Limp Mode - No Error Codes?

[hempo]

Hi all, I have searched for ages but can't seem to find exactly what I am looking for.

Twice now I have appeared to lose power when highway driving. Scenarios as follows;

1. had been driving for 4 or 5 hours around SEQ and on the way home up and down some hilly sections started losing power. I have a Scangauge which was showing normal boost around 12-14 however kept going straight to 99 Load. Tried backing off and on accelerator but didn't help.

2. driving home for about an hour or so, up large hill with lightly laden trailer only around 500kg, and near the top had feeling of losing power. Scangauge once again said 99 Load. Tried backing off and on to no avail. As only a few km flat to home continued home.

Both of the above I was close to home however felt like I had to go back to 4th gear just to get up to 100kmh. Ended up doing 80 Kmh at one point.

Neither times showed any errors on the scangauge and when I started the car again later that day it drove fine.

Are the above a result of 'Limp Mode'?

Should I pull over and turn off the engine as soon as possible?

I have 2013 GU9 - has only occurred since 3" Exhaust with Dawes Valve at 18psi. I don't have a needle valve.

I really want to know if this is Limp Mode as such and if so would it be best to either back off the Dawes Valve or install a Needle Valve to fine tune.

I don't have an EGT gauge so can't comment on Temperatures. I will consider adding one of these also as I appreciate the benefits of knowing when the temperatures are getting high I can back off and ensure I don't over do it.

I hope the above makes sense and I look forward to your thoughts. If you want to ask me anything else also please do.

Cheers
Hempo

[threedogs]

I'd be fitting a EGT gauge as you can drive by what you see ,
back the boost off a touch too and fit a needle valve to control spool up

[hempo]

Cheers threedogs.

What's a good max temp - 550?

[threedogs]

CRD's run a bit hotter than the Di's I wouldnt be holding that
temp for too long, They can tolerate temps up tp 600 C

[Rock Trol]

Did it feel like you where pushing the motor when this happened? The CRD's have a knock sensor that listens for engine knock which occurs when the motor is seriously over fueling. This stops the engine from grenading. I don't think it leaves an error code as when you back off the situation I resolved. Not sure if the 99 load message is indicating this. If its not the over boost problem it may be the engine temporarily detuning as its not combusting properly. Di's don't have this feature.

[Rock Trol]

Just checked on another forum about the LOD display on the scangauge. This is the load on the engine and 99 is the max load so sounds like you where pushing it a bit.
Also check for obstructions in the intake or your filter as high restriction can also affect this value(according to other web sources). With the new exhaust did you change your driving style? are you pushing the engine harder now?

EDIT: I had not used the LOD feature before so I just gave it a try. Seems quite useful as it shows the % of power being used in that gear/rpm range. It can start quite high when the revs are low (30% at idle) then goes higher with revs when taking off and then drops as the revs increase (all in the same gear).

[Rock Trol]

Just read that the "LOD is defined as airflow ratios, not torque. For a given airflow torque will depend on the A/F ratio and such" on the cleanmpg forum. Air restriction (dirty filter) or even a dirty MAF could affect what the ECU thinks is happening in the system and cause it to go into limp mode.

http://www.cleanmpg.com/forums/showthread.php?t=21590

[hempo]

Great thanks Rock Trol.

I will refer the above to the mechanic. His thoughts were same as ThreeDogs i.e. back off the Dawes and add a Needle. We will get Dyno at same time to double check A/F ratios etc. Will ask to also check filters and MAF.

I don't think I drive it any different now than before the exhaust. But then again maybe a little harder on occasion. But yes, definitely much harder the second time it happened as I was going up the range and wanted to overtake some slow bugger.

Thanks again guys for your help.

Cheers.

[threedogs]

You really need gauges for these motors,imo
If it starts getting too hot you can back off a tad.
The term drive by your gauges could not be truer
than with the mighty ZD30

[Ronin]

I had similar issues as u before. On hills etc when going up the Patrol would seem to go into sorta limp mode with no code.
I installed a 3" exhaust the issue went away.
It is most likely related to boost. CRDs have some special code in ECU to prevent over boosting.

[hempo]

Thanks Ronin. Glad the exhaust fixed your issues, most appear to be after the exhaust fitted. Did you get dawes and needle?

Yep ThreeDogs, getting some pricing on EGT and Boost gauges for the pillar.

[threedogs]

Over boosting is common when new exhausts are fitted.
Thats why most will stress its important to fit gauges before any mod you make.
Just something you need to do owning a ZD30 motor
Some find 12psi is just right where others can acheive 25 psi with no issues

[Ronin]

Thanks Ronin. Glad the exhaust fixed your issues, most appear to be after the exhaust fitted. Did you get dawes and needle?

I dont have dawes and needle setup. What you could do is do some data logging to see whats the Boost is at when you hit that sudo limp mode.
Something like this would help.

http://www.nissanpatrol.com.au/forums/images/imported/2015/10/24.jpg

http://www.nissanpatrol.com.au/forums/images/imported/2015/10/25.jpg

[abeeke]

Its worth mentioning that just because your Scan Guage doesn't show any codes doesn't mean there isn't one there. my $3000 snap on scan tool sometimes won't show a code that my friends $10,000 does.

Depends on how advanced the software is, and if it is a generic OBD2 code, or a Nissan specific one

[hempo]

thanks guys.

that's some pretty impressive data logging. is that generated by the ECU and accessible by the scan tool?

will get the mechanic run his tool on also to double check.

Cheers