quick question about running injectors w uncalibrated MAF

Night Shifter

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Dec 24, 2005

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Oct 20, 2010

#1

• Oct 20, 2010

• #1

just a quick question...i know you have to have the MAF calibrated for the same size injectors but will it be ok if i throw in 30lber's with the stock MAF and drive the car 25 miles to the tuner? he's gonna calibrate/tune the stock MAF for the 30's but i dont want to mess anything up..

is the car even going to run?

thanks

 

Night Shifter

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#2

• Oct 20, 2010

• #2

oops, meant to post this in tech...oh well

 

sneaky98gt

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#3

• Oct 20, 2010

• #3

When I put my supercharger on, I put in 39 pound Cobra injectors. Before the tune, it ran like crap. I would definitely not have driven my car like that. All I had to do was get it on and off of a trailer, so it wasn't a big deal, but I would not have driven it more than a half mile like that. It was running rough, smoking, stalling, etc. I put on the Lightning MAF (that I was going to anyway), and it ran a little better (enough to get onto the trailer), but still rough.

I'm not sure how different the 30 pounders will be from my 39 pounders, but if they are anything similar, I would not run it like that. I've heard that it can wash the oil off the top of the cylinders and burn a hole in them.

I'd drive it there, and then swap them out. It isn't a big deal anyway. 4 7mm bolts, IIRC, holding the rails down. Lube up the O-rings and pop the new ones in. I could probably do it in less than 10 minutes. Just have a couple rags handy to soak up any fuel that spews out.

 

Night Shifter

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#4

• Oct 20, 2010

• #4

cool thanks for the info...i know its an easy job, ive done it a few times but it was just trying to save a few minutes with the tuner...oh well id rather be safe then sorry...

 

BurningRubber

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#5

• Oct 20, 2010

• #5

sneaky98gt said:

I've heard that it can wash the oil off the top of the cylinders and burn a hole in them.

Click to expand...

Think about that for a second... it doesn't make any sense.

Burn a hole in the cylinder, or piston? Neither should have oil on top of it when the compression stroke is occurring.

If it's a piston, there shouldn't be oil on the top of the piston period, and if it's the cylinder, the rings scrape the oil down and off the walls as the piston travels down in the cylinder. If there was more than just a trace of oil left, it'd burn off, AKA what you see coming out of the exhaust on a car with bad rings.


Not calling you out, but just trying to figure out why someone told you that...


Injector bolts are 8mm though.

 

B

blksq10psi

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PHILLY

Oct 20, 2010

#6

• Oct 20, 2010

• #6

youll be ok driving it to the tuner stay outa the boost and keep it under 3,000 rpm

 

Dark04GT

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#7

• Oct 20, 2010

• #7

I would ask the tuner if he has any canned tunes he could send you so that you can get to the shop. If that is not an option you might have a rough ride there, you probably would make it but I'd consider towing.

What size are your injectors now? stock 19's?

 

sneaky98gt

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#8

• Oct 20, 2010

• #8

BurningRubber said:

Think about that for a second... it doesn't make any sense.

Burn a hole in the cylinder, or piston? Neither should have oil on top of it when the compression stroke is occurring.

If it's a piston, there shouldn't be oil on the top of the piston period, and if it's the cylinder, the rings scrape the oil down and off the walls as the piston travels down in the cylinder. If there was more than just a trace of oil left, it'd burn off, AKA what you see coming out of the exhaust on a car with bad rings.


Not calling you out, but just trying to figure out why someone told you that...


Injector bolts are 8mm though.

Click to expand...

Yea, I meant to say pistons. I'm not exactly sure of the details, but I know for a fact that I've read before that running way to big of an injector can cause holes to be burned in the pistons. May or may not be true, but I know I've heard that before. Now that you say something, I'm leaning towards not true.

BUT, after doing some reading around, and remembering what my tuner told me back before I got tuned, running it untuned with big injectors WILL foul up the spark plugs.

 

BurningRubber

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#9

• Oct 20, 2010

• #9

Yeah it will foul the the plugs, but not put a hole in the pistons. Running too lean and causing the piston to get too hot will burn a hole through them, though. Very common with forced induction/nitrous fuel delivery problems.

 

Night Shifter

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Oct 21, 2010

#10

• Oct 21, 2010

• #10

lot of good info guys thanks! but like sneaky said, my bolts were 7mm when i pulled the fuel rails last time

looks like ill be doing the swap at the shop....i really dont want to burn a hole in these 8k mile pistons...that would piss me off lol

 

sneaky98gt

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Oct 21, 2010

#11

• Oct 21, 2010

• #11

I don't think you have to worry about burning holes in anything.

BUT, you probably would foul the spark plugs. So you have two choices:
1. Leave the 19 pounders in and swap in the 30's at the tuner. Or,
2. Change out the injectors now, and swap spark plugs at the tuner.

Both require spending time changing something at the tuner, but choice 2 involves buying new plugs. Should be an easy choice.