Its not so slow anymore Options

[wortdog]

I have been chasing down a nasty misfire for the last couple of months(since the weather has cooled off and the air density has gone way up, basically). I changed plugs, wires, fuel pump, hotwired the pump, MAFs, ECUs, power transistor, and the coil pack. Seeing I was pretty high on the duty cycle with the injectors, I swapped to the ones I just bought for the Buick, 750cc. Don't buy GM style injectors for a DSM unless you're willing to hack them in a bit, they definately don't fit 'properly'.

I've recently acquired the means to burn DSM chips, so I burned a chip for a stock, unhacked MAF, 750cc injectors, 8k redline, and a patch that halves the Hz count from the MAF so that values up to 3200 Hz can be logged. This didn't fix the problem at all, although it did get my duty cycles down to 57% at 5k.

The MAF patch came in handy however, as it allowed me to note a disturbing trend in the data. Before 5k rpm, the airflow signal climbed a bit as the RPM went up, which is expected. After 5k, where it peaked at 1940 Hz or so, it started dropping dramatically. By 5200, it was knocking a bit, by 5500 it was completely cutting out. It was down to around 1300Hz right before it droppped dramatically as the car began cutting out. As I had already swapped MAF's before, and I was pretty close to the 2000 Hz point where the 1G MAF starts having issues with over-running, I decided to try a 2G MAF.

I burned a new chip to match the new MAF, along with some duct tape, some sacrificial 1G wiring connectors, and a borrowed 2G MAF, and it was back to datalogging. This time, the data looked a lot better, with airflow tracking RPM for the most part, nice stable 0.89 O2s, and only 8-10 counts of knock at the top of 4th gear. Still had a slight pop to it.

Then I remembered that I had purposely swapped in janky plugs to see if I could change the problem at all. A quick swap back to NGK-R plugs, and the pop went away, along with some of the knock Duty cycle is up to 71% around 6800, which seems a bit high for just a port-matched EVO III 16G. Boost is creeping up to 18psi from a set 15psi on the boost controller, so I don't think I have a major boost leak, but I can't rule that out. I did notice on the way back into town that the outside temperature was only 17 degrees, so that may explain the large fuel thirst.

Big thanks to KOU Motorsports for letting me borrow a sensor to test. I imagine I'll have to give it back fairly soon, and I'll need the injectors for the Buick anyway. My current thought is to get a set of 660s or 720s and run a GM MAF straight to the ECU with no translator. There is a group of people working on this, and we're probably 25% away from doing it. There are also a couple of people working on a speed-density style re-write of the ECU code, so that a 3-bar MAP sensor would replace the MAF entirely ala HKS VPC. Some interesting things in store for the DSM EPROM ECU, assuming they quit exploding left and right. I noticed some cap leakage on mine for the first time tonight

[awd4kicks]

This is some of the most interesting stuff I've heard on the DSM's in quite a while. Good job Eric and keep us up to date on your progress. These custom burnt chips for particular air sensors....WOW! Bring it on!

[xian 1g]

i've got cash for a chip, if your willing. name your price.

nice work, i'm jealous of your knowledge.

[JBone]

My GOD!! Your knowledge and ability is downright amazing.
That's pretty cool that you can burn chips now. I see many a great things in your future with this, Wortdoggy dogg

[turbohcar]

I've got that 2G MAS that's hacked in the proper areas, has a hardpipe with modified recirc tube, K&N cone filter kit, and the wiring harness conversion so that it plugs into a 1G plug. All for $100 (or something to trade). Let me know if you want it.

[haunter]

I am taking credit for making it take longer by side-tracking him half of the night

[xian 1g]

half of the night

what are you talking about doug? that's not how long your girlfriend told me you take?

[turbohcar]

OWN3D!

BTW, congrats Eric, I'd like to reserve the passenger seat sometime, if that's ok with you.... ...for a ride I mean.

[JMoushon]

Awesome stuff Eric. Do you think at any time you will have the ability to reprogram the non eprom ecus? Are you doing the programming yourself or are you outsourcing the programming and burning them yourself? Finally, as others have asked: Are you selling your chips?

[wortdog]

i've got cash for a chip, if your willing. name your price.

nice work, i'm jealous of your knowledge.

I ordered some chips this weekend Xian, we can talk about what you want whenever.

Don't be jealous, you too could be an armchair tuner since you have all day at work to browse the internet.

[wortdog]

Awesome stuff Eric. Do you think at any time you will have the ability to reprogram the non eprom ecus? Are you doing the programming yourself or are you outsourcing the programming and burning them yourself? Finally, as others have asked: Are you selling your chips?

At this point I'm not selling chips, that may change in the future. I am doing the programming myself, with the information that's available on the DSM ECU Yahoo group.

Also, there is no way to reprogram a non-eprom ECU without using an expensive, no longer available daughtercard that fits over top of the main CPU on the board and allows the use of an EPROM.

[wortdog]

Just got done turning the boost up, since I only have a 20psi boost gauge that's all the more I'm going to run for now. 20psi + 17 degree weather + 5,000rpm stutterbox = big time fun

[wortdog]

http://autos.groups.yahoo.com/group/dsm-ecu/

[natedogg]

That's some cool stuff, Eric. It would be great for someone who doesn't want to modify or tune their car beyond what it was when the chip was burned for him. But the moment the car is further modified or the owner decides he want to do some tuning of his own, it presents a problem.

That is the main attraction to the MAFT if you ask me. The fact that you can tune with it, not necessarily the fact that you can run a GM MAF vs. a DSM MAF, although that is certainly a plus as well.

If you could develop a way to tune or flash the chip on the fly by simply hooking a laptop up to the diagnostic port, now that would be incredible. Many of the capabilities of a stand-alone without all the cost or complexity. Something similar to what the 2G guys have in DSMlink. I understand its alot easier to do with 2G OBDII common protocol, but it shouldn't be that hard to crack 1G OBD protocol even if it is Mitsu proprietary. Maybe someone on that website has done it already. I don't know. The next step would be to use Eprom chips that can be written to on the fly, or even just session flashed.

If I had more time I'd look into it myself, but I'm busy enough writing, deciphering, and flashing Cat's proprietary protocol.

[wortdog]

If someone was willing to initially go for large enough injectors and a GM MAF, the same chip could work well no matter if they're running a 14b at stock boost or a FP3065 at 35psi. The chip does lock you into using the same injectors with the same MAF, but it can adjust for anything else.

The fuel table in the chip is actually populated by a bunch of target AFRs. The ECU uses the O2 information from closed loop to trim the MAF compensation tables such that they line up at 14.7, and it then extrapolates using the MAF comp. table and that trim setting to hit that target AFR. It'd be nice to run a wideband on it sometime to see if the commanded AFR matches the real one.

One of the guys running a MAP sensor has code that allows real time updating of the fuel maps, injector constants, stutter RPM, etc. from a Palm based datalogger. He hasn't released much information on it yet though.

[natedogg]

Its a good step in the right direction and I agree that it would work great for cruising around town, but what about at WOT where closed-loop is no longer an option? I can set my MAFT to correct for 650cc injectors or even have an eprom chip burned for 650cc injectors and it will cruise around and idle just fine, but that doesn't mean my car is going to run optimally at WOT without extra tuning, especially if I decide to run race grade octane fuels. You found this yourself after having to go through a few chip burns to get the results you wanted.

That last comment is interesting. That is basically what I was talking about. I'd like to see a product with those capabilities released for DSMs.

[wortdog]

I actually only burned one chip for the 1G MAF, and one chip for the 2G MAF. But, you're right, different AFRs are needed to take full advantage of race fuel.

In open loop, the ECU still uses the MAF trims for fueling, it just doesn't update the trims based on the O2 feedback. The O2 signal is never directly used to change the fueling, it just changes the Low, Medium, or High fuel trim depending on what Load Point(based on airflow/rev). The appropriate trim is then applied to the MAF signal no matter if the car is in closed loop or open loop.

The datalogging protocol is at least 90% known now. The guy doing this did have to delete a few features from the code, namely all of the diagnostic features, to make space for uploading and storing his maps.

[natedogg]

In open loop, the ECU still uses the MAF trims for fueling, it just doesn't update the trims based on the O2 feedback. The O2 signal is never directly used to change the fueling, it just changes the Low, Medium, or High fuel trim depending on what Load Point(based on airflow/rev). The appropriate trim is then applied to the MAF signal no matter if the car is in closed loop or open loop.

I'm aware of this. I guess I'm just saying what the ECU thinks is an appropriate trim isn't necessarily what I would view as an appropriate trim from a pure WOT performance standpoint. That's why its nice to be able to manipulate the MAF signal to tune the car even if I do have to fight the ECU a while. Another reason why it would be great to just change fuel and timing maps real time on the DSM ECU without having to "fool" it by adjusting the MAF signal.

[wortdog]

If you're willing to spend some cash, there is a ready to go, realtime editing solution for 1G EPROM ECUs already:

http://www.moates.net/product_info.php?cPa...&products_id=57

Plus

http://www.supportfitness.com/mark/tunerpro/

Those two items get you real time access directly to the fuel and spark tables.

Note that neither one says anything about DSMs at all, but the DSM ECU group has an .ecu file that works with TunerPro RT well enough to get the job done.

[natedogg]

Those are some cool websites. Thanks for the links. I might look into some of this stuff.