Is this an injector offset issue?
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Is this an injector offset issue?
Got the SVO 42#s in and running fine at idle. IFR was scaled stock * 183%. Anyway, at idle and under throttle, the Ltrims are great... right around -1 to 0%, however under deceleration (zero throttle), the LTrims climb to right around +18% and gradually fall.
Does this sound like an injector offset issue or could it be that my BOV is not working properly and is not bleeding off boost fast enough, after coming out of the throttle (including light throttle).
Does this sound like an injector offset issue or could it be that my BOV is not working properly and is not bleeding off boost fast enough, after coming out of the throttle (including light throttle).
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Re: Is this an injector offset issue?
More like a "what do I calculate, when I have
squat for airflow and high RPM?" issue. I'd say
fuggedaboudit.
An injector imbalance will not cause a total
LTFT error, rather, the car will run poorly
with a nominally-good LTFT (7 cylinders rich,
one lean, average OK, nobody happy).
I would try for LTFT a little more negative, like
-5%, just for some "fuel margin" and tip-in
reserve. But that's just personal notion.
squat for airflow and high RPM?" issue. I'd say
fuggedaboudit.
An injector imbalance will not cause a total
LTFT error, rather, the car will run poorly
with a nominally-good LTFT (7 cylinders rich,
one lean, average OK, nobody happy).
I would try for LTFT a little more negative, like
-5%, just for some "fuel margin" and tip-in
reserve. But that's just personal notion.
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Re: Is this an injector offset issue?
Does not sound like an issue at all. If you are at WOT and suddenly close the throttle blade you afr ratio is going to go way lean. I get 20:1 afr (probably worse but wideband only reads to 20) when you are on it big time then suddenly close the throttle. This happens because you go from a high load to essentially no load.
If you had an injector offset problem you would probably only see it at idle. If you blip the throttle from idle and let off the afr will drop drastically say 12-13:1 because you essentially get puddling.
Gary
If you had an injector offset problem you would probably only see it at idle. If you blip the throttle from idle and let off the afr will drop drastically say 12-13:1 because you essentially get puddling.
Gary
#4
Re: Is this an injector offset issue?
I'm running most of Mike00FRC's LS1 edit file (IFR x 200%)and am having the same problem. I would not say forgetoutit because I am getting major bucking off the throttle. If I accellerate to 2000 then let off the bucking begins about 1500 and ltft's go to 20. Here is my log
200 175
cell 0: -0.78 0.00
cell 1: 4.69 3.91 5.47 3.12
cell 2: 16.41 16.41 -3.91 -6.25
cell 3: 0.00 -1.56 -5.47 -6.25
cell 4: 0.00 0.00 -1.56 -3.91
cell 5: -1.56 -1.56 -1.56 -3.91
cell 6: -2.34 -6.25 -1.56 -3.91
cell 7: -2.34 -2.34 -1.56 -3.91
cell 8: -2.34 -2.34 -3.91 -2.34
cell 9: -5.47 -3.91 -3.91 -2.34
cell 10: -6.25 -5.47 -3.91 -2.34
cell 11: -4.69 -2.34 -4.69 -5.47
cell 12: -0.00 -0.78 no
cell 13: -4.69 -3.91 no
cell 14: -4.69 -3.91 -4.69 -5.47
cell 15: -6.25 -5.47 -9.37 -8.59
cell 16: no data no
cell 17: no data no
cell 18: no data no
cell 19: -0.78 -1.56 -6.25 -5.47
cell 20: 0.00 0.00 -1.56 -1.56
cell 21: 19.53 19.53 10.16 7.81
cell 22: -4.69 -3.91 -3.12 -3.91
cell 23: no data no
cell 24: no data no
Does someone know what these numbers mean and where to correct them?
200 175
cell 0: -0.78 0.00
cell 1: 4.69 3.91 5.47 3.12
cell 2: 16.41 16.41 -3.91 -6.25
cell 3: 0.00 -1.56 -5.47 -6.25
cell 4: 0.00 0.00 -1.56 -3.91
cell 5: -1.56 -1.56 -1.56 -3.91
cell 6: -2.34 -6.25 -1.56 -3.91
cell 7: -2.34 -2.34 -1.56 -3.91
cell 8: -2.34 -2.34 -3.91 -2.34
cell 9: -5.47 -3.91 -3.91 -2.34
cell 10: -6.25 -5.47 -3.91 -2.34
cell 11: -4.69 -2.34 -4.69 -5.47
cell 12: -0.00 -0.78 no
cell 13: -4.69 -3.91 no
cell 14: -4.69 -3.91 -4.69 -5.47
cell 15: -6.25 -5.47 -9.37 -8.59
cell 16: no data no
cell 17: no data no
cell 18: no data no
cell 19: -0.78 -1.56 -6.25 -5.47
cell 20: 0.00 0.00 -1.56 -1.56
cell 21: 19.53 19.53 10.16 7.81
cell 22: -4.69 -3.91 -3.12 -3.91
cell 23: no data no
cell 24: no data no
Does someone know what these numbers mean and where to correct them?
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Re: Is this an injector offset issue?
Brain Drain,
I'm also getting some bucking at light throttle around 2000rpms, but now I'm starting to think that it may just be an inherant problem with having a SC. Under the conditions that I'm getting the bucking, I'm wondering if its right near a neutral boost condition... sort of a zero boost/zero vacuum. Could this cause sort of a flutter in the BOV, where it doesnt want to stay in either the open or closed position?
Also, I ended up re-flashing it with a lower IFR percentage. Went from the 183% to 172%. With the 183 I was a little too lean and started getting some positive LTerms at WOT after letting the PCM learn a bit.
Let me know how it goes at MCR
I'm also getting some bucking at light throttle around 2000rpms, but now I'm starting to think that it may just be an inherant problem with having a SC. Under the conditions that I'm getting the bucking, I'm wondering if its right near a neutral boost condition... sort of a zero boost/zero vacuum. Could this cause sort of a flutter in the BOV, where it doesnt want to stay in either the open or closed position?
Also, I ended up re-flashing it with a lower IFR percentage. Went from the 183% to 172%. With the 183 I was a little too lean and started getting some positive LTerms at WOT after letting the PCM learn a bit.
Let me know how it goes at MCR
#6
Re: Is this an injector offset issue?
I tried 175% first to get a -10% ltft
then 180% for -9%
then 200% for -1
and 210% for +1
these are for cruising at about 62mph - 18-20% TPC
what are your ltft at cruising?
Just got off the phone with MC Racing - their race car blew up and they are too busy repairing it to get me in for another week and a half. They did say however they the bucking will not occur in a properly tuned car.
then 180% for -9%
then 200% for -1
and 210% for +1
these are for cruising at about 62mph - 18-20% TPC
what are your ltft at cruising?
Just got off the phone with MC Racing - their race car blew up and they are too busy repairing it to get me in for another week and a half. They did say however they the bucking will not occur in a properly tuned car.
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Re: Is this an injector offset issue?
If I remember correctly, I was getting anywhere from -3.x to +.08 at cruise. With the reflash at 172%, I'm going to put one or two hundred miles on it and record some normal driving.
I need to do some more checking on the bucking. Once my gauges get here things should be a little easier.
I need to do some more checking on the bucking. Once my gauges get here things should be a little easier.
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#8
Re: Is this an injector offset issue?
Heres my idea: Since we only get injector flow rate to play with then it must be the problem, I was watching my manifold pressure and I only get bucking when its between 5-9inHg. So I drove around and logged a bunch of data then speadsheeted it, converted to kpa then made a guess at where the flow rate should be. I need to run 200% at 40kpa because thats where my ltrims go slightly negative. I need less than x 175 at 10kpa because 175 still gives me +10 LTFTS. so I went something like
Kpa_-%_____X%
0___28_____172%
5___28_____172%
10__28_____172%
15__21_____179%
20__14_____186%
25__10.5___189.5%
30__7______193%
35__3.5____196.5%
40__0______200%
45__0______200%...
Ifrs are a little wacky but still within tolerances. Bucking is down. I think if I work on my curve a bit it will be better plus I still need lower values for 0 - 15 kpa
I still think someone somewhere had 42# injectors and know how to fix this problem...
Kpa_-%_____X%
0___28_____172%
5___28_____172%
10__28_____172%
15__21_____179%
20__14_____186%
25__10.5___189.5%
30__7______193%
35__3.5____196.5%
40__0______200%
45__0______200%...
Ifrs are a little wacky but still within tolerances. Bucking is down. I think if I work on my curve a bit it will be better plus I still need lower values for 0 - 15 kpa
I still think someone somewhere had 42# injectors and know how to fix this problem...
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Re: Is this an injector offset issue?
The LTerms sounds like your bypass valve isn't 'passing' all of the boost back to your inlet..... not a big deal unless you decide to up your boost, then it could become a 'keep hose clamps on' problem.
The bucking is from improper tuning. My recommendation would be to try and richen up the car at the point in which you are getting the bucking. You can do this by kicking the car to WOT earlier, or playing with the VE tables.
Good Luck
The bucking is from improper tuning. My recommendation would be to try and richen up the car at the point in which you are getting the bucking. You can do this by kicking the car to WOT earlier, or playing with the VE tables.
Good Luck
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Re: Is this an injector offset issue?
Thanks,
At 172 across the board, I'm still getting some positive LTerms in the part-load cells, although the average is negative. I'm going to try to step it down a few percent... probably to 168 and give it another go. I havent stated to tune the PE or VE tables yet. Once I get the IFRs nailed down, I'll work on that. Between the cam and sc, I'm still having some surging at idle and at 2000, in addition to the hot starts problem. One thing at a time.
Nogo,
Thanks for the info, but both Brain Drain and I are running a Bosch BOV which vents to the atmosphere. I plan to drop the VE 400-1200 to take care of the problems from the cam, but which way should I go in the 1500-2200 area? (EDITED) Got it, need to increase the VE tables in this area.
Thanks,
At 172 across the board, I'm still getting some positive LTerms in the part-load cells, although the average is negative. I'm going to try to step it down a few percent... probably to 168 and give it another go. I havent stated to tune the PE or VE tables yet. Once I get the IFRs nailed down, I'll work on that. Between the cam and sc, I'm still having some surging at idle and at 2000, in addition to the hot starts problem. One thing at a time.
Nogo,
Thanks for the info, but both Brain Drain and I are running a Bosch BOV which vents to the atmosphere. I plan to drop the VE 400-1200 to take care of the problems from the cam, but which way should I go in the 1500-2200 area? (EDITED) Got it, need to increase the VE tables in this area.
Thanks,
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Re: Is this an injector offset issue?
Kevin- Which way do you multiply to richen or lean the fuel curve in the VE tables? Really appreciate you guys sharing info on the tuning...TIA -jason
#12
Re: Is this an injector offset issue?
stock car 98' ltfts
Cell 0: no data
cell 1: error
cell 2: error
cell 3: no data
cell 4: error
cell 5: -7.81 -7.81
cell 6: -7.81 -9.37
cell 7: no data
cell 8: -0.78 +1.56
cell 9: -1.56 -2.34
cell10: -4.69 -5.47
cell11: -0.78 -0.78
cell12: no data
cell13: no data
cell14: -1.56 -1.56
cell15: no data
cell16: no data
cell17: no data
cell18: -5.47 -5.47
cell19: no data
cell20: -1.56 -1.56
cell21: -1.56 -1.56
cell22: -6.25 -6.25
cell23: no data
cell24: no data
avg -6.14 -6.36
Cell 0: no data
cell 1: error
cell 2: error
cell 3: no data
cell 4: error
cell 5: -7.81 -7.81
cell 6: -7.81 -9.37
cell 7: no data
cell 8: -0.78 +1.56
cell 9: -1.56 -2.34
cell10: -4.69 -5.47
cell11: -0.78 -0.78
cell12: no data
cell13: no data
cell14: -1.56 -1.56
cell15: no data
cell16: no data
cell17: no data
cell18: -5.47 -5.47
cell19: no data
cell20: -1.56 -1.56
cell21: -1.56 -1.56
cell22: -6.25 -6.25
cell23: no data
cell24: no data
avg -6.14 -6.36
#13
Re: Is this an injector offset issue?
The LTerms sounds like your bypass valve isn't 'passing' all of the boost back to your inlet..... not a big deal unless you decide to up your boost, then it could become a 'keep hose clamps on' problem.
The bucking is from improper tuning. My recommendation would be to try and richen up the car at the point in which you are getting the bucking. You can do this by kicking the car to WOT earlier, or playing with the VE tables.
Good Luck
Good Luck
I am dumping my %variable IFR tables for a straight one again... I'm guessing the problem lies elsewhere. It was worth a shot.
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Re: Is this an injector offset issue?
The Bypass valve was just a stab. If you both are running aftermarket bypasses, then most likely that isn't an issue.
As far as the bucking, here is something you could try to determine if it is a supercharger related problem. Just disconnect your supercharger discharge tube from the rest of the system (assuming you have a blow through MAF and not a suck through). Take the car for a quick spin (mind you won't be using an air filter for a few minutes) and see if you can get the car to buck. If the car bucks try logging MAP, MAF, Ignition Advance, KR, LTrim, and IPW. What you are looking for is an abrupt change or spike in either the MAP, MAF, Ignition Advance, or IPW during the bucking to point you in the right direction.
If your car doesn't buck with the hosing off, then you know it is a supercharger related problem. And if it is a supercharger related problem most likely it is messing with either the MAP sensor, or the MAF sensor. I would try logging these two perameters and check for spiking during the bucking to point you in the right direction.
Just a suggestion.
Good Luck.
As far as the bucking, here is something you could try to determine if it is a supercharger related problem. Just disconnect your supercharger discharge tube from the rest of the system (assuming you have a blow through MAF and not a suck through). Take the car for a quick spin (mind you won't be using an air filter for a few minutes) and see if you can get the car to buck. If the car bucks try logging MAP, MAF, Ignition Advance, KR, LTrim, and IPW. What you are looking for is an abrupt change or spike in either the MAP, MAF, Ignition Advance, or IPW during the bucking to point you in the right direction.
If your car doesn't buck with the hosing off, then you know it is a supercharger related problem. And if it is a supercharger related problem most likely it is messing with either the MAP sensor, or the MAF sensor. I would try logging these two perameters and check for spiking during the bucking to point you in the right direction.
Just a suggestion.
Good Luck.