sinlab

I've searched and can't seem to narrow down the issue. A little background:

1996 C280. Have replaced plugs, fuel filter, fuel pump relay, and all 3 ignition coils.

I'm still getting random/multiple cylinder misfires where a simple code clearing seems to help for about 100 miles.

Last night I was driving home, doing around 70 mph. All of a sudden I felt a small hesitation (as if the car was running out of gas). I had just filled up to half a tank earlier that day. The car continued to cut out and ZERO throttle response. I managed to pull over on the side of the road and when I came to a stop, the car wasn't running and every light on the instrument display was lit up. I kept trying to start it but no luck. I ended up having it towed home and the internet search began.

It acts like its out of fuel so I'm guessing its a fuel delivery issue. I've read that it could be the fuel pump or OVP relay.

Also, this same issue happened about 2 years ago with my wife. The next day the car started right up. I swapped out the fuel pump relay and filter since then.

Anyone here hear of this happening? An OVP seems to be the cheapest fix or am I going in the wrong direction. Any help would be appreciated.

Thanks,

Adam

YNVDIZW124

Fuel pump? or fuel pump relay?

jagata

Check your engine wiring harness.

RANDY_P

put the car to run but not started, check your dashboard- is the check engine light turning on?

If not, probably OVP relay. $45 @ pelicanparts.com

Mine did that the other day. just dropped dead and felt like a fuel problem.

garcic43

I had the same problem with my c230 died.. on the freeway doing over 70.. and it was my maf sensor.. (massive air flow sensor) it was dirty with oil... and so.. I cleaned the sensor.. with a MAF cleaner from Autozone.. and cleaned the oil excess from the oil separator. and never had the problem again.

$tallion

wheres the relay?

sinlab

Thanks Randy, all the lights do come on including the CEL. I'll probably swap out the OVP anyway.

I tried to start it today and it actually turned over, made some popping exhaust noise (almost like a backfire but from the engine compartment), and actually ran for about 10 secs and then died.

Based on that, whatcha think? dirty MAF? Fuel Pump?

sinlab

Not sure this is a big deal but I'm also using a K&N air filter.

RANDY_P

Update- I made it 50 Miles on a cold day, came home parked the car, cam out 45 minutes later and guess what?

Same fckin problem.

So, it was apparent that the problem manifests itself when the car is warmed up.

Decided to get a bit more scientific about it- no CEL, no pending codes, but ran great cold. Drove it till it was fully warmed up, parked the car for 5 minutes and instant stall upon restart.

It would start again, then stall a minute later- as if someone turned the key off. Just would straight up die, no sputter, so spazzing out nothing.

So, it was the Crankshaft position sensor- what a PITA to change...

I just got done doing the same tests, running it up and down the highway, and let it lidle, shut off heat soak, let it idle and got everything nice and hot for 3 hours now and not ONE shutoff.

Changing the damn thing sucks azz, hope you have smaller hands and some patience, otherwise you will get pissed quick.

http://www.peachparts.com/shopforum/...d.php?t=288189

PS- on the CEL- on my car is isn't supposed to come on unless there's a fault, verified with my owner's manual and the new OVP isn't powering it up anyway. That was bad info on my part.

My bad.

check it out:

RANDY_P

Lastly, when the CPS fails it's typical the car shuts off or starts to miss and when it shuts off it won't restart for 10 minutes or more-

the reason being is the CPS overheats and stops sending signals to the ECU, and in turn that shuts off the fuel AND the spark- that's why it's just a silent death.

Once the CPS cools a bit you can restart the car. It's typical that guys call a tow truck and when they get the car off the trailer it starts up fine.

My car however would just die but it would restart.

rjp

sinlab

Ugh. CPS eh? I have the allen socket but will need to buy the other stuff. My hands are on the larger size too. Any idea what a shop will charge to swap the CPS out?

RANDY_P

Well, before you resign yourself to getting that thing changed, make sure it's heat related.

From what I gather it's typically between $200-$400 at a shop

Where are u located?

Once again, my car flipped after it's been warmed up. When cold it's like new-

- if the car stalls and then won't restart for a few minutes, suspect the CPS

- if it just drops dead, no sputtering, no signs of dying, suspect the CPS.

Just for the hell of it I'd replace the OVP since it also has similar failure modes except with an OVP failure it doesn't seem to be heat related...

sinlab

Thanks Randy. I cleaned the MAF today and replaced the air filter. No dice. I ordered an OVP from pelicanparts and will swap that out on Thursday. I will post my results as soon as I plug in the OVP. If that doesn't work, I'm guessing CPS and/or Fuel Pump.

I replaced the fuel filter a couple years ago so I'm thinking about doing the fuel pump. I heard its next to the filter. Is that true? I'm hoping its not in the tank.

sinlab

The fuel pump relay is in the truck next to the battery. Green plug-in type.

RANDY_P

IIRC it's next to the filter...

Do a pressure test- find a Harbor freight and get a fuel pressure tester first or try to rent one somewhere.

Good luck

PS Pelican rocks- I've been a forum member there and customer for over 8 years now. They are the ONLY place that seems to have accurate data on MBZ - even tho they are primarily Porsche / BMW.

That site was the only one that had the right plugs for my mother's Benz and the correct O2 sensor for the C36


the only site.

rjp

theC280

Bad Coil and or fouling plug or two. change the wires too.

I had the same exact issue happen to be at 70mph but the car died, came back, died, came bakc twice before it just died and I cruised to the highway shoulder and had the car towed home. found out 2 of my coils took a dump and 3 of my plugs fouled out.

theC280

fuel pump is right next to the fuel filter, only smalller.

jagata

I have a temperture problem but the opposite, when the car is cold it sputters then stalls but when warm it doesn't stall. Any ideas?

RANDY_P

can you keep it running with your foot?

Temp sensor on top of thermostat housing.

rjp

jagata

If I keep my foot on the pedal it will not stall but sputter and won't stop the sputter. Nice write up on peach Randy, any update with the new maf?

RANDY_P

YA- problem solved. Between the new OVP, new crankshaft sensor and new maf it's like a new car.

It's hard to believe that the MAF made that much difference- I can wheelspin even rolling from 10 MPH now.

It's never driven this well since I've owned it for 16K miles. Even fixed the hot start sputtering (mimicked a leaky fuel injector- was about to reseal them - no need now)

rjp

sinlab

I swapped out the OVP. No dice. All three coils have been changed within the last 6k miles. I'll check out the plugs/wires and replace if necessary. The good news is I found a mechanic willing to install the CPSfor $25 bucks! I just have to bring him the part. Hoping to find one for around 70-90 bucks. Autozone wants over 360bones for a CPS. Crazy.

UPDATE: Found a CPS at autohausaz for around $80. I'm also looking at replacing sparkplug wireset. They have a bosch set for $60. They are for engine serial number up to 011794. Dumb question....Where do I find the serial number of my engine? I checked the door jam and this metal plate under the hood. Nothing close to that number is showing up.

RANDY_P

SN is on the passenger side of the block and you have to see it under the car. It will be on the front half of the block, stamped on a boss- it's pretty easy to see if you just look up and clean it off.

Frankly, those wires rarely if ever fails- They are just braided copper with resistance ends. I'd check them for resistance and see if any are wildly out of spec.

Unless they are obviously cooked I'd check 'em and keep on rollin.

How about the MAF?

rjp

jagata

My car is still sputtering on cold starts after replacing with a new Bosch maf, sometimes on start up it will go to 1k rpm for a few seconds then just die. I'm not sure if this is related to the cold start up problem but another thing my car does at 70mph it sometimes misfire or lose power and regain power and lose again back and forth. Any help?

sinlab

Thanks. The MAF is about 30K old I'm guessing. I have to check my records. I did remove and clean it a week ago when I changed the OVP. With that being said, I have used a K&N filter for that last few years and I've heard they don't play well with the MAF. I've also changed to a FRAM air filter.

Before the car just died, I did have a history of misfires (mostly cyl 1 and/or 4 or multiple misfires). These misfires would usually happen upon acceleration out of a slow curve. I'd hit the gas and feel a hesitation and then bam, CEL and default mode (running on less than 6 cyl). The codes would usually be cyl 1 or 4 misfire or multiple misfire. I would clear the codes with my reader and would be fine for a couple hundred miles.

So before I tow this thing to swap out the CPS, I'll check the plugs and swap out the MAF (found one cheap) and see what happens.