John Speake

Do you notice a increase in Temp 2 readings on ST when "heat soaked" ?

Is this heat soaked when driving, or with car stationary ?

dprantl

Did you check your warmup map (cat and non-cat) to make sure it's zero'ed out after 80 deg F or so?

EDIT: Sorry, I meant 80 deg C duh

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

bd0nalds0n

Dan and John raise interesting questions.

When I start the car in the morning, the Temp II reading is higher than I would legitimately think the real temperature is. Say, reading somewhere north 90 degrees F. First thing in the morning, the car fires right up, faster than it ever has. It's perfect and brings a smile to my face.

When I start the car at the end of the workday, it's not uncommon to have the Temp II still showing in the 147 degree F range. I have added enrichment even at that level (and higher), because I noticed that if I start the car in regular Cat mode, the car idles like complete crap (lean) during the o2 warmup phase. It would be jerky pulling out of a parking space, sounding like it was misfiring. I noticed that when it was going to closed loop, the o2 adaptation was maxing out at -20%. So I bumped the enrichment to the point that it's around -17% once it goes closed loop, just barely within the range of what the adaptation can handle, for temp II readings that are, (with the benefit of Dan's post), much higher than 80 degrees F.

Even so, the enrichment is in the "30" to "20" range (moving from cooler to hot), so I don't think it should be contributing whole point movements in the AFR.

I am still struggling to find the proper cranking pulse width intra-day. The car cranks a lot when trying to restart after it has sit for between 10min and 4 or more hours. I generally have to open or pump the throttle to get it to fire up and don't really have a sense of whether it's too lean or two rich, and I've not had a lot of success finding the proper pulse width for a not cold but not hot startup condition. It doesn't really roar to life as much as it seems to lumber awake.

I guess that the warmup enrichment can be lingering too long, and only phases out once the car is really good and warm. If so, maybe I need a new Temp II sensor that (hopefully) more accurately reflects the true temperature, so that I can use warmup enrichment when the car is cold, but not keep the warmup enrichment going longer than it otherwise should.

All my tuning is done with the car moving, not stationary.

FredR

Jim,

downloaded the latest update and it seems to be working fine-hopefully it will stay that way.

Interestingly, I loaded a base fuel map by pasting the EZK map from Excel to compute the knock corrections required [I am now working the EZK optimisation]. At the endo fthe session I saved the data. After reopening the Sharkplotter, the base EZK map [and update map] did not show but I had a file called EZK update map in my file. This evening I pasted the base EZK excel file into a notepad file, saved it as Base EZK map.txt and everything worked fne. The update file appeared. Hence it seems that it is best to paste into a txt file rather than use excel.

Regards

Fred

dprantl

This is important. When you copy data out of some programs, they may not put the data as text into the clipboard. The easiest way to make sure you have just text in the clipboard is to paste it into notepad, then copy it again.

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

John Speake

When you say you "add enrichment" is that to the warmup map ? I think this is so from your comments, but just wanted to check.

During warmuip phase before O2 loop comes into play, if maps are identical then car should behave (or misbehave) the in the same manner, whether in cat or non-cat mode.

Do you think you might have a leaky injoector ? Do you have a fuel pressure gauge to check pressure bleed down time ?

bd0nalds0n

Yes, I was talking about enrichment on the warm up map.

Driving this afternoon, and running several errands, it occurred to me to start checking the voltage. I'm wondering if I'm getting a voltage drop when the car (and alternator?) heats up. In some cases, the ST was showing voltage at idle (with AC on) in the 12 - 12.6 range. The LM-1 was showing even lower voltage while the WB was heating up, although I do currently have it powered by the cig lighter rather than directly wired to the battery.

I'm assuming that, as far as running open loop is concerned, voltage plays a part in how much fuel is delivered per cycle, and reduced voltage = less fuel? Furthermore, does it follow that 42lb injectors are more sensitive to voltage fluctuations at idle, since the duty cycle is so low?

It's at idle and just off idle that I'm seeing the biggest changes in AFR towards the lean side after the car has been run for a while, especially like today which had a lot of errand running, getting the car hot, shutting it off and letting it sit for 10 minutes, then starting it back up again to go somewhere else...

Is the warmup map on a timer, or is it entirely temperature dependant?

On a side note, it would be interesting to have two WB02 sensors monitoring each bank in real time, then overlaying the plots. Other than injectors that are not flowing identically (and these are/were brand new injectors with less than 2k miles on them), is there any reason to think 1 bank should/would run richer than the other? I need to tune, then run the LH, using the driver's side bung, I can't tune with the WB on one side, then switch to the NB on the other side. But if I use the same exhaust stream, there's no problem between the WB and NB.

For a while I was running the more advanced ignition curve to induce retard. The #1 cylinder is the one that likes to knock most, followed by #2 and #5.

Is it correct that if I knew that the injectors were flowing diffeerently and by how much I could then put the fattest injectors in the holes most prone to knock and the leanest injectors in the holes least prone to knock? Would that matter or help? Or is it just best to have them flow most identically as possible, and let the EZK deal with those cylinders most prone to knocking?

John Speake

Hi Brian
The LH is fully voltage corrected, which is essential of course. It does seem necessary for you to sort out this side to side difference.

jcorenman

You should fix that. Cig-lighter plugs work fine most of the time, the problem is that the contacts get dirty and sometimes drop a lot of voltage (and get hot), sometimes back out a little and disconnect. If the wbO2 runs for very long without it's heater then it's toast (so to speak).

Just temperature. From your previous posting it sounds like TempII is reading high for the LH?

No, as John said that's a problem that needs to be addressed. It's either one or more funky injectors (new <>good), or a big air leak on one side (intake gasket not sealing??) or something.

Yes that may help, and for sure you want to avoid having the lean injectors in the cyl's that like to knock first. It's been discussed and on my list of "to-do's" but don't know anyone has actually done that. From what I've seen #2 and 7 seem to get retarded first, more often than not-- your #1 seems a bit odd. (But not "seriously odd"-- your left/right AFR difference gets that prize).

Are you going to be at Sharktoberfest??

FredR

Brian,




I suspect a new set of injectors is no guarantee of exact flow balance any more than a new MAF is a guarantee of exact air flow [ask John on that one] but they should be capable of flowing within a few per cent of each other. I like to know that my injectors are flowing evenly and our local agent cleans and flow checks them for me for very little money. The companies who run these rigs do no like to test "dirty injectors" because of the risk of contaminting the expensive "test fluid" and the going rate for cleaning is about $200 your side of the pond [I believe]. Once the injectors are put on a test rig you can ask the operator to record the exact flow for each injector and record it- needless to say each injector must be labelled.

It is well known that the flow through each inlet runner is not even, indeed, this is by design [to a small extent apparently]. Cylinders that knock first suggest more air flow thus presumably a leaner mix. From my limited experience with Sharkplotter/ST2 I have already seen that when operating in certain cells like in the 3900 rpm band, the engine knock performance is very sensitive to air temperature and AFR. In my case No2 cylinder is most sensitive to onset of knock whereas some cylinders see no knock whatsoever. If you have your injectors flow calibrated you could indeed rationalise this and with the help of sharkplotter you could determine where to place them. If your knock trend is different to other owners then I suspect you may well have an air leakage problem of some kind although what could cause it on just one side tends to limit the source of the problem to the manifold to head joint or the bifurcation joint on the sub manifold assembly both of which seem unlikely to me.

Presumably you have checked the cam timing on each bank.

I would think it wise to check AFR on both banks before you try to fix "the problem". I intend to do that once I have nominally finished my ongoing iterations.


Not sure if you are aware but Carl at 928 Motorsports now markets manifold plenum spacers to improve top end and also [perhaps] even out cylinder air flow. On stock it gives an improvement of about 10 to 15 bhp but at the expense of some mid range torque.

For sure both ST and Sharkplotter can help you identify which cylinders are knocking and once your injectors are calibrated you can assign them appropriately.

Regards

Fred

John Speake

Hi Brian
I missed the reference to how you power your WB. To be safe, wire it to a direct igntion switched 12v feed and a good chssis ground.

dprantl

The tendency of some cylinders to knock is partially based on intake manifold and the way it distributes air to the cylinders. I also find that on mine #1 and #5 tend to knock more and my manifold is similar to Brian's. The stock manifold tends to knock on #2 first. I agree with the rest that you need to get the cylinder bank AFR differences under control before going further.

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

PorKen

I see a leanout on S3s when the engine gets hot, especially after removing the belt driven fan (depending solely on electric fans), and sitting in traffic. Because of hot fuel/hot MAF electronics/whatever, WOT AFRs go up to a point leaner, but if you tune for that, when the engine cools down, it's too rich. I chased my tail for days until I figured this out.

What I did is use the warmup map to add fuel by richening up the last/hottest cell. The next cell, which is the normal (ideal) running temp, is zero. As the coolant gets hotter, more fuel is progressively added (interpolation between cells), compensating for the hot lean effect. It works fairly well, at least keeping the AFRs from getting dangerously lean if you are silly enough to got WOT suddenly with a hot-hot engine.

You can do this with LH2.2 (S2/S3) because the last two cells of the warmup map are 90C/195F and 120C/248F. Unfortunately, the last two cells on LH2.3 (S4-up) are almost the same, 95C/203F and 97C/206F so you'd have to have John/Niklas (make the option to) change the scaling for the warmup map to make the last cell ~120C.

On a side note, you -can- lean using the warmup map (even though it is additive only), by subtracting from the entire base map, and adding that value to all of the warmup map cells, except where you want to subtract. EG. take 10 out of every cell in the base map, and add 10 to all of the warmup, except where you want to subtract, by adding less, EG. 5 or 0.

John Speake

Good suggestion Ken, although I think Brian is saying problems mostly when not heat soaked.

bd0nalds0n

No, John, the opposite. Problems occur when the car is very heat soaked. The car fires right up when cold, runs great for the first 45 minutes or so, but after stop and go traffic, or after an afternoon of running errands with several stops/starts, goes somewhat lean (and a bit erratic) especially at idle.

I've got another WB sensor on the way, and I'll rewire the LM1 this weekend. The WB sensor has started to deliver faults with some frequency after several WOT runs. I think it's been overheated. I also purchased a heat sink, so the next WB sensor should avoid getting cooked.

Cranking/starting the car when warm is also something I'm sorting.

Can someone else who's using 42lb injectors let me know what their cranking pulse width is, and what kind of cranking enrichment they're using in the various cells/temperatures?