94 Jimmy Help Spark

[ralmo94]

Hello.

I am trying to tune a 94 GMC k1500 5.7 4L60E.

The problem I am having is that timing is retarded to a negative number when the throttle is hammered.

Burst Knock is disabled.

Minimum Retard is set to 10 deg.

Data Log says its retarding.

I can't seem to figure out why.

Knock Retard not showing up

Nor Burst knock.

Changed low octane

seems a little better, but data log still shows that it is retarding, when it retards there is no power. I don't understand what to change.

I wouldn't mind if it preformed as a Non Computer HEI distributer. Am I wrong in thinking it can be programed that way?

It has a small RV cam in it, True dual exhaust, 3.42 gears. Throttle body spacer otherwise stock

Running open loop, trying to get ve dialed in with wide band. altered shift patterns, deleted egr.
Thats all I can think of.

Thanks in advance

16196395. Service number TBI pcm
BJLF BCC code

[ralmo94]

forgot to add, i have searched and all I can seem to find, is people dealing with knock retard. can't seem to figure out why it is retarding, but knock retard says 0

Thanks Again

[ralmo94]

Incase anyone is reading this, I tried the bin I uploaded on The original post, and now I have 12 degrees advanced. ALL THE TIME! I don't know what to try next. I was thinking of downloading another bin to start from. I would real like it to just run the open throttle sa table. Nothing but the table. Without adders or retard. I don't know why I am getting 12 degrees now. When I get time this evening, I will post a data log running the above tune. And also the bin I was running while it was regarding.

Is there any TBI $OD guys on here anymore? It would be nice to hear from someone, Even if you have no idea what it is.

Thanks for reading.

[PlayingWithTBI]

I'd be glad to help you out but, that's too new a PCM for me, ha ha. There are a bunch of great guys with plenty of knowledge about $0D and $0E, (7427PCM?). That's all I know, keep the faith and post your log once you get it.

[ralmo94]

Thanks for the reply. I think it's pretty much the same as 7427. From my research. Looked into tuning pretty hard before buying anything.

[ralmo94]

I realized I may have been confusing with the bin and data log I posted in the first post. So, I renamed files with what the issue.
I will post them now.

Has anyone ever had an issue like this on anything? I know there are a lot of experienced tuners on here, what would you look at if you had the problem?

I have looked at everything that I am able to edit in this bin. I have used the difference finder compared to the stock BJLF bin. I installed a new distributor when I installed the cam. It has a good cap rotor coil and plugs. New module. I really think this is not mechanical, but something in the bin. The fact that I changed something and just got a steady 12 degrees, tells me that. The thing is, that was not intentional. I don't know why it did that. I am pretty much running the stock timing table with a few degrees added. Base timing is set at 2 deg with the connector shorted, entered in the tune. I would really appreciate any ideas any one has even if it doesn't help.

PLaying with TBI, I am guessing you tune stuff like the 7727? I know that is completely different, but what would you look for if you had something like that?

I really appreciate these forums, I have found answers to all kinds of questions, without posting anything. I dialed in the VE pretty close, then the shotty muffler shop job came apart, and the thing breathes a lot better now. For some reason they had put a 1 -2 muffler on backwards, with dual pipes, running all the way back to the muffler. The muffler exit was only 1 3\4 inches. Once that crap fell apart, it ran a lot better even though the VE was off again. Now trying to dial in the VE again, I noticed the issue.

I was originally contemplating switching to carb and HEI, but after reading these forums, I felt confident that I could get it running well with the PCM, and I would still need it for the transmission anyway.

I'm sorry for such a long post, but I figured with more information, maybe someone might have an idea of something I missed or should try.

Thanks Again. I will update here as I try other things, so if anybody else has a similar issue, maybe it will help them.

[ralmo94]

Next thing I am trying is, I downloaded a BJLH bin, Copied my ve table, shift tables, and EGR stuff. Also disabled Burst Knock and made it open loop. On the difference tool there were a lot of unmapped differences. So, I am guessing it is something I can't see and edit?
I suppose we will find out. I'll post another Data log after I run the new bin tomorrow

[stew86MCSS396]

What xdf are you using to mod the bin and adx are you using to log the data?

[ralmo94]

What xdf are you using to mod the bin and adx are you using to log the data?

I had modified the ADX for using lambda

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?303-16197427-PCM-Information-0D

I downloaded both from the 7427 info thread, along with starting bins


Thank you

[ralmo94]

Ok. Tried new bin this morning. Sounds snapier seems to run decent, BUT STILL SEEMS TO BE LOCKED AT 12! I'll post log file later. If I zero out bias values what would that do? Thank you

[ralmo94]

Ok here is the data log, looks like its a little lean also, I guess I forgot to change stioch to 14.1. Only thing I can think of now is to try and start with stock bin again, turn egr off, and see if it retards on stock. I really don't understand why i am getting a constant 12. almost like the timing connector is pulled and set at 12.

Thanks for looking

[ralmo94]

Tried another Bin at lunch today. Pretty much stock BJLH, with EGR changed, VSS set, and VE table Open Loop, And Burst Knock Disabled. I have variable timing again, but still going negative, like what I would expect from burst knock. Data Log says Burst Knock is not active. I got 2 data logs of it.

[ralmo94]

Also tried the same bin, but zeroed out the spark bias values. This resulted in a extremely high spark value and knock retard, and audible knock. I stopped and put the other chip in. zif socket sure is nice, but i forgot to stop and start the data log, so I have 1 log running both bins

[ralmo94]

Here is a screen shot of the data log when it goes negative. I'm thinking of trying it with the temp for negative spark maxed. Don't know if I will get a chance to do another data log tonight or not, but i will post the bin.

[ralmo94]

I just figured out how to use the edit log for the bin file

Edit Log for BJLH Mostly Stock With EGR Delete.bin created by TunerPro.
************************************************** ************************
07/09/2020 17:34:29 Scalar: Main Spark Bias changed from 9.8 deg (0x1C) to 0.0 deg (0x00).
07/09/2020 17:34:33 Scalar: Coolant Spark Bias changed from 20.0 deg (0x39) to 0.0 deg (0x00).
07/09/2020 17:34:38 Scalar: Altitude Spark Bias changed from 9.8 deg (0x1C) to 0.0 deg (0x00).
07/09/2020 17:34:51 Scalar: Minimum Temperature for Negative Spark changed from 85.3 C (0xA7) to 151.3 C (0xFF).

I'm going to return all of these settings except the last one, Minimum Temperature for Negative Spark. I guess I don't need to post the bin. I will post the data log when I have it though.

[ralmo94]

Got a chance to do a data log. Still getting negative timing. seems to come on at about 55 kpa, but when throttle is lifted enough to take load off SA goes back to positive even at higher map than 55. looking at the bin, I now am going to change a low octane value.

07/09/2020 20:21:32 Scalar: Minimum Temperature for Low Octane Retard changed from 80.0 C (0xA0) to 151.3 C (0xFF).

Does anyone think its low octane settings?

I realized I had broken a rule of tuning. Changed a bunch of stuff and didn't know did what. So I will take this one setting at a time.

[ralmo94]

Alright, with the low octane settings disabled, I was still seeing negative timing.

[ralmo94]

So what I tried next was to limit the minimum spark advance. There was not a scalar named that, so what I did find was one named maximum retard. so I changed that.

07/10/2020 17:44:33 Scalar: Maximum Spark Retard changed from -9.8 deg (0xFFE4) to 2.1 deg (0x0006). Now I longer have negative timing.

Now the timing never goes below 4 deg. seems wierd to me since the minimum I set was 2.1, but at least it's a positive value now.

So, moving on, I am now trying to figure out what is keeping it from running the amount of advance that if in the main table. It should be commanding about 14 deg, and its only 4.

[ralmo94]

Looking through all I can find, I see, Cat overheat protection. Doesn't say anything about spark, but I am still surprised its enabled on a 94. I dissabled that and we will see if that makes any difference with timing.

07/10/2020 19:46:42 Scalar: CAT Minimum RPM for Overheat Protection changed from 0 RPM (0x00) to 6375 RPM (0xFF).

I kinda feel like I'm trying to re invent the wheel here. Has anyone ever set up an $OD tune to run only the main spark map? Seems like that would be how you could figure out what timing your engine likes. How do you know if there are variables it's adjusting for, but you don't know which ones.

at least I have gotten rid of negative timing. That's progress. seemed pretty straight forward with h p tuners. Maybe I can get back to tuning ve now that I don't have negative timing, but I really want it to run what I set. Does no good if I don't understand why its not I have looked at Coolant Temp Adjusters, Altitude Adjusters, Everything I can think of, and at the cells I'm looking at they should not have any effect as the stock tables read 0's. Running out of ideas. I've tried to tune spark before with newer stuff, and seemed to get knock retard with stock tables, and ended up running stock timing. This however does not run the table.

Any way If anyone has any Ideas to try you are more than welcome to suggest. I still don't understand what I changed exactly to produce a steady 12 degrees.

I'll keep updating this thread with things I try. Seems like it shouldn't be to difficult to get a computer to do what springs and weights can do.

Thanks for reading. I'd like to think with the high view count maybe I'm being helpful.

[ralmo94]

figuered it out!!!

[ralmo94]

I read an old post of someone else having about ten degrees less than the main table. What it was in that case was the altitude bias. They changed thiers to 0. I previously had zeroed all the bias values out, and skewed up. So I went ahead zeroed out just the elevation one, even though in the table it was mostly zeros. Ran the bin. Checked the data log and it seems to be running what the main table has now. Runs better. Now I can put a starter spark curve in and tune VE.



The thread I found.


http://www.gearhead-efi.com/Fuel-Injection/showthread.php?7472-Logging-10-degrees-less-timing-than-my-BIN-should-command-0D


Can't believe it was so hard to find that, but hopefully it will help others. If so please let me know. Had a lot of views, so if I haven't been helpful, I hope I was entertaining.

[Mark Still]

Did you end up using the BJLF bin with the $OD XDF and ADX?

[ralmo94]

Did you end up using the BJLF bin with the $OD XDF and ADX?

I had started out with jf, as it was the stock bin with the truck. As a diagnosis, I tried starting from another stock bin, bjlh. Didn't make any difference, and I didn't think it would. Basically same bin with different vss is what I seen. I have used both bins with the same adx and xdf I posted in the thread. Both bins are $OD

I hope that answers your question. Main culprit seemed to be altitude, but I left low octane blank as well. seems to run what is in the main sa map now.