Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Haltech Injector timing changes between Batch and Semi sequential

General Tuning Discussion

Forum Posts



Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads


I have just started to get my Haltech Elite 1500 up and running and have noticed some strange behaviour with regards to injector timing.

I am coming across from an old DTA E48 ecu that ran batch fire injection and wasted spark using an EDIS coil pack. This was installed on a Stock B16A2 with Jenvey 45 ITB`s and a 36-1 crank trigger.

In moving to my new setup I have installed a Home/Sync trigger and setup the timing correctly to ensure that No.1 fires at TDC compression.

As I am using ITB`s I am using Aplha N and have TPS vs RPM for my main fuel map. I have populated the fuel and ignition maps the same as my old setup up but I don’t get the injector time as the value in the map. I was hoping that the fuel and Ign maps would read across and just have to work on the warmup/transient throttle stuff.

I have checked all the compensations ECT/IAT/02 STFT etc and cannot find why the injector output time is different from the Base Map fuel time. I have noticed that this changes also depending on the type of injection is running.

Below shows a datalog during a stationary idle and short throttle blip, the top two traces are semi-sequential and the bottom two are batch injection.


Does anybody know why the posted Injector 1 output time differs depending on the style of injection selected? I would expect that whether using Semi-sequential or Batch injection the injector ms time detailed within the base fuel map would be the amount that the injector is driven.

well, a batch system fires half the time, twice as often.

David, Thanks for your response. I understand this but for the bottom trace (batch)the demanded amount is 2.6ms and the injector output is 3.3ms. This is 126% of the requested amount. Where as for the semi-sequential the demanded is 3.6ms and the injector output is 2.2ms. This works out as 63% of the demanded amount.

For batch I would expect to see an injector drive of 1.3 then this twice per cycle totals the requested 2.6ms.

I am still no clearer as to why the ECU is not delivering the demanded fuel.

Perhaps the deadtime is included. You would have double the deadtime in batch mode.

Hi David,

Why would the deadtime need to be doubled when running in Batch Fired operation? I haven't seen this needed to be done on engines that that I have worked with that run in Batch or semi sequential.

What I mean is that the injector open time in batch fire, included the deadtime for each injection, and since there were twice as many injections, then the deadtime will show up twice (ie, it shows up double) I think the issue is that the reported injection time includes the deadtime, and is not the "effective" injection time. I would expect the effective injection time to remain the same.

Perhaps an example would help. If the fuel table requests 2ms of fuel, and the injector has a deadtime of 1ms, then the injection time would show up as 1+2 = 3ms in sequential mode, and 1+(2/2) + 1+(2/2) = 4ms in batch mode, so you see a 33% increase in injection time when in batch mode.

I looked at the graphs a little more closely, I see that short term fuel trim, and air temp correction is also affecting the fuel output, so comparing the injector time to the base fuel table amount may not be telling the whole story here.

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?