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Following on from my post re pyro temps it appears that I have a problem with my new truck . before I embark on the 'getting it right' journey I would like to make sure I understand the principles behind the zd30 issues, I have read the ref doco and think I understand it. ok here goes. from what I have read the primary reason for zd30s going boom is abnormally high combustion temps, these are caused by overfuelling, this occurs primarily in the 3rd and 4th cylinders. the cause of the overfuelling can be attributed to a few factors; firstly the MAF sensor becoming either fouled or damaged thus giving incorrect information to the ECU which then delivers a rich fuel/air mix to the engine, secondly a combination of PCV fumes and EGR gasses mixing in the intake manifold and causing an oily/sooty residue to buildup which restricts the flow of air into the engine again creating a rich mix thus increasing temps. Also the EGR gasses already being hot increases the EGTs.
How am I going so far?
Also from reading the ref doc I believe that boost actually cools down the EGTs because it is forcing more air into the mix thus leaning off the air/fuel mix in the engine, reducing temps?
Overboost is an issue for these engines as well, however I am not sure what problems it causes? apart from blowing intercoolers what does it do to the engine? what effect does it have on EGTs?
Before I bought the car I did a bit of reading and I thought I understood the issues and how to prevent them. I am, however, now not so sure.
Also I have:
2003 GUIII Manual ZD30 140000 ks on the clock, EGT gauge fitted.
Any help or clarification would be really appreciated. Also thanks to all those who have already helped out with info.
ZD30 woes
. before I embark on the 'getting it right' journey I would like to make sure I understand the principles behind the zd30 issues, I have read the ref doco and think I understand it. ok here goes. from what I have read the primary reason for zd30s going boom is abnormally high combustion temps, these are caused by overfuelling, this occurs primarily in the 3rd and 4th cylinders. the cause of the overfuelling can be attributed to a few factors; firstly the MAF sensor becoming either fouled or damaged thus giving incorrect information to the ECU which then delivers a rich fuel/air mix to the engine, secondly a combination of PCV fumes and EGR gasses mixing in the intake manifold and causing an oily/sooty residue to buildup which restricts the flow of air into the engine again creating a rich mix thus increasing temps. Also the EGR gasses already being hot increases the EGTs.
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