crembz

hi there, this may sound like a stupid question, but how can I tell whether my supercharger is engaging correctly? I mean short of installing a mechanical boost gauge which I'd rather not do.

Reason I ask ... I know these things are meant to be capable of ~5.2s 0-100km/h. I've always felt the car seems slow since I bought it (about 4 months ago) compared to my previous turbocharged subaru.

Today I did a quick 0-100 run using a bluetooth obd adapter and the torque app. I sat at the traffic lights and just punched the accelerator and held it all the way down until it pulled past 100 km/h.

The result ... 6.4s!!! lol what a pos! That's n/a v6 territory.

Anyway that got me thinking ... either the torque app is not very accurate (shows 12psi boost although I think it is a calculated value rather than a real reading and 250 HP) or maybe the supercharger on this thing is not engaging at all and never has.

Things I've done so far:

replaced ic water pump ... IATs reading below 30celcius now ... previously around 90
replaced sc pulley bearing
replaced tcc pwm solenoid (the jerk is gone!!!!!!)
idler pulley (although something is still making a crap load of noise)
new battery

The car has 135000 kms on it. I have a service B coming up in 5000kms which I'm planning to change spark plugs, fuel filter and fuel pumps and a psk.

Anyone care to chime in? Thanks in advance.

Grip Grip

Keep in mind, the 5.2 is likely in good air. What's your altitiude and temps during testing?

crembz

Thanks mate, temp was 12 celius and about 100m above sea level. wouldn't have thought those conditions would impact acceleration so much

Lenin

Are you doing any data logging? What are you using?

crembz

Just using an ELM bluetooth dongle connected to my phone (torque app). I just had it on real time performance timers which start counting when the car starts moving and stop when speed hits 100km/h. It has logging functionality also but I've not done any logging yet.

Lenin

Then what are you waiting for? Log MAP and IAT and you will know if your supercharger is engaging.

crembz

Ok so I did some quick logging. Iat was 33 on hard acceleration would jump to 38 and quickly drop back down to 33 once backing off. Intake manifold pressure (guessing this is map) would be about 5-7 psi at idle and hit just under 24psi under acceleration.

Call me an idiot but I'm not sure these readings are normal. What would normal readings look like?

Lenin

The IAT is supposed to be 1*C to 5*C above ambient while cruising. And the pressure should be the reading you get from OBD2 - 14.7 PSI at sea level. So, in your case, if the ambient was around 30*C, then you IATs are normal. And since you are at 100m above sea level, you started at -7 PSI (vacuum) and moved to 10 PSI (boost). If you hit it hard then 10 PSI boost is low.

crembz

Ok something must be wrong ... It was about 13 degrees ambient but no lower than 32 degrees iat.

If I use the boost calculation of the torque app I get a reading of about 12psi. I'll try again tomorrow when I have a little more road and less traffic but the iat definitely looks off. I recently changed the ic pump and installed an isolation kit ... Iat dropped from about 85 degrees when cruising but never gets to within 2-3 degrees of ambient.

Faulty iat sensor or blocked ic maybe? I haven't noticed any loss in coolant so I doubt the ic is leaking.

crembz

Is there a way I can force the supercharger to disable so I can feel what the car drives like without the sc?

Lenin

Did you bleed your system properly? Have to make sure there are no air bubbles. What kind of an isolation kit did you install? You should be able to disconnect the supercharger from the relay. There is a plug in the front on the side of the SC clutch. Your IATs may be higher than normal vs. ambient but 33*C by itself should not cause such a problem. it is summer time in the US and my iATs are easily above 33*C and the car runs fine. Check the gap between the SC pulley and the SC clutch. It should be 0.25mm-0.3mm. If it is not the case, this may contribute to your problem. It may also explain the
occasional jerk that you wrote in your other thread.

c32used

Sounds fine to me....the specs on times are closed circuit with professional driver....it take practice to match those times. The way car is factory set its easier to launch modify it and it's harder

c32used

hey guys what I need to make my iphone 5s into a scan tool for my C32? I'd like to measure IAT and MAP. THANKS

Lenin

Here is some information for you. http://tunertools.com/iphone-***-and...ning-plist.htm
I like the Innovate OT-2 setup since you can add AFR monitoring (plus more) to it. Kiwi is also popular.

Supgee

Believe me, your supercharger is engaging. Albeit nobody knows how well, or how efficiently. When the supercharger disengages on this car, people say it is like having a C320. This is not the case. Engine timing is retarded severely when the supercharger cuts out, and the car feels like its running on 2 cylinders. (revs high, will not accelerate).
Your supercharger is definitely working, but not sure how well.

crembz

I'm using a nw isolation kit. This morning again I logged map an got just over 25 psi. I'm guessing that means the sc is engaging albeit not reaching 14.5psi like it should be. I'm hitting about 11 psi boost by my calculations. I don't think it's cutting out as I can't feel any sudden loss in power at any point. Maybe the belt is slipping. I also logged the maf which read about 220. Iat rises suddenly at wot and drops quickly once I let off ... Always about 12 degrees higher than ambient though. I'll try get a feeler gauge to measure the gap. I did notice that the stock sc pulley seems to have a lot of flex at the backing plate.

macbryanie

+1 , when IC pump goes S/C goes and it is a 2 cylinder at best.
The flex in pulley shouldn't make a big difference, when you put on NW PSK the ider is gone and wraps belt harder (less chance slip). Other wise it could be anything reducing the power (inclusive of plugs,leads,injectors - what you plan for next service etc). At 130km maybe needing something. However again it is only 260kw stock so I would get a tune to liven things up anyway.
I have no idea 0-100 for me. I have pulled easy (1-2 car length) on the hatch sti,C63's, HSV's,F6's 335 TT, M3 before BUT so too have they pulled 1-2 car lengths on me at launch. Some of the modded cars around Melbourne are incredible- i will pull at launch and have a good length on them and then at 80-120 ish - they will shoot past me like a bat out of hell.
If really concerned, maybe get a dyno or leak down test but personally I spend that money and get a pulley/tune combo and enjoy. Happydays,
oh and burp the coolant if you added iso.

crembz

Yeah pulley tune combo is definitely on the shopping list. Just want to make sure the rest of the car is close to 100% first... Don't need anything going pop lol. Now that the tranny jerk is gone I'll get the next service sorted and then start having fun. Think I'll definitely go the psk. I'll try burping the coolant lines and see if I can get any more air out.

Boris_Balkan

I had the same symptoms as you in my 32, it ended up being bubbles in the coolant.
If your pump went out, it will also feel like the car has about 75hp LOL So if that hasn't been replaced yet, do it anyways, because they always fail.

The engine is not likely going to 'pop' either, it is handmade and forged, and I have seen setups of Nitrous and methanol on that motor run VERY hard at the track without fail on the SLK32/SRT6

crembz

Yeah I already changed the pump iats were getting close to 100celcius when cruising! That's when I ditched my indie who said that was normal on a sc car lmao!

I've clamped off the return line for the ic coolant this morning and opened the water reservoir cap. Ill go for a drive and see how I go getting any bubbles out.

Boris_Balkan

Take your time, and be as methodical as possible about removing the air bubbles. You 'might' even have to start all over again. But it'll be worth it in order to get it running smoothly again.

Also, if you plan on modding your 32, check out this page http://www.needswings.com/Products.a...2-5D21B9AB2DB5 for cooling/efficiency options BEFORE starting to add boost and bolt-ons. A good defense built FIRST, will give you a more rewarding experience when you decide to start modding for power.

And if you have not done a transmission and differential flush, I highly recommend it. It might be a bit 'slushy,' but it is a STOUT, durable transmission, worth putting some love into.

crembz

Thanks for the advice mate. What do you mean by being methodical and starting again? I'm following this guide: https://mbworld.org/forums/c32-amg-c...ed-system.html.

I followed those instructions and got the following results today:

outside temp: 12 celcius
iat@80km/h: 20 celcius
iat (stuck in traffic): 40 celcius
coolant temp: 97 celcius

Also noticed a squeaking noise on cold starts over the weekend, thinking it's either pulley or belt. Sprayed on some belt grip and the squeaking has not returned, albeit now I have a hissing sound from the belt instead instead lol.

I tried a 0-100 run this morning after having applied the belt grip coming onto the freeway but hit traffic at the start of 2nd gear and had to back off. Pulled just on 12psi max, which is the highest I've seen since I started monitoring. Maybe if I had space to max out 2nd gear I could've seen higher.

I just did the transmission fluid, replaced the TCC solenoid to get rid of the jerk @ 1500rpm. Love driving in traffic now, it was driving me crazy to the point I preferred driving my gfs c200k!! I haven't done a diff flush yet, but I'll get that and brake fluid done at the next service interval coming up in 5000kms.