junkyard

First post- I checked the threads and I can't find anything that describes exactly what I'm seeing, but forgive me if this is redundant.
I just picked up a 2003 C230K 2 door from a mechanic that was selling a customer's car. He just did the head gasket and put in a new radiator, and it only has 85K miles. I need to get a smog and though the I/Ms are all set, I have a CEL. The only code it is throwing is P301 Cylinder 1 Misfire. I changed the #1 plug and also swapped the #1 and #2 coils to see if the misfire followed the coil, but it didn't. It sometimes takes ten seconds or so to catch when starting and it also occasionally runs really rough for another ten seconds-sounds like it is fuel starved. I put a fuel pressure gauge on it and it makes 55 psi or so when running, then gradually drops down to 0 once the engine is shut off. I've cleaned the MAF with CRC MAF cleaner, and that did seem to get it running a little smoother. It is also losing coolant somewhere-I've checked the back of the motor for the known leaky plastic tube but I don't see coolant there or anywhere else.

A couple of questions: Should there be residual fuel pressure that stays in the system, and if so how much? This car has a "dampener" on the fuel rail, as opposed to a regulator with a vacuum line; I don't see how it could leak pressure, but is that a possibility? I want to avoid erasing the codes if possible so I don't have to set the I/Ms again; will it eventually erase the stored P301 DTC if the misfire is corrected, and will the CEL also turn off eventually? if so, how long does it take? Does the coolant reservoir have an overflow that dumps excess fluid when it is overfilled? I really appreciate any input!

junkyarddawg

Based on the information you have provided it seems like the #1 fuel injector could be leaking but there are other possibilities. The car has a "returnless" fuel system which means there is no fuel return line going back to the tank. Because air has no way to escape, other than through the fuel injectors, the system relies on having solid fuel in the line at all times. When internal or external leaks occur in the system it will allow air to get into the system and the engine will have long cranking times, run rough and misfire until the air is purged. The #1 fuel injector is at the front end of the line and can be subject to getting more air and contaminants from the fuel system. I think the pressure regulator and check valve are built into the fuel filter. The fuel pressure should hold around 28psi for 30 minutes after the engine is shut off and will usually hold some pressure for much longer than that. If the regulator check valve is not holding it will allow the fuel pressure to leak down every time you shut the engine off and displacing the fuel in the line and rail, requiring the line to be purged of air every time you restart the engine. So the root cause of the problem could be at the other end of the line, the filter/regulator, and the injector may not actually be "at fault". The problem with testing fuel pressure is that the gauge is designed to read pressure so when you look at the gauge you have no way of knowing how much of the reading is "air pressure" or how much is "fuel pressure" and the fuel pump can create both if air is in the line.

slammer111

Try swapping an injector and see what happens. Since you've already had a go at the plug and coil I would look there next. Any fuel leaks would also be obvious once you have the rail exposed.

As for the coolant loss, it has to be going somewhere. There are several pipes that are known to go bad. People (myself included) have had leaks at the connection points at the side and front of the engine as well. In every case it has been the pipe cracking where the O-rings go, where the material is thinner. Look for dried white stuff. Should be very obvious. Hopefully it's not getting burned up in the cylinders, which would be a much bigger problem. Good luck.

Bob T

Since the head gasket was just replaced by a mechanic and radiator. There should be NO coolant leaks. You don't know if it is coming from the work that he did. I would take it back to him and point out the coolant leaks and see if he could determine from where it is coming from. If it is his work, he should repair it for no charge. If you points out something else is the cause, then you can fix that yourself if you care to, now that you know what the problem is. I would replace on the injector oring gaskets. I would also replace that one injector as well. You can get them for around 40 dollars or so new with the Bosch brand nowadays. Check out rockauto online, pelican or autohauz.

junkyard

The mechanic did the work prior to selling me the car; he also did the water pump at the same time, and the recent work that addressed some known flaws was a selling point, and I agree with you that anything cooling related should be his responsibility. It sounds like an injector swap is the next thing to try. I won't be able to get to that for a few days, but I will post on the forum once I get some results. Thanks to all for the excellent input!

PelicanParts.com

If you need anything please do not hesitate to shoot me a PM. Good luck.

junkyard

Ok, the mechanic said he would take care of everything and I was pretty busy, so she dropped it off, and we waited... ten days later she picked it up and it seems to be running fine, but it still has to crank a while before catching. Unfortunately, some of the mechanic's commentary got lost in translation since my girl doesn't really speak auto, but she says he said one plug was the wrong kind (I replaced it with the correct Bosch part, so I don't understand this), and that a loose clamp caused the coolant loss. He indicated that it needs a fuel filter and possibly a fuel pump. I don't believe it needs a fuel pump since the pressure was steady @ 55psi. The filter is cheap, easy to replace, and recommended every 30K, so I will do that, but I have a gut feeling that the correct diagnosis for the misfire is still pending. I want to know what the mechanic has to say about the fuel pressure not holding for a reasonable time, so I am going to talk him myself. I'll keep you posted-