Tuning with CIS - Page 9 - PeachParts Mercedes-Benz Forum

400Eric · #1 07-09-2009, 06:24 AM

I want to try the CTS mod on my 88 M-103 now but it's been sitting too long and now it's giving me a bit of trouble. Maybe some of you know what the problem is? Here's the thread: http://www.peachparts.com/shopforum/tech-help/244582-88-300e-m-103-auto-turns-over-wont-start-post2239365.html#post2239365

Please weigh in with your thoughts. Thanks.
Regards, Eric

JayRash · #2 08-22-2009, 01:26 AM

Well been playing around with the M104 C36AMG and for the first time i heard incredible amount of knock. I couldn’t believe what I heard, the first time I ripped it up it was in a small tunnel and the sound of this engine is gr8 but something was off. The sound had that familiar knock I used to hear when I first boosted the M103!

I thought this engine had knock sensors, and if you check the engine test logs on the DAS star you will find that the ECU pulls timing per the cylinder that has knock and not just dial the whole map down. SO why on earth then did it knock so hard and so loud. I mean I have test pipes in place of the cats on this car, and its loud, loud enough at least.

Any way this proves that the CTS trick does up the timing significantly

and thus now I need to install the wide band cause it seems ill need to mix in some alcohol to make use of the trick which will make the car run leaner

so I need to keep an eye on the AFRs

400Eric · #3 08-23-2009, 04:48 AM

Maybe you had a bad tank of gas Jay. Some dishonest fuel stations are dispensing "regular" fuel from "premium" pumps. It's been proven time and again here in the states that 25% of the "premium" pumps aren't dispensing premium.

I can't guess why your ECU wasn't able to pull enough timing to compensate.
Regards, Eric

JayRash · #4 08-23-2009, 06:19 AM

Quote:

Originally Posted by 400Eric

Maybe you had a bad tank of gas Jay. Some dishonest fuel stations are dispensing "regular" fuel from "premium" pumps. It's been proven time and again here in the states that 25% of the "premium" pumps aren't dispensing premium.

I can't guess why your ECU wasn't able to pull enough timing to compensate.
Regards, Eric

It very much can be, but i do know my gas owner well, and the fuel he uses, but still it can be that.

I think the reason the ecu didnt pull the timing is cause with my trick the ecu reads the water temp at less than 60C' so it just might be that the ecu thinks its a cold start and waits for water temp to rise before it engages full control, like knock and closed loop.

Not sure abt this, just an idea

jadewombat · #5 07-26-2010, 10:53 AM

Hi, I'm new in here. I've messed with CIS for years on VWs and just found this website recently, great stuff BTW. Anyone messed with an adjustable fuel pressure regulator for tuning?

http://shoptalkforums.com/viewtopic.php?f=23&t=114309

duxthe1 · #6 07-28-2010, 01:25 AM

You'll almost never see an adjustable pressure regulator on the CIS Mercedes cars. They have a system pressure, a control pressure, and a delivery pressure. Simply raising or lowering the system pressure isn't necessarily going to yield beneficial changes in either the control or delivery pressures. Having said that, I'm not going to say that there isn't any possibility of tuning with CIS pressures. I am going to say that there is a complex relationship between the three that needs to be understood before any meaningful tuning can begin.

JayRash · #7 07-28-2010, 11:28 AM

an adj fuel pressure reg will do u no good what so ever. if u need more fuel flow for an NA setup, then u need to mess abt with the EHA it has a tiny screw which will result in more or less fuel flow.

if u need to up the system pressure to counter the boost pressure, then u need to know what ur doing and u need a fuel press reader and it is complicated to do.

400Eric · #8 06-08-2011, 09:22 AM

OK, I Finally had a chance to take Benzer 1 to the track this past week-end and with NO OTHER CHANGES from the previous time I had Benzer 1 at the track, except for the substitution of the ECU bearing part number 002 545 97 32 and the removal of the resonator and muffler, Benser 1 went a full second quicker in the quarter mile in much worse conditions than what we had the last time we were there! We are talking an uncorrected 15.95 @ 87.27 (15.487 @ 89.939 MPH corrected) where last time we couldn't do better than a 16.95! Mind boggling! We repeatedly spanked a Bimmer 525i in the process too! (Well, actually, slaughtered the Bimmer.) I honestly think that I was more thrilled to get that 15.95 out of Benzer 1 than I was when I got that 14.348 out of Benzer 3!

So now we have some "real world" numbers to back up all of the theories we have discussed here in this thread. It turns out I was on the right track, I just needed to finish the job by freeing up the exhaust and trying that older, Non-California ECU! Sometimes we are just looking in the wrong places! We have to take care of the basics first. Now this car might be more responsive to some of the other tricks discussed here in this thread!
Regards, Eric

gsxr · #9 06-08-2011, 10:55 AM

ECU bearing? Please tell us more! Or did you remove them muffler bearings and install them on the ECU...? (sorry, I couldn't resist, lol...)

jhodg5ck · #10 06-08-2011, 11:53 AM

fresh headlight fluid makes an extra 20HP last I read on the interwebs!

Congrats Eric

400Eric · #11 06-09-2011, 02:10 AM

Yeah, and adding a wing on the back will reduce your E/T by a half second!
Regards, Eric

pentoman · #12 06-18-2011, 05:09 PM

The thought occurs that if you want to try tuning the CIS the best start would be a junk yard for an EHA valve thing. Then you can adjust and fiddle with it to your heart's content, knowing that your factory-set one is safe there ready to refit if you screw everything up

400Eric · #13 06-19-2011, 06:18 AM

The very next thing that I'm gonna try is my dummy CTS trick. It did provide me a documented, repeatable gain at the track with my M119 and I fully expect it to do the same for my M103 since CIS-E M103s are even easier to fool than LH M119s are. The neat thing about the CTS trick is that it also gives you additional ignition timing and is by far the quickest, cleanest, easiest mod of them all to do and undo! Just unplug the plug from the stock one and plug in the dummy! When you leave the track, do the reverse! I've obtained TWO EHAs from the P-n-P but I'm hesitant to mess with the EHA on the car because I don't want to jeopardize my street fuel economy. My dummy CTS mod allows me to switch back to "street mode" far easier than switching out EHAs would.
Regards, Eric

400Eric · #14 06-27-2011, 07:47 AM

Well, first of all, I've been doing you all a disservice by referring to my dummy CTS mod as the dummy CTS mod when I should have been calling it my dummy ECT mod. (The CTS is the one that tells the cooling fans and temp gauge what the engine temp is while the ECT is the one that tells the ECU what the engine temp is.) While I'm confident that most of you still knew what I really meant, I still need to be more accurate, especially because some of the newer members of this board may not know the difference.

Well, the results this time were a wash. No gain. (No loss either.) I don't know if it's because the ECT that I used was actually from an M119 car (It is in fact the very same exact one that I used when I tried this mod on my M119. I thought they were the same!), or if it's because I couldn't put the dummy ECT in a location where it could stay as cool as I was able to do on the M119 (the ECT is on the back of the M103 while it is on the front of the M119), or if it was something else. Who knows. There is no doubt though that since this mod did work so well before (as documented in back to back testing at the track on my M119), that it would work well on this car too since, again, M103 CIS-E cars are easier to fool than M119 LH cars are. (If only I could figure out what the problem is.) I would like to have this mod as an option because I really do love to have that "plug and play" ability.
Regards, Eric

gsxr · #15 06-27-2011, 12:21 PM

Quote:

Originally Posted by 400Eric

since, again, M103 CIS-E cars are easier to fool than M119 LH cars are. (If only I could figure out what the problem is.)

I suspect that the fuel & ignition maps on the M119 LH and EZL do not vary the mixture/spark as much as the CIS-E does, given different inputs. It's not that the M119 is harder to fool, it's that the M119 doesn't reduce output as much during "less than optimal" conditions.

FYI, the FSM (more specifically, the Diagnostic Manual) specifies that when dyno testing the M119 engine, a fixed IAT of 20°C and fixed CTS of 80°C should be installed. I've tried 60°C vs 80°C and found basically zero difference in power output between those two points.