I have a 90 c1500 pu 502 RAMJET, 42# injectors. I was told this was the oem size. I have all idle and cruise tables down to 128 + or - 3 . When I started to make some WOT pass's for fun I could only get O2mv up to 780 mv. useing a MT2500 scaner. I was to scared to even hook up the WO2 and see the real ratio.

I am useing a 7730 ecm with the S_AUJP file and TUNERCAT RT. My VE tables at 90 and 100 are max and when when watching PW it is at 7.2 .

Is there any way to get more fuel without another injector change,or am I missing some thing?

I could not have got this far without all the vast knowledge that has been posted on this board .

Thanks and if there is not a quick fix it's back to the nuts and bolts to fix the hard problem

 

It's a problem with the $8D code ...

https://www.thirdgen.org/techbb2/sho...hreadid=256693
https://www.thirdgen.org/techbb2/sho...hreadid=272121

 

I was just reading the second thread you listed and hope I have not wiasted a lot of time and money, but what I am seeing I am at a dead end road for now.

I don't want to go to an OBDII or after market system, and the MEFI3 never seems consistant. Is there another ecm I can use?

My lack of knowledge in code holds me back from helping, but I will keep reading and learing and hopfully a fix can be found

 

With your setup, I'd leave the 7730. Just leave the displacement set at 5.7 L, and the injector constant at stock. Then just fiddle with one cell that you know is correct in your current calibration, and change the VE to get BLM to 128 there. It could even be done near idle, or free revving. That'll get you a multiplier that should hold true everywhere, I think. The VBatt offset may screw up that theory a little, though, not sure. That will eliminate any PW limits, and Airflow limits. You don't have anything else to worry about in that setup, I believe, like no egr, and closed loop will still operate the same as stock. I'll do the math later and get back to you, but it'll at least get you close, and you won't run into a PW problem.

I'd be scared to do any of that WITHOUT a WBO2.

 

Did some math, and I don't think the Vbatt will cause any problems. Use a VE multiplier of about .76 (.753) in your new cal with 5.7L and 22 pph injectors (vs 8.2L and 42 pph). It should give you about 24% more room for fuel.

 

You can also consider the $58 (or talk to Bruce about his version the $60). It can run on the 7730 also.

But try Red's suggestion first of "fudging" the displacement/injectors and then build a VE table to correspond. It's worth quick try.

 

Thanks Red for the math, I will give it a try hopfully tonight if the wife dosnt have any plans .

WBO2 will be on boad for the next runs. Hopfully weather will give me a brake to try some WOT runs .

Thanks again for the help and input

 

Reducing the displacement term does work as a work-around to this $8D issue. To have things even out set the displacement to 5.7L (as suggested) and reduce the injector flow by the same proportion:

5.7 / 8.2 = 0.695

42# * 0.695 = 29.2 # injector

This does affect the airflow term as used for a handful of closed loop fueling functions and emissions releated items, but it isn't going to break anything.

RBob.

 

What RBob said.

 

Well guys got a couple of hours of dry time and tried the changes. I was able to get 11.8 ms pw and was able to control PE fuel.
I Have a freind in Portland that has a dyno and I have use of it for a full day this week. This should produce some good results and a useable bin.
I will post my findings when I get back.

Thanks again

 

Good news, But first I would like to say thanks for all the help it paid off.

Spent 6 hours on a Mustag dyno and was at 444hp and 498lbsT@RW. Torque seems down a little but that may rise with some tweeking here and there. Had some problems with idle, blms 118and int128 and WB said lean 15.8, I figure this is due to the overlap in the cam. I'm not to woried about it, once off idle every thing else looks good.

Now for the bad news. The diff looks like a Ballpark Frank commercial. Ohwell it's winter and time to build a 9in. and maybe if I can swing it I'll get the back half done.

 

One of them *Iron enriched- Well Done* ones?.

 

Well after along two years of health problems and a new grand son, our first that is now 20 months old, I finale went to the shop and said it was time to bring the old girl out.

Didn't back half her, But did build a 14 bolt 4.10 that should take the punishment!

I have been doing a little, BS, A lot of reading and it seems everyone has gone to Tunerpro for the SUPER AUJP. I have only TC software. When I made the Ball Park Frank Commercial TC was the ticket.

My question is. Is TC still compatible with the SUPER AUJP, Or should I load Tunerpro?

Any positives or negatives would be grateful.

I still want to say, Thanks to everyone that helped get the old girl on track.

 

I use TC still, even with S_AUJP

Sometimes I switch between the two. Just different interfaces really.

I know, I'm weird

Good luck

-jason

 

A couple of comments here. I believe that Z69 has fixed the PW limit on large cube motors in SAUJP V3. There was a hard code problem that was incorporated.

I have been fighting this same problem with a 327 motor and 195cc heads that flow. I am running LT1 injectors that are supposed to be rated at 24lb/hr. So far I have cut my injector down from an original setting of of 24.8 to 17.5 after trying other solutions. The last run I had a setting of 19 and I was still at 106% of my VE table based on the run. My VE tables have been maxing out in the 4k 70-80kPa region. There is a big hump in the table and so far this is the only way to get what I need.

 

Yeah, a quick note here, I have done some investigation on the 502 injectors, and I beleive, though I could be wrong, that they were/are actually 36lb injectors, not 42lbs. So it might be beneficial to check your injector constant, whether you are using the later fixed version of the SAUJP or scaling the injector/displacement.

 

The $8D pulsewidth limitation fix by Z69 (mentioned above) is here:

https://www.thirdgen.org/forums/diy-...limit-fix.html

 

I was able to confirm this a while back. I have a friend that had his 502 RAMJET down for some top end upgrades, And sent his injector out and had them flowed. They are 36lbs. I checked the PN on mine and they were different.so I sent them up and spec sheet came back with 42lbs. After doing some research found out prier owner had installed these.

If the damn weather will hold out I am going to try the S_AUJP3 file this weekend and set constants as what I am running. If all gos well I will put her on the dyno to see if we can get some better numbers.

Again, Thanks for the input.