I haven't had the best luck with googling this scenario that's happening to me. So about once a week the car takes an extra 5 seconds to start and fires up normally. I didn't think much of it, just thought it was normal.

The past two weeks the car will "hiccup" and jerks around like a 15yr old learning to drive stick for the first time. It's started happening at all speeds, accelerating and cruising. The past two days now a new symptom has started and when I'm doing about 45-50 and I'm coming up to a stop I'll go from 6th to neutral and the RPMs will drop like normal to idle and then the battery light will flicker and then the car will stall.

At first I thought that it was my alternator giving me problems but Torque Pro is reading 12.9V and I know the adapter is ~1V lower than the alternator.

So before I have my wife order the part and wait two weeks for it to get to Guam I just wanted to check with my peers that I am in the right ballpark.

Thanks all.

 

How old is your battery?
I had replaced my CPS with an Advanced Auto one.. a few months later I noticed it seem to take and extra second or so of cranking to start. I
was ready to put my spare Bosch brand in come the upcoming holiday weekend.

This went on for about a week or so.. then I had a battery without enough juice to engage my "autostart".. just one click and that was all.

Gotta figure your reading voltage from the alternator aren't you? Or are you turning on the key and waiting for the blue tooth connect and checking voltage...

 

I have read about CPS failures on this forum since I joined in 06. I wonder what fails on this instrument? Anybody know? I don't have one to bench check.

 

MrM, I got a new battery last June when I got my xfire, and back then I had my alternator tested as well and it was pushing 13.5-14V so I figure the adapter is 1V off in relation to the alternator. I'll have to head to the garage tomorrow and double check it with a multimeter.

I've also done throttle resets and removed the negative battery lead for 30 minutes and it hasn't helped. Torque Pro doesn't show any codes either.

Actually I just thought about it, my negative battery lead looks like crap, I'll shell out the $4 and get a new one and double check the numbers with a multimeter.

Similar issue happened with my friend's Civic, the terminals were so corroded that the car would randomly die and would have no power at all, my xfire isn't that severe but 9/10 with the electrical issues I've had with my underglow and such has been traced back to a bad ground.

I'll keep you all posted.

 

The Crankshaft Position Sensor is simply a wire wrapped around a magnet, so it can be only 3 things :
1. the wire coil has an intermittent connection ( likely )
2. The magnet lost it's magnetism ( highly unlikely )
3. The connector / harness has an intermittent open.

On the other hand, the Camshaft Position Sensor is a Hall Effect transistor.
This device works by a magnet coming in close proximity to the transistor, which turns it on.

 

So changed out the negative terminal and got rid of my pending secondary air injection system code, I drove around and now P0101 shows up, Mass or Volume Air Flow Circuit Range/ Performance Problem.

New Maf?
I don't have an engine light on, this is just what Torque is pulling up while I'm driving.

 

Just wanted to update this thread for continuity and to help people out in the future. My secondary air injection code went away after I changed out my negative battery terminal since it was old and nasty looking. Also my P0101 MAF failure was fixed after I cleaned my MAF and cleaned the throttle body, cleared everything with Torque and drove for about 50 miles and everything seems to be in sync again.

 

Hi All,

I believe my CPS has failed in my limited 04 (crank but no start when i turn the key!). I did manage to get it started using a clutch start so if you are ever stuck this will work.

I need help in purchasing the right CPS module, I need to know if I am ordering the latest bosch OEM part number as I understand there have been a few releases of this part? so I want to ensure I am getting the latest revision and best brand, bosch right?

I found it available at needswings, but it is the hella OEM brand does anyone know if this is good, or should i stick with bosch?
Crank Position Sensor

and I found this on eBay, is this the right quality part? part number for this is 0261210170 < is that latest revision?
Mercedes-Benz Crankshaft Position Sensor - BOSCH - 0261210170 - NEW OEM MB Crank | eBay

 

Just replaced my Crankshaft Position Sensor with the genuine bosch same part number, but still no engine start..

I screwed it in securely etc, managed to just get the car started once! But then cant anymore. Just sits there cranking... Click click click click...

Any ideas??

 

Another update, so I finally was able to get a new MAF here, I plugged it in, and got new gaskets and used sensor safe RTV to make sure the housing is sealed. After clearing codes and doing a reset I now have code P0104 which is another MAF code. I also upgraded to the 74mm Throttle Body.

I checked the connection to the MAF sensor and when I pushed on the adapter it sounded like something in the throttle body moved. The only other thread I've read with the P0104 error said the mechanic just put some seafoam in the engine.

Have done throttle reset.

This makes sense I think, I'm at 95K and don't have an oil catch can. Anyways I'm going a little out of my mind trying to fix this and just need a second person's opinion.

 

Just wanted to update this thread, since I hate seeing dead threads with no answer in the end.

So it finally hit me last week that his was a Relay Control Module issue. Last week I turned off my car and the secondary air injection pump was still spinning really loudly and I didn't think anything of it at first but a few minutes later it was still going (I thought it was the radiator fan at first). So the fact that the pump was still on after the car was off tells me it's the RCM issue. I haven't gotten around to resoldering it yet, the main three points at the bottom look fine. I plugged the RCM back in and the car ran perfect for 2 days, yesterday it acted up a bit. I unplugged the RCM for a second and once again it is running fine.

 

The trouble you have is probably the contacts of the fan relay, they are sticking together, look at them you could see that they are black and burnt. If not then something else is keeping the fan going for too long. The fan relay needs to be energized for the fan to operate normally, a sticky relay or an errant signal will make it run when it should not. Run the fan for too long and it will get ruined, no big deal unless you need a pollution test.

You may have other problems that may be solved with the re-soldering of the three joints.

 

I'll look into it somemore I think it is a relay sticking. Usually the first time I start the car in the morning it runs 100%. But after that the car likes to stall out whenever I go and start it. RCM unplugging and plugging back in seems to fix that. Hopefully it can be fixed and I don't have to buy a new one.

 

Problem solved, since I'm not an expert with soldering I just bought a new RCM. I've had the new one in for a week now and no problems.

 

So the Saga continues, it's a MAF issue. I ended up not getting a genuine MAF sensor that I got from Ebay. The engine had a really rough idle and the whole car was shaking. I plugged the MAF and it ran smooth again.

Just to check I turned off the car and started it again without the MAF plugged in and the car ran fine. Plugged it back in and ran rough.

I'll be buying a BOSCHE MAF sensor very soon. Sad to think all this time I've possibly been only driving my car at half power!

According to Torque Pro the MAF is only reading 140g/sec of air at WOT. I may be wrong but I think it's supposed to be over 200.

 

I've got mine set for CFM .. WOT @ 6067 RPM shows 1246.3 CFM if yours is Gal/Sec.. 140 = 1122.9

At Idle I show 25.3 CFM .. app. 3 G/S

155 g/s is approximately my 1246

 

What do you read at idle?

So is the MAF the culprit if the car runs perfect with it unplugged? The issues are usually at idle and when taking off.

 

From what I've read.. yes..

 

Thank you very much for your help oh mighty wise MrMiata!

Hopefully I'll be able to race this weekend!

Drag racing on 4th of July, God Bless America!

 

The wisdom is from too much time on the forum..