First, I would like to thank the forum and all of you here who provide valuable information that help me to complete this task!

So I was on 180mm pulley with box tune for it and finally had chance to do the 82mm throttle body and 550cc injectors yesterday. (hum… just realize, I should have changed my spark plugs when I was there). There were some small issues here and there but finally wrapped all up well to finish the job.

I totally understand that “re” tune is a must and best and a data logger is a must when touching A/F. So please do not flame me. For the current box tune for 180mm pulley, it will make the car run a bit leaner and a bit more advance timing than stock. The rule is more air requires more gas, so to keep the A/F same ratio, both A and F have to be changed in the same ratio. Before doing the job, I did a little math to estimate that it would increase 23% of air to go from 74mm to 82mm throttle body and 31% gas going from stock to 550cc injectors. Even though the increase percentage didn’t match, I was hoping that the ECU would accommodate for the change. (I am not a mathematician nor an expert, all numbers were calculated as estimates)

Good part: The job is completed. The car runs fine so far (about 15 minutes idle time + 30 miles so far). I do smell a bit more gas when I first start my car, but it will go away (or maybe I get use to the gas smell lol). The mpg is still about the same for that 30 mile trip so it is not that bad.

Bad part: Car is running on the old tune

Here is my question: What is the consequence of running too much gas besides paying $4.50 a gallon? The only thing could be damaged is the CATs right?

Thanks,

PS: As for the exhaust, I only have X pipes and 2nd CATs removed. Yes, I am looking for shorty headers .

Couple pics:
550cc on stock fuel rail:


Engine complete:

 

Depending on how rich you are actually running, possible effects can range from fouled spark plugs, O2 sensors, and perhaps in the worst case scenario if not corrected for a long period of time, increased ring wear from washdown on the cylinder walls.

 

i thought the supercharger had to come off to do this?

 

You should have gotten a looped rail in there too to equalize fuel pressure.

 

Thanks!
Yes, I am looking forward to a dyno tune or at least re-tune.



Yes, the supperchager did come off in oder to do 82mm throttle.

 

Yes, I should. I was too lazy and did not have enough time to do the loop. Welding shop is not open on Sat and I did not want my car to be down for long. I personally, think loop is best but not really important since I already have 550cc injectors (Please do not quote me on this assumption)

 

The reason you need another tune is because it is programmed to open the injectors for a certain amount of time (injector ms) and having a larger injector open for the same amount of time as a smaller injector was programmed for is going to dump a lot more fuel. You are going to lose quite a bit of power from this as well as issues that others have mentioned above.

Oh and I assume you are going off the center display saying your gas mileage was the same, well that is not going to be correct with the larger injectors. For example my car with 550cc injectors will say I am getting 21mpg on the highway cruising and get an average of that for a trip but when doing the math on how much fuel it takes to fill the tank back up and how many miles I went the mileage was more like 19 and it is the same way on my other car with bigger injectors but it is way off in that one with injectors over double the size of the stock ones.

 

A retune is a must. You should still be very rich even with the new mods but dont beat on it until it's tuned properly.