ORIGINAL: nothsa

The timing was off before, whichI did fix.

I was planning to have the MAFrecalibrated like it is being done now. Can somebody let me know why that is going to cause the car to not want to shut up then not start and then decide to start? I'm not too familiar with MAF and injectors but I do understand that the injectors won't be providing as much fuel as 24lb injectors normally would. So wouldn't it still be the same as running 19lb injectors.

I knew this could be a contributing factor and have talked to a few people about it, but I didn't realize I hadn't mentioned it in this thread.

-Jeff

ORIGINAL: samseed101

24# injectors are larger than 19# injectors. When you swap out th stock injectors, you have two options. You can buy an aftermarket MAF that is calibrated to 24# injectors to "trick" the computer into delivering enough fuel. Or you can get a tune and have a chip burned that will correct the numbers in the computer itself. They don't actually recalibrate the MAF in that situation, them simply tell the computer what's going on.

Without getting too technical, they do this by adjusting the injector high slope, injector low slope, injector offset vs. battery voltage, and the MAF transfer.

If you don't do either of those, then your computer will think everything is stock. To give an example, lets say that your car's computer sees that your MAF is measuring 200 kg/h of airflow. The computer knows that it want's a 14.7 A/F ratio. It knows how much air is coming in. it also "knows" you have 19# injetors. So arme with this information, the comptuer knows that in order to supply enough fuel for 200kg/h of air with injecors that have an opening of size X, it has to open the injectors for Z seconds. So it opens the injectors for Z seconds, then it closes. And the A/F ratio is right on the money.

But in your situation, you neglected to tell teh computer that you have larger injectors. So the opening is actually much larger than what the computer thinks. of course, the computer has no clu so it still does the calculations assuming you have smaller injectors. So it opens up for eh same exact amount of time as it would for 19# injectors.

So for another analogy. lets say you have a garden hose and you are filling up a bucket. You turn on the hose for exactly 10 seconds than turn it off. After exactly 10 seconds, the bucket it filled right to the top perfectly. You didn't spill a drop. So now you know that you need to turn the hose on for 10 seconds to fill up a bucket. So the next day you get a hose from a fire truck and hook it up to a hydrant. Then you open up the hose for 10 seconds again to fill up the bucket. But what happens this time? because the fire hose is much larger, a lot more water flows out than you need. And because of that, the bucket overflows and makes a complete mess after 10 seconds.

Well common sense tells you that if you want to fill up a bucket that's the same size, but you are using a larger hose... you don't need to leave the hose turned onn as long. Perhaps only 5 seconds.

The same thing for engines. if you know that you need a 14.7 A/F ratio and the amount of air isn't going to change, then you need to shorten the time that the injectors are open if you are going to use a larger injector.

You've told the computer that you have timy injectors but in reality you are spraying a ton of extra fuel in there. That's causing you to run pig rich. Way too much fuel is going into the engine. meanwhile, when in closed loop your O2 sensors sense that you are rich, but they can only compensate so much. Once their limits are reached, there's nothing more they can do. And while all of that is happening, your plugs are getting fouled to **** with fuel. They run good at first, but as they get worse and worse (from the excess fuel) they become less and less efficient until finally, they stop working alltogether.