View Full Version : How can you tell if you have a injector that is pluged?

01-31-2013, 02:16 PM
It was unusally warm yesterday almost 60 but today back to 26.
I took My van 2006 out for a spin after changing the tranny filter and after about 15 miles it was hot I floored it from a stop.
There was a minor sound kind of a tick but not really like that.
Maybe more of a miss but the frequency was not right for a miss.
Or a shortage of fuel ?
It seemed to keep a consistant timming but kind of slow maybe a couple repititions per second.
It was more prominent when It was nearly ready to shift at full throttle.
if I floored it after being up to speed I couldnt hear it.
Seemed like there was more noise at what I am thinking is full boost from the turbo closer to peak rpms.

It would spool up kind of steady and then I could really feel the turbo working then it would kind of taper off accelerating and the sound would show up somewhere toward the mid to end of the power band.
I didn't do it enough to get a good feel for it not wanting to abuse it.

I am wondering if it has a partially plugged injector or if it is just the nature of the beast.
Could it be the turbo limiting or reducing bost to its top level?
Not real sure how the turbo is set up so not sure what it is supposed to sound like.

I don't floor any vehicle on a regular basis but after talking to a diesel chipper guy he was noticing that once in a while he would hook up the scanner and notice one or two of the injectors were getting plugged a little not sure how he did it ,he told me but it was over my head.
Something about certain levels were low.
He would put some fuel aditive with injector cleaner in and he had run it harder than normal for a tank of fuel.
After that tank of fuel he would recheck the levels sure enough it would be back to normal.
He attributed it to clogged injectors.

I'm new to modern diesels in general so I am wondering if you should blow them out once in a while with spirited driving and some injector cleaner?


01-31-2013, 02:21 PM
It was unusally warm yesterday almost 60 but today back to 26.

Is that centigrade or fahrenheit?? It will sink in when the metaphor becomes obvious ...

01-31-2013, 02:37 PM
I guess You have it pretty rough over there, deg f. here.

01-31-2013, 02:45 PM
Injector leak off test

01-31-2013, 02:48 PM
Without some idea of how many RPMs your Sprinter was shifting up at, how much peak boost you were actually getting, and how many RPMs you ran it up to, it's
very hard to give you much info on whether what you are feeling/hearing is normal or not.
It's not a bad idea to accelerate pretty hard a few times a day to get some flow through your intake and exhaust tracts.
Run it up through all 5 gears hard enough so that it "auto upshifts" @ 3200-3500 RPMs.
Be aware that the boost pressure and fuel flow are completely regulated by the ECM (Engine Control Module) and the transmission
is completely under the control of the TCM (Transmisson Control Module) when you select D for Drive.
These 2 modules interact with each other and with the TPS (Throttle Position Sensor) so that when you step on the accelerator pedal
you are simply telling the "system" that you want more power (I.E. you have increased the "DEMAND").
The modules will decide how much more fuel and how much more boost (turbo charger pressure) it will take to balance that demand
As the demand decreases (you reach your crusing speed, the big wind gust in your face went away, etc) the ECM will back off the
fuel flow by decreasing the injector rate and duration, and signal the turbocharger actuator to reduce the boost level to balance the
new fueling rate.
You have no control over any of this......it's all done by the computers in your Sprinter. Your only input is with the accelerator pedal
attached to the TPS which you can use to tell the system you want more.....or less.... power.
You have a little more control over the TCM as you can override it by manually downshifting and upshifting until it gets into 5th gear, then
the TCM takes over completely.
So, when you feel like your turbo is backing off....that's exactly what's happening. The ECM has signalled the turbo actuator that the demand
level has been reached and the higher fuel flow and higher boost level can be backed down for better efficiency.
Do you run in Drive (D) alot in your Sprinter?
Understand that 5th gear (D) is an overdrive gear and that it's probably not real good to run your Sprinter an < 2000 RPMs alot of the time, especially with a
heavy load on the engine.
Manual downshifting is very easy...simply tap your gear selector lever to the left (NAFTA/USA LH driver position here) and the transmission will downshift
one gear.
The 5th down to 4th gear manual downshift (or if you load it heavily the "kickdown" auto downshift) increases your RPM by 523 Revs.
Also understand that when you are in overdrive, the NAG-1 automatic transmission never completely "locks up".
The 5th gear (OVERDRIVE 0.83:1 ratio) clutch is always slipping a few percent.
So, nothing wrong with manually downshifting, watching your tachometer, and shifting back up again when your speed increases enough to put your RPMs @> 2000.
Think about getting a ScanGauge II or something similar so you can monitor what your % engine Load; Boost Pressure (MAP); digital RPM and Digital MPH actually are.
There are many other useful parameters that you can monitor with this type of "performance monitoring gauge system" that can help you to keep your Sprinter
running at it's peak efficiency.
Hope this helps,

01-31-2013, 05:41 PM
I'll have to read up on the leak off test.

Anything else to look for under general maint.
I just got it so Not real familiar with sprinters.
I checked all of "things to check when buying used sprinter thread" I think about 10 items.
those were good so far.

01-31-2013, 07:15 PM
If you had access to a near-dealer-level diagnostic tool (DAD, CarSoft, AutoEnginuity, snazzy SnapOn, DRB-III), you can access the internal codes (if it decided to capture any) and run some of the engine tests, one of which runs the engine and detects the cylinder-by-cylinder contribution to crankshaft rotation speeds.... this can detect an "underfiring" cylinder