Needle lift sensor G80 P00542 / Seeking injector advice

[Benjamis]

I have been getting random misfires for over a year. I replaced relay 109 and then I didn't notice any misfires for the rest of the summer and over 1,000 miles, but as soon as temperatures started to drop, started getting the misfires again and longer crank times and tons of smoke on startup. Found out the glow plug relay stopped working thanks to output tests in VCDS. Put in new glow plug relay and tested each glow plug through the glow plug harness, and they all light up. Had a new backup set and put them in anyway and will save old ones as backup. So glow plugs are good. Timing is mechanically and dynamically in spec. No error codes in regard to the misfires, checked with VCDS numerous times for a year. Finally I left the engine running and went around wiggling wires trying to make it misfire. Never figured it out, but realized when I wiggle the needle lift sensor wire, that there is a humming sound. The humming can be heard with engine off and ignition on, and it comes from the N75 and QA, which is slightly frightening, but only when the connection to the G80 is interrupted. Finally got the P00542 code, cleared it, and it immediately came back on. Checked the resistence across the two terminals of the G80 plug with ignition off, and resistance was 93 ohms, within the 80-120 spec. Doodled around on other things for a minute, then checked it again and resistance was infinite. Found out if I wiggle the wire, resistance fluctuates between in spec and infinity. Isolated it to where the wire enters the injector. The black wire sheath was in excellent condition, no chaffage. Cut off the black sheath to expose the two white wires, and one white wire was severed.

Anyone ever have this happen?

20210923_134919.jpg

• Benjamis
• Sep 23, 2021

Yesterday, I cracked all 4 injectors with engine running and they all make the engine sputter, meaning they all work properly right? However the injectors are of unknown age, and obviously old enough for a wire to cut itself off inside of a sheath. I have had this car for 4 years, 30k miles. I actually removed and took apart the injectors 2 years ago and cleaned them all up and checked the spray patterns and all seemed good. Only thing was #4 injector had a few rust spots on some of the internal parts, which was surprising. Would love to buy a whole new set of injectors, but the price tag is rather uninviting. What would you do, buy a new #3 and new nozzles? Would you buy a new #4 too, or all new? Or you have a trick to fix this?

Hoping to clear up the cold start smoke. I have always had a small cloud on startup when it is not summer hot. Kind of embarrassing.

 

[ToddA1]

If you’re looking to buy new injectors, be ready for sticker shock.

Personally, I’d buy a known good, used set from a running car and have new nozzles swapped in, unless the seller has history on the existing nozzles.

Whenever I sell complete sets of injectors, they’re sold as cores, even if the engine ran fine. Usually under $150 shipped for a good set.

-Todd

 

[Benjamis]

Are you saying you have a good, used set for under $150?

 

[ToddA1]

Unfortunately, I don’t. Sold my last set about a month ago. Check the classifieds.

-Todd

 

[Steve Addy]

Make sure if you buy used (core) injectors that they're from a MT car and not AT. That is if they're from a Mk4. If they're from Mk3 or B4 then there's no problem since they were all MT.

Steve

 

[Abacus]

There is a manual ALH in a local junkyard, I can pull the injectors, pop test them with my tester, and send them out if you want. I’m not sure what they get for them but doubt it’s much.

 

[Benjamis]

Thanks for the offer. I might take you up on that. I'm seeing that I could get some new quality injectors from trusted vendors and with new nozzles in the 500-600 range. If so, what do you think about larger nozzles? I would guess I have stock nozzles, possibly originals. I just put in a stock clutch and have no chips or mods, not looking to do anything crazy, just economical point A to B, but if I can get more power without sacrificing economy as some say, I might be down, although I am currently satisfied with the power that this engine produces. That is the sad thing, these injectors are fine, just that wire. But for all I know they leak and give me the cold start cloud.
In the meantime, can I hurt anything driving with this disconnected? I suppose I could re-rig it a little better than it was before, seemed to be no harm done.

 

[ToddA1]

Make sure if you buy used (core) injectors that they're from a MT car and not AT. That is if they're from a Mk4.

If one is specifically looking for core injectors, I’m not sure that matters. You’d be swapping in the nozzles, of your choice. The only thing I’d be verifying, is the plug for #3 is rectangular, not oval.

-Todd

 

[Abacus]

If one is specifically looking for core injectors, I’m not sure that matters. You’d be swapping in the nozzles, of your choice. The only thing I’d be verifying, is the plug for #3 is rectangular, not oval.

-Todd

The plug end can be swapped on the car to match. I have an ALH one in my stash somewhere for just this reason but won’t need it.

 

[ToddA1]

Swapped meaning depinned? I looked at these many times and the plug appeared to be molded on. The most recent time was about a month ago.

if you mean cut and splice, yes.

-Todd

 

[Benjamis]

So if you buy cores do you send them out to be calibrated or just install and see how they do?

 

[ToddA1]

Well, that’s your decision….

Unless they’re very low mileage, I’d think the entire point of cores is so people can send them out for new nozzles, without taking their car off the road. If you don’t rely on this car, take it off the road, send your injectors in and save some money.

Calibration is a debated topic. I pay for calibration.

-Todd

 

[Steve Addy]

So if you buy cores do you send them out to be calibrated or just install and see how they do?

I would always assume that core injectors need nozzles and calibration unless proven otherwise. And unless I know the person selling them I wouldn't probably believe anything they said...like miles etc. People will typically say anything anymore.

Well, that’s your decision….

Unless they’re very low mileage, I’d think the entire point of cores is so people can send them out for new nozzles, without taking their car off the road. If you don’t rely on this car, take it off the road, send your injectors in and save some money.

Calibration is a debated topic. I pay for calibration.

-Todd

I'd pay for calibration too...new nozzles need calibration.

Steve

 

[Benjamis]

Who is your top recommendation for calibration?

 

[Benjamis]

So I got reconditioned and calibrated injectors and went with DLC520 nozzles. I'm loving them and have driven 1,000 miles and have not had a single misfire. Glad to finally get that sorted out.

Cold starts are way less smoky and the exhaust is way less stinky.

IQ is at 5.0 and is a little smoky at full throttle, but as someone mentioned here before, can be nice when dealing with a pesky tailgater. He he.
I tinkered with the EGR in adaptations to give MAF specified of 360 at warm idle. The EGR valve was made non-operational by a previous owner by severing the vacuum line and plugging with a screw. Timing is advanced near the top line of the graph. Mechanical timing is spot on.

I was bummed that I only got 44.0 mpg on my first full tank, could be from revving more than usual and enjoying the extra power. I'm used to high 40s or low 50s, and that was with injectors of unknown age and way out of balance according to group 013, as in deviations on the order of -2.5. Glad that is under control now.

Any recommendations on settings in VCDS for the 520 nozzles? Everything else is stock. Looking for max efficiency and low smoke.

 

[JordanTr]

Just another datapoint for this older thread. My car had the exact same stench and poor revving. See: https://forums.tdiclub.com/index.php?threads/new-member-1996-b4v-bc-canada.521130/post-5808419. I swapped in newer, used injectors and it's much better! My injector balance as shown on VCDS wasn't even that bad (0.48, -0.28, 0.37) but the newer injectors made a world of difference still.

I saved a post from DBW a while back recommending 2.8 IQ for stock, 4-7 for injectors only and 2.8-6 for tune + injectors.