Help with lean condition/hesitation
06-17-12, 08:02 PM
#1
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Help with lean condition/hesitation
Okay im finally getting around to putting my turbo vert on the road but ive been chasing this problem for a few days and cant seem to straighten it out. Im assuming its fuel delivery related. Itll start and run, idles like a 7, but when i try to give it throttle it goes completely lean according to my aem wideband. If i gently increase throttle input til i get to the point the secondaries kick in it richens back up and the hesitation goes away. The tps is tested good, fuel pressure is coming in around 40 psi, however when i test voltage at the fuel pump i get 10-11 with the pump unplugged and 6-8 with it plugged in. I tried running an a jumper from the battery direct to the pump and voltage still drops to 9 volts across the pump. Do i have a walbro thats crapped out and cant supply enough flow? All new lines front to back, new filter, older pump.
06-17-12, 08:17 PM
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Oh and it smells pig rich too. im wondering if i dont have a weak pump and or sticky primary injector. Injectors have brand new clips but i should probably pull the and have them cleaned
06-17-12, 08:55 PM
#3
How are you testing voltage drop across the fuel pump? Understand that in a circuit with one source and one load, all voltage should be dropped across the only load, so 12v should be seen if you're measuring voltage from the positive wire to the negative wire. If you add more loads in series with the pump, you will have lower voltage drops across all components based on how much resistance they are. So if you didn't run a new ground wire, it might be acting as a resistor, dropping the 3 volts.
Now, as for why it goes super lean when you stomp the gas, it could be a number of issues. It could be your fuel pump running on 9v. You should definitely fix that. However, if I were you, I'd start by hooking up a voltmeter to the MAP sensor (boost sensor... pressure sensor... I forgot what Mazda called the damn thing) and use a vacuum pump to change pressure on it while you watch the voltmeter change. It is the right MAP sensor for that ECU, right?
Also, did you verify it's timed properly?
Now, as for why it goes super lean when you stomp the gas, it could be a number of issues. It could be your fuel pump running on 9v. You should definitely fix that. However, if I were you, I'd start by hooking up a voltmeter to the MAP sensor (boost sensor... pressure sensor... I forgot what Mazda called the damn thing) and use a vacuum pump to change pressure on it while you watch the voltmeter change. It is the right MAP sensor for that ECU, right?
Also, did you verify it's timed properly?
06-17-12, 09:03 PM
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Well i check resistance on the ground circuit and had only .4 ohms, i measured voltage both across the fuel pump pins at the connector and by using an outside ground source. Im using a fluke meter. All sensors ect came from my turbo donor car that started to exhibit this condition prior to the swap but it used to go away as the vehicle warmed up. I just purchased a new water thermo sensor but i still need to install it. I do have another 318 map sensor that ill try swapping in
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06-19-12, 08:39 PM
#9
I get it now. What I meant was that you need to check the pump side wiring to ground. With it unplugged, check the +12v and gnd wires (once again, on the PUMP side) to ground. Verify there's not a short there. That's a bad day if you do.
Now, with the pump running, if you're still getting 9v at the pump, you need to voltage drop the rest of the circuit to find out wtf is happening. So take a voltage reading across the piece of wire going from the connector to the battery (pump running). Then do the same on the ground side.
Now, with the pump running, if you're still getting 9v at the pump, you need to voltage drop the rest of the circuit to find out wtf is happening. So take a voltage reading across the piece of wire going from the connector to the battery (pump running). Then do the same on the ground side.
06-19-12, 10:02 PM
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That's when i get 9v. Ive ran a jumper from the battery positive and have 12v obviously, i depinned the power lead from fuel pump connector. As soon as i attach it to the pump power drops to 9v. I think my pump has bad windings and creating too much draw. I have tested EVERYTHING else i can think of. Short of replacing the pump and fpr i dont know what to do.
06-20-12, 11:01 AM
#11
Here's what I'm talking about. Take a look at the drawing. In order to find out where the other 3v are going, you have to voltage drop the wires individually. You already know the pump is dropping 9v. So that's a 9v drop from B to C. That means there's still 3v in the circuit that's unaccounted for. Take a voltage reading (pump on) from A to B, and then another voltage reading from C to D.
You should also unplug the connector and read the resistance to ground on the pump side of the connector.
You should also unplug the connector and read the resistance to ground on the pump side of the connector.
06-20-12, 07:44 PM
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Those measurements were taken with current batt voltage of 12.4. I depinned the power lead from the fuel pump harness and ran 2 jumpers from the battery, one to power the pump and another to test off. Im using the factory ground point through the harness with the fuel pump ground still pinned
06-20-12, 09:00 PM
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Stock sized (idk what is it like 16-18). No different than i have on my brothers and his has no issues (s4 na swapped to t2, except he doesnt have a resistor pack obviously) his pump runs at 11.7 volts across the pump positive and negative
06-20-12, 09:06 PM
#16
It's pretty obvious you have some sort of high resistance connection if just plain old wire is creating enough resistance to drop any sort of significant voltage. Wire should show a voltage drop of damn near 0v. I use 12ga wire on mine, but others say to use larger wire. 16 or 18ga wire is pretty damn small (for using any aftermarket pump).
I'm still not saying this is the definite cause, but with no resistor pack in series with your pump, you should definitely be getting a full 12v. Did you ever try swapping over the MAP sensor? Also something I didn't mention earlier is that the AFM could easily be sticking, causing your lean condition on accel.
I'm still not saying this is the definite cause, but with no resistor pack in series with your pump, you should definitely be getting a full 12v. Did you ever try swapping over the MAP sensor? Also something I didn't mention earlier is that the AFM could easily be sticking, causing your lean condition on accel.
06-20-12, 09:32 PM
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Tried swapping another 318 map, 318 maf, verified ign timing, verified tps, swapped coil packs, verified no codes using an original mazda oem code scanner, new water thermo sensor and oxygen sensors, new plugs, msd 10.2 wires, new fuel filter, new fuel lines, pulled thethe pump andand verified pick upon filter clean, very minimal debris in tank.... im running outta ideas. Oh and thanks for the help in case i forget. Im gonna pull the intake mani and put a replacement fpr in. Ive also verified no vacuum leaks
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