charliegt

Does continuity between the posts on the EGR sensor mean that the egr valve is opened or closed? The FSM doesn't really specify, and I'm trying to determine is the valve is stuck open without actually removing the y-pipe and taking it off. This is on a 94 btw.

Thanks,
-Charlie

DaleClark

iTrader: (55)

Are you getting a code for the EGR valve? They will throw a code/check engine light VERY easily.

From what I understand, the ECU tells the EGR vacuum solenoid to go, which supplies vacuum to the EGR valve to open it. When the EGR valve moves, it trips the switch, which gives continuity to the circuit. The ECU sees that and knows the EGR valve moved. If the diaphragm is broken/torn or something's wrong with the vacuum line, the ECU won't get the signal from the switch and it will throw a code.

The EGR system is TOTALLY useless on the FD. The passage for the EGR is literally a pin hole - Mazda just had to put it on the car to pass federal emissions requirements. The JDM FD's don't even have the system.

Also, I doubt it could stick open. If you're troubleshooting a problem on the car, I'd look elsewhere.

Dale

charliegt

Dale,

Thanks for the reply. I am troubleshooting a startup problem and getting desperate. Since the only code I'm getting is 16, I figured I'd check the valve to make sure it isn't stuck open. When I test the plug I get continuity - and I won't have a chance to finish taking off the valve until this coming weekend.

I'm getting to the point where I am just going to start replacing parts. Here is a description of the problem and what I've done so far:

- cold starts are rough (feels like its running on 1 rotor), but smooth out with a little throttle. once the car has been running for 15-20 seconds everything is smooth and perfect. It almost seems like for 10-15 seconds something isn’t functioning, then it clicks on and everything is great.

- hot starts are worse. I'll crank the car and it will fire, then quit. After that I can get it to start by cranking with the throttle wide open, pause, then crank normally and it starts - I then need to apply WOT to keep it from stalling, it misses for a few seconds then rpms start to build and I can let off the throttle. This seems to have gotten progressively worse with the hot weather leading me to believe that whatever is failing is performing even worse once it is heat soaked.

- one strange thing that I did notice is that the fuel system doesn’t prime for 2 seconds when I first switch the ignition on. I originally thought this was the problem, so I removed the fuel pump relay and put in a paperclip (powering the pump whenever the ignition is on) – however the problem persisted.

Aside from the first 10-15 seconds after starting – the car runs and idles pretty much perfect. At idle warmed up I am at about -14 vacuum. No smoke or bubbles in the coolant.

I currently have a fuel pressure gauge hooked up to the car. The pressure is good and the hot start solenoid is functioning properly (pressure is above 40 when the engine is hot, then drops to 32 after about 30 seconds of idle). The fuel system holds pressure great (35psi for an hour or so).

Here is a list of everything that I’ve tested/replaced:

Replaced plugs and plug wires
Replaced coolant temp sensor
Replaced fuel pressure regulator
Replaced fuel pump
Replaced most of the vacuum hoses
Had injectors cleaned, rebuilt, flow/leak tested
Compression test (95psi on 3 faces of front rotor / 90psi on 3 faces of rear)
Tested fuel pump relay and fuel pump (speed) relay
Tested fuel temp sensor
Tested intake air temp sensor
Tested TPS
Tested MAP
Tested AWS valve
Visually inspected double throttle control, idle control, ect.
The battery is less than a year old, and I just had it tested today and it checked out OK.
I checked and all 4 plugs fire as well.

I've spent a considerable amount of money (and a ton of time) trying to figure this out, and I'm getting pretty frustrated. I'm wondering if I have a bad coil, but I want to see what you guys think before I buy yet another new part on a hunch.

If anyone in the Cincinnati or Columbus area has a spare set of coils or a spare stock ecu that I could borrow I'd really appreciate it.

My car is almost completely stock (its a 94) with the exception of a downpipe, catback, af gauge, and boost gauge.

Thanks in advance, I appreciate any advice that you guys have to offer.
-Charlie