New Problem...No power to injectors 944S
01-11-2018, 09:48 AM
#63
Same as it has been all it's life, 150 across all four. Yes I know that's low for this car but I have a reconditioned head to go on the new engine I am building. This is just to get the old one back on the road till I complete the build.
Cured all of the gremlins in my car.
01-16-2018, 09:31 PM
#65
Replaced the Ignition Control Module and tried a known working coil and DME from a running car. No change. I decided to hook up the Fuel Pressure Gauge to show the bar (see below).
I have eliminated Spark and Compression so at this point it is just getting too much fuel. The NOID like pulses so the injectors are not stuck open.
That leaves the Injector Ballast Resistor bank, FPR, and Damper. The FPR is only a couple years old and no fuel leaks from either the FPR or Damper. The Ballast resistor checks okay too.
Despite that I have a replacement damper and ballast resistor on the way. If those don't effect anything I'll try a new FPR.
Here is a pic of the Fuel Pressure (non trying to start)
Fuel Pressure (not trying to start)
01-16-2018, 10:46 PM
#66
Rennlist Member
Now "that" sounds like the bad AFR problem I mentioned in post #40 (unlike your prior video). Have you checked the voltage on the AFM/MAF? It should be in the .6-.8 volt range. Also test the DME temp sensor and quadruple check for vacuum leaks. If you think it's rich, you may be able to confirm by creating a leak at the ISV (or elsewhere) and see if it runs that way. Or play with the FQS settings.
01-17-2018, 05:34 AM
#67
Now "that" sounds like the bad AFR problem I mentioned in post #40 (unlike your prior video). Have you checked the voltage on the AFM/MAF? It should be in the .6-.8 volt range. Also test the DME temp sensor and quadruple check for vacuum leaks. If you think it's rich, you may be able to confirm by creating a leak at the ISV (or elsewhere) and see if it runs that way. Or play with the FQS settings.
I shorted the DME temp sensor connection and no change. I will do those voltage checks. Maybe a lead broke and it thinks it is wide open? I tried my spare AFM and no change.
I’ll report my finding.
01-17-2018, 08:47 PM
#68
Now "that" sounds like the bad AFR problem I mentioned in post #40 (unlike your prior video). Have you checked the voltage on the AFM/MAF? It should be in the .6-.8 volt range. Also test the DME temp sensor and quadruple check for vacuum leaks. If you think it's rich, you may be able to confirm by creating a leak at the ISV (or elsewhere) and see if it runs that way. Or play with the FQS settings.
I then went to the ISV. I first rechecked that the IPS was set and working correctly by testing the continuity at the end of the harness. That was fine.
However, I figured I’d see what the voltage is at the ISV. It stayed at just under 12 volts (key on) no matter what position the throttle was in.
Is that something that only changes when the engine is running?
EDIT: I see it should be on as long as the engine is cold.
Last edited by CVR_Rally; 01-17-2018 at 09:25 PM.
01-17-2018, 09:55 PM
#69
Rennlist Member
Tom unfortunately it isn’t the AFM. Used my tested AFM and also checked voltages and that part of the system is in tip top condition.
I then went to the ISV. I first rechecked that the IPS was set and working correctly by testing the continuity at the end of the harness. That was fine.
However, I figured I’d see what the voltage is at the ISV. It stayed at just under 12 volts (key on) no matter what position the throttle was in.
Is that something that only changes when the engine is running?
EDIT: I see it should be on as long as the engine is cold.
01-17-2018, 10:30 PM
#70
The ISV is controlled by pulse width modulation -- i.e., super short little bursts of 12 volts turned on and off 100+ times a second. This is a digital computer's way of approximating variable voltages. The signal can't be tested with a typical multimeter. You'd need a very fancy multimeter or an o-scope. I've never actually looked at the pulse with the car not running, but it regulates the RPMs, so has nothing to do when the motor isn't running. Here's a video I did a while back to check the basic functionality of the valve (though the DME driver can go back too). If you suspect a bad valve, just block it off and open the idle screw a bit and the motor should start and run. Have you checked the DME temp sensor? If it is broken or the harness has a break, it will over-fuel your car because the DME thinks you are in sub-arctic conditions. Very easy to test with a multimeter. Clarks has the ohms, but you're looking for a few thousand ohms when the car is cold, and a few hundred when its warmed up. An open sensor will flood the car, and a shorted one will make it go very lean.
https://www.youtube.com/watch?v=pAZhtdtvnGo
https://www.youtube.com/watch?v=pAZhtdtvnGo
I have replacement ballast resistors and damper on the on the way so that’s next.
01-17-2018, 10:44 PM
#71
Rennlist Member
i was actually looking for that video earlier. Yes DME temp sponsor is good as is the harness back to the DME. It was suggested I short the pins to force the engine lean and it had no effect. This is a total stumper.
I have replacement ballast resistors and damper on the on the way so that’s next.
01-17-2018, 11:05 PM
#72
More often than not, it's something fairly straight-forward and normal, you just have to find it. Have you tried a spare DME and/or looked for cracked solder joints? If you have a fancy multimeter or o-scope, I'd be inclined to look at the signal going to the injectors.
01-20-2018, 01:16 PM
#73
I edited the main post as well.
So although the DME Temp sensor seemed to test okay a few weeks ago it turns out it wasn't and today it read open. I had bought a replacement, installed and it fired right up! I've had one go bad before but it didn't act like this and my reading earlier had led me astray.
So although the DME Temp sensor seemed to test okay a few weeks ago it turns out it wasn't and today it read open. I had bought a replacement, installed and it fired right up! I've had one go bad before but it didn't act like this and my reading earlier had led me astray.
01-20-2018, 02:02 PM
#74
Rennlist Member
I edited the main post as well.
So although the DME Temp sensor seemed to test okay a few weeks ago it turns out it wasn't and today it read open. I had bought a replacement, installed and it fired right up! I've had one go bad before but it didn't act like this and my reading earlier had led me astray.
So although the DME Temp sensor seemed to test okay a few weeks ago it turns out it wasn't and today it read open. I had bought a replacement, installed and it fired right up! I've had one go bad before but it didn't act like this and my reading earlier had led me astray.
You're not the first and won't be the last to "rule out" the true cause of a problem. Good for you going back to test it again. Some people can be fairly stubborn when diagnosing and convince themselves for whatever reason that it can't be XYZ because of some ill-conceived logic or iffy testing. When 99.9% of the time a problem is caused by the same 3 or 4 issues, you're well-served to exhaust all efforts testing them before convincing yourself that YOU are the guy with that 1 in a 1000 problem... But I digress...By the way, the Vitesse MoMonitor basically shows you all sensors at a glance too -- no OBDII needed.
01-21-2018, 02:39 AM
#75
Three Wheelin'
VEMS shows all data live on the laptop or your phone, it would have been clear first time you look at the screen.
I remember suggesting to short coolant temp sensor connector pins (on the wire side), it should have started (though with some effort depending on ambient temperature).
I remember suggesting to short coolant temp sensor connector pins (on the wire side), it should have started (though with some effort depending on ambient temperature).