Hard starting after injector change...

Hello All,
I am having a bit of a time with hard starting when cold in my 2000 Golf, and in my Dad’s 01 Beetle.

I am sure there is something that I am missing, but here are the details...changed the injector nozzles in my 2000 a Golf to some PP764’s. Had them gone through by DBW, and followed the instructions for everything to get them back in and IQ changed to about 3.8.

On the Beetle, it got my old nozzles which were some older P520’s. These also got sent to DBW for cleaning and service. Got those back and set the IQ to 5. Both of these IQ changes were via the Hammer Mod.

The trouble I am seeing is when it is 60-70 degrees, they both have to crank like it 35-40 degrees. Prior to injector changing, they both would pop off with a couple of revolutions when the key was turned.

When they are warmed up, they pop off with a quick turn of the key, much like they used to when they were cold at warmer temps.

I don’t see anything leaking on either one, but am stumped at this point. Can anyone see something I missed?

Thanks for any help!

3.8iq seems a bit high for those size of nozzles, try turning it down a little more? Also check to see if you have compression leaking past your injectors from poor sealing. Soapy water.

How are the glow plugs?

I have thought about changing the IQ on the Golf to be a bit to be closer to 4 or 4.5, but will certainly check to see if we have any leakage past the injectors with some soapy water.

Being it is 60-70 degrees the glow plugs don’t come on, but they are good in both cars.

Check the timing on the VCDS graph, and the injector balance. Also pop pressures, although that requires testing by someone familiar with the our 2 stage injectors.


Did you ask for a specific "setup" for the nozzles? I had mine calibrated by my local diesel shop to be at the top end of the scale, 220/300, there "margin of error" was +/- 10. He warned that doing so might retard timing, which it did a little, no problem to tweak the pump a tad. With large nozzles, (.230) I'm after better atomisation.

Playing with the IQ won't solve a timing, or pop, problem.


Nero Morg recently had his injectors reworked by Franko6 to good effect.

I was under the impression that DBW checked and adjusted pop pressures when he cleaned them and set them up.

Per his website, the Beetle’s injectors were ultrasonic cleaned, and pressure balance tested, which brings them back to new tolerances.

Seems to me when I ordered my new injector nozzles that it was asked how I wanted them set up. This is what it read for the 764’s...” (Professional Nozzle Mounting Service:Mounting, pop-testing, digital calibration/flow testing.”

Sadly, I do not know my way around Vag-com well, can the timing and balance be changed, or just monitored?

Injection timing, once the car is RUNNING, is under control of the ECU.

HOWEVER static timing is extremely important for starting performance. You can check that with the timing graph in VCDS (note that the engine has to be warm for it to be valid, but the instructions will tell you this if it's not as it checks the coolant temperature.)

You cannot change injector balance electronically; they're either ok or they're not, as it's a mechanical thing.