VR6 crank sensor probs ** Now Dastek/Unichip probs!

[dr_mat 0]

L O all.

 

Been having some major hesitancy recently (like the engine forgot to put fuel in, not a misfire as such), and scanned the engine today after a couple of hiccups on the way to work (BEFORE turning the ignition off and losing any info), and got the dreaded "Engine Speed Sensor - Implausible Signal" error. (Very specifically I didn't get the "No Signal" ..)

 

I had a shufty around the cable clips and stuff, and noted that the sensor's cable isn't clipped into the right supports (cable doesn't seem to reach the right spot even) and I wonder if it's been routed round the wrong way..? The problem only seems to occur when suddenly opening the throttle, which would coincide with the engine moving back a bit, so I wonder if this is combining with the cable routing to cause a connection problem.. I waggled the cable around a bit with the engine running and had no problems with idle, so am sceptical about the "cable routing" theory myself, but ...

 

I am pretty much assuming that I will need to replace it, but then comes the question - where's the best place to get one from? I hear GPC can get them, but I don't think the price was ever confirmed. Any ideas?

 

Another thing - I notice that there's a disconnected cable hanging down from the same part of the wiring loom that the CPS connector comes from. Just a single wire, with a single plastic shielded spade terminal on the end... Not sure if that goes anywhere...

 

Any pointers/ideas/experiences?

 

TIA,

 

M.

[Henny 0]

what colour wire?

[dr_mat 0]

"dirty"..

 

Good question, will have to go check. I think it's just mucky white.

[Henny 0]

"dirty"...

 

:lol:

 

Well, if I didn't ask, someone else would have! ;) :lol:

[dr_mat 0]

Spoke to GPC. They can get them, but they are listed as £126+VAT from VW, and they can supply one for £96+VAT, but they point out that as an unofficial import, they wouldn't be able to offer a warranty ..

[Supercharged 2]

They should give you a 1 year warrantly with anything but VW give you 2, I'd see what discount you can squeeze out of your dealer!

 

You could also try a bosch dealer (if it is a Bosch part!?!)

 

Also - have you had the sensor out and cleaned it to see if it improves things...

[dr_mat 0]

Nope, not tried anything that complex so far. And now it's pissing it down, so I doubt I will be doing so for a while..

 

There ya go! Here's the bunny. Error goes away if you stop the engine and restart it, as I suspected, so I have to scan it when I get to the end of a journey before turning the ignition off.

 

----

 

Control Module Part Number: 021 906 258 CP

Component and/or Version: MOTOR 2,8L 6-Zyl.

Software Coding: PMC 1 HS

Work Shop Code: 0261203565

1 Fault Found:

00513 - Engine Speed Sensor (G28)

27-10 - Implausible Signal - Intermittent

[Supercharged 2]

2.9L??? I assume thats normal...

[dr_mat 0]

Yeah, that's normal, or so I'm told!

[fla 9]

If there is a fault with the crank sensor then you cn only check it when the car cuts out BEFORE turning off the ignition and try to restart. Otherwise this get deleted.

Try removing and cleaning it and clean the block down too where it is seated - this will probably be a bit rusty. Also, the static resistance test (1kohm iirc) may help somewhat. Check the resistance from the connector and also from the main loom connector for continuity.

HTH.

[dr_mat 0]

The car doesn't seem to cut out much, the problem only seems to crop up during acceleration, so the motion of the car is enough to keep the engine turning and the ECU fires the spark next full revolution, so we carry on. Just a big kangaroo thang..

Sounds like a clean-up is in order.

Cheers folks!

[RW1 0]

The car doesn't seem to cut out much, the problem only seems to crop up during acceleration, so the motion of the car is enough to keep the engine turning and the ECU fires the spark next full revolution, so we carry on. Just a big kangaroo thang..

Sounds like a clean-up is in order.

 

Sensor problem like the ABS. Starts at higher rotational speeds and gradually gets worse.

 

Solutions:

 

- Defective sensor, most likely as it's occuring at higher rpm's.

 

- Loose sensor in the engine block at the lower nearside front.

 

- Loose sender wheel, part no. 021 405 189C - search ETKA to see where it is. It's sandwiched in between the crank & the flywheel so I would have doubts with this one as you would be complaining of clutch funnies.

 

As you say dr_mat clean up the item first as that costs nowt in case it's a bad earth but if this was the case, I'd ecxpect to see failure at low rpm's also.

 

.

[dr_mat 0]

Hi RW1,

I do get failures at low rpms too, but only under acceleration it seems. (There were stallings at junctions once or twice too, but that was months ago and very occasional - like 3 or 4 times.)

The clutch was replaced when the timing chains were done (around 9 months before the first hiccup showed up), so I would hope that the sender wheel hadn't been knacked, and I don't have any clutch funnies.

Time to have a shufty at it, and see if it's tight/clean I think.

The only other factor was that there's a dastek chip on the engine, which if I understand correctly, sits between the ECU and it's wiring loom.

[Kevin Bacon 5]

Replace it mat, it's lost it's resolution. Every so often the square wave the ECU is expecting turns to a soft sine wave or a flat line and the ECU thinks, ay up, that'll be an implausible signal then and it's intermittant.....hence the lovely plain english VAG-COM translation ;-)

 

They start off like that and progressively get worse until they fail completely. A magnet only has a finite life in a hot, dirty environment.

 

VW basically charge what they like for it cause they know the engine won't run at all without it, unlike the other sensors which have substitutes.

 

Mine did exactly as yours did, replaced it, fine ever since.

 

Cleaning them does nothing. It's a magnet. The only thing that can affect it physically is excessive swarf, which you're unlikely to find.

[dr_mat 0]

That was what I was expecting to happen, to be honest ...

Wonder if it wouldn't be a whole lot cheaper to rip one off a late VR lump in a scrappy though. Surely they only go wrong due to old age, and my guess is the part's the same on the newer cars, no?

[Supercharged 2]

According to ETKA, should be the same as most mk3 based vehicles...

[dr_mat 0]

Cool, at least they're three years younger than the C...

[dr_mat 0]

Righty ho. Crank sensor is, to all intents and purposes, perfectly fine.

A local guy had a good look at the VR with me today, he's a pretty good motor electrician. We had the sensor on an oscilloscope, and it's producing a nice sharp square wave, as it should. The resistance is (consistently) 550 ohms or so, within the factory spec 500-700, and the wave form doesn't decay when the car gets warm or anything.

This guy reckons he's never seen a crank sensor go like this (they usually stall, and the car is hard to start afterwards).

He also checked the main engine earths and they're perfectly fine, so all in all it's hard to justify going to VW to fork out cash for a perfectly good sensor.

 

So, this leaves a few possibilities:

relay 109 (refitted it, looks perfectly fine)

very intermittent break in the sensor wiring

the Dastek chip, which is piggy-backing off the ECU. the car has only ever had this problem since it was fitted, but that's not to say it's had this problem EVER SINCE this was fitted...

 

Think I need to run the car without the dastek. Which is easier said than done when you don't know how to fit it...! Need to talk to Stealth about this I think.

[dr_mat 0]

Stealth were kind enough to post me a bypass plug for the unichip a few days back, and it's fixed my problems.. so it seems the unichip is failing. Reconnect it and the car is hiccuping again like mad, and I'm getting crank sensor errors in the ECU. Very weird!!

 

But nice to know there's nothing wrong with my crank sensor, anyway. Glad I didn't fork out for one of those then!!

[Dutch24V 0]

Is this a common fault with the Dastek does anybody know??

 

I have one of these to fit to my car, but have been advised to throw it away by some vw tuners over here as they say that the response time on the Lambda/Co etc. is terrible?

 

Asim reported no problems with it fitted to his car though?

 

Dutch

[Kevin Bacon 5]

Nothing will outperform an onboard chip.

 

I had the same problem with K star back in my 16V Turbo days. It had 4 or 5 maps onboard, each loaded automatically depending on MAP signals. The engine physically stammered as K star loaded the next map, so as you say, piggy backs are slow to react. And with K star/Dastek etc, you can only reduce timing and fuel, you can't add it like you can with onboard chips.

 

But at the time, it was the only alternative to expensive DTAs etc.

 

Similarly with the Dastek, Vince doesn't have inhouse chip blowing facilities and always got AmD in to do that when necessary, so again, the Dastek was the only solution. Vince is currently looking at doing rechips in the near future though, now that Geoff Everett has moved out of the country.

 

My K star box packed up, so yep, they can and do fail.

 

I wouldn't junk it based on the strength of one man's findings or what people over there say you should do. If it's running right now, leave it until it does break and worry about it then!

[Dutch24V 0]

Well, it's not actually fitted to my car yet. I was planning to do that tomorrow too, while my VW mechanic mate is doing the matrix.

 

Depending on weather, will fit it tomorrow and see what happens then. If it does break though, is there another way I can trigger the flap on the VSR? Can I use the shrick solution with my ECU (AG)?

 

Dutch

[Kevin Bacon 5]

You can trigger the flap with a switch on the dash :-)

 

The schrick solution is the only solution on the VSR I thought? I have heard of dedicated VW ECUs which had an output which switched the solenoid on at 4000rpm, but I've never actually seen one.

 

Yeah the schrick controller wires into the AG fine....

[dr_mat 0]

The early VR6 ECUs had an output wire that could be used to trigger the VSR flap, but you needed the VSR EPROM to make that work. The rare combination of VSR, VSR EPROM and early VR6 ECU was a factory-quality job, and would be a joy to live with, compared to the Unichip..

 

The unichip is quite slow to react. If you're running with the schrick and you have pinking issues, you'll have to be careful. Progressive onto the throttle if you're in the Schrick zone, otherwise it'll pink for .5 secs until the unichip gets it's act together. I wish I'd gone the custom EPROM route now, no question.

 

The Schrick control unit works with any ECU, because it taps directly into the RPM wire that comes out of the ECU, and it therefore does it's own switching.

[Dutch24V 0]

lol, that would be interesting!!

 

I thought the vacuum stuff was from shcrick, just wasn't sure.

 

Yeah apparently the earliest VR6 ecu's had this connection and the chip that comes with the VSR plugs straight into them and opperates this connection at 4000 rpm. Not seen one either but no use on my coil packed VR anyhow unfortunately!

 

Cheers...

Dutch