low coolant temp, other symptoms

[resinguy]

The car: 2002 Golf, 59000 miles, Upsolute.

For the last several days the coolant temp gauge has not come up to 190F. Stops about one mark low. But this has not been consistent, for a few days it was low, then up to 190F one day, now low again. Coincident with this, occasionally the car will not respond fully to throttle input; as in going down the road at 75mph, give it throttle, and there is almost no response. Now this morning as I was driving, the CEL came on. Pulled over on the highway, shut it down, turned the engine back on, and the CEL came back and has persisted.

Ideas welcomed. Thanks!

 

[dieseldorf]

The car: 2002 Golf, 59000 miles, Upsolute.

For the last several days the coolant temp gauge has not come up to 190F. Stops about one mark low. But this has not been consistent, for a few days it was low, then up to 190F one day, now low again. Coincident with this, occasionally the car will not respond fully to throttle input; as in going down the road at 75mph, give it throttle, and there is almost no response. Now this morning as I was driving, the CEL came on. Pulled over on the highway, shut it down, turned the engine back on, and the CEL came back and has persisted.

Are we trying to blame this on Upsolute? I've heard everything else but low coolant due to a chip

Idaknow.

Resin, have you had the chance to verify your car is NOT suffering from coolant migration. You may have multiple issues, you should not be loosing coolant - - chip or otherwise. Can we start there? Do you have VAGCOM?


Now you know why I've stated so many times: VWoA should included a 2 year subscription to VAGCOM with every TDi sold in NAmerica!!

 

[NorthernMage]

Is your coolant temperature sensor (CTS) working well, there was another problem similar to this today, funny how things happen in groups. If your sensor is telling the ECU that the engine is cold will it affect anything? Can you go into Autozone and get the CEL read?

 

[resinguy]

No, 'dorf, I am not trying to implicate the chip. I have been happy with it for 55k miles. I just listed it in the interest of full disclosure. I could have mentioned the Spec clutch, ventectomy, and EGR adaption, but they seemed less relevant.

Clarification: the coolant is NOT low; it is at minimum. The coolant temperature has indicated low for several days, then back to normal 190F, now reading low again.

I pulled the coolant probe plug and the socket is clean and dry, so not likeley a migration issue. I do not have VAG-COM; can the usual shop OBD scanner offer any constructive help?

 

[dieseldorf]

resin, you've got tons of OH brothers. I know someone can help you out. It's ideal to have the VAGCOM (5 digit DTCs) as they offer max info which can be x-refereced in Bentley. Sure, the diagnostic scanner can provide tidbits of info but Bentley+VAGCOM is better.

 

[Powder Hound]

First, I'd recommend checking the plug to the coolant temp sensor. Make sure it is fully seated and making good contact. If that is OK, then replace the sensor.

And yes, a CTS reporting cold temperatures will affect what the ECU lets the engine do.

 

[Chemboy]

First, I'd recommend checking the plug to the coolant temp sensor. Make sure it is fully seated and making good contact. If that is OK, then replace the sensor.

Before you replace the sensor, you may want to make sure the THERMOSTAT is working corrrectly. If it is stuck in the open/partially open position or opening too early, a code will be set from the coolant temperature sensor. I had a code show up (I'll have to go back and see which one it was - maybe something like "coolant temperature below control range - intermitant") and the dealer replaced the thermostat...all is good.

First things first - get the code(s) read.

--Andy

 

[resinguy]

I don't know how many Cleveland VAG-COMmers there are, but you only need one.....John Beyer is going to help me out tomorrow

btw, the coolant temp was back up to the standard 190F on the drive home, but the CEL has persisted.

 

[mojogoes]

The same thing has happened to me a couple of times and its always been the C.T.S which when down shows low readings on the dial , i would say change this first and yes as stated the ecu because of the low reading will think the car has not wormed up.

There for tricking the ecu which then will usually add more fuel in order to worm the car up and keeping the vehicle in a state of open loop , which usually makes the car fast.....smokey but faster and not sluggish as you've reported.

 

[resinguy]

Update.

I drove over to John Beyer's last Friday. On the way, the coolant temp display was back to the standard 190F, and the CEL was still on. While cruising at 75mph, I punched the throttle and the car responded as normal, ran up to ~85 and then it just went flat, no more acceleration. Very much like a previous incident:

http://forums.tdiclub.com/showthread.php?t=79644

Never really determined what happened that last time, consensus seemed to be the engine/oil got too hot.

This time we pulled two codes with VAG-COM;

16492 Manifold/Barometric Pressure Sensor (G71)/(F96) Signal too high, intermittent

01039 Coolant Temperature Sensor G2 Open or Short to B+, intermittent

John fiddled with the sensor connection, and it seemed OK. We took the car out for a run, logging some second gear hard throttle accelerations. The boost spikes peaked at 2500 mbar. So that would be 21.7 psi over atmospheric. Is that high enough to cause a soft limp and throw a CEL?

I searched on those codes. There was a lot on the Coolant Sensor. I'll pick one up at the dealer to have on hand, but as temp has indicated normally for several days now, it may just have been a loose connection.

There was almost nothing on the pressure code, don't know what to do about that, except watchful waiting. Any ideas?

Someone speculated that the indicated low temp may have caused the ECU to overfuel, leading to the high manifold pressure. However, that fact that the car went into the soft limp even with the indicated coolant at normal does not fit that theory.

Thumbs up to John Beyer for all his help. If you are interested on a WVO conversion, give him a call, he's done around ten of them now.

 

[resinguy]

Bump for suggestions, ideas (helpful or otherwise), trenchant commentary or outright flames.

Don't you just hate it when your thread fades into obscurity?

 

[weedeater]

Coolant migration should be checked at the plug to the coolant resevoir bottle. What happens is that the bottle develops a small leak at the plug and high pressure coolant moves up the wiring into the harness. Ugly and expensive to fix.

Dont worry about the boost error. The code indicates a loose connection.

It might be interesting to see if the wiring for the coolant temp sensor and MAP share a common ground....

 

[dieseldorf]

We took the car out for a run, logging some second gear hard throttle accelerations. The boost spikes peaked at 2500 mbar. So that would be 21.7 psi over atmospheric. Is that high enough to cause a soft limp and throw a CEL?

That's high. Was the signal saturating at 2.5 Bar or peaking? - - please clarify.

I'd look into this further. You can also run a requested boost vs. actual boost log...that's always good to have. I like to run this WOT in 3rd or 4th gear. I don't think 2nd works well.

Have you checked your actuator mechanism for free movement?

 

[resinguy]

Thanks, weedeater, but I have checked that plug and it is clean and dry.

Re your idea of a common ground; I don't do electrical stuff, electrons confuse me, my wife does all the electrical work at home (plumbing, too!)

Does anyone out there know if there is a common ground?

 

[resinguy]

You can also run a requested boost vs. actual boost log...

John did log that. I don't have it in front of me now, but if I remember correctly the requested was ~1980mbar, and the (momentary) spikes were ~2500 - 2520mbar. I think some of the runs were in third gear as well, don't know if you can tell from the log. I am not practiced in interpreting the data, but I can share the file with anyone who is interested and sends me an email.

You're thinking the actuator rod is sticking? I guess I'll have to crawl under the car and check it out. John was thinking it might be the vanes sooted up and sticking, but TDI lore says that is more likely on cars that are lugged around at low RPM. I don't have that syndrome.

Keep those ideas coming! thanks!

 

[kwong7]

I'm just experiencing this now. 2001 Golf 5-speed with 125K miles, 2K miles with RC euro stage 2. I was cruising along at 40MPH and suddenly I notice the engine speed drops to zero, the alarm beeps, the oil pressure light comes on, followed by the battery light. I pull over and restart the engine only to notice the glowplug light flash a few times. Everything is all good, but the next several miles my coolant temperature drops to about 110 degrees. The last few days, everything was fun until 30 minutes ago, my coolant temperature gauge slowly dropped from 190 to 110 while I was on the freeway.

Over the last few months, I noticed my coolant reservoir dropping to the minimum but didn't think much of it. I figured that was normal. I took a look at the harness, but no signs of coolant. I'm hoping the coolant migration is not the issue...I wouldn't wish that upon anyone.