My T1N has a misfire in the cylinder 1 P0301 (injector #1 is ok)

myst

Member
Hey everyone. Just recently out of nowhere our 2005 sprinter 3500 started not firing on cylinder 1 and was hoping to get some help here. I know gas engines very well but not so much the diesels.

Anyways this is what is up and what I have tried up until now:

I never get a check engine light, only code P0301 sometimes.

I've tried unplugging each injector with engine running and when I unplug cylinder 2, 3, 4, or 5, you can see that the engine starts running worse so I know those injectors work. Only unplugging the cylinder 1 made no difference as to how the engine continues to run without the inject 1 plugged. I then switched injector 1 and 2 and got the same results. Unplugging cylinder 2 made the engine run worse, but still unplugging cylinder 1 mades no difference

I also wanted to make sure that cylinder 1 injector is getting signal from the ECU so I unplugged the cyl 1 and into the wirings harness plugged in a 12v LED bulb and the bulb blinks so injector harness should be fine, it is getting pulses from the ECU.

I even checked if the gas tank fuel pump works, I can hear it running when you first turn the ignition ON.
Also check the turbo and its in good condition.
Check all the intercooler hoses and they are good as well.
Diesel filter is new...

At this point I'm not sure what to try next. Any advice would be awesome awesome awesome.
Anything that I should check next that might cause cyl 1 misfire?
I know I should do a compression test next but I don't have one for this engine at the moment.
 

BrennWagon

He’s just this guy, you know?
A compression test and an injector leak down test would be the next logical step. An over fueling injector can crack a piston.
 

Duckmang

Qualified Personel
The high pressure injectors used in these and similar engines are not 12V injectors and should not be unplugged when running.
 

myst

Member
Damn I'm really hoping its not something internal. I'll do the injector leak down test tomorrow

What voltage do you think goes to the injector plug? Because my little 12v LED bulb didn't burn out from me plugging it in. Just wondering maybe there is an issue with the harness or even the ECU itself not sending enough voltage/current to injector #1 harness plug?
 

jrod5150

Well-known member
The high pressure injectors used in these and similar engines are not 12V injectors and should not be unplugged when running.
High voltage T1N ecm? The injector drivers from the ecm are not high voltage
 
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jrod5150

Well-known member
Damn I'm really hoping its not something internal. I'll do the injector leak down test tomorrow

What voltage do you think goes to the injector plug? Because my little 12v LED bulb didn't burn out from me plugging it in. Just wondering maybe there is an issue with the harness or even the ECU itself not sending enough voltage/current to injector #1 harness plug?
Compression test Is where I would start as suggested above.
 

Eric Experience

Well-known member
Myst.
No need to do the leak down because the injector is good because it worked in no 2 pot. If you had a cracked piston you would have a lot blowing out of your dip stick hole, That leaves a stuck valve or a wiring fault, I would unplug the engine loom from the ECU and look down the loom at no one and then another with an ohm meter, If both read the same then wash the pins on the plug and socket with contact cleaner, If that does not fix it pull the hose of the inlet manifold and listen to the intake pulses if they are even then that only leaves an exhaust valve Eric.
 

jrod5150

Well-known member
Myst.
No need to do the leak down because the injector is good because it worked in no 2 pot. If you had a cracked piston you would have a lot blowing out of your dip stick hole, That leaves a stuck valve or a wiring fault, I would unplug the engine loom from the ECU and look down the loom at no one and then another with an ohm meter, If both read the same then wash the pins on the plug and socket with contact cleaner, If that does not fix it pull the hose of the inlet manifold and listen to the intake pulses if they are even then that only leaves an exhaust valve Eric.
Even though the bulb test may not be the most accurate it does give some voltage testing to show the injector is getting a signal. Of course it may not be enough to fire the injector. Since he has the ability to run the engine, a dealer level scan tool that could show cylinder rpm or removing the glow plug and doing a physical compression test would save a lot of harness pulling and voltage testing.Van could still have a ring or piston issue since it is misfiring.
 

Midwestdrifter

Engineer In Residence
The Injectors need a significant bit of current initially to open. So an LED may not be showing a high resistance circuit. I would ohm out each wire back to the ECM to make sure the connection is good. That doesn't rule out the contacts, but its a starting point. Typically a bad driver circuit in the ECM would cause a bad ECM code, not always though.

The next step after that is to put a oscilloscope on the injector line with the injector connected, and then compare to one of the good cylinders.
 

autostaretx

Erratic Member
Although the T1N training pages discuss the injectors starting at http://www.diysprinter.co.uk/reference/T1N_service_scans/048FuelInjection.jpg
... they don't talk about the voltages involved.
But much further in, they show the waveform on http://www.diysprinter.co.uk/reference/T1N_service_scans/234Scope.jpg
and it looks like this:

234aScopeInjetors.png

So they are being short-and-spikey ... minus to plus almost 40 volts (so a total of 70 peak-to-peak).
(that image is at idle). The "light bulb test" will smooth that out ("integrate" it), and doesn't care about polarity.

--dick
p.s. T1N training: http://www.diysprinter.co.uk/reference/T1N_service_scans/
 

myst

Member
Lots of good information here guys, thank you all.

I wont be home for a next few days but I will start with checking the Ohm resistance on each injector wire, plug to ECU. And also closely examine plugs on ECU side since the injector side plug looks good.

Friend of mine also has a camera, if it fits in that tiny injector hole we might be able to check for pistons or valve damage or even a stuck valve. But I don't have much hope for it fitting down in there. Not sure how common a stuck valve is on these engines.

If I had an oscilloscope I would defiantly first check the voltage to compare it to the waveform in the pic above that would reveal a lot

Thanks again for everyones input, I'll keep you all updated
 

owner

Oz '03 316CDI LWB ex-Ambo Patient Transport
Do you have access to MB star diagnostics? It can do a relative compression test without having to break out any tools.

Is there any white smoke from the exhaust? and/or any blowby?
 

myst

Member
Had time today to test the wire resistance between the ECM and injector and all 5 are about same resistance so that isn't the issue.

No MB star diagnostics unfortunately.

When I check oil dig stick only a tiny bit of smoke is coming out, looks normal.

No weird smoke coming out of the tailpipe and I did not find anything that would indicated coolant in the oil either. Also not missing any coolant nor oil but I only drove it like this maybe 10 miles just to limp home
 

jrod5150

Well-known member
Had time today to test the wire resistance between the ECM and injector and all 5 are about same resistance so that isn't the issue.

No MB star diagnostics unfortunately.

When I check oil dig stick only a tiny bit of smoke is coming out, looks normal.

No weird smoke coming out of the tailpipe and I did not find anything that would indicated coolant in the oil either. Also not missing any coolant nor oil but I only drove it like this maybe 10 miles just to limp home
The injector driver internally in the ecm could still have failed causing the misfire as mentioned above by mwd. It’s not common but is possible. Compression test or waveform/voltage/scope would be your next step. Personally I’d recommend you take it to someone with the tooling because there’s no real thrifty fix here and to throw an ecm at it or an engine tear down from an incorrect diagnosis...
 
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myst

Member
Can you just swap out an used ECM on these cars without any kinda syncing or dealer programing? Also is the vehicles mileage stored in the ECM or just in the cluster gauge like some cars? I may just buy an oscilloscope, always kinda wanted one

PS one thing that makes me think there is something wrong with the ECM is that when I had codes like P0301, and one with something about under boost detected... check engine light never came ON. The light on the gauge cluster does work however.
 

jrod5150

Well-known member
Can you just swap out an used ECM on these cars without any kinda syncing or dealer programing? Also is the vehicles mileage stored in the ECM or just in the cluster gauge like some cars? I may just buy an oscilloscope, always kinda wanted one

PS one thing that makes me think there is something wrong with the ECM is that when I had codes like P0301, and one with something about under boost detected... check engine light never came ON. The light on the gauge cluster does work however.
Yes you can swap the ecm but you will need a 3 piece matched set. You need the ecm, wsp and fob/key all from the same donor vehicle.
 

myst

Member
Just an update for anyone possibly in the future...

So checked the wiring with an oscilloscope and everything was fine as far as the ECU injector voltage signal goes so injector drivers are fine. Than did a compression test at it showed 0, yes ZERO compression in cylinder 1. Took the head off and yup hairline crack and a small hole in the piston head... Quality of these trucks cease to amaze lol.

Did find out that someone before us defiantly already worked on cylinder one. Only injector 1 and glow plug 1 look new. I suspect we purchased the truck with the hairline crack in the piston probably from a leaky injector 1 in the past and after us driving it for a few thousand miles the crack became a hole...
 
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