Fuel Injector Lag Times Chart
 

http://injector-rehab.com/shop/lag.html


Discussion on this? This is really hard data to find on the nets..

The two Ford 19lb injectors, are the Design2 & Design3 types.


The D2 ones, -really- fast open times.

Looking for what -should- be used to tell the ST how fast your injectors really open.

This thread has some info from Jim Corenman

https://rennlist.com/forums/8134623-post19.html

If you follow the links to the specs on the ford racing parts site, you 'll get the voltage offset and can work out the multiplier for your fuel pressure.

Of course, ifyou've got some other injectors, you need to make the assumption that all design II/III injectors are created equal (i.e. no real difference in opening time between Ford Design III versus OE Volvo Design III)

I believe the LH parameter for injector opening time is specified at 13.1V. Here is my reply to Jim's post linked above:

https://rennlist.com/forums/8135095-post21.html

I do have to say that the 0.64ms 42lb injector figure @ 13V linked on Jeff's initial post is much smaller than what I got from Ford Motorsports' specifications.

From my research, Ford Motorsports M-9593-C302 19lb injectors should have an opening time of 0.77ms at 13V and 55psi fuel pressure. Here is the link for reference: http://www.fordracingparts.com/parts...-9593-c302.pdf

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

Don't suppose anyone ever managed to find opening times for EV6 19lb injectors? (the thin-body Design III type with 4 holes).

I can find comprehensive data for the Ford EV1 (single pintle) 19 lb injector, and also for both EV1 and EV6 24lb injectors.. but I can't find any opening time data for 19lb Bosch 4-hole EV6 injectors.

Short answer is no, not that I've been able to find. There is data for the Ford Motorsports part#'s, but not the Bosch part#'s. And the charts that I have seen, such as the one that Jeff posted a while back (above), don't include part numbers... :banghead:

If you are switching from stock 19# to something different (e.g. newer 19#) then it is pretty easy to find an appropriate opening-time (latency) with Sharktuner, assuming you have a decent fuel mapping for idle (e.g. AFR close to soich in non-cat mode, or O2-adjust averages within a few percent of zero using the NBO2 sensor in cat mode). All you have to do is get the car started and warmed up, then fiddle with ST's opening-time until the AFR (or Ox-adjust) comes out right. If the idle fuel is too rich, then reduce opening-time and vice-versa. The opening time number should come out somewhere between 0.7 and 1.5 ms.

The theory is this: LH starts with the MAF reading (which won't change with different injectors), calculates a "net" injection time, then adds the opening time. If you change to a "quicker" injector then the fuel will be too rich (the actual injector-open time is longer, because it opened faster than the old injectors). So if you reduce ST's opening-time, then that reduces the total injector time, so that the actual injector open-time comes out the same as before.

This is only a first approximation, because injector-opening isn't a simple linear function and the flow rate is probably not exactly as advertised. So you will still need to at least check the fuel mapping, but it should be close.

Cheers, Jim

Yep, thats what I concluded with a fairly exhaustive google (mostly finding ford forums where people want the data to change injectors and adjust the factory ecu to match).

Not a huge issue for now - I'll just tune AFR's for the new injectors.

What we need is someone with a good selection of injectors, and an oscilloscope :)

Here's an excellent page on measuring injector waveforms:

http://www.automotivetestsolutions.c...rWaveforms.htm

(link came from this good discussion on opening times at megasquirt forums http://www.msextra.com/forums/viewto...p?f=89&t=31326)

Ok.. some digging..

Bosch 0 280 155 710 - aka Ford F6VE-A5A are 4-hole 19lb design III injectors (I actually have some here somewhere bought a long time ago but rejected for 928 fitment). They're used by a couple of guys who tune their EEC in Ford Rangers etc. One of them spent some time figuring out settings for the injector offset, and I pulled the graph below out of his ECU binary file.

Using interpolation, it gives an opening time of 0.48ms for some design III 19lb injectors. That sounded a little extreme to me, especially as the data wasn't from the manufacturer or someone I trust to measure accurately, so I went with data based on this spec sheet for Bosch-made Ford design III 24lb injectors:

http://www.fordracingparts.com/parts...9593-aa302.pdf

I set my injector opening time to 0.66ms, and the car is much happier on the stock maps.

I'm using Bosch 0 280 155 746 - which are a 19lb injector commonly found in volvo's and cheap to pickup, plus they have the correct grooves for mounting on our fuel rails with the stock retainers. This will do until I get my hands on an O-scope and can get the actual waveform :)

Not too long ago I swapped out my original injectors for some Ford 4-hole that everybody seemed to think provided better atomization. I'm back to just running my stock LH and stock O2 sensor (which is new) and stock exhaust (no x-pipe). Car seems to be running very well, but fails smog with high NOX. Passed fine 2 years ago.

I found a split injector o-ring and thought that was leaning out that cylinder. Fixed that. Smog results were even worse.

Do I need to be concerned about the opening time of these 4-hole injectors versus stock? If so, that's not practical for me, and I'll go back to the stock injectors after a Witchunter cleaning.

Ok.. the injector opening time has been niggling me.. so I just ordered a 2-channel digital storage scope (usb PC based). I'd like to know what the actual opening time is for my injectors :)

I should be able to connect up the scope to a single injector and the nearest knock sensor, and with a set of test leads manually fire the injector to compare the time between voltage drop and the noise of the pintle/disc opening or closing. I'll jumper the fuel pump and use a mityvac on the FPR to set fuel pressure to idle spec while testing.

I'll post an update when I get a chance to take readings for the injectors I have in both 928's - one has stock S4/GT/GTS injectors, the other has the volvo 4-hole ones which seem to be a lot faster.

edit: In the sharktuner software, it states injector opening time is specified at 13.1V, so thats where I'll set my supply voltage. What it doesn't state is test pressure - any ideas? I'm going to assume either idle pressure, or perhaps 3bar.

The way I normally do this measurement requires a 2 channel scope, a switch, and a pressure sensor. I pressurize one size of the valve, and then on the other side I have the pressure sensor followed by some kind of restriction. In this case I would think just a plugged hose with a small hole in it. You put the switch signal on ch1 and the pressure signal on ch2 and just measure the sucker. When I do it I use a high current square wave instead of the switch, but the switch should work if mind the bounce.

The knock sensor will detect the open event too (the "click" noise when the pintle/disc hits the stops). The delay in detection can be worked out using the speed of sound through aluminium (e.g. 0.031 of a millisecond at 20cm from the sensor). Here's an example pic linked from the msextra megasquirt forum:

http://lh4.ggpht.com/_UxZNtXbBtw4/TI..._I_U_knock.gif

You can see the detection of open/close on the knock sensor compared with voltage for the pulse. I figure by connecting to a knock sensor and the closest injector, it'll provide an easy measurement of the opening time.

While I could just pick an opening time and tune the car to the AFR's I want through the whole range, I'd like to start from a point where the stock fuel map produces stock-like results with the new injectors, to preserve the option of stock emissions with non-stock injectors. Currently I know from experience that switching to the disc injectors makes the car run a lot richer at idle, implying a much faster response time for disc vs. pintle.

Plus there's the handy side effect of a little more headroom on the duty cycle from faster opening times :)

Why not just do a bunch of open loop logging runs with stock injectors, then switch to the new injectors and move the injector size down until you see the same AFR logs as with the old injectors? With no other modifications other than injectors, this should be pretty accurate.

Dan
'91 928GT S/C :eek: 475hp/460lb.ft

I've never worked with the shark tuner or modified a injection computer, but I worked with solenoid valves a bit. In general the amount of fluid that goes through a valve is (some non linear function of the pressure difference on the two sides of the valve) * (the time the valve is actually open) where the time the valve is actually open is the energized time - the opening time + the closing time. Since the opening time and the closing time are often quite different this results in a non linear function of fluid volume vs energized time. This may not be too big of a deal unless you are running closed loop, where you are trying to use feedback about what your valve opening time did in the real world to adjust your valve energized time. When you have this sort of loop the nonlinearity can easily make the loop unstable. The loop usually does not actually blow up, but the instability can cause the loop to operate with a surprisingly large error. I have tried different ways to design the feedback loops to try to stabilize them, but so far I have not come up with anything that works as well as having a reasonable idea of the opening and closing times and factoring them explicitly into the feedback logic.

That would work as long as all the injectors were performing to their full potential.

Unforunately the reason I swapped out the stock injectors on the 87 is they weren't flowing evenly from bank to bank - i.e. at least some of them are clogged (I had very different AFR's between each side of the engine).

I had already decided to do some testing between each 928 (both are non-cat - there is no O2 loop) - by swapping the same MAF between each, noting the CO pot value with stock injectors on one car, and then setting the other car with non-stock injectors up with the same MAF and CO Pot value, I should be able to comparatively determine the opening time by changing it to achieve the same AFR on both cars.. but it still relies on the assumption that the injectors in both cars are clean (the 89 is running 24 year old stock injectors).