VQ20 to VQ25

[Jason_10]

Hi guys!

My Cefi's VQ20 engine is starting to show some problems. I want to upgrade to a VQ25. Have some questions also:
1. Can I use my VQ20 ECU on the VQ25 without issues? Like CEL, wrong fuel map?
2. I have an M/T is everything bolt on?
3. Are the parts like head gasket, oil seals, etc the same as the VQ20?

Thanks!

 

[sb3]

Hi guys!

My Cefi's VQ20 engine is starting to show some problems. I want to upgrade to a VQ25. Have some questions also:
1. Can I use my VQ20 ECU on the VQ25 without issues? Like CEL, wrong fuel map?
2. I have an M/T is everything bolt on?
3. Are the parts like head gasket, oil seals, etc the same as the VQ20?

Thanks!

Since no one have answered ur question , i will start the ball rolling:-

1. No, you'll have to use VQ25 ECU. You will have some running issues using VQ20 ecu (later)

2. Yes, you can bolt on your M/T. Some ppl will complain the rpm will be quite high during highway cruising.:stupid:

3. Yes , but recommended to use the correct specs for the items u have mentioned.

 

[Jason_10]

^Thanks.
Which issues should I look out for? Would my old harness bolt on to the engine and the VQ25 ECU?

 

[sb3]

^Thanks.
Which issues should I look out for? Would my old harness bolt on to the engine and the VQ25 ECU?

Hmm.. Lets start with rough running, wrg air/fuel mixture, lean running, etc. Thats only small fraction of issues u might face . Not to mention ecu pins are not compatible ( I've tried using JDM harness with my local ecu, no luck). Since u r swapping engine + plus ecu , i reckon the vendor will include the harness, rite?

 

[Jason_10]

^Again many thanks. The shop was selling only the engine and use my old tranny and ECU. So I guess the engine will run but not run properly.

BTW, my car is LHD (I am from Manila). That means I have to get an engine complete with harness and ECU then modify the harness to fit my Cefi.

 

[seizai]

LHD? can use US VQ35

 

[sb3]

^Again many thanks. The shop was selling only the engine and use my old tranny and ECU. So I guess the engine will run but not run properly.

BTW, my car is LHD (I am from Manila). That means I have to get an engine complete with harness and ECU then modify the harness to fit my Cefi.

Yup, thats a safer bet, i guess... Remember use a crimping tool for wirng and not to twist both wires together. Good luck.

I'd put my money on a good workshop manual, otherwise hayness or chilton manual would be heplful too. Btw r u undertaking the swap by youself?

 

[Jason_10]

No. I will have it done by a mechanic.

Just in case I just have the VQ25 installed and use the old VQ20 ECU and harness, can I just use UNICHIP programmable piggyback ECU and have it tuned?

 

[dream.tent]

No. I will have it done by a mechanic.

Just in case I just have the VQ25 installed and use the old VQ20 ECU and harness, can I just use UNICHIP programmable piggyback ECU and have it tuned?

Generally it sounded ok...

But something that we are not so sure about:

I think your motor is VQ20DE? or it's already VQ20DD?
If you are getting a VQ25DD, then i think ECU would be different...(very!)

Refer to Nissan VQ engine - Wikipedia, the free encyclopedia@@AMEPARAM@@/wiki/File:Question_book-new.svg" class="image"><img alt="Question book-new.svg" src="http://upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png"@@AMEPARAM@@en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png

So be careful when you shop for the new engine and make sure what u want is correct.

 

[Jason_10]

My stock motor is VQ20DE. Planning to install VQ25DE + Unichip. As much as possible, I don't want to modify the harness, unless I find an expert mechanic.

 

[dream.tent]

My stock motor is VQ20DE. Planning to install VQ25DE + Unichip. As much as possible, I don't want to modify the harness, unless I find an expert mechanic.

I think this would be easier and the ECU should be matching.
Best to let your mechanic compare the ECU connectors before hand.

Another point is that the VQ25DE is mounted on a Wagon chassis. Meaning it is expected to carry heavier load than a sedan. My take is the ECU on VQ25DE would have the max torque bring up to lower RPM range.

Good luck hunting.

 

[Jason_10]

I was hoping the ECU pins could match so less modification, less work.

Here in Manila, there isn't much people who modify the cefiro's engine. Only a handful that's why info here is very limited.

 

[dream.tent]

I see.
What about UniChip? Any good tuner in Manila?
Has been like 5 years since my last trip to Manila....

 

[Jason_10]

Unichip is piggyback ECU. Its very flexible since it can change ignition timing, fuel map, etc. There are a couple of good tuners here like Autoplus and Speedlab to name a few. But my engine swap will be handled by another shop, to save on costs. hehe.

 

[sb3]

Unichip is piggyback ECU. Its very flexible since it can change ignition timing, fuel map, etc. There are a couple of good tuners here like Autoplus and Speedlab to name a few. But my engine swap will be handled by another shop, to save on costs. hehe.

Piggybacks are lot more easier to tune than standalone ECU. At least you don't have to tune the base mapping from the scratch. Like the name suggested, its always attach to your ori ecu. Happy tuning. By the way, I am always against mix'n match engine components, over here we call it rojak. If you can tune it correctly well done, otherwise i won't go into that area.

Good luck.

 

[calvin9683]

hi, was searching for such info then come across this thread....
sorry to hijack ur thread.....

just swapped a VQ25 engine lantai for my dad's A32 (ori VQ20)....
blew the engine last week on the highway...culprit is the cracked radiator which wasnt noticed (covered by air dunk for air filter)....just my luck....towed the car back to my mech place....n he suggested to get an engine lantai n direct swap (although i initially wanted to drop a whole halfcut....he asked me not to waste money)....so ok....get the full engine lantai (block, head, intake, tb, injectors) n drop it in....collected the car in 1 week time...noticed very significant improvement on torque....
but still rather worried abt AFR as still using VQ20 wiring n ecu....only injector using VQ25.....
although dun see much prob as this car will be driven by my dad....no full throttle/high rev....but in heart....still rather worried on AFR....was considering to get a cheap AFC (those old skool 5button type) n get it tuned on dyno.....

so....any suggestions on my case????

 

[sb3]

hi, was searching for such info then come across this thread....
sorry to hijack ur thread.....

just swapped a VQ25 engine lantai for my dad's A32 (ori VQ20)....
blew the engine last week on the highway...culprit is the cracked radiator which wasnt noticed (covered by air dunk for air filter)....just my luck....towed the car back to my mech place....n he suggested to get an engine lantai n direct swap (although i initially wanted to drop a whole halfcut....he asked me not to waste money)....so ok....get the full engine lantai (block, head, intake, tb, injectors) n drop it in....collected the car in 1 week time...noticed very significant improvement on torque....
but still rather worried abt AFR as still using VQ20 wiring n ecu....only injector using VQ25.....
although dun see much prob as this car will be driven by my dad....no full throttle/high rev....but in heart....still rather worried on AFR....was considering to get a cheap AFC (those old skool 5button type) n get it tuned on dyno.....

so....any suggestions on my case????

Just keep an eye on the temp & engine knock
sound. I think it would run leaner.

 

[calvin9683]

engine temp??? guess the temp gauge is useless....
never show any sign of overheating even dat time the engine piang on highway coz of the leaking radiator.....
but so far so good la....m using it now for outstation....still monitoring on FC....
also din rev high....most also 4k....gonna try one time full rev when i;m back in JB.....

 

[Skyfiro A32]

hi all,

i'm planing to drop my engine frm vq30de to vq25de end of this year,might jus swap the engine kosong w/o the vq25de ecu.is there any issue on this?

 

[dream.tent]

Problem is, if you are buying engine kosong and without paper work, you can't get to register in JPJ too.

If you manage to find a 2.5L running condition..just transfer everything la...no need to worry later.