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Justbadger

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I have a vt calais with an ecotec in it. Have just decided to put super 6 injectors and msd coils on and it sounds rough as. has anyone done anything like this before do I need to get it tuned or something..
 

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Moved to the correct technical section.

Fail. Changing injectors to a different size without altering the tune to suit will cause the exact symptoms you describe. Effectively you are just injecting way more fuel than it requires. Put the old injectors back in, bigger injectors does not equal more power (unless you have upgraded other engine bits that require more fuel than the original injectors can provide and then you would still need a tune to suit).
 

Justbadger

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Moved to the correct technical section.

Fail. Changing injectors to a different size without altering the tune to suit will cause the exact symptoms you describe. Effectively you are just injecting way more fuel than it requires. Put the old injectors back in, bigger injectors does not equal more power (unless you have upgraded other engine bits that require more fuel than the original injectors can provide and then you would still need a tune to suit).
[/QUOTE
 

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Only a super 6 needs super 6 injectors. I wouldn't be running that engine til I swapped back and change your oil straight after
 

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Thanks I going to look into tunes.. I do have msd coils n air intake and 2 1/2 high flow cat n rear pipes .extractors all new pulleys n pumps. Iridium plugs. New radiator n thermo.. tune should fix it you reckon??
 

Justbadger

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Nah pre sure old injectors were shot... so do I mess with tuning or 150 for new (old) injectors.. blah
 

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If you bought new injectors and don't want to go back to your old ones than you will need a tune adjusted to suit. The1 (user on this forum) or MACE (forum sponsor) can probably do a tune to suit the different injectors.

The problem with fitting larger injectors and not adjusting the tune to suit is that you will have put considerably more fuel into the engine than required which has the potential to bore wash the cylinders (excess fuel running down the bores and washing off all the oil that lubricates the rings and makes everything slippery) as well as contaminating the oil/diluting it. You may have also potentially fouled the spark plugs.
 

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An ecu in essence turns the injectors on and off at a specific duty cycle so it meets the fueling requirements. Thus the fuel delivery rate is based on injector duty cycle. It‘s all defined within the tune itself for the specific characteristics of a specific injector.

So changing injectors to something that deliver a differnt flow rate vs the duty cycle than what the ecu program expect will just cause issue. Bigger injector tors just throw too much fuel into the mix.

Put another way, your ecu may order the injector to operate 20% of the time which will result in a specific fuel delivery. If you just install larger injectors, then for the same 20% duty cycle, you may deliver 30% more fuel and it will run way to rich... it’s like putting a 4 barrel carbi from a 5 ltr V8 on a 2 ltr 4 cylinder engine. It just won’t run well and will cause issues.

Putting in lower flow rate injectors will result in a too lean mixture which can be catastrophic for an engine..

That‘s why you need a tune to correct the fuel delivery... but without associated mods, you’ll never use the injectors at a reasonable duty cycle so it’s a waste of time and money... Getting the correct injectors for the engine is the best approach forward.
 

Justbadger

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If you bought new injectors and don't want to go back to your old ones than you will need a tune adjusted to suit. The1 (user on this forum) or MACE (forum sponsor) can probably do a tune to suit the different injectors.

The problem with fitting larger injectors and not adjusting the tune to suit is that you will have put considerably more fuel into the engine than required which has the potential to bore wash the cylinders (excess fuel running down the bores and washing off all the oil that lubricates the rings and makes everything slippery) as well as contaminating the oil/diluting it. You may have also potentially fouled the spark plugs.
Thanks this helps alot
 
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