It's Alive - Delco 173

[Holden202T]

it looks to me like every time you give it a bit its lean as at higher map readings, maybe the injector rate needs to be a bit closer to .12 still.

but definitely make sure its running on 6 cylinders, your wasting your time tuning if its not!

as for WB readings, if a cylinder isn't firing there will be more o2 in the exhaust so will slow lean as you thought!

[stevemc32]

Haven't had a chance to do any testing or a cylinder check but got a quick little idle run in the other day and it opened up more questions.

There are two similar events in the attached log of interest, the first at 0:53 and the second at 2:45, where the idle becomes unstable without any external input. The second event looks to have been triggered by entry to closed loop mode (commanded 14.7 AFR) when the coolant temp reached 44 degrees in accordance with "Closed Loop Params - Closed Loop minimum coolant temperature While Idling". I can't figure out what caused the first unstable event to occur. I'm using the Innovate LC-1 simulated NB output into pin D7, would it be useful to remove this and run without any NB input?

In both cases, rpm starts to drop, IAC reacts to the rpm, MAP increases and spark advance drops with the MAP increase. Throughout the events the VE remains fairly constant (within 10%) however the BPW climbs up and the WB goes very lean for the duration. Can the BPW be considered as a direct indication of the amount of fuel being supplied, ie 6ms BPW is 3 times as much fuel as 2ms BPW?

I've spent about 2.5 hours running through that first event, researching and trying to learn what is happening but I just can't figure it out.

[Holden202T]

what injector rate are you using ?

im beginning to think the majority of your VE table is lean due to a wrong injector rate, but its hard to say.

personally I have never had much luck with narrow band simulation and just don't run it on my race car and also either had a second bung for proper narrowband or didn't use it while tuning cars.... might be just me! - regardless I don't think that's your issue.

ok so what im seeing, and the 2:45 part of the log is a nice example....

well to begin with, your idle WB is like 15.90!!! that's way too lean, especially when the computer is commanding 13.3 at the time. then like you say, as it goes to 14.7 commanded AFR it just gets leaner and leaner, and you can see as it looses vacuum (map increasing) so is the lean condition.

so you either have to do one of two things, change the injector rate so at idle the wideband is matching the commanded, then if that is happy like I said, put it in gear and load the motor up on the brake (like doing a burnout) and see if it goes lean as you get the map sensor over towards 100kpa, if that is ok then you might be able to start loading it up more at higher revs (really need to drive it for this) and see what it does.

if you don't want to change the injector rate then the other option is to start adjusting the VE table. use the CalcVE histrogram to plot what it should be and make the changes and see how it works.

the end result will be dictacted by the VE table, if you get to 100 in any VE table cell, then you need to adjust the injector rate to richen the whole ve table up till you can get highest value about 85-90.... but this really requires you being on the road or a dyno.

also I assume you are running the tune changes I made ? if so what injector rate ?
this is telling me, that entire 800rpm row in the ve table is too lean, and for it to be like that the injector rate is likely out.

[Holden202T]

another thing to check, if you have a gauge in your fuel rail, check the pressure at idle, if you don't have a gauge then have it running at idle, note the wideband, then unplug the regulator and note if the wideband changes, should go rich if the regulator is working properly.

[antus]

if you don't want to change the injector rate then the other option is to start adjusting the VE table. use the CalcVE histrogram to plot what it should be and make the changes and see how it works.

... and its important to keep it smooth. Collect some data, look at the graph and identify any trends you can see, then modify a whole area (eg 5x5 cells more or less, and smooth out the edges to match back in to the rest of the table. Data collected from calcve can only be used if the VE table was smooth looking to begin with (not like a porcupine!)

[Holden202T]

If its te one in the post above I adjusted it is pretty flowy !

[stevemc32]

Yeah sorry, should have mentioned any changes that I've made for each log. That last one was using the bin modified by Holden202T with the only change being an injector rate of 0.1123.

After reading injgtr202's "First Fire Up" thread last night I went and had a look for some part numbers on my injectors today. They are 0 280 150 203 which turns out to be the correct part for the VK and the flow rate is listed as 17.6lb/hr with the kinjflow calculator giving 0.107. Before fitting them I put new filter buckets, orings and pintle caps on each one and tested them with a 12V supply to check the solenoid was operational. All seemed ok with that quick test.

I'll get a chance to run it again on the weekend so will do a quick cylinder check by pulling each injector plug in turn and will also do the fuel regulator check by unplugging the vac hose. Could an exhaust leak upstream of the WB cause a lean indication? I would have thought that the pressure in the exhaust would keep any free air out of the system as the exhaust pushes out of any leak.

[stevemc32]

Just found this information while researching a possible exhaust leak.

"The exhaust fumes follow the path of least resistance and your exhaust piping is just that. There is a GREAT deal of exhaust trying to escape at once and it will try to "follow the pack", for lack of a better term,lol. Once it creates a flow, it will indeed suck air IN from the leaks and introduce air into the stream like zl1560 mentioned. This suction is known as "scavenging" and is why sometimes its better to use an exhaust system rather than go with open headers on some setups because the 'scavenging' effect literally aids in the exhaust being pulled from the combustion chamber, helping to lower the back pressure even more than an open header could."

Guess I'll have a good look over the exhaust as well on the weekend as there could be an issue with the intermediate pipe I had made up to join the headers to the old exhaust system.

[Holden202T]

Yeah but your symptoms suggest the wideband is right and it is infact lean, not wanting to idle, stumble on throttle crack etc.

I always thought the vk injectors were 19lbs but I have no idea for sure.

One way to check, plug color if they are black it's rich, if it's white or light color it's more than likely lean...

Also plug colors between cylinders will give you an idea if one cylinder isn't firing properly.

Try my tune without changing the injector rate and see if that helps. If it does it should be everywhere!

[stevemc32]

That makes sense about the exhaust probably not being a problem given the other factors.

I got the 17.6lb/hr number for the 0 280 150 203 injectors from this website http://www.fuelinjector.citymaker.com/F ... Rates.html but I've just had another look at it and now see it has listed them at 2.5 bar so for a 3 bar application it would be 19lb/hr as you thought.

I got in a chance to do another quick run and have some logs, the first one is stationary, second one a brief run up the street. I'll attach the bin as well, this is virtually just the one you uploaded a couple of pages ago after your adjustments to the VE table with the only changes I made being aligning the MapB inj rate and PPK value. When this one was uploaded it had an injector rate of 0.124 which we considered too high as kinjflow was suggesting 0.104 and I did end up getting it down to 0.112. Today's logs were done back up at 0.124 as per the uploaded bin.

I haven't shown the warmup log this time but the AFR was generally between 0.5 to 1.0 on the lean side of commanded until warmed up then rich as shown in the first log. I also checked all 6 cylinders were firing and the fuel pressure regulator operation with results exactly as expected so all is good in those areas.

Thanks again for the help, when I get a chance I'll do a quick run on the brakes to see if I can load it up a little.