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arf

Member Since: 02 Jul 2016
Location: North West
Posts: 10

Power Loss - Suspect CHT Sensor, your thoughts?

Hi everyone, I'm hoping the great Defender2 community can help me out on this issue I'm struggling with:

- Disclaimer, I'm used to modifying turbo petrol cars and still figuring my way around the Defender

A month ago my 110 2008 2.4 Puma was travelling at 70 on the motorway for approx 15 mins, moderate throttle, started to get some hesitation and pulsing in power when overtaking and then after about 5 mins a gradual power loss taking me from 70 to 50, regardless of throttle position. After pulling over the revs were limited to 3k RPM without load, no warning lights and temp reading stable. I suspected the EGR may have stuck so I triggered the cleaning cycle (not sure how effective they are?), started up and although power delivery was a bit dodgy I did not have any total power loss for the rest of my journey.

Suspecting the EGR I disconnected it and it ran very well with none of the usual hesitation ~2k RPM, just a check light.

Until it died again the next day while testing on the motorway, same conditions, ruling the EGR out.

At this point I'm suspecting the power loss is being triggered by engine management, potentially due to the CHT sensor reading high. Checked my coolant level today and ruled this out to an extent as it is slightly below normal range, but not enough to cause concern.

I've also seen that this could be due to inlet temperatures, and the stock intercooler is not effective enough? However the only modifications I've done prior to this are a K&N Panel filter, so it's not exactly running big power.

Which makes me think either the CHT sensor is faulty, or is reading correctly and the cylinder head isn't being cooled correctly, for some reason.

Please let me know your thoughts

3rd Jul 2016 1:14pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19723

Check the MAF for oil contamination from one of those filters.

3rd Jul 2016 2:27pm

Cupboard

Member Since: 21 Mar 2014
Location: Suffolk
Posts: 2971

2011 Defender 110 Puma 2.4 HT Corris Grey

Get yourself a fault code reader.

MAF and EGR system error codes are often related, EGR valve problems can trigger MAF sensor errors.

The EGR valves are notoriously rubbish. The cheapest fix is to get it disabled by one of the tuning companies, or you could replace it but that costs more and the problem will return.

3rd Jul 2016 5:17pm

dgardel

Member Since: 30 Nov 2008
Location: Veneto (Heart & Head)
Posts: 3586

control also the MAP on the inlet manifold, the "black oil mud" is a heat trap and sometimes it is the problem.... Discovery 5 td6 HSE Stornoway Gray Outback Engineering Limited Edition

IID Pro MV License

4th Jul 2016 10:34pm

arf

Member Since: 02 Jul 2016
Location: North West
Posts: 10

Thanks everyone, so far I have inspected the MAF but all appears fine, gave it a good clean anyway while I had it out.

Interesting twist is after separately topping up the coolant I had no issues for two weeks. Makes me think the power loss is the ECU going into overheat protection, and I am eyeing up an UltraGauge to confirm this... Will report back

19th Jul 2016 10:59pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19723

Where is your temp gauge sitting at full temp?
Mine sits ever so slightly on the cooler side of halfway the gauge.
It should be more warmer than half in my opinion.
Ultra gauge would be more accurate though...

When was coolant last changed? Although it should have a 5 year lifespan.

19th Jul 2016 11:13pm

Cupboard

Member Since: 21 Mar 2014
Location: Suffolk
Posts: 2971

Thinking back, when I was having EGR issues which triggered MAF faults it usually came up the the engine management light.
I do sometimes get power loss on a long run that doesn't trigger the light, and that's fault 0234 Turbo Overboost. I haven't worked out how to fix that yet but it causes the same symptoms you've got.

Either way, you still need to get a fault code reader. Ultragauge is one option, then there's the iCarsoft one that's fairly cheap, or get one of the decent hobbyist ones like the GAP IIDTool or the Nanocom.

20th Jul 2016 12:33pm

arf

Member Since: 02 Jul 2016
Location: North West
Posts: 10

To follow this up I got my local to take a look while getting some shocks fitted and it's been traced to the turbo, over and under boosting

custom90steve wrote:
Where is your temp gauge sitting at full temp?
Mine sits ever so slightly on the cooler side of halfway the gauge.
It should be more warmer than half in my opinion.
Ultra gauge would be more accurate though...

When was coolant last changed? Although it should have a 5 year lifespan.

Temps were either dead centre or slightly on the cool side. I'd check when the coolant was done but to be honest I don't trust the history on the car, I think I'll change all fluids myself when I get chance for peace of mind!

Cupboard wrote:

Thinking back, when I was having EGR issues which triggered MAF faults it usually came up the the engine management light.
I do sometimes get power loss on a long run that doesn't trigger the light, and that's fault 0234 Turbo Overboost. I haven't worked out how to fix that yet but it causes the same symptoms you've got.

Either way, you still need to get a fault code reader. Ultragauge is one option, then there's the iCarsoft one that's fairly cheap, or get one of the decent hobbyist ones like the GAP IIDTool or the Nanocom.

Looks like that's exactly my issue. They reckon its either the turbo itself or the loom, which was resting on the actuator! Apparently the actuator itself seems to have free movement so they've tied the loom back, will report back on whether that fixed it.

Definitely right about the fault code reader, Nanocom is interesting but may angle for the Ultragauge and go for a dash install on it: Credit to... http://www.defender2.net/forum/topic31673....ltra+gauge

1st Aug 2016 2:36pm

arf

Member Since: 02 Jul 2016
Location: North West
Posts: 10

PS cheers for the help everyone!

1st Aug 2016 2:40pm

Cupboard

Member Since: 21 Mar 2014
Location: Suffolk
Posts: 2971

The Ultraguage will tell you the basic fault code but that's it, it won't go in to details and won't do much (if any) Defender specific stuff. It will tell you when you're pootling down the motorway that it's P0234 though.

For what it's worth, I have an Ultragauge semi-permanently installed with Velcro on to the top of my dash. It sits there nicely, was minimal effort and looks right. It means that I can also pull it out when I want to read codes on another vehicle which has been very useful on a number of occasions. I also have the GAP IIDTool for Defender specific things, and an Autel MD802 on the way because I'm getting

off having to remove the Ultragauge every time someone wants their fault codes reading or the light reset. It's quite an extravagant way of doing it but it was one of those cases where if I was going to spend the money I thought I might as well do it properly rather than be annoyed that it can't talk to vehicles I want it to talk to.

Is urine-d off a swear word here? Wow.

1st Aug 2016 7:04pm

Dieselhead

Member Since: 21 Oct 2012
Location: Pulborough. West Sussex
Posts: 552

This sounds like a problem I am having with mine

If you drive it carefully its fine. It used to pull very well in 5th with foot to the floor. Now all it does is just be flat.

Done all the change MAF . Cleaned MAP . Changed Air & fuel filter. Blown out intercooler & checked & changed pipes. Even changed the VCV & yes its better but still does not go like a cut cat like it did

I am guessing the turbo or wiring breaking up

Can someone tell me which bit of loom has the issuse as you can replace it so been told. Do the wires break down causing probs??

Thanks Chris

2008 XS 110 2.4 Utility. Tonga Green
1953 Series 1 for restoration
1983 Mini Mayfair
2004 VW T5 Camper
2008 Diahatsu Sirion. Thats hers
Classic Bolens Garden Tractors

2nd Aug 2016 10:17pm

arf

Member Since: 02 Jul 2016
Location: North West
Posts: 10

Resulting this in the hope it helps another forum archaeologist in the future... If it does do post up, I know there's several Puma owners suffering with similar problems!

So in this case I had problems with power at more than 50% intermittently and at some times the turbo would stop functioning until the car is restarted, no MIL light but Turbo Overboost OBD code P0234 being logged

After suffering for a bit and doing some forum archaeology I took it to my local and we cleaned the MAF, MAP and used a carbon cleaning machine to clear out any deposits in the system. Early days but it appears to have fixed everything, don't know which one of the three unfortunately but the MAF and MAP are easy to get to and can be ruled out quickly.

I think this whole thing has been caused by oil from the K&N filter attracting carbon buildup *somewhere* in the system, so I'm going to switch to something less oily soon.

Good luck to anyone else out there

2nd Dec 2016 8:37pm

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