Right it just takes the rotor out of the equation in the opti, and the high voltage. Gives you a more reliable setup for oiling too. I have used this to fit the lt1 pcm up to old school 400 sbc's using the opti as my crank trigger through a modified lt1 timing cover.

The timing at idle is due to the fact that the idle rpm is going over and under the target. The lt1 uses timing as a secondary faster iac but generally ends up chasing its tail. Also it could be the screwyness that your tps was doing at the beggining of the log. You know um, I dont know how your map sensor is rigged, but consider a restrictor in the line to damp the rampant fluctuations at idle from the map sensor.

Btw you have almost no vacuum at idle at all like 3-4" hg by your map readings. Are your sure when its hot your lash isnt too tight, thats kinda low vacuum for what you're running.

I will look it all over tommorrow and give you a little more input, had a couple of engineering finals today and i'm pretty beat/drunk/whatever.

 

I have not checked the lash hot. I set it at .018 intake and .022 exhaust cold per bret and llyods instructions.

the 360 performance plenum has 2 vacuum ports on the bottom of it and I have a vacuum hose hooked to one of those and ran over to the map sensor that is zip tied to the wiring harness near the fuel rails.

 

Well after some not alcohol filtered log review. Your tps sensor needs some work, either you need to crack the blades a little more, or slot the holes on it so you can give it a little more preload. You actually do not come back to idle but instead you stay in cell 18 (idle is 16) because it thinks you're on the throttle. This makes your timing crazy and your idle fluactuate all over because it thinks you're tipping the throttle. That makes your idle rpm fluctuate all over the place due to timing.

On your map sensor, make a little bracket out of some sheetmetal so that it can be solidly mounted by slipping the bracket over the carb studs and using 2 of the nuts that hold your intake elbow on to secure it. It should not be allowed to flop around while in use. You could even mount it on the wirewall etc just not zip tied in whatever orientation. It is designed to be used mounted horizontal and rigid for best results.

I would pull your valve covers with the engine warmed up to temp and see where the lash was at. You may not be where you think you are. Too tight on a solid roller will drasticly kill off idle vacuum as the clearance ramps on the cams are HUGE. .018" sounds a little tight, but if thats what the man said then go with it I guess, a little looser may pick it up in the mid/low range though. Keep in mind valve lash is a tuning tool on solid roller cams.

Tell brian to set some of those damn idle over and underspeed timing tables down to zero. A big cammed ride like yours cannot hold a steady enough idle to keep from being all over the place with timing because of those tables period. Your car cannot hold idle within 25rpm, and there is an idle over/under speed table that adds or retardes 2* of timing if you get just that far off of target idle rpm. It needs zeroed out to about 50rpm on each side of it. It can be cut down more on the overspeed up to about 100rpm over. I like to keep it stock on the underspeed so if your idle sags down, it will help the engine correct before the iac takes action.

Your idle is rich because of your extremely low map signal. You are idling right around 90kpa on the map. Your target idle a/f ratio drops from 14.2-12.9 at idle, that is why you are pig rich at idle. However with the limited map signal that you have the fix is not in the open loop tables it is in the maf calibration. Brian is going to have to get creative here and miscalibrate the maf tables, tell the car it is not seeing as much airflow as it is to trick the car into leaning out cruise and idle. You cruise about 75-80kpa, your target a/f there is about 14.2, no bueno buddy. He needs to me more aggressive with the slope here. Take the a/f target to 14.7-14.9 all the way to like 80kpa. Or he can just lean it out using the maf.

It is not going to be a one shot deal to fix all this with him doing it remotely. If you were local to me i would hook my wideband up for you and get this sucker lined out in a hurry. His target a/f ratios are good, they're just in the wrong place with regaurds to map because your car makes no vacuum at all. the crux is just that at high airflow situations you do need what he has prescribed for those map vaues. At low airflow you need it leaned out, again the fix is just to lie about what the maf airflow is seeing. He could just go ahead and set the 70-100 map target a/f ratios the same all across the board, and lean you out using the maf sensor for low airflows. That way when you hit high airflows the maf reads correctly and automaticly you snap to a very nice 12.9 a/f and you're pulling away at max power.

SORRY FOR THE BOOK, but you asked sucker .

 

texas is nice(and hot) this time of year, you should come and visit.


is a dfi system with a set of wbo2 sensors any easier to program?

 

This is not hard to program, I just think you have a couple of issues that need addressing. Your maf tables need manipulation, and thats it for the tuneup. Your tps is acting a fool and that needs fixed. I think you need to rigid mount your map sensor and put a restriction in the line to it. I also think you need to check the lash on your valves hot and see where its at, 3" of vac is insane for what you are running. Ask lloyd or bret what kind of vacuum you should be making. Bret can tell you pretty closely.

Aftermarket efi systems are nowhere near as good as the oem stuff unless you plan to do something completely insane. I have btbd and big stuff 3 is the only one I care for, the fast system comes in about two notches below that imo. The oem pcm has half a dozen different modes and ways you can configure it to run and is basicly idiot proof, it will get you home when the other junk wont.

If you cannot get the oem pcm to be happy with your abilities do not even attempt to run an aftermarket pcm. You will never get it to drive right. Wot is easy and can be dialed in quick, part throttle can take up to a month of weekends to get nailed.

I think your best bet would have been to get somebody local who is good and can sit in the truck while you drive it and address the issues one at a time. I have no doubts brian can make it run correctly but it is not going to be a one shot deal, show him my thoughts on the issues at hand and give him that log and i bet he gets you a whole bunch closer. You work on the map sensor bracket, and figuring out what is up with your tps and your idle will get much much more steady.

Dont feel bad and dont give up man, I have flashed my daily drivers computer probably 100 times making small revisions just for drivability reasons. Think of computer tuning as a polishing process, start rough and get progressively smoother as you go and things come into line.

Illinois is nice and hot this time of year too, need scuba gear just to go outside its so humid, and as the icing on the cake its 100* too.

 

I saw he was in open loop. Did I miss something here? Personally, I like tuning my MAF controlled engine because it is very straightforward, if lengthy with the iterations, to get the calibration right.

Slammed, this car can be tuned you are just going to have to put in the time to learn. If it is like the time I put in, it will be possibly 60+ hours to get everything worked out because you are just starting out in the learning curve.

Hell, take my situation, I never dealt with such a large cam before in my RX7 and had to spend probably 12 hours just tuning for that. Now I have it dead on and runs fantastic but I knew what to do in Tunercat up to the point of big cams.

I see everyone here has given you a tremendous amount of good advice. What I suggest now is showing a few more DataMaster files to us to see where you stand.

Something I would suggest for idle control is closing the blade all the way and letting the idle air passages in the plenum control the air flow. The factory put them in for a reason. I did this and all my big cam reversion/split BLM problems went away.

GL
Ben

 

You missed the fact that due to his large cam you cannot command different a/f ratios effectively in open loop based on map values. So he is cruising at a commanded a/f or 12.9 because he has such low manifold vacuum, this is also the case at idle. Now if you wanted to lean out cruise and light throttle to 14.9 or so (perhaps not so much at idle). He could multiply his maf values by about .85 up to say 35-40 g/sec. Since there is no correction in open loop, this would effectively lean his cruise and part throttle operation. At higher airflows his maf would read correct and he would run at the max power a/f ratio of 12.9. The thing you missed is how target a/f is looked up in open loop mode, it is based on temp and map readings. He idles with about 85kpa, and cruises in a similar range which is up around max power kpa for most people, he doesnt have enough cells to differentiate a/f for idle and wot or part throttle.

This is just a more advanced technique of tuning wild cammed cars that make no vacuum in open loop. Sometimes the things that need done is just tricking the computer in wild cammed rides. I can get the stock pcm to jump through quite a few hoops using unconventional methods.

What would be ideal and give you alot more tuning ability is if you could find a 0.5bar map sensor. You would double the cells that were usable, but you would have to scale the values. so you know where you're at.

 

My only problems are that while I do have lt1 edit, It is extremely old and I cant find half of the things in there that you talk about, and this truck has open headers and I just cant change something and drive down the road to see if it did anything one way or the other. Im on the fence on spending the money on an updated version of lt1 edit or tunercat just because I dont know that Im going to able to use the stock pcm due to the rpm restriction. If I have to end up buying a dfi system, that is going to cost enough that I dont want to have several hundred dollars worth of useless software that I will not be able to use any longer.

 

slammed98gmc, you have an email.

 

I downloaded tunercat and bought the EE defination files and Im trying to get familar with all the tables. There are a ton more than my 8 year old version of lt1 edit. WS6, I can see what you did with the idle overspeed and underspeed areas when compared to the other tune I had. That makes easy sense. Im going to check the vacuum tomorrow night probably and see what kind of vacuum I have compared to what the map sensor is reading. Then I will probably need some help with either the afr vs map area or in the maf tables so I can get my afr a little closer to the 880-890mv area like it used to be at wot.

 

Good deal, i'll be curious to see if the changes I made to the maf calibration and the afr table for cruising helped you out. Like I say a wideband would be the best thing for getting whats commanded vs what you're getting to sync up.

Just another question, how far is your maf from your tb in this thing. Is there any way you can move it kinda far away like a couple feet from its current location. Sometimes, and this is just my experience speaking again, really large cams will have enough reversion to blow air across the sensor the wrong direction. The sensor reads flow in both directions, and then makes the idle go rich, which it will be anyways because of the map value and the resulting commanded afr but I think I have a bandaid over part of that for now.

Just ask when you decide what needs done and I can help you iron it out. Just a little precursor, turn your sample rate up pretty high when you do a wot run and keep the total recording time short. Freescan can be a bit faster than datamaster when it comes to that. As for trusting the nbo2's to tune your engine at wot, that is your call. Those values are what I generally see once something is pretty well set, but yours are in kind of a harsh environment compared to most.