Cold Start Issues Still

[JasonS5555]

Oh, my prevous post should have been earlier in the thread. What about adding fuel in the afterstart enrichment vs. ECT table?

Looking at a few of my logs, my car is adding a ton of fuel right at the start of cranking. Yours isn't. Try bumping the afterstart enrichment table and maybe moving the decay table back up too. Looks like you moved it down from the stock values in some cells.

Jason

[JakeFusion]

I hate the IAC. I don't even understand what it is doing. I agree it pulls the car down and chokes it out. I thought it was because in a startup situation, you actually want it to "choke" - less air and more fuel to light it off, and then quickly allow in more air to keep it running until it comes up to speed and the airflow requirements are eased.

That's why I was thinking of porting the IAC port (as other have done - but I doubt that's what I need). I may need more air at low temps than what I have - open it up as much as possible and let the IAC work to control it. But if the IAC steps are off then it might not matter. I think the NW has enough IAC passageway for me. The IAC tables aren't stock - I'm going to put them back to stock and see if that changes anything. I'm also going to swap out my IAC motor from some autozone one to the one that was on the car. I thought I had an IAC issue early on and bought a new one, but I don't know if it operates correctly.

I also thought about adding a 3/16" hole to the TB - yeah i know everyone frowns on that. But that would assume the IAC is fast enough to react to keep the car from doing stupid things. When cold and the airflow requirements are more, the drilled hole might allow just enough bypass air. That might keep it alive under load. I would just need to close down the TB some more. With the NW open at .69V, I have plenty of adjustment down. I just don't want to do that yet. That's somewhat permanent change.

Last thing is my spark tables. I have a ton of spark. It works, but was thinking of maybe adjusting the 400 and 600 tables, though I rarely hit them.

Edit - I'll look at afterstart enrichment. Do you have any suggestions on how much to bump it up?

[JasonS5555]

Yeah, if we can solve the fuel issue, then maybe move to the air issue.

Also, maybe kill your adaptive idle until this is solved to it isn't doing things as well that we're not accounting for? Shouldn't be an issue with the cold ECT, but just one more thing to cross off the list of culprits.

Jason

[JakeFusion]

It surges pretty well without adaptive idle. I typically have to lean it out even more to get stable idle. But to get a stable idle, I've had to take so much fuel out, that it had no throttle response. So that was a balance in finding what would work in terms of acceptable idle and acceptable throttle response.

I'm going to go out and load this up. I hope it's cooled down enough for me to get a "cooler" start.

I made sure my afterstart enrichment was at least equal to stock, added 5% to the cranking fuel tables, killed some spark in the lower cells, added a little spark to startup, and returned the IAC tables to stock.

I'll see if this changes anything.

[GHuggins]

Well, the way I have it setup is it's in closed loop from 1200 rpm up. Idle is in Open Loop due to the overlap. It idles absolutely fine at temp. In fact, if I could operate at 180 ECT only, I wouldn't have any issues at all. I do not want to enrich the idle in the VE tabe. I went through the hunting idle due to a rich condition and am not going back to it. I use the F/A Open Loop table to add fuel when cold (as you can see, I'm at 1.00 above 176 there and in the 1.06 range when cold in the 65-70kPa range). I show richer idle (see the attached log). You can watch it lean out as it warms up. It does not like being rich at idle at all. I've even thought of leaning out the F/A OL table some more.

The whole point is, at temp, the car works exactly as I want it to. During the warm up or cold start, it does not.

I appreciate the help. Just seems like I've done everything that can be done. Which leads me to believe it's not even an issue with the tune. Something mechanical. Or something off with the injector data. My VE table is in line with other large cams. The fueling requirements at startup are not.

I understand this. I was just wondering if the more fuel in the VE table would help your starting issue or not.

Next question. What changed to cause this issue to start happening. In other words how long has this been going on?

Have you tried leaning out the OL tables to see if it would idle any better? From what you've said this engine combo doesn't like fuel.

[JakeFusion]

It's always done this. I've never found a fix for it. 7 months since I finished the build and have messed with it at various times. Never has it started as intended.

I've leaned the OL table out. I had it fairly lean today. I had a lot of gas and it set at 1 and even .98 at one point. I'm thinking of adding fuel to the cranking VE table. I made it look like my "regular" VE table, but now I'm wondering if I shouldn't go back to stock and try that? Although, the reason I leaned it out was because of the no start condition.

Btw, I drilled a 1/8" hole in my NW TB. If for no other reason than to give me headroom as I was at .69V just to get it to idle at 50 counts hot. Now at .67V it idles at 0 counts hot in drive (so I need to close it down some more), but 50 in park (another weird anomaly when I swapped to the NW - the commanded idle in P/N is never hit even tho in drive it is - I idle at 950 in Drive and routinely near 1150 in park). I didn't have that issue with the FAST and didn't need to open the TB nearly as much, despite having a much smaller IAC port. So I'm wondering if there is something up with the NW TB.

I do plan to open up the IAC port on the FAST. The NW IAC port looks plenty big, so I didn't want to open it up. And since the blade wants to be so open, I figured a small hole wouldn't hurt anything. And it didn't. It gives me more headroom for a stroker down the road... That is unless the FAST with the hogged out IAC port works better.

[JasonS5555]

Hey Jake,

Attached is an old log of my car (all I have at work). Notice the commanded inj pw when cranking, and then after start up its 4.1ms. Near the end of the log, its 2.9ms when warm idling. I think your car may be too lean on startup. But its hard to say... Did richening up the after start enrichment make things better or worse? Your car seems to crank and fire, but the issue seems to be that it won't run for more than a few seconds without dying. So I don't think the cranking VE is the major issue as it does actually start and rev up to ~1300. The issue seems to happen right after that which is why I was targeting inj timing and/or after start enrichment.

012415 a.hpl

Jason

[JasonS5555]

Comparing your last "no start" log and my log above, it appears that you need more air and more fuel. You O2's look lean, the AFR error is pretty big (is that using the WB?), the PCM is reducing the IAC counts. Have you tried upping the idle air table in the colder ECT? Worst case this should just cause the idle to hang high instead of dying like it is.

Jason

[JakeFusion]

I'm about to go log with the new tune I've put together and the wideband going. I'll have a new log here shortly.

[JakeFusion]

Well, I should have put my wideband in open air to recalibrate. I've left it in the pipe too long and it was telling me it needed to recalibrate, but I didn't and so now I'm not sure how accurate the AFR readings are. I'll have to go pull it off the car and let it calibrate before the next log. The errors are enormous. I have tuned with this wideband before and nothing has changed to throw off the VE table by counts of 50+ so take them with a grain of salt... Also, it's raining, so I didn't drive it around. I just let it sit in the garage and idle.

Attached in the tune used to create the log fle. I kept my EOIT at 6.25 for now. The VE table had been tuned there so I wanted to keep that variable out of the equation. Also, I returned the cranking VE to stock. I also added 1 degree of timing to the startup spark table (now 3 degrees over stock) and added fuel in the cranking fuel tables. You can see it's still not wanting to start.

As far as the log goes, it idles in P/N first until it gets some heat in it and the RPMs are still way too high. The RAF called for is higher than what's in the tune. I'm not sure why it's idling 200 RPM more than commanded. Even if i take over with bi-directional controls and command 800 it doesn't budge. You can tell when I go into gear, the RPMs drop to 950ish and the timing map goes crazy. But it holds. And when warm and driving, it doesn't die coming to a stop sign or anything. I'm about ready to throw the FAST TB back on there with a hogged out IAC and see if that makes any difference at all.

Log reference frames:

Frame 900 = In Gear idle
Frame 1500 = P/N idle again
Frame 1700 = in gear idle again
Frame 1900 = in gear with A/C on
Frame 2300 = P/N with A/C on
Frame 2600 = P/N idle with no A/C
Frame 2670 = free rev in P/n
Frame 3370 = back to in gear idle
Frame 3600 = in gear with a/c again
Frame 3800 = back to p/n idle with a few revs

[JasonS5555]

Hey Jake,

A few thoughts on cold start issues:

1. What ever the issue is only occurs cold. -- So whatever we look at needs to have ECT as part of the equation

2. It DOES start. It just won't stay running. -- So I don't think any of the cranking tables are the issue.

So with these things in mind, look at the latest log. The 2nd, 3rd and 4th time it starts, immediately after fire up the NB O2's look rich. As soon as the startup fuel is burned, the NB O2's go MASSIVLY lean and the motor barely runs then dies. If you look at the 4th time it starts, it limps along massively lean until the motor heats up enough for the fueling to get better (around frame 328). Notice that the IAC count does not change. I don't think this is an IAC issue any more after seeing this log.

To me this looks like fueling right after startup. So I would return the decay table to stock, and increase the initial adder vs ECT table in the cold cells by 30% from what you have now. Then, look at the O2's and see if the motor is still massively lean right after startup. I would also increase your primary ve table in the 60-100kPa 400-1200 rpm range

Thoughts on the high idle:

Really seems like the idle air table needs to be addressed. If it is too high, the car will idle high. Did you try commanding like 20 IAC with the bi-directional?
HTH,
Jason

[JakeFusion]

Thanks, Jason! Which of the decay tables in the afterstart enrichment are you referring to the return to stock?

I'll try that. I have to let it cool back down now... such a pain lol.

[JasonS5555]

Hey Jake,

I just revised the previous post. See bold text.

The decay in revs has been decreased from the stock value of 100 revs to 50 in some cells. Fuel - General -Afterstart enrichment - decay

Jason

[JakeFusion]

I see it now.

I'll go out and play with the IAC counts. The PID tables were messed with and those may have something to do with the IAC acting as it does. Plus the IAC scale was changed by Ed. I trust him to know what works best there.

The other thing is he zero'd out was the adaptive idle airflow. I'll ask him why he did that. That's probably to take the IAC out of the equation for idle swings... But that would have no bearing on high idle.

[JakeFusion]

That worked for a "cool start" of 130 ECT. I'll try tomorrow with it cold, but it fired right up. I still need a little work with the A/C on. I took it for a short drive and coming to a stop with the A/C almost killed it, but it held. So I need to mess with that some more.

Also, the reason the wideband O2 readings were so off - I managed to burn my wiring harness on the exhaust. Damn!

[JasonS5555]

Which part worked?

There is a section for ac in gear airflow in the adaptive idle - airflow - adaptive idle section. Maybe bump that some to deal with the AC on issue.

Sucks about the WB harness

[JakeFusion]

Adding 30% to the afterstart enrichment table and returned the decay to stock. That's the only change. It lit off three different times. Not at like sub 90 degree ECT. But much colder than operating temp. Tomorrow will be the test. I think I know where to add fuel tho to keep it going now.

[JakeFusion]

As for the cold driving stuff... I think I've figured it out as well.

I am in OL at idle and CL above 1200 RPM. So the Open Loop F/A table only works on the idle - so adding fuel there doesn't help with off-idle stumble, sluggish response, or other lean condition driving. It makes sense when I hit the gas for it to sputter and act wonky unless I get into PE mode when the motor is still "cold." What table would I need to look at the increase fueling in the CL portion of the colder ECTs? Or do I have to rely on the O2s to help enrich the mixture until I am up to temp?

I ask, because my VE table is extremely lean at the lower RPMs, but at temp, that's exactly where the car wants it to be. I need to find a way to add fuel in to the CL operation based on temp. What table can help me do that? Is it under transient fueling?

Well one thing I found as I reviewed my tune - I had set my O2 switchpoints at 300mV... returning to 450. I think that might help in closed loop operation.

[JasonS5555]

Hey Jake,

So did that 30% work for true cold start too?

Did you move the cold cell inj timing normal table up to 6.6? I sent you an IM. That will help cold driveability a ton, and won't effect the VE tables that you're worried about w/regard to inj timing.

Have you looked at the fuel-open closed loop-open loop - EQ ratio table?

That has an ECT vs map for open loop operation table which I think is what you're looking to tweak.

HTH,
Jason

[JakeFusion]

I added 2% fuel to the cold areas in the OL EQ table (below 176). Also switched the O2s back to 450mV. Seemed to do a little better. I also delayed closed loop on until 170 degrees ECT. That way I can keep the extra fuel from the OL EQ table in there.

I managed to kill the car turning the A/C with it warmed to 160 degrees. But at 185 degrees the A/C didn't even pull the motor down. So weird how finicky it is based on ECT. I'm guessing until the engine is good and hot it just isn't going to do well with that big cam.