Upping the Boost on my VF SC'd 540. Testing the Failure Limits of the Stock M62?

[JimLev]

Let me check mine, hope to have something for you tomorrow.
Both elements of the dual temp sensor should read low ohms, like 1-3K.
That would probably account for your timing to be pulled.
Last time I was at Redshifts he had a similar camera that I was going to buy but forgot about it.
I'll get this one right now.

Edit:
Just looked at my notes.
1-2 reads 6.3K @ 20C
3-4 reads 2.5K @ 20C

My engine is cold so hot may have a bigger difference between the key in pos 1 & 2.
Key in Pos 1 reads 24C
Key in Pos 2 reads 23C

[philly98540]

Hey Jim, thanks for the info! Much appreciated! Looks like mine is shot on the pin 1-2 element. I bought a new one from FCP last night. Looks like I'll need to drain out some coolant to put er in. I hate coolant!

I assume this side of the element goes to the DME since the temp gauge still reads fine. What's wierd, is the car drives fine except for the wot timing pull. I would think it would be adding extra fuel since it thinks it's cold? That would drive trims negative. Hmm? Maybe it also looks at the IAT sensor and ignores the bad coolant temp? Also, no codes set. Odd. I hope my tune does not go whacky once I replace this.

[tptrsn]

I thought you had a wideband? Assuming yes, what are your AFRs at WOT when you're having the problems? Are you seeing the negative trims in closed loop?

Do you think a low reported operating could be causing a timing problem that might relate to your recent knock events? (or did you already cover that on the last page or something?)

Oh yeah, since I clearly don't have enough question marks in this post yet, do you need me to check resistance on a non-TU car later today?

[geargrinder]

Sorry slow on the update Chris, busy day yesterday...

WDS says in fact its 1-2 to the cluster, and 3-4 to the DME.

[philly98540]

I do have the wideband. AFR's are good in both closed and open loop. Trims are great. What I wonder is, when I tuned the car myself, was this element bad at that time? I guess I'll find out when I put in the new sensor. Lol.

I'm not sure what your referring to in regard to knock events. I have not heard knocking. I did mention that I may need a new knock sensor though.... this bad temp element may not be the cause of the timing pull, but I'll remain hopefull.

No need the measure resistance as the TU and non TU use the same dual element at the water pump. Thanks for offer

[tptrsn]

Sounds like I'm confusing threads then... I thought your timing pull was from reported knock. I've found that a lot of knock can't really be heard inside the car -- det cans of some sort are pretty much a necessity. Especially with the hundreds of pounds of sound insulation in these E39s.

[philly98540]

JC, thanks for pulling wds. Question. If my 1-2 element is bad, how does my temp gauge still work correctly? Odd

[JimLev]

Chris, when you pull the temp sensor keep the cooling system closed up, cap stays on expansion tank.
Only a few drops of coolant will leak out of the sensor hole.

[philly98540]

Sounds good Jim. Let no air in, and not much leaks out! Genius! I like it.

[Mach540]

Or you can open the cap, squeeze the radiator hose, close the cap. This applies a slight vacuum on the system.

[philly98540]

^ even better! Thanks.

At lunch, while idling the car, I unplugged the temperature sensor. As expected, temp gauge went to red and KTMP went to minus 40 or something. Engine did a minor stumble, but came right back to normal idle while the temp sensor was still unplugged. Not sure why it stumbled, but the DME must know it was unplugged and changed to some other table or something. I scanned for codes, and sure enough, a code popped for the temp element.

So, this is interesting to me. BMW puts in this dual element sensor, one side for the gauge, and one side for the DME. OK, makes sense. But, they do not send a code when the temperature data going to the DME is totally garbage? WTH. It was getting data, sure, but way illogical. All the codes that can be set for the gazillion things that can go wrong on these cars, and nothing for this one. Makes me wonder if we should all be periodically checking KTMP in both key position 1 and 2 to verify proper sensor operation. Also, the WDS wire numbers appear to be reversed at the Temp sensor. Not the first error I've seen on the WDS.

[JimLev]

I checked my KTMP tonight, the outside temp was 95F.
Engine running KTMP was reading 93C. Shutting the engine off the KTMP dropped to 92C.
Probably just a function of slightly lower voltage with the engine off.

[philly98540]

Makes sense Jim. My new sensor should be here in a couple of days. I'll report back what happens. Just odd that the cars runs pretty normal even though DME thinks the coolant is super cold. I hope nothing changes with my trims once I replace the sensor. If so, it's back to modding my fuel tables again.

[JimLev]

I got my HD camera today.
Won't be able to check it out for 3+ weeks, leaving on a cross country trip to Campobello island in the Bay of Fundy in 2 days.

[philly98540]

You hitting some good stuff this year! Retirement feels good I bet.

[philly98540]

I just put in the new temp sensor. KTEMP is now good in both key positions 1 & 2. No coolant leaked at all with coolant cap closed! Thanks for that tip.

Now I need to get some drives in and see if anything changed.

[tptrsn]

I'm confused about what that bad sensor was even doing....

Maybe it will become apparent after some more of your testing.

[philly98540]

I'm not sure if it was somehow affected the huge timing pulls I was getting below 5k rpms. It supplies the coolant temp data to the dme. DME was getting coolant temp of like 5 deg. C even when engine was fully warmed up. It needed to be replaced. It's raining here so I have to wait to drive it.

[tptrsn]

Maybe if the low timing is a safety measure for an engine that hasn't achieved operating temperature it makes some sense... But otherwise it seems like it didn't do anything, huh?

[philly98540]

Replacing the $25 temp sensor seems to have solved the timing pulls below 5k rpms. Car is running normal again! Trims did not move, so that's good. No need to adjust the fuel table. Not sure how or what the DME is using this coolant sensor for exactly. I would think it would have gone into a fuel enrichment mode if it thought the coolant was cold, but it did not. Maybe it also compares it to the IAT and makes a decision? Not sure. More puzzles.

So, long story short, check KTMP is key position 1 and 2 to verify both elements are properly working. If it's malfunctioning, there is no notification (at least on my old pre TU car).

[tptrsn]

EXCELLENT news!!

Now time to head to a drag strip to get a trap speed!

(Don't worry about your ET, that's just for cars that are setup to launch like a drag car)

[geargrinder]

Interesting! Thinking about pro-active dual sensor replacement. Might be the kind of sensor that 'drifts' over time.

[philly98540]

Thad- I wish a strip was closer to me. Oval dirt is the local track. Modifieds and street stock mayhem! I would like to hit a 1/4 mile at some point.

JC- check KTMP in key positions 1 and 2 at startup and fully warmed up. They should match each other within a degree or so. Odd I get no codes with mine out in left field.

[JimLev]

I wouldn't be surprised if you were in the low to mid 12's at 110 MPH or better.
Have you checked the temp sensor resistance now that it out of the car and probably closer to 20C ambient?

[philly98540]

Yeah, likely in that area Jim! If I'm lucky, maybe a bit faster accross the line.

I did check it quickly. It read like 5 Mohms on the bad element on the bench. So waaay out of spec.