stuttering, stalling

SOJ

Member
Joined
Sep 2, 2020
Location
California & Oregon
TDI
2003 Golf
Hi, been troubleshooting my stalling problem and thought I'd throw out what I have to see if anyone more experienced can chime in. Recently had a leaking IP changed at a shop, since then with the "new" used pump, the car will stutter and sometimes stall when driving, but never when idle. Once the engine gets up to temp, I start seeing air in the clear line to the IP. Was thinking it could be a restriction in the fuel line making too much pressure on a seal somewhere, or just a bad seal.

I pulled the sending unit, looked fine but I cleaned it out. Its the later model without the return valve anyway. Replaced some screw style clamps with the spring type and the t-valve on the fuel filter since those seem to be common leak spots people mention. No change.

Relay 109 is new.

Just got VCDS on it today, and got more than a couple codes:

17978 - Engine Start Blocked by Immobilizer
P1570 - 35-00 -
16612 - Throttle Pedal Position Sensor (G79)
P0228 - 35-10 - Signal too High - Intermittent
16705 - Engine Speed Sensor (G28)
P0321 - 35-10 - Implausible Signal - Intermittent
16502 - Engine Coolant Temp. Sensor (G62)
P0118 - 35-00 - Signal too High

That's a lot of sensors. I was going to start by checking the connector and ohms on the engine speed sensor, as I've seen a thread about it causing similar to what I'm experiencing. My door remotes don't work and haven't for awhile, the locks themselves are also quirky. I was told these are all controlled by the ECM- the same computer that manages the engine? Wondering if I should just be changing that computer out. A check of it's connections seems to be in order, at least.

Thanks in advance for any suggestions or correction!
 

SOJ

Member
Joined
Sep 2, 2020
Location
California & Oregon
TDI
2003 Golf
Engine speed sensor ohms out of range, got 1,160-1,200 instead of 480-1000 range in the service manual.
If this was not working when they did the timing on the new IP, I'm guessing it could mess up the readings and it may be set too advance.
Is that crazy or make sense? I'm not sure it actually uses that in the timing adjustment, but I would think so.
 

Nero Morg

Top Post Dawg
Joined
Oct 19, 2017
Location
OR
TDI
2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
Since you have a fault for the engine speed sensor, and the resistance is out of range, I'd replace it. Get an OEM one, or you'll be right back where you started.

The door locks utilice the comfort control module, not the engine module. Chances are, if your auto locks work with the button on the inside of your door, it's probably the fob not working. You can check and try to resync your fob with VCDS, under the comfort control module.
 

SOJ

Member
Joined
Sep 2, 2020
Location
California & Oregon
TDI
2003 Golf
Ah, thanks for the info on the comfort control module- my interior auto-lock does not work, actually, so it's probably that module and not the fob. Now that I have VCDS I'll have to replace that after the engine issues.

I found some other threads on here that also read ohms similar to mine on working speed sensors, but it's cheap-ish and in my list of codes, so I'm still going to try it anyway.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
First thing I'd do is record the codes, clear them, go for a drive and see which ones come back. I would suspect the new used pump, but you want to rule out everything else first. Take a look at the injection quantity. It should read 2.2 - 9.0 mg/H, we lkike it around 4 but it should work anywhere within the range. If it fluctuates, could be a sign of worn pump internals. Also check timing, engine warm Start of injection: range 12 - 75 = 2 degrees ATDC - 3 degress BTDC
 

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
I found some other threads on here that also read ohms similar to mine on working speed sensors, but it's cheap-ish and in my list of codes, so I'm still going to try it anyway.
From my one experience with a faulty speed sensor and the countless threads on here, my opinion is the sensors can either completely fail at once or start being troublemakers. They don't always throw a code, never get better, and it's the one thing the ECU relies on that needs to be 100% working. Get a new one.
 

SOJ

Member
Joined
Sep 2, 2020
Location
California & Oregon
TDI
2003 Golf
Well, I changed the sensor since I had it and, but also discovered the IQ was off so i adjusted with the hammer mod and so far so good, no stuttering or stalling. After a couple drives, though, engine light came up and the IQ had gotten higher than I set it, so I guess I need to adjust better. However, the new code was EGR system insufficient flow, so I also have the EGR valve off and am creating a pile of soot.

Thanks for the values to check, Bob, that was very helpful- also, is that you in the hammer mod video? The blue Beetle matches your pic.
 

SOJ

Member
Joined
Sep 2, 2020
Location
California & Oregon
TDI
2003 Golf
I actually haven't checked. I think it showed as retarded in VCDS before I adjusted the IQ (I was just stumbling around exploring VCDS, wasn't really looking for it), and haven't checked again after. I didn't have the counterhold tool with me, so was gonna explore timing when I had it handy.
Maybe I should have done that first? Actually I'm not even sure I need that if I'm not changing the belt, I've seen people do it without in videos. Was gonna figure it out on the fly. 🙃
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
The ECU handles any timing within the range. It is critical that mechanicals are timed correct. IQ we like around 3.5 to 4, but should work anywhere within range (2-9). That's not me in the video. The increase in air in fuel line and the IQ fluctuating could be the pump is not in good nick.
 

SOJ

Member
Joined
Sep 2, 2020
Location
California & Oregon
TDI
2003 Golf
Actually, after I adjusted the IQ the air in the line was worse, but after two drives, ~40miles, it was gone and haven't seen any air at all since (another ~60miles). I had it at about 4.2, but when I checked again after the ~100 miles it was at 5.8. It doesn't fluctuate while I'm checking it, maybe .2 at the most. I was thinking that was what you meant, but maybe you're talking about it changing over longer times and driving. 🤔
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Yes, bouncing while checking. Believe your IQ is fine.
It's hard to stall a diesel engine. One of the engine management controls. Often we see these older cars develop wire/connect issues.
 
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