600HP CLUB
Ah! Good. I'd forgotten about this post til I saw it again today. My cars boost needle does not reach the zero mark with the key to ON, and I thought it was just a bad gauge. Til one day I was fooling around and had the vac hose off the sensor and the engine running and spied the needle right on the zero mark. So I figure with the engine running and everything connected up, the gauge is accurate. Something I proved sometime ago looking at the voltage output of the boost sensor and comparing it to this site: https://www.rx7club.com/forum/attach...&postid=601960

 

Yes the boost gauge doesn't move until after 8-9 psi.. it jumps right up there too like it was stuck and then got freed up, not gradual either, it has only two positions either all the way down or right at about 2/3 way up.

I did some testing tonight and here is what I got. I tested the boost sensor at idle and I get around 1.0-1.1v or so. I checked the wire right at the ECU and verified same voltage. I stepped on the gas quickly and it jumped to about 2.*V which is about 0psi. When the key is on the gauge shows the lowest point. It doesn't move at all. When I remove the hose it stays at the same spot. If I remove the electrical connector the gauge moves to about 20hg 1/2 way between 0 and 40. The autometer boost gauge is connected to the same hose as the stock gauge and the AM gauge works fine, no problems at all. I have good vacuum on the hose going to the sensor at idle. That's what's really wierd about the whole thing. I checked all the connectors on the ECU and reconnected them just in case.

What's wierd is the car will not hit fuel cut regardless of boost. There is no hesitiation but I can tell that the ECU is not kicking the injectors up like it should on the top end. If it was just the sensor or even the stock gauge that was bad that wouldn't keep the fuel cut from working right?

I have a battery drain on my car and I don't think it is the alarm so I'm going to try that test on it in the next couple of days.

Any of you guys in Dallas area want to stop by and make a new friend, I could use the 2nd brain w/ this car. just a thought, I could compensate you no problem (if you can help fix it) I also have a headlight problem but that's another story...


help!!!

thanks for the input guys, I'm on the right path it sounds.

My shot in the dark gut feeling is telling me that there is something up w/ the electrical system in general, maybe a bad ground to the motor (which I've had a hard time verifying). I had the really bad engine noise that appeared all the sudden.

(oh I just remembered a wierd thing about the engine noise: For a while the noise was intermittent.. I would hit the car around the side of the dash and it would go away. I think I hit it on top by the clock) One day the noise never went away. The noise was so bad that at higher RPM the distortion on the music sounded like AM radio mixed w/ a popcorn popper.

 

Somethings wrong with the boost sensor. It should read 2.3 to 2.7 at idle. That's with everything connected up.

The boost/pressure sensor is what determines fuel cut, if you don't have a fcd on the car, that is.

I'd say you need to stay off the boost until you can patch in a good sensor. What are all the numbers that are written on the top of your boost/pressure sensor????????

The secondaries??? If you could buy a couple of wire taps and some extra wire, you could tap into the secondarys at the ECU, and put a digital meter on the wire taps. Then go for a ride. They should read 12v (indicating not in use) until you hit 3500 rpm under a load, where upon the voltage should drop down dramatically to some figure like 4-7 volts, depending on how much load is detected.

 

Look at this: https://www.rx7club.com/forum/attach...&postid=601960