Lambda Controller - PeachParts Mercedes-Benz Forum

JayRash · #1 12-02-2008, 04:00 PM

on my old NA setup i had 2 variable resistors which if i recall did alter the resistance of the temp sensor input to both ecus injection and ignition. Any way did dyno the car and ended with a 203 hp M103. Later on with a more flowing exhaust i got it up to about 210 but then i had to move the R16 euro ECE SWITCH to inside the car as that also changes timing advance / retard. Did that cause i had become so used to knowing to which position the R16 needs to be at depending on ambient temps. Winter / summer and sorts.

duxthe1 · #2 12-02-2008, 09:04 PM

The throttle switch on CIS cars doesn't activate until WOT, so the car should remain in closed loop until it is activated. Part of the beta testing will be to determine if the full load throttle switch needs to be disconnected.

I agree that timing has a good bit to do with power production but at this point I'm not too concerned with it. Open hemispherical combustion chambers (like open chambered 103s) tend to not tolerate much spark advance so I don't think there is a lot of room for improvement. For now I'm just concerned with control over fuel, given that the ignition trim resistor give a small bit of control over the spark map.

JayRash · #3 12-03-2008, 02:10 AM

Quote:

Originally Posted by duxthe1

The throttle switch on CIS cars doesn't activate until WOT, so the car should remain in closed loop until it is activated. Part of the beta testing will be to determine if the full load throttle switch needs to be disconnected.

I agree that timing has a good bit to do with power production but at this point I'm not too concerned with it. Open hemispherical combustion chambers (like open chambered 103s) tend to not tolerate much spark advance so I don't think there is a lot of room for improvement. For now I'm just concerned with control over fuel, given that the ignition trim resistor give a small bit of control over the spark map.

Take it from me, this car will love advance, enriching wont give u much pwr especially if u consider how restricted the air flow is in those cars at low engine speeds. what the M103 lacks is pull low end, and advance will improve that. IMHO. I admire your efforts and i understand the drive behind tuning this system, good luck

Joreto · #4 12-03-2008, 04:17 AM

Quote:

Originally Posted by duxthe1

Part of the beta testing will be to determine if the full load throttle switch needs to be disconnected.

I see one problem here and that is that if the WOT switch is disconnected than the ECU would think that it's at part throttle and will not enrich the mixture, you could go around this problem by enriching the mixture with the controller but that would mean that you'll be also running very rich a part throttle i.e. when cruising ... what you could do is maybe disconnect the WOT switch from the ECU and then have it activate the controller, it might work but it's not the best solution. Best way in my book is to find a way to modify the signal to the EHA, say monitor rpms, engine load (map sensor) and modify accordingly .

duxthe1 · #5 12-11-2008, 10:15 PM

I did my first testing today

I logged about 20 miles without a C/E light. Most of that driving was with the controller set for no adjustment, outputting the same O2 voltage as was input. I did most of the driving with no adjustment making sure that my circuitry would be able to mimic the O2 signal sufficiently to fool the CIS. So far, the CIS module is interpreting my output fine. I put the Lambda tester on it at the shop and it had good oscillation. After work I pulled it in and put it on the gas analyzer. Turns out it worked better than I though it would. I recorded my CO and HC values at idle and at 2000 RPM. Unadjusted my idle CO was ~.40 - .70% and at 2000 my CO was ~.55 - .85%. The Lambda controller would lean the idle to .12% and lean 2000 to .16% CO. Not bad, I must say, but it turns out it will richen much better than it leans. At full rich adjustment idle would go over 7.0% CO and 2000 would go to ~6.6% CO. I really didn't expect it to richen that well but my ASSumption is that the CIS is willing to work harder to prevent a severe lean condition than a rich one. Remember that I get an adjustment by fooling the CIS lean to get it richer and vice versa.

I did get one good stoplight to try an enriched acceleration. I'm not going to say that it was night and day but I did notice a bit better pep.

I am not confident saying that there is more peak power but it felt like the power band had gotten wider. Typically my TE doesn't get any steam behind it until the revs are up quite a bit. Enriched, it felt like it was willing to pull with gusto sooner and longer.

Having the O2 sensor voltage display is neat to watch but also distracting in traffic. I was surprised how much time is spent in a decel fuel cut. If there is one thing CIS does well, it is cut and apply fuel without hiccups. Maybe that smoothness is why Mercedes stuck with it well after most manufacturers switched to EFI.

duxthe1 · #6 12-12-2008, 07:44 PM

I did all of my driving today with various amounts of negative enrichment. At the higher settings the power loss is evident. I didn't notice any pinging but it is pretty cold here and the air is thin. Pinging isn't normally a problem for my TE, even in the summer with 85 octane, but I do see 103s that will ping on cheaper fuel once in a while.

With another 20 miles under it's belt, still no C/E light

duxthe1 · #7 12-13-2008, 10:09 PM

Today was a mix of driving with fuel being added and subtracted. No real problems to report. There is a bit of a delay from setting the controller to add fuel until the CIS actually adjusts it. Since the controller affects the CIS's feedback system, it has to see the adjusted values for a bit before the mixture actually starts to change. I noticed this on the gas analyzer and now during actual driving. The dealy seems to be around 10 to 20 secs. I think that when the O2 sensor is really good and hot the delay is less. At stoplights I adjust when the crosswalk signal changes and that seems to work well. I have gotten a couple of good enriched accelaration runs today. It definately likes the extra fuel. I have a fair hill near the house that has a 30mph limit. At 30 mph, I normaly am just on the border line of being able to climb it in high gear without a down shift. When leaned out a downshift is certain, when enriched it pulls the hill in high gear with ease. Not emperical data, I know, but proof of concept none the less.

I've been talking with my co-worker about trying it in his stroked 500SL. That puppy really likes to run rich but he keeps it tuned pretty lean most of the time.

duxthe1 · #8 12-20-2008, 05:25 PM

I tanked up today so that has been one tank full through the car with the controller providing the O2 signal. That's a bit over 200 miles and so far so good, no problems or c/e light. It cruises quite well when leaned out. Most of the driving so far has been spent with it leaned out. Why burn more gas than I have to right. A couple of times I've dialed in more fuel but that has only been in short bursts. When leaned out I just back off on the fuel until I feel a slight power loss and leave it that way. I havn't pulled the full load contact and as of yet don't think I need to. Since most of my driving is with it leaned out I like having the full load contact there to bring it out of closed loop when I need the power back for merging and such. I may still experiment with removing the full load contact but don't see it being critical to the function of the controller.

300EVIL · #9 12-21-2008, 12:33 PM

WOW! Sounds like your project was a success! However, If you could manage to get some dyno time along with a WBO2 in the tailpipe. You'd then have some real data to look at. It's not cheap but it would be adventagious to you as numbers would really help sell your kit if you plan on producing them.

c280nz · #10 12-22-2008, 01:33 AM

yea sounds like it works well! im sorry about all my sceptical questions!
it all worked well in the end, and ur obviously like me with the fact that you made it yourself and it works makes it so much cooler

duxthe1 · #11 12-22-2008, 07:25 PM

No apologies needed, I posted here about it so that you guys could come up with some things I didn't consider. Criticism is appreciated, though it appears that the controller does indeed work as designed. I did all my driving today with it on the car but I don't think I got in closed loop much at all. It was so cold that with the heat blowing inside the engine wouldn't warm up enough to get out of open loop. So much for trying to measure an MPG improvement over this tank of gas.

Turbo E320 · #12 01-22-2009, 10:46 PM

The rear o2 sensor of most SFI cars doesn't affect the fuel trims of the car, including Mercedes, so I think your controller would work. It would be helpful to tune the closed loop fueling of the car, making the transition from closed loop to open loop smoother when making custom fuel maps.

gsxr · #13 01-23-2009, 10:04 AM

I believe all LH-SFI use a single O2 sensor. The dual sensors didn't start until ME injection rolled out in 1996, AFAIK. Interesting idea about modifying the MAF signal on LH cars, though!

RunningTooHot · #14 01-23-2009, 01:38 PM

RBYCC - Thanks for the suggestion, but that unit works by feeding a false signal directly to the EHA, therefore it is not applicable to LH-SFI systems.

Turbo E320 - I believe that the function of any second (post-cat) O2 sensor is strictly to provide feedback on catalyst efficacy.

GSXR is correct, the LH-SFI systems ARE single 02 sensor systems, therefore (in theory) this type of signal "correction" could work.

Duxthe1: Any interest in potentially expanding your market beyond CIS-E?

P.S. I'd love to hear more about setting the baseline lambda mix on LH-SFI cars, even though it is a "difficult" hack. Nothing worthwhile is easy.. (usually)

Joreto · #15 12-03-2008, 03:44 AM

Quote:

Originally Posted by JayRash

on my old NA setup i had 2 variable resistors which if i recall did alter the resistance of the temp sensor input to both ecus injection and ignition. Any way did dyno the car and ended with a 203 hp M103. Later on with a more flowing exhaust i got it up to about 210 but then i had to move the R16 euro ECE SWITCH to inside the car as that also changes timing advance / retard. Did that cause i had become so used to knowing to which position the R16 needs to be at depending on ambient temps. Winter / summer and sorts.

Modifying the temp sensor signal works to some extent since unlike the lambda, the ECU doesn't ignore the input for the temp sensors at WOT. I'd guess what happened in your case is that you changed the resistance to report colder temp which in turn caused the ECU to advance the ignition and add a bit of fuel

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