02 Jetta TDI Starts But misses.

[memphis tdi]

Car starts fine but misses until reved a few times. It does this hot or cold, and every time it is shut off and restarted. Still getting around 30mpg in town, car is an auto.
Does not miss when running down the road.
has a slight surge when I step on it, over 1/2 throttle.
133,000mi.
no check engine light.
Does not use oil.
is not smoking.
Engine has reved a little on its own when started a few times in the last week or two.

Intake has never been cleaned.
Injector pump is original.
Injectors where cleaned a few thousand mi ago.
fresh fuel filter.

 

[dr.diesle]

have you checked the intake manifold ?, If its restricted you may not be getting enough air for 1 or 2 cylinders ...unless your burning bio or european fuel you will have carbon..

 

[memphis tdi]

I have removed the egr and cleaned it as well as the intake as far in as I could reach, but have never removed the intake and cleaned the intake
ports.

What I don't understand is that it does not miss all the time, only when started and some times when idling.

 

[ultrasparc]

Cleaning the intake without removing it is generally a bad idea. Did this problem occur after the cleaning ? How much buildup did you find ?

I could be that some of the buildup you couldn't get to chunked off and got stuck between the valve and the seat causing low compression in that cylinder. After a while the carbon would break up and make its way through the engine.

Otherwise I might suspect a malfunctioning injector. You can see the injector balance with a vag-com.

 

[whitedog]

Do you have any fault codes?

Note that this is a different question than, "Is the Check engine light on".

My guess is two bad glow plugs.

 

[memphis tdi]

Just bought vag com and am still learning to use it, how do I check fault codes and injector balance?

Miss did not start after cleaning the egr/intake.

It will miss when hot, so I don't think it is a glow plug problem.

Car has good power & does not use oil, so I don't think it has low compression, but I will go and get a diesel compression tester and check to be sure.

I am also going to install a lift pump to make sure it is getting enough
fuel to the injector pump. Is there a way to check this with vag com?

My best guess is a plugged intake port or bad injector, but I would like to rule everything else out before I remove the intake.

 

[whitedog]

Open VAG-COM

Click stuff, but stay away from the things that say "Consult manual".

You will find what you need eventually and find lots of stuff that you don't need, but are fun to find anyway.

 

[jasonTDI]

Did you remove them to clean the? Like take the tips off? You could have broke the pins off of the body that hold the nozzle.

 

[whitedog]

I missed the part about not removing the intake manifold. It's not that difficult, it's just dirty.

 

[ultrasparc]

I missed the part about it happening every time prolly not carbon then.

Kinda odd about it happening every time it is started, could it be air getting into a injector line and taking a few seconds to clear out ?

Make sure the pump is not leaking, put your hand underneath feel around and see if there is any fresh fuel.

I would think a clogged intake port would be noticable drivng down the road.

 

[whitedog]

I missed the part about it happening every time prolly not carbon then.

I would think a clogged intake port would be noticable drivng down the road.

Wild guess here, but maybe velocity has something to do with it? At low idle, air velocity is lower so maybe partial blockage is effected more. At High Idle, the velocity of the air is fast enough that a small blockage isn't as noticed.

Yeah, it's far-fetched, but it's the only thing the Doctor could find with the flashlight.

 

[rdkern]

Yeah, it's far-fetched, but it's the only thing the Doctor could find with the flashlight.

Scholar is now a doctor? Congrats.

 

[Trog thou Meatier]

Sounds like air in the fuel lines to me.

 

[diy_fool]

I think it is a bad injector, leaking fuel and letting air back into the line. This part has me concerned:

"Engine has reved a little on its own when started a few times in the last week or two."

The engine shouldn't have a mind of its own. It can only rev if it has extra fuel, hene the leaking injector. If it lets air in the line, that would be the cause of missing when starting.

That's my diagnosis and worth totally what you paid for it! Good luck.

 

[memphis tdi]

Bought a compression gauge today. Checked compression 3 times:
#1 525-525-525
#2 515-525-525
#3 405-200-205
#4 510-520-515
Car is not using oil and runs good most of the time. I think a chunck of
crud from the EGR/intake is hanging the #3 intake valve open. ULTRASPARC was probably right, it just took a while for the crud to work its way down to the valve.

Will remove the intake and valve cover to investigate further.

 

[memphis tdi]

I did the BG Diesel Purge and the miss went away!!!!
Car runs stronger & starts easier.
It must have been a chunk of crap hanging a valve open.

All is well.

 

[jasonTDI]

It can be softened up with wd40 in some cases. You can remove the GP's to blow out the excess fluid with the pump disconnected when done. You probably have damaged the lifter at a minimum and likely bent a valve.

 

[memphis tdi]

The miss has returned but is intermittent.

 

[joetdi]

When you say that the car revs on its own it is sucking oil and/or this is an issue with the IP

 

[diy_fool]

I did the BG Diesel Purge and the miss went away!!!!
Car runs stronger & starts easier.
It must have been a chunk of crap hanging a valve open.

All is well.

I don't see how cleaning the injectors will fix a hanging valve and low compression. My original post suspected a leaking injector which may have been one of several problems.

Re-check your compression and see if cyl 3 is any better.

 

[memphis tdi]

The BG setup is not just an injector cleaner, it is ment to disolve carbon build up in the combustion chamber and on the pistons.

I will recheck this weekend.

 

[jasonTDI]

It'll clean up the carbon. You should see the stuff I see come in. You'd never believe the amount of crap built up on pistons....

 

[memphis tdi]

It is not using oil.
No codes for the pump.

 

[cheeba]

Bought a compression gauge today. Checked compression 3 times:
#1 525-525-525
#2 515-525-525
#3 405-200-205
#4 510-520-515
Car is not using oil and runs good most of the time. I think a chunck of
crud from the EGR/intake is hanging the #3 intake valve open. ULTRASPARC was probably right, it just took a while for the crud to work its way down to the valve.

Will remove the intake and valve cover to investigate further.

You have a misfire on cylinder 3 and your compression figures are way out of spec. for cylinder 3 (should be no more than +-73 psi between all cylinders and no lower than 276 psi for any one cylinder). Something in that cylinder is leaking pressure: rings, valves, head gasket, injector seat, glow plug, or possibly bent rod. It's simple to eliminate the glow plug and injector seat by just making sure there's no air coming from either while the engine is running. My advice for the other possibilities is to get a leak-down test down.