Alright guys, I'm an intermediate level PROM burner and I'm having some rather perplexing problems with my car. I've known for quite awhile that I needed bigger injectors and have recently purchased new ones. The car was originally equipped with 22lb injectors and through scanning I found I was pushing them through 95% duty cycle. I decided to buy 26lb Accel injectors to cure the problem but after putting them on have caused a new one. The car will only start when it has cooled down for a minimum of 4 hours and the AFPR is reduced all the way down to 35psi. For those wondering, yes I changed the injector constant, I've even played with the cranking fuel PW but it too has shown no improvement. This though isn't the perplexing part, when the EPROM is removed from the ECM and the car is forced to run on the network resistors (i.e. limp home) the car at any pressure fires right up then dies a few seconds later. From this I think its safe to assume the injectors are working properly but that the ecm or PROM calibrations are working against me. Because I know you'll ask, the car starts great with the 22lb injectors and there are no other mechanical problems to speek of. And buy the way the car will not even act as though wants to light with the EPROM in place. I went back to the 22lb injectors to make sure the ECM and EPROMs weren't bad and found every thing to work just fine. I then changed some of the PROM calibrations to verify everything was working as it should and everything checked out fine. I decided to put the 26lb injectors back on the car only to have the same problem. I'm desperate here, I've read through over 300+ posts trying to find someone in the same boat and found zilch. If you could please take some time to help me out I'll most certainly be in your debt. Like I said I'm desperate, PLEASE HELP!!!!!! I'm using WinBin for my editor and use the original PROMS bin and the 6E009.ecu file to modify the PROM. If you want any info on the car look at my sig. Thanks for reading this, any most of all thanks for any help you give. LATER!!!!!

P.S. I wnat to drive my car BADDDDDDDDD!!!!!!

 

I just went out and measured the voltage across an individual injector under two separate conditions. The first with the computer running off the network resistors which yielded .4-.5 V, the second with the EPROM which yielded .1-.2 V. No other changes were made. These readings were taken while just cranking the car over with the ignition system disabled. The reason for diabling the ignition was to prevent the car from starting while running off the network resistors. What would cause the readings under the two cases to be so different? I mean really, that is a significant difference. Is there anything in the PROM that can be adjusted to produce a .2-.3 V increase as seen by the injectors at startup? PLEASE HELP!!!! I'm not joking this is really annoying, and if there is a simple fix PLEASE let me know. Even if you can't be sure your suggestion is warranted, give it; any help is better than no help!!!!!

 

did you buy these injectors new or used?

 

I bought these injectors new directly through Lingenfelter Performance Engineering. They were pretty pricey but they were flow tested to be within .8%lb/hr of each other. They are direct fit high impedence injectors. I would like to correct my previous post. After burning a few more PROMS I found that crank fuel alterations did help. I changed the Crank Fuel PW vs.TPS and the Crank Fuel PW vs. Coolant Temp functions and the car finally responded well. I changed the multipliers @0%TPS & @12.5%TPS to 2(originally 1) and the PW @90 F & @ 111 F to 15.63msec (originally 11.72 & 7.81 msec respectively). These four changes resulted in a voltage at the injectors of .9-1.0 V, most importantly though the car started perfectly. My question now is why did this work and where can I obtain some formulas to compute the other values to insure startup? I did test the car after it moved into another PW vs. Coolant Temp cell that was untouched and as before the car didn't start. Therefore modifications of these tables are necessary. Has any one else had to change these tables and if so what formulas were used to limit fuel pulse width to a minimum for startup? Keep in mind by changing the multiplier to 2 now all the changes I make in the %TPS table for PW are doubled. Is this the correct way to solve this problem or can ya'll think of another? Thanks for the help.

 

Should I make a global change to all the values in the tables? If so what would be the appropriate amount? What formula should I use? Should I leave the Crank Fuel PW vs TPS array alone and concentrate on the Crank Fuel PW vs Coolant Temp array? Or visa versa? If I should concentrate only on one table, could you be specific as to why? I'm learning here, and as we all know there is definately a steep learning curve to PROM burning; especially if no one else has posted a similar question in the forum archives. Thanks again for all the help. I'm finally working through this but feel someone else's experience could reduce tuning time dramatically. Later!

 

If you put your stock 22#s and everything is fine AND then install the 26#s with the SAME eprom and the car won't start, I suggest the injectors (or some of them) are faulty. With the original eprom, the WORST your car should do is run rich. But it shouldn't prevent it from starting.

 

Since the car started perfectly when it was running on the network resistors(limp home), I think bad injectors can be ruled out, besides it was LPE that directed my to mess with the aforementioned tables to resolve start up; when I asked if they had any recommendations they said they usually only mess with aftermarket programmable ECUs and that I should fiddle with the crank fuel values until it started. Now that I've seen a marked improvement after modifying these tables in the PROM, I think their suggestions were right. Anymore ideas?

 

What did you set the injector constant to?

Post a copy of the modified BIN you're using with the 26# injectors and I (and probably others) will take a peek.

 

I've finally come to realize the 26lb/hr Accel injectors must be rated at fuel pressures above 43.5 psi or that they are incompatible with the stock GM ECM. I found that after altering the crank fuel tables (increasing PW should have been the first indicator) that the car would run incredibly lean with the injector constant set at 24-26lb/hr. This in itself indicates that the injectors are flowing less fuel than expected. I actually had to reduce the injector constant to 21.5lb/hr to achieve 128 BLMs. I'm not sure as to why, but these injectors are definately flowing less fuel than the stock 22lb\hr injectors. Has anyone else had this same problem with the Accel fuel injectors? At first, I just refused to admit the injectors were bad, after all removing the plenum to a SuperRam isn't easy, but now I've come to realize with all the tuning info I've gained that they are just plain crap. As for the .bin file, I've included the last modifications needed to acheive 128 BLMs and zipped them for you to download. Now I'm back to square one, needing a set of larger injectors. I know SVO injectors are rated at 30 psi so most of their line is actually advertised undersized, but I'm at a loss as to which size to go with. They offer 19(too small), 24, 30, 42, and 150 lb/hr sizes. The 24lb/hr injector is actually a 28.9 lb/hr injector if rated at the standard 43.5 psi or 3 bar. The 30 lb/hr injector is actually a 36.1 lb/hr injector at the same pressure. Technically I'm running an FMU so an extremely large injector isn't necessary. If I'm correct about the sizing, the only logical replacement is the SVO 24lb/hr injector which would be only a slight step bigger than the 26lb/hr injectors I initially bought. Have any of you ran this injector and needed to change your injector constant to 26-28 lb/hr to acheive 128 BLMs? If so, what kind of a recommendation would you give them? Are they less prone to fouling, do they seem to hold up to higher fuel pressures? I'm really irritated that my first injector purchase turned out to be a flop. Any help or recommmendations you give will be a *** send. Thanks guys, keep it rollin.

 

With a solid 355, 12 lbs boost and NoS for fun, is a 26 lb injector even large enuf? The new Lightening comes with 42 lbs stock. Personally, I'm looking at getting some 35 lb turbo coupe injectors and seeing how theydo. cheers, Bob

 

I checked out the bin you posted, the checksum was invalid (show-stopper, the ECM will run the car in limp-home mode).

I don't use WinBin so no idea what to tell you to try, but GMEPro or TunerCat are a good investment of $75.

Fix the checksum and test again.

Also, the initial spark advance is set to the factory 6deg BTDC, what are you actually running as indicated with a timing light and EST disconnected?

-Kevin

 

The checksum works fine with WinBin. It just may have been the way I imported the file. I've left the timing at six degrees as verified by a timing light with the est connector disconnected. I actually have an MSD Timing Master with timing control **** on the car allowing me to vary initial timing as I want. As for the timing having anything to do with it not starting, I think that's a moot issue considering I just made an injector change. I'm sure the initial timing could tolerate 8-12*initial but I'll get to that later. Right now injector size and quality is the issue. As for a 26lb injector being large enough, your right it is on the small side for the blower and nitrous, but I'm not running a dry NOS setup anymore. The new setup consists of a Fogger system plumbed directly into the sides of the SuperRam plenum and running off its own feul line and pump. As for 26lb injectors being enough for just the blower, the car is still using ATI's super FMU. Therefore, 26lb injectors should be more than adequate for the existing setup. A SVO 30lb injector could be used but I'm trying to stay on the small size to help gas mileage and fuel atomization. I would also like to make this extremely clear, the .bin file is allowing the car to run off the PROM and not in Limp Home mode, which is easy to verify considering it is going into closed loop operation and allows me to vary injector constant value to adjust BLMs. As far as the questions I asked earlier, has anyone else had problems with the Accel injectors being smaller than advertised? This is really weird, in order to achieve 128 BLMs I have to set the injector constant to 21.35lb/hr. At the same pressure (48 psi) and with the stock 22lb/hr injectors, setting the constant to 22.36lb/hr yields the same results. This means the injectors are really only 21-22lb/hr yet the solenoid housings have been stamped 26lb/hr and I purchased them under the premise they were 26lb/hr (YES, they are brand spanking new, not used). If anyone else can explain the sizing issue, please do. I'm ready to listen to anyone's comments. I've finally come to the realization that they HAVE TO BE changed, if there is another suggestion that would prevent me from having to take the SuperRam apart again please speak up. Thanks for the help, keep the comments coming!!! By the way to validate the checksum make sure your using a good 6E009.ecu file since there are some bad ones out there.

 

I tried to open the bin in TunerCat, and had a friend try it with GMEPro, got the checksum error message in GMEPro and TunerCat just plain won't open it. Could be a file-level problem as you said, hard to tell.

As I said earlier, I don't use WinBin so can't help there. Good luck and I agree the Accel injectors sound suspect. If they're a recent purchase I'd send them back and pick up a set of Ford 24# injectors (they rate 24# at <40psi so their rate at your 44+ psi is in the 25+# range).

 

Well I have used ford injectors and have encountered similar problems as yourself.

My first experience was with a built 355 race engine I converted to TPI. I used 30s and ended up setting the constant to 25 and fuel pressure to 48psi.

My next experience was with my mildly modified 91GTA I used 24 ford injectors and ended up setting the injector constant back to 22 to get it to run right. I left the fuel pressure alone.

It has been my experience so far that it is hard to match the aftermmarket injectors to the constant on the prom. I also use winbin. Maybe there is a bug in winbin that we do not know about or we are clueless to some setting that needs to be made in winbin.

I am seriously contenplating TunerCat and I have built three cars using WinBin.

 

go into the arrays is winbin and rework the
injector pw vs battery voltage correction. youve got some values there that could be hampering you. also remeber the larger the injector the longer the bpw needs to be to sustain an idle. i would reduce my feul pressure and ramp up the pulse width. this may get you farther what you could be fighting is in suficent injecotr opening time. try going a different road. i noticed in the bin your using that it has a 2nd fire option for the injector flow. im new to tunning these ecms but are the injectors firing twice per engine cycle ???? so in theory it would half the pw to .670 msec 2 times per cycle instead of 1.240 for one fire. thats assuming that there firing twice per cycle??? got bone up on these ecus a little more. anyways get out an osiliscope and check the signal going to the injectors. you could have a bad ground ?