JC316

I just realized that I made a boo boo. When I did my mark VIII swap, someone had already swiped 3 fuel injectors on the Mark VIII, so I took 3 off from my mustang. The part numbers matched, but I have 5 blue top injectors and 3 yellow top injectors. Looked that up and I found that the blues are 24lbs injectors and the yellows are 19lbs. So, what are the consequences of this? It runs strong and smooth with no check engine lights, but I KNOW that it has to be screwing something up.

Now what to do? Should I go get 3 more 24lbs injectors, or get 5 more 19lbs injectors?

0949er

obviously get 3 more 24 lber's. I doubt the price difference between 24 and 19 is THAT much, so its deff cheaper to buy 3 insead of 5... plus youll now have 24lbs if you ever needed them...

this part is just a pure guess. But could you not run the injectors AS IS as long as you tune the 24lbs and just treat them like 19lbers? (by the tune, "pretend" you have a 19lb injector limit, so the 24 lbers "max out" at the same time your 19lbers actually do max out. ) Complete guess. thinking out loud haha

ddmsgtr1

This is also just a guess, but I believe your engine management system just sends pulses to the injectors, it has nothing to do with the actual amount sprayed, taking the reading from the MAF and sending the proper pulse length to the injectors. If you have the tune set for 19lb injectors, your 24lb injectors are going to run those cylinders rich, if you set the tune for 24lbers, your going to run the cylinders with 19lbers lean. You need to get the injectors that either the MAF or the tune is calibrated for.

0949er

yeah and on second thought, it MIGHT be better for you to get all 19's instead. it really depends on what you car was tuned to run off of... 19s or 24s?

ddmsgtr1

If the engine originally had 24lb injectors on it, 24lb injectors is what I would put back in.

JC316

It's tuned for 19lbs injectors.

Hangwire

Aren't the blue tops on Terminators? Those are 42lb right?

JC316

No, the lincoln blue tops are 24lbs.

Hangwire

Ahhhhh I seeeeee. Why would they do that. They need to taste the rainbow and get creative.

cliffyk

Unfortunately it's a somewhat confused guess, the injector pulse width has everthing to do with how much fuel is sprayed...

The PCM calulates a precisiely timed pulse each time the injector is commanded to inject fuel. The length of the pulse is based upon a whole things, however air flow as measured by the MAF, IAT, ECT, throttle position and what it knows about the injector capacity (from the low and high injector slope settings in the tune).

In closed loop operation the PCM also considers feedback from the front O2 sensors when calculating the injector pulse width.

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OP, if you were to datalog your car you would like find that the fuel trims on each bank will be very different. The adaptive learning system can handle up to +/- 25% added or reduced fueling which makes it able to handle the 19lb/H and 24lb/H mix (barely).

But, it is not good. Do you know what the tune is set for (19 or 24)?

Are you sure they are yellow and not orange?