Here's an update for some people who know what I've been trying to do with my car lately. For others, well this is what I've been trying.

Since we know that by leaning out the SAFC you get a little more ignition timing, I decided to try something out.

I have put 30 lbs injectors in my car hoping that all I would need to do is use my SAFC to lean the car out even more to get the A/F ratio to "normal." The car would see less MAP sensor voltage (due to the settings on the SAFC) and would therefore, in theory, give me more ignition timing and hence more power.

Well, I thought it would be tough to get the car to idle or run correctly at part throttle and low load, and easy to tune at WOT. I was mistaken on both accounts.

With the1bill as copilot monitoring the pocketlogger (like those engineers on old prop planes I guess) we were able to get the car to run normally while just crusing along. We landed the car out a little bit at low throttle and it seemed to work. The short term fuel values would fluctuate around zero, gong from +4 to -6 or there about. And, the car drove around and idled just fine.

But, the long term fuel values would constanly hover around 17 or so. I'm not sure why, as we drove around for quite a while and gavet eh computer plenty of time to figure things out. Also, if anything, I'd expect negative numbers (car taking away fuel becaus it is too rich) not positive numbers.

So, at WOT, with the same (or similar) setting to what I had with the stock injectors, the car seemed to run fine, but the O2 voltage was reading low, VERY low, 0.1 or 0.2 Volts. Fortunately, the car wasn't knocking, and didn't pull timing (it was the same as witht he stock injectors, because I didn't run the car any leaner on the SAFC at WOT) and seemed to run fine, but I wasn't going to risk leaning it out anymore with these strange results.

This makes absolutely no sense. Why would I have to ADD fuel when I just put BIGGER injectors in the car?

Since I'm heading up to the track soon, the stock injectors are going back in for now. I'll probably try to put the bigger injectors in again sometime next month, if I can figure out what was going on with my car. Maybe, I'll try 24 lbs injectors instead. The 24 lbs injectors might agree with the car more, since they are not so far above the stock ones.

And thoughts/opinons?

Maybe you don't actually have 30lb injectors.

There is no way that is right. .1-.2 at WOT?! I think something might be off with your O2. That's the only thing I can think of. If you have bigger injectors you should be taking away fuel ... not needing to add more. My .02 cents.

You're exactly right Thura. I should have to take fuel away, not add it. This is why my results are so confusing.

Maybe I have the wrong sized injectors. It seems unlikely, as they are red-topped units from a mustang GT, but I guess ya never know.

I'm assuming that no one would know how to identify 30 lbs injectors from other types of injectors, besides the color. (red ones are supposed to be the 30lbs. units)

I thought that it might have been the O2 swensor, so I watched the front sensor and the rear sensor. The downstream sensor's readings corresponded to those of the front O2 sensor's. I think that maybe they are clogged HARDCORE with crap. I'll clean them out good before we try this again.
-=B-=

yeah, i agree with bill. they are probably clogged. It is very unlikely you have the wrong injectors. get them biatches cleaned!

I thought blue top injectors were ford 30lb's.

Maybe you have drowned the O2 with soo much fuel it thinks it's around like 1.02v, but only shows .02 because of the way the datalogger is set up. I'm sure some dyno time would be enlightening, but expensive.



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I'm sorry, I'm a little confused here and have questions to help me get an Idea of what you are doing.

are you running on a stock fuel pump and regulator at stock fuel pressure?
did you try running without the safc?
what were the dataloggers results without it?
did you start with the stock injectors and compare results?

I'm trying to remember which cams you have in the car. is it possible that the 30lb injectors are the appropriate injectors with those cams, but your fuel pump/fuel pressure can't keep up?

I'm just really interested and would like to know more.

>I'm sorry, I'm a little confused here and have questions to help me get an Idea of what you are doing.

No problem

>are you running on a stock fuel pump and regulator at stock fuel pressure?

Yes

>did you try running without the safc? what were the dataloggers results without it?

I had the SAFC set to the same settings as when I had the stock injectors, and the O2 sensor was telling me I was running lean, which makes no sense.

>did you start with the stock injectors and compare results?

The stock injectors were behaving normally before the swap, and are behaving normally again (I drove around for a while last night to check everything).

>I'm trying to remember which cams you have in the car.

Crane #10s, which I think are not different/radical enough to make a difference.

>is it possible that the 30lb injectors are the appropriate injectors with those cams, but your fuel pump/fuel pressure can't keep up? I'm just really interested and would like to know more.

I don't think the 30 lbs injectors are appropriate for those cams. They are too big. I'm playing games with the computer by REALLY leaning out bigger injectors to try and give the car more timing advance.

Hope that helps :thumbsup


It's possible Bill the injectors are just clogged up. A nice bath will do them good anyway :D



>Maybe you have drowned the O2 with soo much fuel it thinks it's around like 1.02v, but only shows .02 because of the way the datalogger is set up. I'm sure some dyno time would be enlightening, but expensive.

Mike, this is what Bill and I were thinking, that maybe the O2 sensor is at 1+ volts and the pocketlogger is just reading it as 0.1 (or whatever).

I put the stock injectors back in (I'm getting too good at this, the re-install went quickly and smoothly, and I didn't have to take the top part of the manifold off either) and the O2 sensor, tuning, everything is running normally.

After racing is done this year (the end of this month is it), maybe then I'll try it again. I might want to try 24 lbs injectors before trying the 30 lbs units again, but I'm not sure.

I still don't think you had 30lb'ers. With stock fuel pressures, your car should have been spitting raw gas out at idle.

bosch injectors(ford red) have a number on the designating that they are 30#'ers the number goes something like 0280150..... this is the injector part number and there sre several listings on the internet that show what each number's flow is or where they were used. It is possible that you don't have 30#ers or if you bought them used, they may just be clogged and needing a cleaning! When i put 30#ers before i switched to 440's my ltft were all like in the -15 range so something is totally not right!

lates
james

Could it be your fuel lines....maybe the lines are to small for the amount of fuel your wanting to run through those injectors




"Indy DSM rulez you"

Its completly normal to have LTFT's in the higher negatives. If your STFT is always in the negative, the that drives up your LTFT. The only way to keep the LTFT in the low negatives, or close to 0, is to have your STFT go into the positve numbers, and hit those positives fequently. The more/longer you can keep your STFT alternating from low postives, and low negatives, the closer you can get the LTFT to 0. BUT, your LTFT values are really not that important, as its just telling you what the ECU has been adjusting fuel trim over a longer time frame. Instantanous fuel adjustment uses STFT, and is what you should concentrate on. Anytime you run larger than stock injectors, it will be difficult to get your LTFT like stock. I have seen stock trims usually alternate from low positives, to low negative numbers, and that is considered normal. I would have to agree, you may not have the right size injectors/clogged injectors.

Thanks, good tip about long term vs short term fuel trims. I was able to get the STFT values around zero with some + and - fluctuation.

I think the injectors might be clogged, that is the only way to explain the WOT readings.

I installed some 30 lb. injectors before. They were indeed red top.

side comment:

would modifying the water temp sensor voltage output to the efi do any good for modifying injector pulse duration on our cars? because i know it uses that to keep the injectors open longer (like when the car is cold) to get it to op temp faster

just asking
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I got some 30 lb injectors and they're red. But a kinda dark cherry red no a bright red that I've seen. It doesn't match some of the 30lb injectors also. I had them cleaned and tested at cruzinperformance.com and they came out in good condition and sprayin at 30lbs.

just wonder how much did you lean the mixture for idle? I just got my safc installed and been playing around with the 30lb injectors I just installed. I got something like a -30% for 1000 rpm, it seems to idle good.

even at WOT its still runs hecka rich even after I leaned it hella, it must be that inline pump but I redlined it tonight and it seems to be sorting things out still.