7427 install, first impressions

[gregs78cam]

My Camaro was doing something similar, only it was very noticable. i found out that it was going lean. I turned off closed loop and it went away. I have a feeling it had something to do with the LM-1 supplying the simulated narrowband input for the ECM. Just don't have time to test it.

So maybe turn off closed loop and see if it goes away. Or look at your log for a lean spike.

[EagleMark]

Your in trouble JeepandGuns!!! We got three answers for your issue!!!

Least you got some input on what to look for... guess a datalog with issue happening may be in order?

[dave w]

I would look at timing. I was able to clear up a lot of that low load surge in a few cars by adjusting timing. Depending on the car more timing helped, in others, reducing timing helped.

I agree 100% with this statement! I had 3/4 4X4 '427 conversion with excessive low load surge in 4 Lo. I increased the Near Idle TPS% to 7% and tweaked the Near Idle timing table to eliminate the low load surge. Having two timing / ve tables in the '427 is nice!

dave w

[JeepsAndGuns]

It will stop if I push the gas a little more to make it start pulling a bit, and stops if I let off completely. So its only when I am at the in between spot.

I do remember back when I was building my timing table with the old 7747, that it would make a noise real simillar to this when I didnt have have enough timing. I would be emulating and then raise the timing some in the area and it would smooth out. So it could possiably be timing, I'm not sure. I will will just have to do a log and see if there is anything that sticks out when it does it.
All I know is it never did this with the old 7747, and didnt do it with 7427 untill I got the speed sensor working.

Oh yea, alsmot forgot, it seems to do it when I am putting around in 2nd gear (I have a granny gear 1st) at parking lot speeds. I was thinking about starting to play with the idle timing table some and see what I could do with that. The only question, is tunerpro says its "closed throttle" So does it switch to this table any time the throttle is closed, or what dictates when it goes into this table? Right now I have both tables exactly the same.

[EagleMark]

[quote=dave w]

I would look at timing. I was able to clear up a lot of that low load surge in a few cars by adjusting timing. Depending on the car more timing helped, in others, reducing timing helped.

I agree 100% with this statement! I had 3/4 4X4 '427 conversion with excessive low load surge in 4 Lo. I increased the Near Idle TPS% to 7% and tweaked the Near Idle timing table to eliminate the low load surge. Having two timing / ve tables in the '427 is nice!

dave w[/quote:rwhyzn21]
Man I would not want to tune one of these without emulation! To much stuff! This is just a quick look, but since it started with VSS install it may have to do with MPH paremeter of some kind. Also JeepsandGuns is a conversion so he probobly has done Min Air Adjust, who knows where his TPS% is at idle?

Here's some things I see with advice given, not to say it's one but lots of varibles.

[attachment=0:rwhyzn21]JeepsandGuns.jpg[/attachment:rwhyzn21]

[JeepsAndGuns]

Ok, I didnt have as much time today as I wanted, but I was able to drive around with the laptop for about half a hour this afternoon.
To first answer the question about min idle. A couple weeks before I did the 7427 swap, I re checked and re set my min idle. With the iac drove all the way closed (by jumping the aldl pins) and then un hooking it when it was closed, I set my min idle to 500 rpm. I then used the super 42 data log screen to re set the tps voltage to .54 volts. On the 7427 0E data stream dash, it shows tps voltage as .6 volts when throttle is closed.

So here is what I noticed today.
I tested at several diffrent speeds, rpm's, and throttle. It seems to be doing this pretty much without fail when tps voltage is .8-.9 volts, and map is around 35 kpa. But it also will do it at most everything between map 30-39, but only at around .8-.9 tps volts. It doesnt matter what speed I am going, or what rpm the engine is at, and since it doesnt matter what rpm, I dont think its going to be timing, as at every rpm and speed I tested, timing was diffrent each time. So it didnt seem to matter what the timing was. And when it was doing it, I paied a little more attention to it this time, and it has just a ever so slight (I mean slight) surge. I watched the datalog dash as much as I could when driving to try and see what was going on (took a long time to narrow it down to the specific tps and map. I couldnt look but a couple seconds before eyes had to go back to the road) But when it was doing it, timing never changed, but injector bpw was bouncing around. It seemed to be jumping between .98 and usally somewhere between 1.08-1.15. I coulnt narrow down the high side, as it was constantly changing. I'm kinda almost wanting to think fuel?

Also, another question, as lots of the tps adjustments in the bin show it as tps %, is there a way to convert tps voltage to tps % if .6 volts = closed throttle.

[EagleMark]

That's what I was thinking and where I was pointing you, look at data list in ADX file and below TPS voltage is TPS Position! That is your percentage!

Because you have a conversion, nonstock for ECM engine, it is, in my experiance always needed to do min air setting, this changes TPS percent! But when you elongate holes in TPS to adjust back to .54 volts it SHOULD go back to correct TPS percent! But I have noticed in TunerPro ADX files on 7747 that TPS percentage is wrong.

Looking at 427 XDF SO many things happen at idle, off idle and are effected by TPS percent that for example, "TPS to Return to Idle Spark" is set to 2.0% so you may go to 1.9% while driving?

Or "Maximum TPS for Idle VE" set to 2.3% and you let off gas while driving and go to 2.1% while driving?

Not to mention TPS % settings for MPH to idle or off idle or DFCO or? SInce your problem came up after VSS I think it's going to be a TPS% vs MPH setting. Just a guess from start... not really sure how yours ran without VSS as I thought these PCM needed VSS and this whole issue and thread learning experiance shows how important VSS is to this PCM. Although dave w knows how to make them run without? Why take away something that is so much more important to this PCM, compared to 7747.

And several others that I just looked at that change what PCM is doing. Is it idling or is it driving? PCM is confused and could be as little as .1% in TPS angle screwing up driving or idling.

[EagleMark]

My Camaro was doing something similar, only it was very noticable. i found out that it was going lean. I turned off closed loop and it went away. I have a feeling it had something to do with the LM-1 supplying the simulated narrowband input for the ECM. Just don't have time to test it.

So maybe turn off closed loop and see if it goes away. Or look at your log for a lean spike.

See, your having the same issue and what JeepsandGuns found in datalog was exactly what you said. lean spike. Although could be simulated O2?

Just a theory right now but what everyone has tuned out with fuel and spark may have been a TPS% VS MPH at idle, off idle because of all the paremeters to do with TPS%... just a theory as you all know I am new to this PCM...

[JeepsAndGuns]

look at data list in ADX file and below TPS voltage is TPS Position! That is your percentage!

I am a little confused about this?
So I bring up the ADX like I did when I entered in my base timing and injector flow?
Or are you saying that tps voltage is percent? Meaning 1.0 volt is 1%, 2.5 volt is 2.5%, .9 volt is .9% ??
What is stock tps voltage when throttle is closed? Should it be .5?

I too was wondering about the VSS, I wonder why I never got the error code for it? How did it run without one? Read my first post and every post up untill I posted that I got it working. It ran fine without it, actually better than fine, it ran better than the old 7747 did.

[EagleMark]

ADX Aqusition data side. Not XDF bin file side.

Voltage is a reference from TPS sensor and percent is position of throttle blades, based off TPS reading... both show up while connected to ECM and show in data list view.

[JeepsAndGuns]

It took me a couple days to figure it out, but I now see what your talking about.
I was thinking you had to go to edit adx, and under the tps settings, it would display what voltage equils what tps %.
I had a DUH moment tonight and noticed you said under data list, meaning the data log info! I click on that when I datalog, but I always use the drop down menu and change it to display error codes, I have never even really paid attention to the sensor data part of it.
I will definately watch that next time I get some time to fool with it. Not sure if I will have time this weekend, as saturday is my birthday and my mom is coming in from out of state to spend a few days with me.

[EagleMark]

You can also watch your recorded data over and over again with Data lists, historygrams, moniters and dashbord. they work while recording data and when playing data back!

[JeepsAndGuns]

I dont think I have ever reccorded any datalogs. I have always run it connected with the tables to check my fuel. I would then just go inside, make the required changes, burn a new chip then clear the tables out.

[EagleMark]

Ahhhh! Tuning live!

I do that but after I click connect so I can watch data I also go to "Aqusition" then "Record" when your done you click "Stop" or if you forget and close TP it will remind you to Save As.

Then you can play back anytime, watch slow or fast or frame pause frame pause frame pause... you can find glitches!

[JeepsAndGuns]

Ok, the update this thread about the above issue. I finally had some time to do some more tuning. I figured first I would try timing. So I fired up the emlator and did a little tweeking. I higlighed the high map areas and simply raised the timing just a little and it has now went away. It just simply wanted more timing!
I also tweeked my idle timing table and pulling out has now improved. Having two timing tables is pretty sweet. Best of both worlds!