Injectors firing without the engine running

arr_kid · Post by **arr_kid** » Wed Nov 07, 2007 12:33 am

When I power up MicroSquirt the fuel pump primes then the injectors start to fire & flood the engine. Pulse Width is showing 2.3mSec and the Runtime Status shows the engine in RUNNING.

My uSquirt is driving an EDIS-4 module and has been running the ignition only for a few days. Iâ€™m getting resets when the engine is cold but it settles down when up to temp so I decided to take the plunge & remove the L-jet & connect the injectors up via the stock resistor pack. My CHT & IAT are only roughly calibrated for now.

Hopefully Iâ€™ve just cocked up some settings up in Megatune but Iâ€™ve search through and nothing is biting me on the nose.
If someone could take a look at the attached msq and make some suggestions itâ€™d be appreciated.

arr_kid · Post by **arr_kid** » Thu Nov 08, 2007 12:17 am

Bit of an update. Re-flashed usquirt with a fresh download of v2.881 but still shows the same Pulse Width and Runtime Status is RUNNING as soon as it connects/powers up.

I pulled the plugs off the injectors to stop it flooding, 12v on one bank & zero on the other. I changed the Injector Staging from Alternating to Simultaneous which changed to 12v on one side and 9.5 on the other.

Thinking it may be stuck in test mode or something I changed the Injector test mode & cycled the power which caused the fuel pump to run. Changed back to Normal Mode & cycling the power but the fuel pump carried on running. The only way I could stop it was to re-flash again.

Tested the resistor pack which checked out at 6ohms each and are wired in series with the injectors which are all about the 2.4ohm mark.

Starting to think there may be something more serious going on, any suggestions?

Matt Cramer · Post by **Matt Cramer** » Thu Nov 08, 2007 7:17 am

Your data log shows a zero duty cycle, so it appears the Microsquirt "thinks" it is not injecting any fuel, but had instead fired a priming pulse and stopped. It could be damage to the injector drivers, but I'd check the injector wiring first.

arr_kid · Post by **arr_kid** » Thu Nov 08, 2007 10:46 am

The wiring checked out ok. Itâ€™s a 4 cylinder flat four with one side of 2 injectors wired in parallel to each of the INJECTOR9 & INJECTOR10 wires. The +12v from the relay connects to one side of the 4 resistors then onto the other side of each injector.

With the injector plugs in place, measuring resistance between Amp plug Pin 9 and +ve gives 4.2ohms & Pin 10 and +ve gives 4.3ohms.

Iâ€™ll try the latest V2.883 code but if that doesnâ€™t work is there anything else I can do before forging ahead with some micro surgery to replace U6 & U7?

arr_kid · Post by **arr_kid** » Thu Nov 08, 2007 11:14 am

Same deal with the V2.883 code.

Am I the first one to blow up a uSquirt?

Matt Cramer · Post by **Matt Cramer** » Thu Nov 08, 2007 11:56 am

arr_kid wrote:The wiring checked out ok. Itâ€™s a 4 cylinder flat four with one side of 2 injectors wired in parallel to each of the INJECTOR9 & INJECTOR10 wires. The +12v from the relay connects to one side of the 4 resistors then onto the other side of each injector.

Could you draw a diagram of this? That doesn't sound right, but I may just be confused by your description.

arr_kid · Post by **arr_kid** » Thu Nov 08, 2007 12:36 pm

No probs, it did sound a bit strange.

Matt Cramer · Post by **Matt Cramer** » Fri Nov 09, 2007 6:01 am

Ok, that clears things up. When you measured the voltages, was that with the injectors plugged in and the Microsquirt powered up but the engine not running?

arr_kid · Post by **arr_kid** » Fri Nov 09, 2007 6:18 am

Voltages were measured at the injector plug (unplugged from the injector) with MicroSquirt powered up (but not running obviously).

Strange that the engine status returns a 1 for engine running or is this normal?

The resistances were measured at the AMP plug (MicroSquirt removed) and the connection to the +12v to the resistors.

I'm racking my brains to think what I could've done wrong here.

BTW Thanks for taking the time to look into this.

arr_kid · Post by **arr_kid** » Sun Nov 11, 2007 1:54 pm

Right, managed to score a couple of fresh mosfets and had them professionally replaced, they had definitely blown.

Megatune engine status still reports the engine in running mode as soon as it powers up, shows cranking while turning over (no plugs or injectors connected) then the running mode goes out after cranking (Engine status = zero). Could someone confirm this is correct please?

Rather than burn out another pair of drivers I decided to connect a set of 4 high impedance injectors (without fuel) and by-pass the resistors. I altered the Injector Characteristics as per manual

â€¢ If you are running high-impedance injectors (greater than 10 Ohms), then set the:
o PWM Time Threshold to 25.4 msec, and the
o PWM Current Limit (%) to 100%.

But I donâ€™t hear the injectors opening while cranking, they work ok with 12v applied directly. Any ideas before I give the low impedance injectors another go?