UGH......thinking about starting over from scratch.....

Specs: 1985 GMC S15 with a 3.4l from a 1993 Firebird. Has the GM 220 TBI with 7747 ecm.

I am currently running a modified ATKX bin. (it's an ansync bin)

Since it's been at least 6 months since I've done anything with this tuning, I've forgotten why I am using that bin.

About a month ago now, I had to replace a freeze plug in the driver's side of the block. That sucked. While the cooling system was empty, I also replaced the radiator with a factory original from a 1988 S10 that was super clean. I've noticed since then, it seems something is different. I'm thinking that the temp is either more stable, or flow is better.

It seems to idle smoothly after warm up, and I know there are cells in the VE and spark table that still need tweaking, but haven't had time for that.

While driving home this morning, I noticed something that I've not noticed before, which was during a constant speed with a slight coast, the INT seems to go wacko. It seems to have just started. I got thinking maybe the O2 sensor maybe getting lazy, but it's only a year old. Map readings look ok, unless I missed something.

Looking at the cross count, O2 seems ok, but I've not found what the lowest count is acceptable. I've read that the O2 sensor should cross the .45 volt mark once a second, or about that. Looking at the log attached, it doesn't, but shows the counts being on average of 80 and up with some dips in there.

Part of me thinks that it's the weather change that is affecting all this.

Part of me thinks I should go back to the 1228062 ECM/BIN combo and stick with tweaking a BIN for 60 degree engine.

I hate the idea of feeling like I am giving up, but I just can't seem to find the time truly needed to tune these 90 degree bins.

Any thoughts, criticism and/or ridicule is accepted.

NOTE: the attached bin is a $42

I looked at your data log, on my pc the o2 is switching like it is suppose to. here is a old bin you posted I changed a few things in it.the 15a bin had 4-6 degrezz timming retard in the coolent timming compensation at 60 - 73 centegrate. turned off the burst knock so watch for" knocks at operating temp" if you get knocks take 2 degrezz off from your main timming table at a time till they stop.i would also take about 12% off the ae "tps and map " then see where you stand in your blm. you have to remember gm didn't make the set up you have.it is still running in sync bin except when you are off the throttle for a second. I forgot what tunning equipment you have. if you start over I would start with a 4.3 bin for the 747 and lower the basic pulse with by 12% then data log.

Hey Ony,

thanks for checking that out.

I am running a laptop with the cable connected to the serial output using the transistor adapter to log data using TunerPro.

One of the things I noticed after posting about this is the coolant temp. Since putting that cleaner radiator in, and I did not notice this until a couple of days ago, but it's running lower than 190.

I don't recall what thermostat is in there, and, am not sure of how old it is. So I am going to replace that first and then do some more logging.

As far as starting over with a new bin, I may do that depending on what the results are after putting a new 195 thermostat in.

I believe a while back, I did ask about the differences in BINs regarding 60 degree cranks and 90 degree cranks.

I can't recall for sure.

Well, something else going on. Not sure what exactly.

Pulled the thermostat and it's a 192 degree. Pulled the temp sensor also and used a Fluke 52 and a Fluke 87v to watch sensor resistance and temperature of water on the stove to see what's going on. Appears that the thermo is opening up at about 195 and closing about 185. Resistance readings of sensor are good.

damanx, open your bin and look at[sa coolent comp spark ] compare it to other v6-v8 bins. the ecm uses 40 kpa as the last reverence you are 4-6 degrezz retarding at operating temp. the bin you was running in November- December had pretty good logs.

Hey ony,

So, I got everything back in and the EzRay scanner is reporting op temp of about 180.

Not sure what's going on with that.

I'm going to take a look at the bins and compare as you stated.

I think I may go back to the ASDU bin that I initially started out with.

Later, when I get a chance, I am going to read through all the posts I have here and try to figure out why I went to the ATKX bin.

when the ecm goes closed loop I think it goes to the main timming table,the cool comp table may be why you have running problem when you first start your engine and have to run it a bit before you drive off.

Hey ony,

Will be doing some reprogramming today. I've been doing some reading and I think that I might understand better what is going on. Since having put a cleaner radiator in, the flow of coolant through the engine is better, thus, lower operating temp, because I believe, that I had somewhere between the coolant comp table and the main spark table, reduced the timing due to the previous radiator not flowing as well.

Does this make sense?

That ATKX bin is a 4.3l bin.

I am still curious about the spark table as I don't remember if it's the original to the BIN with tuned adjustments made, or, if I copy and pasted from the 3.4 table from the bin for that specific vehicle which did not have a distributor.

I suppose though that the table is a mute point since I'd essentially be moving the timing up as much as possible just before knocking anyway.