-2004, 03:46 PM
#4
Drifting
P1691 says there is no connection between the MIL and DME. Only thing you can do is trace the wire back and check continuity along the way.
Did they change your DME when you added the supercharger? Or perhaps pinch a wire near the DME?
Did they change your DME when you added the supercharger? Or perhaps pinch a wire near the DME?
05-17-2004, 04:03 PM
#5
Race Car
Thread Starter
They soldered in a new chip Proprietary GIAC tuned Motronic Control Unit. I get the Check Engine Light when this error occurs. It started out intermitently when I got the car back and now is on every day. Starts as a pending DTC and then goes to Check Engine Light. I have been having various fault codes such as P1123 and P1125 and P1539. Now I simply get this fault code and none of the others. All systems seem GO, Fuel Trim normal...Oxygen Sensors rapidly responding, MAF fine. A little rough idle (hunting) but nothing serious. I have to carry my laptop with me everyday just to turn off the light.
When I say other systems are normal,,,this is based on EVO telling me they are normal. MAF reads around 6.50 at idle (up or down 20) Long Term fuel trim is 85 on both banks under heavy load, The only question in my opinion is the Short Term Fuel Trim. Bank 2 ALWAYS is more positive than Bank 1. i.e. if bank 1 reads -1.5, bank 2 will read about +1.5. If Bank 1 reads -15 then Bank 2 reads around -13. Bank 2 is always about 3 percentage points more positive than Bank1. The only exception to this is when I let up on the gas and both readings go to 0.
When I say other systems are normal,,,this is based on EVO telling me they are normal. MAF reads around 6.50 at idle (up or down 20) Long Term fuel trim is 85 on both banks under heavy load, The only question in my opinion is the Short Term Fuel Trim. Bank 2 ALWAYS is more positive than Bank 1. i.e. if bank 1 reads -1.5, bank 2 will read about +1.5. If Bank 1 reads -15 then Bank 2 reads around -13. Bank 2 is always about 3 percentage points more positive than Bank1. The only exception to this is when I let up on the gas and both readings go to 0.
05-17-2004, 07:45 PM
#6
Race Car
Thread Starter
Took a look at the connection and wires of the control unit to see if anything was obvious. Wires seemed undisturbed. Reconnected unit to harness and got the same eror. For fun...I banged on the alluminum cover with my knuckles and restarted the car. NO ERROR. Now...although I have been getting the P1691 EVERYTIMES I start the car and I am not getting them now doesn't isolate the problem yet. I'll drive it awhile more before comming to that conclsion.
I suppose if the tapping did in fact fix the problem...there must be a bad solder joint or other connection in the unit.
I suppose if the tapping did in fact fix the problem...there must be a bad solder joint or other connection in the unit.
05-17-2004, 10:52 PM
#7
Race Car
Thread Starter
Well...that didn't last long. All the faults showed up again.
Pending DTC's:
p1539
p1123
p1125
p1691
I wonder is the p1691 is the cause off all the others. Bank 1 Sensor out of range and Camshaft Adjustment Bank 2 Short? I'll probably have to send the Control Unit back to EVO and have them fix it.
Pending DTC's:
p1539
p1123
p1125
p1691
I wonder is the p1691 is the cause off all the others. Bank 1 Sensor out of range and Camshaft Adjustment Bank 2 Short? I'll probably have to send the Control Unit back to EVO and have them fix it.
