hello, A little introduction My name is Gary im from Ohio, sold my 99 trans am m6 (sold due to the fact it was no longer streetable) andrecently purchased a02 blue 225QC (which i like more than the t/a surprisingly)been lurking alil while now, and I've read about the whole diode mod and it seems to be an "ok" way to go as long as boost is being propery controlled. I've also noticed that nobody with a 225 has tried this mod, I figure with the 4.3v the worst that will happen is that I will get a CEL. My question is a simple one, If I install the diode w/o a mbc will the n75 still hold the boost to factory settings? I am asking this because my plan is to install the diode anddrive with it installedfor a few days to make sure there are no bugs then use the controller afterwards. I assume the n75 will hold unless its gets a maf referenced reading. BTW I love this forum when I purchased the four rings of fire (as I call it) I was worried the tech and enthusiast support wouldnt bethere I WAS WRONG, thx guys

sorry for the length of post
Gary

 

Correct me if im wrong, but i believe the 4.3v would trick your ecu into seeing 11psi. The 225 runs something like 14.5 psi stock. I would think that running a lower boost setting like that could cause some sort of problem. But then again im no expert, This is really a question for cincy. I believe that they established you need a 4.4v diode which does not exist. I'll shut up here and let an expert chime in.....lol

 

yea sorryI should of been more exact i assume if anything happensI will get a cel due to the ecu only seeing 11 psi, but my questions is will the n75 hold boost to the 14.5psi. fwiw I dont think it will throw a cel due to the fact that the 225 doesnt always see 14.5, again I assume the 14.5 is a boost "cap" and not a boost parameter for example the ecu doesnt care if it see lets say12 psi or the factory 14.5 just as long as its not over 14.5

 

oh boy hes not scared *as i crack my knuckles*.... jk, and yes, your n75 should be fine... i hope someone finally pulls off the long waited diode on a 225... good luck. oh and before you do it wait for cincy to have some input cause i think hes really good with the diode mods

 

Yeah, ttkid is correct the n75 will be fine. And you are right 14.5 is just a cap for the stock ecu, not a parameter. When chipped you can run 20+ psi, I on the other hand have the diode mod on my 180, i stay at a constant 16-17 psi. I beliece cincy and some others are actually running 20psi with the diode+mbc/ 4bar fpr. But as of right now it looks like you may have to just get chipped for the extra psi on a 225.

 

but! if your seriously planning on going big turbo hold of on a chip cause youll have to get a new program later on anyway for the new turbo... i found out the hard way so im going to lose the $600 i spent

 

when the ECU seesmax 12-13psi you are actually runing around 20-22psi, guess how the a/f ratio is going to look like... unless a 4 bar FPR is gonna make up for the fuel needed in the mixture you will run too lean if i'm not mistaking. I'm not the expert either, Cincy is the guy to talk to... but that's my .02 here.

 

your MAF will still see the increased airflow and adjust fuel accordingly.

this diode mod isn't anything new. it works.

 

we all know that diodes on 180s have been done... but lets see if a 225 can do it

 

I don't think it'll throw a CEL or cause you any problems based on my experience.

I run a dual stage MBC (change between two boost settings with a switch) and one of them is set to 6 psi max and the other to 20 psi max. 6 psi is WAY below stock boost (11psi) and I've never had any CEL's or problems running 6 psi.