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P1270 error code on Facelift TD4


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I've been trying to fix a P1270 error and a noisy turbo for a little while now.

Our 51 td4 gives these figures for boost:

780 rpm=98.3kPa

2500 rpm=105kPa

4000 rpm=140kPa

 

The problem 55 td4 gives:

780 rpm=99.5kPa

2500 rpm=150kPa

4000 rpm=220kPa

At the rev limiter = 240kPa

Driving the 55 td4 hard I can punch holes in the turbo hoses :ph34r:

 

Swapped vacuum lines, turbo solenoid and accumulator from 51 td4 and there's no difference in readings.

Unplug the power connector from the turbo solenoid and the boost stays around 105kPa for most of the rev range. Turbo actuator arm is free to move, actuator holds vacuum and the turbo vanes are moving freely.

 

I am at a loss as to what it causing the ECU to request the high boost.

 

Edit: I forgot to add that the rpm and kPa figures above are with the cars stationary.

Edited by gadget
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Out of curiosity I tried 2 different MAP sensors and 2 MAF sensors today. No real difference between the sensors.

Logging some data whilst driving shows that boost pressure appears to have a hard limit at 248kPa and air flow has a peak around 1250mg/stroke.

 

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I've found a possible break in a wire on the crank sensor. Chopped and soldered and the P1270 is staying away :)

Another test drive, and if I drive holding the boost at 248kPa (a small hill and 2500rpm in 3th does this) for any length of time I get P1470 and limp home :angry2:

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A little more progress with this today. Although the turbo actuator would move when vacuum was applied it would only move a little when vacuum was triggered via the solenoid. This turned out to be a small piece of debris in the actuator that would act as a plunger when it was sucked into the vacuum feed opening. Maybe with the engine running the vibration was enough to throw it into the opening?  Actuator is back on the turbo and now operates full travel in a nice linear movement when I control it with 0 - 11V externally.

With the engine idling and the solenoid power plug removed I'm seeing 10.92V at the plug with a DMM. (I know it's a PWM signal so I'm expecting that to be around a 70% duty cycle.) The ECU still isn't controlling the boost properly :angry:

With a blip of the throttle the 51 td4 moves its actuator a good way and lets it slide back slowly. The 55 doesn't really move its actuator when the throttle is blipped, and it can still hit 240kPa under acceleration. Irritating.

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I've checked the wiring for the MAP and it looks fine. Two different MAP sensors give very similar readings that look sensible so I'm taking those as good.

Similarly two MAF sensors give pretty much the same readings and the wiring for that looks fine too.

I've found two broken wires so far. The crank sensor and the boost solenoid both had wires that look to have fatigued and cracked.

The burst turbo hoses are another good indicator that the boost is too high.

I read somewhere (I can't remember where) that the MAP sensors upper measurement limit is around the 250kPa mark, so the 248kPa I'm seeing may be the sensor limit rather than the boost pressure 😲

 

 

Edited by gadget
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100kPa=1 bar. It seems you can buy MAP sensors in .5 bar intervals for your specific application. Even GM supply different upper limit parts

3 digit case stamp numbers:

1 Bar: 039, 460, 883, 876
2 Bar: 886, 012, 539, 609, 701
3 Bar: 749, 861

 

I've wondered if the vnt vanes aren't going all the way closed?  The ECU expects the vanes to be fully closed with zero vacuum applied. When needed it will apply vacuum to request more boost. If the turbo isn't at minimum the ECU can't adjust downward other than cut fuelling.

I've put together a circuit that will exercise the actuator and pull it through full range once per second. I'm going to run that for a while and see if it helps.

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11 hours ago, gadget said:

Exerciser circuit worked perfectly. Left it running for an hour but no effect on the turbo boost level. First test drive gave P1470 as usual.

What's P1470 when it's at home?

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Autocom says unknown fault.
The net throws up a few descriptions such as "Variable Intake Balance Valve Always Open", "Supply pressure regulator", "Boost pressure regulation".

In search results I've found many P1470 errors seem to be fixed with a new boost solenoid or vacuum pipes. I've got new vacuum pipes and the solenoids I have all work fine on our 51 td4. The turbo actuator holds vacuum and now moves in and out when controlled directly.

I think the only thing left is the turbo itself.

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  • 2 months later...

I have finally got around to pulling the turbo on this freelander.

Short story is that the vnt vanes had seized solid and the ring that moves the vanes had worn enough to allow the actuator to move but no adjustment was taking place. I've stripped the turbo and replaced the worn bits from a salvage turbo, freed off the vanes and given everything a good clean.

I expect that's the over boost problem solved.

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  • 2 weeks later...
On 9/26/2020 at 8:22 PM, gadget said:

I expect that's the over boost problem solved.

And no, the over boost is still occurring. I am now stumped.

Current vacuum pipes are all sound and hold a good vacuum. (EGR vacuum port blanked)

Vent pipe from turbo solenoid to inline filter is clear and new filter fitted.

Engine vacuum pump is healthy. over 27 inHg at idle.

Testing the turbo actuation with a vacuum pump and gauge checks out. Activation starts at about 4 inHg  hits the end stop at about 19 inHg.

New, genuine, turbo solenoid fitted.

Pin 1 wiring from turbo solenoid plug C1611 to ECU C0606 pin 23 checked < 1 ohm.

Pin 2 on turbo solenoid plug C1611 has 14V.

 

Any suggestions of what else to test? The only thing I can think of now is that this ECU has had its boost map fiddled with.

 

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  • 1 month later...

This is finally sorted.

I tried another ECU - same problem.

Checked everything over again but still found nothing wrong. So pulled the turbo again - eventually found the problem. Nozzle ring on the salvage turbo wasn't correctly oriented. I put it back as I found it :banned:Refitted correctly and it's running fine.

To save anyone else the hassle, when I've finished the last few jobs i'll layout the original turbo bits and take a couple of pictures showing good and bad orientations.

 

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Two faults. This new to us freelander was a basket case that was cheap for a reason :ph34r:

P1270 was the first fault I went chasing down. It was a dodgy wire to the crank sensor.

As far as I have determined P1470 can only be one from of these sources:

Turbo solenoid

Turbo itself

Vacuum pipework

MAP sensor

ECU

Wiring from either MAP or turbo solenoid

 

Intermittent P1470 would lead me to check wiring just before the solenoid plug for fatigue, and the vacuum lines to the EGR and the one over the engine to the turbo solenoid.

 

HTH

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Thanks

Vac lines good, actuator working, turbo vnt arm moves freely and when vac's applied will change the engine note as the arm moves,, so unlike yours, it's all moving inside as well.

I do this stuff for a living!

Trouble is when it's your own car and it really is very intermittent, there's not much incentive to spend the day driving about with it plugged into the code reader.

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Have you pulled the solenoid wires as far out of the protective sleeve as you can to check for hardening/cracks? Our 2001 freelander has hard and brittle plastic on the solenoid wires about an inch into the protective sleeve. Roughly where the white arrow is here.

edit: it's pointing at the sleeve behind the exposed wires.

I suppose you could be just on the edge of the turbo vanes sticking. You have enough carbon build up to catch the vanes, but not enough to hold them?

solenoid.wires.jpg.e738f4540281b9773eb5eb73d49ab19b.jpg

Edited by gadget
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