Still working on lean fuel mix

[jeff1234]

Hello all, I am still getting reading from my fuel/air gauge that indicates a lean mixture. I changed the map to see if that was the problem. No effect! Same results. I installed a fuel pressure gauge, inline, before the fuel rail. my pump is putting out 48 psi at idle, which is right for a 1000feet above sea level I believe. At very light throttle settings I get rich readings that drop back to stoich. At full throttle the lights all but disappear and then go to red, which is lean. I dont see anything on the plugs like aluminum specs. I have a brand new o2 sensor. I haven't checked the pressure under load but I get no codes. Its like the car feels like its starved for fuel until you start to see some boost then it builds some power. I dont see any evidence of raw fuel in the vacuum line for the FPR,:confused2:
jeff1234

[trannybuster]

Whats your setup?

[jeff1234]

Trannbuster, 1985 Shelby Charger 2.2 TII L/M intercooler and single piece intake. Ported exhaust manifold 2 5 inch exhaust system with Magnaflow straight through.Otherwise all stock.
jeff1234

[cordes]

Pinch off the return line with the B+ terminal hooked up to the positive terminal on the coil to dead head the pump. You should see 90+ PSI out of it. If not, the FP may be weak.

[jeff1234]

Cordes, This sounds like a great way to avoid driving down the road with a rubber hose coming out from under the hood and aa fuel pressure gauge taped to the window, but I need a little instruction here. What is the B+ terminal? I am guessing you mean the battery positive post. I am also assuming that the coil and fuel pump on the same circuit? Please verify!

Thanks for your help, jeff1234

[cordes]

Cordes, This sounds like a great way to avoid driving down the road with a rubber hose coming out from under the hood and aa fuel pressure gauge taped to the window, but I need a little instruction here. What is the B+ terminal? I am guessing you mean the battery positive post. I am also assuming that the coil and fuel pump on the same circuit? Please verify!

Thanks for your help, jeff1234

That's correct. The positive battery terminal. Also, the Z1 circuit is the one which both the fuel pump and coil are on. If you energize the positive side of the coil you will energize the pump for all she's worth too. It is a great thing to know for trouble shooting the pump.

[jeff1234]

Cordes, that worked pretty slick, the pump makes 100+ psi, I would say its OK. I checked the map sensor. With the engine off it puts out .9 volts. I am at about 1000 feet here. I revved it to about 4000 RPM and the best reading I could get was 1.6 volts, it should be more than that should it not? jeff1234

[jeff1234]

Cordes, I went out and made another set of readings. Look at these and tell me if they look normal.
With the map sensor unplugged, measuring at the plug that has the power lead. I get 4.97 VDC between the red lead and chassis ground. When I measure between the power lead and the negative wire I get 4.97.
With the connection made to the map sensor and the ignition on engine not running I get 4.12 vdc between the red lead and chassis ground and 4.12 vdc between the red lead and the negative wire. I get 2.148 vdc at the signal wire. As in the previous post I got up to 1.6vdc with the engine revving. I couldn't see the boost gauge but its likely that with the throttle open I am probably getting around -5hg or a litlle less.
What do you think?
jeff1234

[cordes]

Cordes, I went out and made another set of readings. Look at these and tell me if they look normal.
With the map sensor unplugged, measuring at the plug that has the power lead. I get 4.97 VDC between the red lead and chassis ground. When I measure between the power lead and the negative wire I get 4.97.
With the connection made to the map sensor and the ignition on engine not running I get 4.12 vdc between the red lead and chassis ground and 4.12 vdc between the red lead and the negative wire. I get 2.148 vdc at the signal wire. As in the previous post I got up to 1.6vdc with the engine revving. I couldn't see the boost gauge but its likely that with the throttle open I am probably getting around -5hg or a litlle less.
What do you think?
jeff1234

Honestly, I think my head hurts reading that. :nod:

Seriously though, you would be a lot better off using a hand vacuum pump to look at the readings as you progress through vac. Likewise, you could take readings if you have a compressor and a really good regulator and gauge to shoot some air in there.

I haven't seen it in a while, but there is a file out there which has the voltage vs. pressure graphed on it. IIRC Rob Lloyd originally posted it up.

[jeff1234]

Cordes, Hah! Sorry to give you a headache,LOL. I took power from the 5 vdc supply to the TPS to power the MAP. With the ignition on, the tps only has 4.17 available and more is lost at the map sensor. I need to take the power for the map from the board instead. The map sensor needs to have 4.97 volts available to put out 4.90 volts at 14.31 psi. (minimopars website-understanding the Chryusler ECU-logic module components- map sensor, the chart.) At the very least I couldnt get enough volts for 14 psi and the possibility exists that when the TPS is drawing power it is also lowering supply voltage to the MAP. This what I will change next, but I am out of L/M pins. Do you have any available?

[cordes]

Cordes, Hah! Sorry to give you a headache,LOL. I took power from the 5 vdc supply to the TPS to power the MAP. With the ignition on, the tps only has 4.17 available and more is lost at the map sensor. I need to take the power for the map from the board instead. The map sensor needs to have 4.97 volts available to put out 4.90 volts at 14.31 psi. (minimopars website-understanding the Chryusler ECU-logic module components- map sensor, the chart.) At the very least I couldnt get enough volts for 14 psi and the possibility exists that when the TPS is drawing power it is also lowering supply voltage to the MAP. This what I will change next, but I am out of L/M pins. Do you have any available?

I don't have any currently available, but they are the same pins as the sterio connectors for most all the chrysler vehicles from the late 80s through most of the 90s. Just pull out the radio, snip the connectors and call it a day.

[jeff1234]

Cordes, I found one pigtail in my desk. I rewired the the map to take 5 volts off pin 1 on the red connector. Apparently the TPS was sucking power out of the map input like I suspected because my Charger now GOES LIKE HELL!!! YAHOO, YIPPEE, man that thing flyes and I aint jokin.
Thanks to everyone who has helped me with this project. All of the times that I wanted to burn that car because it ticked me off, disappeared in second third and fourth gear! WOW thats FUN!!
jeff1234

[cordes]

Cordes, I found one pigtail in my desk. I rewired the the map to take 5 volts off pin 1 on the red connector. Apparently the TPS was sucking power out of the map input like I suspected because my Charger now GOES LIKE HELL!!! YAHOO, YIPPEE, man that thing flyes and I aint jokin.
Thanks to everyone who has helped me with this project. All of the times that I wanted to burn that car because it ticked me off, disappeared in second third and fourth gear! WOW thats FUN!!
jeff1234

That is great to hear!

[OnLooker]

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