$0D TBI to MPFI conversion, how is your idle quality?

[96lt4c4]

I have actually changed mine from 10* advanced back to 0*. But the cold start stall is still there.
I had my distributor set to 10* for the longest time and my bin set to match it. I had been fighting my AFR being all over the place for the longest time. I ended up one day setting my base timing back to 0 and readjusting the bin to match and blammo, my AFR is now stable. IDK what it effected, but it did something. I dont see how it really effected anything concidering I set to bin to account for the 10* initial timing. So I'm not sure.
I would be interested to see if you may or may not have a simillar issue.

That would make since, with what Fast 355 said, about the injector timing. I am working on a new bin right now and getting ready to go out and fire her up. Gotta load up the 4 wheeler going deer hunting in morning. Getting down to 23 degrees tonight. Going to freeze my ass off...

[brian617]

I have actually changed mine from 10* advanced back to 0*. But the cold start stall is still there.
I had my distributor set to 10* for the longest time and my bin set to match it. I had been fighting my AFR being all over the place for the longest time. I ended up one day setting my base timing back to 0 and readjusting the bin to match and blammo, my AFR is now stable. IDK what it effected, but it did something. I dont see how it really effected anything concidering I set to bin to account for the 10* initial timing. So I'm not sure.
I would be interested to see if you may or may not have a simillar issue.

I think that comes back to a previous post in this thread about the "Degrees of Delay from DRP to Injector Firing" Parameter? More stuff to experiment with. I too run 10* initial advance and been working on my idle quality.

[96lt4c4]

Started like poop, didn't die, but now its too rich, I changed too much at once. I think I may have it figured out though, I will see how it starts in the morning. Just when I have it all tuned and figured out, I am going to swap the injectors. I picked up some 36 pounders today at the junk yard, got 12 of them. They came in the supercharged v6's in Buick Regals, and Pontiac Grand Prix. They are the newer style Bosch thin bodied like LS1 injectors. This is for when the Turbo goes on. The old LT1 injectors wont cut it.

[JeepsAndGuns]

I think that comes back to a previous post in this thread about the "Degrees of Delay from DRP to Injector Firing" Parameter? More stuff to experiment with. I too run 10* initial advance and been working on my idle quality.

Possiable, and would seem like it would make sense, but the thing that confuses me is the CPI bins are set to 15*, but still have 0* initial advance.
Still, it would be something to play around with and I would be interested to know the results. I however do not know when I would be able to get enough time to try it myself. I have been really busy lately with other stuff.

[brian617]

Possiable, and would seem like it would make sense, but the thing that confuses me is the CPI bins are set to 15*, but still have 0* initial advance.

Think about the transit time difference between a TBI firing fuel on the throttle blades and a MPFI set up firing fuel against the back of the valves. The fuel isn't being carried through the intake runners, hence the delay.

[brian617]

I changed mine this morning to offset the 10 degrees initial advance I have on the distributor and it seems to have helped settle my idle. Going to run it for a week and be sure. Seems this is the right thing to do if you are running intial advance on a TBI or have converted to MPFi.

[96lt4c4]

I changed mine this morning to offset the 10 degrees initial advance I have on the distributor and it seems to have helped settle my idle. Going to run it for a week and be sure. Seems this is the right thing to do if you are running intial advance on a TBI or have converted to MPFi.

So did you take 10 degrees out of your timing tables in you bin, or when you put the 10 initial in the tune does it automatically take it out?

[brian617]

I have the 10 degrees initial at distributor accounted for in my .BIN under "Spark Table Biases, Main Spark Bias". That way my timing tables look normal. When doing this you also have to edit the ADX so you can see correct spark advance while logging. Here is my .BIN if you want to look, it is $OE though.

[delcowizzid]

spark table bias shouldnt ever be edited its only there so spark tables can show negative timing numbers or so the ecu can calculate negative values. crankshaft referance angle is what you want to change to suit base timing angle.changing the bias could make all air temp corrections and other spark modifiers etc not work properly

[brian617]

LOL your'e right, What I meant to say was under "Spark/DRP Parameters, Initial Spark Advance"

[JeepsAndGuns]

I changed mine this morning to offset the 10 degrees initial advance I have on the distributor and it seems to have helped settle my idle. Going to run it for a week and be sure. Seems this is the right thing to do if you are running intial advance on a TBI or have converted to MPFi.

So are you still running tbi? (if the vehicle mentioned is the one in your sig line)
So if tbi, you changed it to account for the 10* initial advance. So what about us MPFI guys? I'm guessing try the 15* the cpi bins use? (if running 0* initial advance?)

[brian617]

Yep still TBI. I like to follow these 427 PCM MPFI threads while I gather some parts to convert mine.

[96lt4c4]

I changed my injectors last night, my AFR is more consistent with these new injectors. I also tried changing the initial timing to 10 degrees, also changed the inital timing in the tune to 10 degrees to match. It didn't like that at all. AFR at idle was all over the place going from high 15's to mid 13's. I put it back and it quit. I think Jeepsandguns said he was seeing some thing similar.

My new injectors flow 38 lbs per hour at 50 pounds of fuel pressure. That's what they ran in the Buick Supercharged regal. I got the short pulse adder, flow rate, and pulse width vs. batt volts from a stock 99 Regal via HPtuners. Fired right up, drove it a little BLM's were pretty close. be interested to see how it starts cold.

Picture of injector

http://www.google.com/imgres?imgurl=http%3A%2F%2Fi235.photobucket.com%2F albums%2Fee259%2Fwhitespar%2FBosch_0280155868.gif& imgrefurl=https%3A%2F%2Fforum.efilive.com%2Fshowth read.php%3F14531-36lb-or-stock-LS1-injectors-HC-is-high&h=600&w=600&tbnid=9K-ZiYkxARjkDM%3A&zoom=1&docid=pj9zxnMRlBAz-M&ei=lxBqVNaDGZOdygTzioL4BQ&tbm=isch&ved=0CCYQMygI MAg&iact=rc&uact=3&dur=400&page=1&start=0&ndsp=27

[Fast355]

I changed my injectors last night, my AFR is more consistent with these new injectors. I also tried changing the initial timing to 10 degrees, also changed the inital timing in the tune to 10 degrees to match. It didn't like that at all. AFR at idle was all over the place going from high 15's to mid 13's. I put it back and it quit. I think Jeepsandguns said he was seeing some thing similar.

My new injectors flow 38 lbs per hour at 50 pounds of fuel pressure. That's what they ran in the Buick Supercharged regal. I got the short pulse adder, flow rate, and pulse width vs. batt volts from a stock 99 Regal via HPtuners. Fired right up, drove it a little BLM's were pretty close. be interested to see how it starts cold.

Picture of injector

http://www.google.com/imgres?imgurl=http%3A%2F%2Fi235.photobucket.com%2F albums%2Fee259%2Fwhitespar%2FBosch_0280155868.gif& imgrefurl=https%3A%2F%2Fforum.efilive.com%2Fshowth read.php%3F14531-36lb-or-stock-LS1-injectors-HC-is-high&h=600&w=600&tbnid=9K-ZiYkxARjkDM%3A&zoom=1&docid=pj9zxnMRlBAz-M&ei=lxBqVNaDGZOdygTzioL4BQ&tbm=isch&ved=0CCYQMygI MAg&iact=rc&uact=3&dur=400&page=1&start=0&ndsp=27

That is pretty odd. I have not experienced that issue first hand. Then again the engine I was working with had a much larger cam. Might need to look into the ECM code and find out what it is doing with the Injector Firing. By logical reason if you have a longer duration cam than stock your system should be fine with an earlier fuel pulse. If your engine runs better with the initial at TDC than +10*, you might have benifit retarding the injector pulse even more. If memory serves Injector Timing can be varied substantially without changing physical timing. If you advance the base timing 10* and retard the injector timing 10* in theory you should end up at the same place.

It has been years since I played with this and I have probably forgotten more than I remember with these PCMs, but I remember having to make adjustments to a $0D bin I made for a 95 Camaro 3.4 in an 87 S15 Jimmy. I had to make adjustments to the EST settings, initial setting and the like to run the DIS system on that engine. The DIS system runs at a 60 or 70* (I forget) offset to TDC#1 and the EST system has to command a negative timing value via the PCM to make the system work correctly. Its a pretty weird feeling to put the initial timing at 60* and the command timing minimum at -70* and the maximum at -10* IIRC which gave a range of -10 to 50* of total timing. Just goes to show what these PCMs are capable of doing with the right research and calibration changes.

[1BadAction]

I have a bit of a vibration at idle when the weather is hot... fuel mixture is fine, but it seems like there is some issue with evaporation of the fuel when it's hot outside that is causing a vibration. when it is cooler than 70* ambient, truck runs smooth as glass. Do you guys think firing the injectors earlier will help with this problem?