CBXstan

P0300 - Misfire

20 posts in this topic

Hello all;

New to the Smart car world and I got a code that I am trying to diagnose and solve. Pick up a 06 CDI with 130k. Don't have any history but looks to be in decent shape.

The issue is the check engine light is on with a P0300 code - misfire.

 

Did the fuel filter, cleaned the EGR that didn't need cleaning, run diesel additives to help clear the injectors. No change

Had the injectors tested and they failed so replaced them with Bosh reman. Made a very noticeable improvement in power and it seems to run well. 
It still throws the P0300 coded after running for a short bit and seems to throw at idle.

Replaced the Crank Position sensor, in hopes but no change.

No smoke, runs well.

 

Where else should I start looking to diagnose?  What logic or system would throw a P0300?

 

??

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Check timing chain and measure cylinder compression. Continue using injector cleaner. 

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Still throwing the P0300 code and with our cold weather, hard to start below -2 deg C.

Had the local diesel shop run a compression test as i don't have the adapters.

1 - 290psi

2 - 275psi

3 - 200psi  The shop said they dropped some oil into #3 and it did not change the reading. 

 

It has 135km, Based on the reading, seems i have leaking valves. I wish the shop diagnosed a bit more to determine if indeed the compression was low.

Looks like I have a head to rebuild.

Is it worth it? How do the rings fair in a 135km motor?

 

 

 

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It'd be cheaper to get a good running engine from a wrecker.

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Did some further diagnostics and #3 intake is leaking. 

Got the cradle out and the head ready to pull but it's hung up on the chain guide.

do. Need to pull off the cha chain cover to death the tensioner?

 

image.jpg

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Remove vacuum pump. Pull out both pins for chain guides. I would also remove timing case cover as only way to inspect oil pump chain and sprockets. Of course, best to undo pulley bolt before you do anything else. 

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Well that worked.

Head is off and you can see the valve receded. Off to the machine shop in the new year.

Bores look good, just clean everything else up.

image.jpg

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This is what the intake valves look. I guess they were made with material that is too soft.

 

image.jpeg

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Sent the head off to my local shop. He only charged me $100 to surface the head, valve grind and install the supplied parts. Shout out to Monroe Heads in Kelowna.

Since everything was a part and the turbo shaft had some play and was weaping  oil, thought I will try an eBay cartridge. Showed up surprisingly quick and looked decent. Even came with a balancing report. 

 

Got it all back together and was quite proud of myself till I tried to start it. 

It would not start for me. It cranked, had fuel, glow plugs, compression but refused to start. After a lot of rechecking everything and more it fired up! Never figured out why. 

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Posted (edited) · Report post

On 11/14/2017 at 6:07 PM, MikeT said:

It'd be cheaper to get a good running engine from a wrecker.

 

How much is a new/used CDI engine in B.C?

Edited by RobCDI

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I haven't checked recently but I'd expect $1000-1500 tops

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Well all that work and it is still throwing a P0300 code. 😤. 

It runs really well but seems to take more cranking than it should to start from cold.

New injectors; new crank sensor, rebuilt head, turbo, filters, good glow plugs. Runs great once going.

Thows the code after driving for a bit and when at idle and stop and go traffic.

 

I'm wondering if I should start to suspect the high pressure pump. 

At idle, what should I be seeing for fuel pressure? Or is there a check valve that would lose prime when sitting overnight and cause excessive cranking?

???

 

 

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Checked today on my 2002 Smart 450 Cabrio Cdi: 

Rail pressure at idle is 220 bar. 

Specified rail pressure at start is 296 bar.  I could see actual rail pressure at start was getting near 296 bar but not easy to read as engine started rather instantly. Rail pressure when running flat out can go as high as 1350 bar. 

Electric fuel pump has pretty high delivery so purges any air out in seconds. Electric fuel pump pressure on mine is 2.5 bar.  

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Spent all day on it again. I'm really leaning towards damage to the tone ring of the flywheel.

 

i rechecked the fuel system. Getting 240 bar at idle which seems normal pressures. 

Pulled the crank sensor out again and found chunky metal on it. Looked in the bore as best I could and it seems like there may have been some damage to the tone ring of the flywheel but not certain. I blew some compressed air into the bore while cranking to try to clean out any more metal bits. Reassemble everything and it wouldn't start. Installed another crank sensor and it fired up right away but still giving me the p0300 code.

 

it it likely that the tone ring can get damaged? I don't know the history of this car. Ready to give up on this.

image.jpeg

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Tone ring is grooves machined into flywheel so no way that can get damaged.  Yours have much more iron filings on crank sensor than mine but I doubt that is the cause.

 

 

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0323089-000-010-1.jpg

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It's the the tone ring.

I'm amazed it ran! Now to order me a flywheel.

image.jpg

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dont you just love that feeling when you finally find the problem B)

 

i wonder how that happened...

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