Lean condition--FAST

[RickWI]

Ricky, I finally went through your GTS file you sent a couple of weeks ago and have the following thoughts. First of all reset your TSP on the throttle body to be at 11-12 at idle. Then reset your max TPS position for idle to 14. You are goofing up the AE mapping with it set like you have it. No reason for that. I would say this is a MUST DO to fix the problem. Next set the AE fuel Vs TPS position to 100, 100, 95, 83.5, 64.7, 36.5, 8.2, -23.1. Set the AE Vs TPS rate of change to .17, .39, .55, .69, .83, .96., 1.07, 1.15, 1.18, 1.22, 1.25, 1.30, 1.33, 1.36, 1.41, 1.43. Set your Map AE limit from the 15 you have it at in the MAP parameters screen up into the high 80's. Lower the whole AE Vs Map rate of change screen so the 0/0 point is at .31. The curve is OK just lower the whole damn thing down evely now that you have the Map limit raised up to where it needs to be. Smooth that spark map up in the 56 Kpa and 1800 to 2000 range. Graph that map out and you will see it looks like the smokey mountains in that area. I'd just for now insert something like about 38 degrees or so all around that area so it is not hunting for a spark timing point. Get the fueling sorted then get the spark optimized later. I am assuming this is not a high load part of the map.

I tried to look at the LOG files but for whatever reason I can't get the program to open them up. It just doesn't like them. That kind of hurts cause I can't see what kind of load the motor is really under. Otherwise I would try and give you some better ideas for your A/F map. Which looks real fat down low. I suspect though you are trying to compensate for this "stumble".

After you get your TPS reset and those base AE maps corrected there should be no reason the car shoud not "run" somewhat close to normal through that bad areas.

I spent some time this weekend "goofing up" my program to try and get something like these things to happen. The only way I could get this to occur in a similar fashion, was to gradually take out MAP correction. That caused lean spikes and also would cause a backfire out the tbody and tons of delayed hesitation. Both conditions are sign of a lean condition. Instant hesitation is too lean on the TPS AE and a slightly delayed hesitation with sometimes a backfire through the TB is lean MAP AE.

 

[T66Typhoon]

RickWI,

I have another question following what you posted... what reasoning is there for saying that with the TPS set that HIGH it is screwing up the table? I have mine at 20% at idle and that is just where it was.

Please give some better explanation for me? My understanding was that it was all relative... I have nearly the same issue on my Typhoon. From what you said it is on the TPS Vs. AE map, I just have a stumble, not a backfire.

Thanks for the info.. learning something everyday with this.

I have printed out what you posted.. and I will try it... of course not necessarily the numbers you posted, but playing with what you have suggested. I will also check my timing table in that area.

 

[RickWI]

T66, You lose half your resolution for tuning on the TPS tuning settings.

 

[T66Typhoon]

AHHHHH....ok

That makes perfect sense.... so if I understand correctly... anything over 50% does not matter with the fast correct?

Thanks again, good information as I am learning.

I have to say there is a ton of good information on this board.

Nick

 

[Ricky Trussell]

Rick, my tps will not go below 23-24. My understanding was that what ever the lowest setting you have, set the max. tps for idle one above.

I had already made the change to the max kpa for ae fuel to 88, and have just made the changes you said. I will be driving the car today.
I am on vacation this week, I am planning on going on 3 or 4 days of the Hot Rod power tour which starts this weekend.

I will post back in a few hours, my laptop is dead and needs charging.

 

[Craig Smith]

Ricky,

Where do you have the max TPS for idle set to? Also, what is your TPS reading when you get to the dead spot at 2000 RPM?

Now that I'm leading you into this, do you have any values other than zero in your timing trim table? What can sometimes happen with high-performance motors with large throttle bodies is this: you require so little of a change in throttle angle to get any RPM out of it that before you get past the max TPS for idle threshold, the ECU thinks you're still idling. At 2000 RPM you're idling way too fast according to the ECU, so it pulls timing out according to the timing trim table.

Could this be a factor?

 

[Ricky Trussell]

My tps is at 24 at idle. My max. tps for idle is at 25. The tps when the studder starts is at 28-29 tps at 2000rpm. The timing trim is set at 0 all across the map, no timing trim.

I drove the car again and have some more numbers.
38-44 KPA 2000RPM with a 75 ve setting the 02 is adding 22% to get me a 13.8 A/F ratio.

Map psia is a -9, of course I am lost here but that is the reading!!

50kpa 2100rpm 88 ve setting the 02 is adding 23% at 29lbs. hr. fuel.

I have tried all the way down to 12.2 a/f in the 2000rpm cells and the problem is still there where I have high ve numbers only in the 2000rpm cells.

 

[RickWI]

Originally posted by Ricky Trussell
My tps is at 24 at idle. My max. tps for idle is at 25. The tps when the studder starts is at 28-29 tps at 2000rpm. The timing trim is set at 0 all across the map, no timing trim.

I drove the car again and have some more numbers.
38-44 KPA 2000RPM with a 75 ve setting the 02 is adding 22% to get me a 13.8 A/F ratio.

Map psia is a -9, of course I am lost here but that is the reading!!

50kpa 2100rpm 88 ve setting the 02 is adding 23% at 29lbs. hr. fuel.

I have tried all the way down to 12.2 a/f in the 2000rpm cells and the problem is still there where I have high ve numbers only in the 2000rpm cells.

Ricky, couple of questions. First of all is the throttle position steady at the above studder positions of 38-44 Kpa @ 2000. If you hold the cursor in this cell range by using the brake to control the RPM what happens to the correction after a few seconds or so? Does the correction factor go down? I know you mentioned this question before and said it stays with a high correction factor and stumbles but humor me and tell me again. With a constant throttle position on a level surface and holding the RPM in that celll steady with the brake the correction factor stays high even after 10 or so seconds??????

On the TPS are you saying there is no way to rock the TPS by loosening the attachment screws? That would be odd as I have never seen one that did not have some adjustment on it, even if you have to modify it a bit. I would really like to see that TPS down around 12 or so, so that the TPS AE could be dialed in more like a normal graph and not compensated for the high initial TPS position.

Based on some of your numbers from above this situation seems like it is a tip in problem. You are barely off of idle position when it occurs. To clarify it in my head tell me what you are doing when you are drving to cause this. Is it a slow takeoff from a stop? Are you cruising at low speed through town with the throttle BARELY open and then step on the gas slightly to speed up?

Maybe with that information we can get a bit closer. Take some time also to look at the way the TPS is mounted and make sure there is no way you can set that down a bit. Otherwise the AE corrections I gave you for the TPS won't work worth a hoot. They will be too lean.

Also tell me what you Kpa idle reading is and your cruise Kpa reading so I have a reference to go off of on your VE map.

The other thing that is interesting in you VE map is a lot of the other low RPM cells seem rather high to be given you have 42 lb injectors. Trying to assume where you might idle at it looks like those are in the 50 area which seems rather high. Can you verify this for me. Makes me wonder what you are running for fuel pressure? So what is it and do you know if it is holding steady? Those are mighty big injectors I think for your cam and engine setup. Just a wild guess I would say 30'ish lb injectors would have done you fine.

Lots of questions, few answers, sure would be easier if we were sitting in the car riding together and tapping keys while we go down the road.

 

[Ricky Trussell]

I can hold the engine steady 2000rpm on the highway and the 02 is correcting 22% in the 2000rpm cells.

It will be no or minimal correction in the 1750 cells with a 65 ve setting or the 2400 cells with a 70 ve setting..

I can accelerate from a stop never getting over 2800rpm and get the studder and lean condition as it goes through the 2000rpm cells and clear up as soon as it leaves the cells.

As far as holding the brake and keeping it in the cells I have not done that. But I have ran for 10 miles and the 02 holds that 19-22% correction.

My TPS sensor does have screws and slots in the sensor to move it. I have it adjusted as far as it will move, Matter of fact it was on 23 until I tried resetting it today and I pushed pretty hard in it and it now is 24 so I reset my max for idle to 25.

You are right about my idle VE setting of 54 or 55. My idle kpa is 44-50 at 800rpm.

The studder is only in the 2000rpm cells from 38kpa all the way up the scale to 73 kpa. what I mean by that is I get 02 correction in 18 to 25% from 38 up.

Also if I am in the 2000rpm cells and push the pedal more I move up the kpa in 2000rpm and get worse studder and or a backfire through the tb.

I have all aeromotive fuel system as far as filters and pump with an aeromotive regulator.

I have the regulator mounted on the inner fender and then to the fuel rail. It is a return system with 46-48 pound setting.

I had 30lb. injectors and changed them about three months ago getting ready for nitrous.

 

[RickWI]

Did it do this with the 30lb injectiors?

 

[Ricky Trussell]

Yes it did do it with the 30lb.

I was wondering about my fuel pressure reading. I have a liquid gauge connected to the regulator, I was told this was right. Is this okay or does the regulator have to be on the rail to be accurate??

Also what does the map AE decay rate do as far as raising or lowering the setting.

I went into the AE VS TPS position and went to 100% at 29 tps then tapered down because it also studders during accelaration in the 2000rpm cells at 29 tps. that made no change.

I drove again this morning and with the settings interloped on the 1750 - 2000 - 2400, the 02 is correcting 18% at 38kpa, 22% at 44kpa, and 23-24% at 50 and 56kpa. in the 2000rpm cells the other cells +- .8 - 1.5

67 85 74
65 80 71
65 78 67

My cruise kpa is 38kpa about 60mph. 48 kpa is 65 or 70mph
I went in and added 15% and 20% to the VE table in the 38 cell and the 44kpa cell and come in to eat lunch.

 

[RickWI]

Well hate to tell you RIcky but I'm stumped. About the only thing I can think of is to verify your TPS is reading properly and that at those stumble points make sure the TPS position is above 24. If the TPS is bad and the computer thinks you are at an idle that could be the problem. The only reason I say this is in some of the examples you gave it appears to be under a very light load and very high vacuum condition. Which makes me think you are giving it very little gas. Even so, that TSP start position is odd to me as I usually have no problem setting them at 12. Just for giggles I'd call whoever you got the TB from (Accel?) and ask them about it. Maybe others would have some additional thoughts on this. That start postion just makes for a odd AE map in my mind. I am sure Craig could enlighten us/me on this.

The AE deacy rate is the value used to take out the fuel for MAP AE. The bigger the number the faster it is taken out. Yours was at 96 if I remember and that should be close. You could try to lower it and see if that allows you to drive through the stumble. Otherwise my only other suggestion is to give the engine what it wants and drive drive on.

I don't suspect any problems with your fuel pressure.

 

[bobc455]

Rick,

What happens to the injector DC %? I am curious that if you log the RPM, DC%, TPS, MAP, etc., what happens to the injector DC as you go through that range.

I think you can also log total correction (Grs corr %), see what that is doing- if the total correction is moving around, maybe you can figure out what is making it move (batt corr%, CTS corr %, etc.).

-Bob Cunningham
bobc@gnttype.org

 

[Ricky Trussell]

I have logs that I just run. I will email them.

 

[Chuck Leeper]

TPS??

I went back thru the posts and don't see where the tps was changed out. Could be a dead spot in the sweep windings, and the ECM gets a low voltage. It's thinking the engine has gone to idle, and the fuel is cut back??? Thus the lean spot....
[Just thinking out loud.] Kinda strange that the TPS can't be lower than 22%....
I'd check the sw. w/ an analog VOM, so you can see the needle fluctuate if there's a dead spot.


Back under my rock....

 

[RickWI]

Exactly, TPS

 

[Ricky Trussell]

I will check the tps ---- when I figure out how. I do have a vom.

Just checking, should my throttle follower be set at 23 -24 tps since this is as low as the tps will go. That is what I have it set at.

I am running a 700r4 and 3.70 gears, 2500stall
Also if there is a big change in map ( after shift ) should I maybe put alot of map ae at 29 tps%.

I know this won't solve the steady 2000 problem it seems like a high load issue after the shift.

Out to check the tps now.

 

[bobc455]

Why would TPS cause that much of a problem, unless he is running in Alpha-N?

Did I miss something- where did he say the TPS can't be lower than 22%? Even if that were true, why would that affect mid throttle performance (speed density only cares about TPS for AE when driving, right?)

I'm missing something in your thinking, Chuck & Rick...

-Bob C.

 

[RickWI]

Initial thought was this. If the TPS was not working then as he pressed down on the gas the sesor would still tell the computer that he was at idle. This was not the case as Ricky said the TPS is at 31 under the coditions he has the problem. Second, if the sensor has a dead spot in it than it would not sense movement for AE enrichment. This may be the case as all throughout the rev range he has problems in it is at 31. Third, having the sensor start point basically at the midpoint of the AE graph range reduces the resolution and flexibility for mapping. To me this just makes it that much harder to get things dialed in correctly. Fourth, if the AE mapping is not compensated to the right on the graph then AE enrichment is going to be very lean. Typically by 24-30 TPS position you are cutting out quite a bit of AE enrichment on a standard/typical map, which he was. By 50% your basically all done, which his was.

To me you rough out the basic fueling and ignition so that the typical engine will run. Maybe not great by any means but run. If extremely large variations need to be made, like going from a 50 VE in one cell to a 95 Ve in the next at a low load mid RPM range and it is an N/A motor that just make no sense whatsoever. So, my thoughts are to always put things where the "should" be, like the TPS position for instance and the smoothing of the fuel and spark maps. Then diagnose what the real problem is that is going on. Of course that is always the hard part. But the bottom line is this motor does not require that much fueling in those operation ranges. So something else goofed up. Having the programming all goofed up on top of it will prevent anone from ever finding it.

My gut says to verify sensors, wiring, ground loops, fuel pressure is always worth checking but seems unlikely since WFO it operates fine, but ya never know. Some kind of glitch in the regulator. Of course all this is easy to check when your in the shop looking at it first hand. Just hard to do it via the internet.

Kind of like today, your typical street stock racer is bitchin the new motor had a bad miss and runs like crap. Thinks the cam is flat, yeah the new one. Ya look at the obvious stuff like the ratty distributor that he never wants to replace. Ya bolt it into the dist. machine start spinning it and the shaft is bent and worn, the bushings are out of it, the weights stick like super glue, and it only has 10 degrees of advance. ON top of that each cylinder is firing different. In 10 minutes your done and throw the crap part in his face and tell him to pony up to the bar for a new distributor, and no you won't wpend twice as much money rebushing it and tig'in the weights. Over the internet the cause of the problem would be everything from a broken sparkplug to a bad valve to a flat cam. It's just so much easier with a problem like Ricky has to see, hear, feel, and smell the problem.

 

[bobc455]

Chuck sent me a copy of Rick's .gct and logs. I couldn't read the logs.

Anyhow, I agree there are a few things I would change a bit- I might taper off the AE% vs. TPS position faster also, but I still don't think that is his problem.

If it shows on the log, I am curious what happens to the DC% as the RPM climbs through the 2000 RPM range (with the O2 correction off). Does the injector DC stay fairly constant (indicating an engine / injector / airflow problem) or is the DC dropping off for some reason (indicating a problem in the software side of things somewhere)?

Still befuddled...

-Bob
(p.s. RickWI, I hope you don't think I was criticizing or something)