joedvette41

I wanted to do the DE-K intake swap because I thought it was the only thing separating my 190HP DE from the 220HP DE-K. This isn't true by the way, but it's what I thought before I did the swap. In order for this swap to really make DEK power, it also needs the lower manifold (that uses higher flowing injectors), the DEK y-pipe (which is closer to equal length and better flowing), and most of all, the timing and fuel map from the 00-01 max ECM.

Anyway, on to my fix for 99 EGR delete and persistent P0400. I thought long on this problem, specifically to figure out the simplest way to tell the ECM that it is seeing exhaust flow whenever the EGR valve is supposed to open. The biggest issue was, I didn't really know what the EGR valve was doing while I was driving. So I wired into the 4 ECM wires that control the EGR valve (the connector has 6 pins, 2 are B+ battery voltage and the remaining 4 are ECM signal wires [grounds]). I set the partially assembled EGR valve next to me in the cup holder and went for a drive.

The EGR valve is a stepper motor that receives pulses from the ECM under light throttle acceleration when the vehicle is moving. There are a lot of inputs and conditions that the ECM considers as told by the FSM under the section regarding P0400. So as I drove, I watched the EGR valve push out its center shaft by maybe .25" and retract it every time I was under light throttle acceleration condition and then off the throttle.

With this movement, I decided I would rig a momentary push button to depress when the valve extends. This pushbutton trips a combo relay to switch between showing the ECM the resistance of the EGR thermistor and a 20k-ohm resistor.

The FSM gives you the bare minimum to figure out this sort of ECM trick. However, there is one page of the FSM that tells what the EGR temp sensor voltage readout to pin 63 on the ECM should be... either between 4.5V and 1.0V when EGR is NOT operating or less than 1.0V when EGR IS operating. It was this information that led me to believe that one resistance value in the correct range would fix this check engine light.

So.... this led me to use the EGR valve as an actuator to trigger a relay to look at a resistor. It still feels like a very backwards way to fix this engine light when deleting EGR, in my opinion. If I could think of a good way, I would delete the stepper motor altogether and rig some sort of circuit that read the EGR valve output signals.

ChrisMan287

iTrader: (34)

Any pics? This sounds interesting.

joedvette41

Here's one image. I'm feeling lazy.

lux97Max

iTrader: (24)

Another reason why 95 ECU is golden.

joedvette41

I feel like a 95 ecu would be more work in this situation.... don't you?