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Injector leak-back test

M

matsalka

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Location
Estonia
Car
CU2 K24Z3
Just did the test and the pressure relief valve seemed ok - not a single drop. However I decided to try injector leak backs as well and discovered some bubbles on one injector. Could this indicate a faulty injector?
PcXGNZW.jpg


The bubbly injector also has the most leak-back fuel (second cup from left on the following picture).
fds3U3d.jpg


Background: the car has had occasional starting and hesitation problems lately. So far I have determined slow and not fully closing EGR valve. Physically blanking it temporarily lost the hesitation, but the starting wasn't still as it should. Battery is ok, battery cable and grounding terminals were cleaned, alternator is ok, fuel filter is quite fresh and genuine. I had the inlet manifold cleaned recently, which included removing the fuel pipes from injectors. This was last week and there shouldn't be any air left in system, should it?

Edit: no fuel leaks detected anywhere.
 
I can't explain the bubbling, but the results appear to show that none of your injectors are much worse than the others, so all are OK. Any air would have passed through by now.

Was it OK before you cleaned the inlet manifold?
 
The engine was warm (not hot) and idled for 5 mins at this test.

Behavior was odd also before cleaning, that's why I undertook it along with EGR cleaning and examination.
 
Problem is your egr in both cases.

A slightly leaking egr will cause starting problems as its introducing unexpected oxygen into the system. Seen it plenty of times.

Also interested in how you determined your battery is ok.
 
I blocked the EGR completely, got MIL and the hesitation was gone. So yes the EGR is faulty, but the starting was still heavy with the EGR blocked. Must be something else then, right?

As for the battery, I just went outside and did a quick check on battery. With the engine off, I turned the headlight on high beam on and waited for a couple of minutes. Voltage dropped to 11,7 V. Started the engine and it became 14,07 V and rising slowly. Is this enough?
I replaced the battery in January this year IIRC, so it's quite new.
Deta Senator 3 77Ah 760 A
deta-senator-3-12v-77ah-ak-da770.jpg
 
What is the specific starting issue you have?
 
Usually it starts like in this video (without the smoke of course and this is not my video).
https://www.youtube.com/watch?v=2kU0_uZf7Co
But sometimes it takes about 3-4 seconds to start and when it does, it throws a P*** of smoke which seems blueish. Last winter I sometimes had to crank it very long before the engine slowly started.
 
I'm confused. You're saying it's like the one in the YT clip, but without the smoke? So that would make it pretty much perfect!

When your car produces smoke, does it come from behind the engine (like the YT clip), or out of the end of the exhaust pipe?

I don't know how cold it is in Estonia, but do you think the delays in starting are worse when it gets colder?

Is it using much engine oil?
 
Ah yes, the smoke I mentioned comes from exhaust pipe, not from cracked manifold which is fixed already. The smoke is only present when the cranking takes longer, normal staring won't produce any.

The issue was there even in summer, but as last winter showed, it's likely to become worse in colder weather. It's 2,2°C (~36°F) currently and I'll try to make a video of starting the car later.

I changed the oil exactly a year ago and filled it to top level of dipstick. It's now in the middle of those marks and I haven't added oil in between. Yes I know it's also time to change oil :D
 
It's probably one slightly bad injector..
 
I was about to leave the garage and tried to start the engine, but after a few turns it didn't. So I knew it was the same issue again. I set up the camera behind the car and tried to start the engine again. This is what I got:
https://www.youtube.com/watch?v=yugUr-8_hUw

PS. The smoke is only preset if the cranking takes longer. On normal start I get no smoke at all.
 
Unburnt fuel. Like I said, an injector issue
 
I agree that it's probably an injector - sticking open a little and letting too much fuel into a cylinder during cranking and therefore delaying the fuel rail from achieving enough pressurisation.

It might be hard to find out which one though, unless it is somehow related to the bubbles you saw in the return flow from one of the injectors... maybe compression being released through an injector that is partially sticking open?
 
Yep switch to better quality diesel and try a few shots of forte or a decent additive
 
Fuel should be good enough, but I'll try some additive. I know BG244 is good, but a bit expensive to order to Estonia and local stores aren't selling it. Someone also recommended STP Complete Fuel System Cleaner for diesel. Any words on this?
Edit: searched powerenhancer.co.uk for BG244
BG 244 Diesel Fuel Cleaner (For Diesel Only) £18.99
Goods Total £18.99
Shipping Total £24.74
Tax Total £8.75
Order Total £52.48
Ebay tends to be almost the same, so no go!


I also managed to shred two wheel studs on one wheel today. Two broken out of five, so I've got some bigger problems than engine starting at the moment :D Guess I'll change all of them along with brake discs and pads.
 
Ok got some updates on this. Took the car to Honda dealer today and they suspected injectors and/or fuel rail as the reason of starting problems. They couldn't test everything completely as supposedly the engine must be completely cold to test leak-back etc so they only guessed. When I did the test, the engine was slightly warm, but this isn't accurate like they told. Guess I'll test again with cold engine. Can someone tell exactly how much fuel the injectors must send back in given time? Searched service manual, but couldn't find anything.

As for the hesitation with warmer outside temperatures, they discovered that the front bumper has wrong covers for intercooler airflow. Mine doesn't have any holes in it and they thought that the intercooler isn't cooling enough.
B__4600.jpg

Mines are nr 5/6, but 59/61 are needed.
Also the intercooler has a small leak, but I think this is not the issue here. The bumper and intercooler has always been the same and I didn't have any hesitation problems in the summer before.
 
They're correct about the left side foglight recess as it has an aperture to keep the intercooler cool.

Any leak in your intercooler or boost pipework is not good so you should look to address that asap.

The hesitation will be the EGR, I can tell you this from experience now.
 
Looking for new intercooler right now and will replace it soon.

Did a little drive earlier today, checked the injector readings and they were something like this:
1st -0,7 mg
2nd -0,9 mg
3rd 1.1 mg
4th 0,4 mg

At some point the 3rd and 4th were both near 1 mg. 1,1 mg is quite a lot, isn't it?
Also I would let a friend cut a EGR blanking plate on CNC bench and get it remapped/deleted. But where should the plate go? I'm thinking of putting it between EGR valve and EGR cooler pipe.

plate.jpg

This should do.
 
Pitot between the cooler pipe and face of the inlet manifold.
 

You mean there?

This is the end of EGR system, why not put it somewhere near or even before EGR valve so the exhaust gases won't even enter the pipes and stuff?
 
No reason I just like to block it at the face as that's the first point of entry into the inlet
 
Thanks for the answer Fahad.

Something really strange happened today.
It was quite cold, -8C (~17F). Started the car and drove a couple hundred meters. I was about to park the car and then suddenly it just died. Starter pulled, but the engine didn't start. No MIL, no DTCs, nothing.
Towed it to garage and hooked up computer. Only noticeable thing was fuel rail pressure, which was constantly 1 MPa even when cranking (still no error codes). Fuel was present in FF, but that's all I can tell. Then, all of a sudden, the engine started again and kept running. Everything seemed okay without any trace.

There's still one thing that bothers me. The pressure in fuel rail drops to 1 MPa after a few secs after the engine has been shut. Is this normal or should the pressure in fuel rail remain longer?
 
I've never tested it so have no variables to compare against but sounds like a possibly faulty pressure relief valve..
 
I checked the pressure relief valve when I did the injector leakback test and not a single drop got though the valve during cranking. So the valve should be ok.
 
It might be the electric fuel pressure control solenoid fitted on the fuel pump. I had to replace mine a couple of years ago.

There is an HDS test for this.
 
The pressures quoted suggest the article appears to be written for a petrol system. I once had a problem on a petrol engine because the fuel lines would depressurise when the engine was turned off, then the heat from the engine would cause vapour locks to form in the lines and make starting very difficult until the engine got cold... I even had to leave the engine running while filling up with fuel to avoid getting stuck at the fuel station! I eventually found that a non-return valve in the fuel pump had failed, so I added an external N/R valve to provide a solution. This was a very common Bosch L-Jetronic problem, certainly on Ford Granada 2.8i models.

But fortunately diesel won't vapourise like this. My Accord fuel lines lose pressure very quickly, I ***ume the pressurised volume flows back to the tank through the fuel pump?

It's usual to judge the system by how quickly the fuel rail pressure reaches 200 Bar / 20MPa during cranking... it needs to be a second or two. The ECU will not allow the injectors to function until this minimum pressure is reached.
 
You're right Jon, it was about petrol engine. It was still educating though :D

There's still something I noticed today. Tried squeezing the fuel hand pump in the morning before starting the car and it felt soft. It went harder after squeeze or two. So this means the fuel drains back, which indicates a leak somewhere. I'll attach some transparent hoses tomorrow and see if I can confirm this. Is the blue smoke after long cranking also caused by drain back or does this indicate something more? I've already got a bottle of STP injector cleaner in tank, we'll see if it makes any difference.

Oh and the intercooler arrives in a few days. Ordered a used one for only €30 (~£24). It looked good on picture and I've got 90 days money back guarantee. Which is great!
 
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