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nissan
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Discussion Starter · #1 ·
Hey guys!

I have made a couple of posts requiring help about limp mode for the last month and a half, and I'm proud to say I have won!

I'm making this thread to hopefully help anyone else out there having limp mode issues.

I was originally running 14.5-15psi and I had limp mode under 2500rpm & under 3000rpm. Slowing the spool speed helped the 2500 limp but not the 3000. So turned the boost down to 10psi and still got limp. I knew I had a leaking intercooler but I didn't think that could have an affect as it was after the maf so it wouldn't interfere with the reading, but since I got a new intercooler and turned the boost back to 10psi I havnt had any issues except higher then normal EGTs (300-350c)

They're going down as I'm slowly turning the boost up, and I'm at 11psi now and so far so good. No limp. I'm just going to keep going up until I hit limp again or until I'm happy with the power.

So I hope this helps others having this issue! Go outside now if you have a stock intercooler and check it for leaks! I have never been happier!

Also Special thanks to chaz and geeyoutwo for all the help with my issues
 

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nissan patrol
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The reason the intercooler compounds the problem is because the boost is escaping instead of being jammed into the engine under pressure.

This will effectively increase the flow of the turbo because the air has another path to escape from.

Basically the actual amount of flow going past the air flow meter is getting higher as a result, which makes the ecu think there is more air going into the engine etc... causing boost cut.
 

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Y2KGUII ZD Wgn
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The reason the intercooler compounds the problem is because the boost is escaping instead of being jammed into the engine under pressure.

This will effectively increase the flow of the turbo because the air has another path to escape from.

Basically the actual amount of flow going past the air flow meter is getting higher as a result, which makes the ecu think there is more air going into the engine etc... causing boost cut.
Yes, I said in his other thread that I'd like to see the actual leak, it must have been fairly substantial (like a small hose split), my OEM IC leaked in the corners but had no impact on my MAF. If all else is OK he should be able to go to 14-15 straight off without difficulty. That is when he will start to see a positive impact on EGT.
 

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Discussion Starter · #5 ·
DieselTuner I just bought a pack of .8v diodes i was going to use, but a few people posted that it made there car sluggish, obviously because the fuel was a lot leaner due to the lower voltage,

geeyoutwo right now is were im going to be careful with my adjustments, i also want to make sure i do the right thing (meaning if i adjust the needle valve or dawes). what adjustments should i be making now? boost is at 11psi, has the occasional spike to 12ish, and the needle is holding the actuating arm a few (3-4mm) off the vnt screw.

im probably not going to go past 12-13psi, because 14psi was still limping, ill be checking my gauge for leaks this weekend to make sure im not just getting a false reading.
 

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Currently in PAD rehab
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I have defeated all limp by putting a 3.9v maf clipper in.
It allows all normal voltage to pass through, but if it reaches 3.9v it holds it there... no limp..

I have an aggressive spool up and now run 16psi so my egts are very low.

For example this morning I took off from the lights up a hill... 16psi, 320egt and it just kept going...

Well worth looking into.. I can adjust my fuelling now via jvdm but never hit limp... which is equally annoying and dangerous..
 

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Discussion Starter · #7 ·
Well without a maf clip or jdvm what boost do you think I will be able to go without any issues? And will speeding the spool help EGTs or doesn't that change anything?
 

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Y2KGUII ZD Wgn
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Well without a maf clip or jdvm what boost do you think I will be able to go without any issues? And will speeding the spool help EGTs or doesn't that change anything?
You should be able to get to 15psi relatively easily, what I would do is close the needle valve and see how high you can get before limp, once you hit limp you can then balance with the needle, I've never been a great believer in the classic adjust the needle to the VNT arm, I know it's the text book way but I went away from it a long time ago, using a good needle valve with around 6 turns open to close, you should be able to beat limp using no more than 1/2-1 1/2 turns open and when I set one up for someone I utilise that range.

I'm running now not using my needle valve, with my VNT wound down 1/3rd turn, using 18.5psi, all out at 18.5v by 2100rpm, god knows what it would be if I set my VNT back to std ;), I utilise MAF voltage up to 4.25v above 3000 as after that is my 3rd limp zone. Now I rarely use that but it's there if I want it

It depends on what you want out of your vehicle, if you are satisfied to live with a bit of EGT and just get rid of limp, then that is easy, just do the above. If you want a bit more than that, then that is what takes the time and effort and if that's what you are after, then I'm not convinced limiting the MAFv with a diode or locking system is the best way, I had a TurboSmart FCD2 and that is what it did, I could adjust the max to 3.9v and it would never go over it, but as I went on I wanted more and I'm achieving it, so that had to go and was replaced a couple of years ago with the JayCar unit, which I've spent a lot of time on, I'm dialed in to within .01v of each limp point (2450, 2950 and 3450rpm).

You decide what you want out of your vehicle then you move on from there, there is no right or wrong answer, just options.
 

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Well without a maf clip or jdvm what boost do you think I will be able to go without any issues? And will speeding the spool help EGTs or doesn't that change anything?
15psi is a good number to give good power and egts.
 

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Discussion Starter · #10 ·
That's what I'm doing. Taking it step by step! I have to say though this weekend has been nothing but great! Everything has come together. New Cooler, no limp, replaced crank angle sensor and the car is a dream.

Ok so I'll wind the needle in all the way (quick spool) and then keep going up with the boost until I hit limp, then adjust the needle to try and balance it out to get rid of
Limp and if that doesn't work go back to the max boost where it wasn't limping?

For sereason my car doesn't like 14.5-15psi. But to be
Honest I'm feeling the same power if not more at 12psi then I was at 14. I'm just increasing it now to settle the EGTs.
 

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Y2KGUII ZD Wgn
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That's what I'm doing. Taking it step by step! I have to say though this weekend has been nothing but great! Everything has come together. New Cooler, no limp, replaced crank angle sensor and the car is a dream.

Ok so I'll wind the needle in all the way (quick spool) and then keep going up with the boost until I hit limp, then adjust the needle to try and balance it out to get rid of
Limp and if that doesn't work go back to the max boost where it wasn't limping?

For sereason my car doesn't like 14.5-15psi. But to be
Honest I'm feeling the same power if not more at 12psi then I was at 14. I'm just increasing it now to settle the EGTs.
I'm surprised you say it has more grunt at 12 than 14psi, although this is quite possible if it's not making full use of it's breathing capacity, but you will see a drop in EGT as you go higher, most zd30's cannot fully utilise boost above 16-16.5psi due to the limiting of the breathing, this has been proven on the dyno, it takes a few more mods to achieve better breathing, but again EGT will still come down.
 

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Discussion Starter · #12 ·
I had it out in the bush last night and I'll tell you what the old girl just walks up and over anything! Didn't need to winch once where In my last 4wd (06 hilux) it didn't have anywhere near the capibility the troll had!
 

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Y2KGUII ZD Wgn
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I had it out in the bush last night and I'll tell you what the old girl just walks up and over anything! Didn't need to winch once where In my last 4wd (06 hilux) it didn't have anywhere near the capibility the troll had!
Well we are certainly pleased you saw the light and made the "leap" of faith to a decent vehicle ;).
 

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Y2KGUII ZD Wgn
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Got cold limp this morning, how to you fix that? Slower spool?
Yes, how bad is it? a lot of us just drive through it until it goes away itself.
 

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I have defeated all limp by putting a 3.9v maf clipper in.
It allows all normal voltage to pass through, but if it reaches 3.9v it holds it there... no limp..

I have an aggressive spool up and now run 16psi so my egts are very low.

For example this morning I took off from the lights up a hill... 16psi, 320egt and it just kept going...

Well worth looking into.. I can adjust my fuelling now via jvdm but never hit limp... which is equally annoying and dangerous..
Dronus4x4 where do you buy these clippers??? how are these fitted???


Thanks
 

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Currently in PAD rehab
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Y2KGUII ZD Wgn
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Oh!! So cold limp is when the engine is cold, not the outside air??
It's a mixture, the outside air is cold and that is what causes it because of the density of the air, but as your engine warms up so does the air as it travels through the system and the density changes as well. Elevation and Temperature all play a part.
 
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