Injectors stuck on. Components changed Page 3 new results

[cypriot_boy_2k7]

Been having issues recently with my MS1 v3 extra

First was getting shocked every time I touched the inlet manifold when then engine warmed up, think this was due to a split HT lead. Cannot test as have not been able to start due to next issue.

Injectors
I managed to get some info on the injectors I think I have that states they are infact low impedance, my settings were set for high impedance injectors. So I changed the settings to low impedance as per the mega manuals. Started and ran for 10 secs as soon as I gave a little throttle, the car cut out, since then it will not start. I have spark, I hear the fuel pump run.
What is my next test?

[Matt Cramer]

First, check the injectors with a multimeter and measure the ohms. High impedance are 10 ohms or more, low impedance are usually 1 to 4 ohms.

Next:

[DaveEFI]

Sadly, it's possible to burn out low impedance injectors with no series resistors if the settings are wrong, and no suitable fuse in circuit.

[cypriot_boy_2k7]

First, check the injectors with a multimeter and measure the ohms. High impedance are 10 ohms or more, low impedance are usually 1 to 4 ohms.

Next:

MSQ + data logs

Measured my injectors they are infact LOW impedance, bosch part number 0280150804, readings on multimeter set on 200 the lowest setting was 03.0 on all injectors.

The have been running on high impedance settings for over 1000 miles

[Matt Cramer]

There appears to have been some noise that took the MS offline when it stalled, and a processor reset. Where is the MS grounded?

[cypriot_boy_2k7]

There appears to have been some noise that took the MS offline when it stalled, and a processor reset. Where is the MS grounded?

Hi Matt its grounded to the block

[cypriot_boy_2k7]

Any ideas? Can I test any components on the board?

[Matt Cramer]

Try these low impedance injector noise reduction mods.

1. Cut the center leg on Q9 and Q12 or desolder it so it does not reach the PCB.
2. Run a length of jumper wire from the center leg of Q9 and Q12 to an unused pin on the DB37 connector.
3. Wire this pin to a 12 volt source in the wiring harness, separate from the Megasquirt's power supply wire.
4. Solder a 0.1 uF capacitor in the H1 (boot) header on the main board.

[cypriot_boy_2k7]

Hi Matt have not done what you said as of yet, i did notice 2 cables shorting in the engine bay, they are for my Idle control valve, i have since repaired the cables and tried to restart, i also done a firmware reflash, i have the data log here.

This is the diagram of how mine is wired:

http://farm3.static.flickr.com/2108/222 ... 9243_o.png

http://wiki.diyefi.co.uk/index.php?titl ... Conversion

[cypriot_boy_2k7]

I powered the megasquirt directly to 12v supply and tested (don't have a stim)

First, check pins 2 and 4 on U4. If they're not getting 5 volts in the off state :
pin 2: 1.29v
Pin 4:0v

Turn the power off and ohm out R14 and R17 :
R14 to CPU pin 21 = 02.1
R17 to CPU pin 22 = 02.1

U4 is an inverting driver. If you don't see its output on pin 7 go high when pin 2 is grounded, or pin 5 go high when pin 4 is grounded, you've got a bad U4.
IS THIS THE PROBLEM
Pin 2 grounded pin 7=0v
Pin 4 grounded pin 5=0v

Time to move on

Check the input signal on pin 1 of Q1 and Q5. Q1+Q5=0V It will be a little lower than the voltage at U4, but not by much. If the voltage has disappeared, power it off and check the ohms on R15 or R20 as appropriate.
R15=23.2
R20=23.2

Either R15 or R20 has failed, or the transistor in the current limiting circuit (Q14 or Q15) has shorted out and needs to be replaced.

If the signal is making it to Q1 or Q5, but the injector driver isn't working, first check for continuity from pin 2 of the FET to the DB37.
Pin 2 to DB37 No Continuity

[cypriot_boy_2k7]

Just checked pins 21 & 22 on the U1 my voltage on is 1.30v on each. Is this not meant to be 5.0v?

[Matt Cramer]

Just checked pins 21 & 22 on the U1 my voltage on is 1.30v on each. Is this not meant to be 5.0v?

What voltage do they get with the daughter card removed?

[cypriot_boy_2k7]

Just checked pins 21 & 22 on the U1 my voltage on is 1.30v on each. Is this not meant to be 5.0v?

What voltage do they get with the daughter card removed?

Are you saying if I remove the CPU? And check the corresponding pins?

[Matt Cramer]

Correct.

[cypriot_boy_2k7]

Hi Matt just checked this with the daughter card removed voltage on both pin 21 and 22 are at 0.80v

[Matt Cramer]

Try desoldering the FET driver. If the voltages go back to normal on these pins, replace the FET driver.

[cypriot_boy_2k7]

Hi Matt, desoldered the FETs and have found the pins to be at the same voltages as per tests above

[slow_hemi6]

Measure the voltage on either side of r14 and r17. You should have near enough to 5v on the vcc side. If you do have the 5v present then there is something pulling the other side down that is not supposed to be. No 5v and you have a supply issue.

[cypriot_boy_2k7]

Ok just tested this, I have 5v on the Left side and is dropping to 1.4v on the right side, what's next to check?

[slow_hemi6]

I just noticed you replied to Matt that you removed the Fets, but Mat actually asked you to remove the Fet Driver U4 and test.