Next Tuesday, Marc and I are going to try and dial in the General Leif on the dyno(Dynojet). I have been on the dyno before but never played with tuning on it. I have been "street" tuning after driving the car on the track(without a passenger seat, so drive, pull over, change and drive again), but it went wacko on me at the Pacific race earlier this month and didn't respond properly when I tried to lean things out. This past weekend I read the fault codes and found that it had stored an (internal?) ECM fault that may have come up during flashing, so I wonder if that had something to do with it maybe being in a limp mode? It would have turned the check engine light on if we had one.
Yes, I know, you will say ditch LH2.4. To that I say, once decently set up, it's been fine for us for the past 8 years we've been racing it!
SETUP:
-LH2.4 with an 012 MAF
-960 throttle body on a 90? adapter elbow with a B21F intake manifold with NO idle motor. [Switched to an 850 non-turbo throttle body with the 960 throttle shaft and new seals on both sides.]
-Orange 850T injectors
-B230 bottom end bored .030" over with 16V flycuts in b230F pistons
-405 head shaved .123"/3mm with mild(NO?) port work, stiffer springs, modified/opened up combustion chambers with a single groove on the larger quench pad.
-ENEM K13 camshaft
-"Stock" Elring headgasket.
-Combustion chambers were roughly measured as around 44-45CC which put our static compression ratio between 10.5:1 and 11:1 depending on what numbers I use for other information.
-Cranking compression with the K13 camshaft's intake clearances set to .015" is between 193-210psi(#4 is a bit low).
I did a track day in it a couple months ago and played around with the maps and fuel injector constants during the sessions. I got it to be pretty decent between 12.5-13:1 at WOT by the end of the day with Lambda feedback turned off. I can't hear detonation from the engine inside the car with the current engine mounts, so I put the ignition timing at what I felt was pretty safe based on what I've done in my street car and ran it without issue(both for the track day and the race).
After the track day I decided to bump up the IC1 one notch from 90 to 91, made some minor tweaks to the main fuel map and added some WOT switch fueling to try and help flatten the AFR curve for the next time we went out. I then turned on Lamdba feedback because usually these things lean out a little on me over time in my street car and then we went racing. It was too rich at WOT and would dip below 11:1 enough that the wideband wouldn't read above 4500rpm. I could at least let off the throttle and get it to start reading again, though.
For Sunday's race I dropped the IC1 back to 90 but when racing it was even richer! I couldn't get the wideband to read ANYTHING it was so rich, even at part throttle. I did NOT reset the computer after I experienced this, and later found it had a fault code suggesting an ECM or programming error(maybe for checksum?). I should have tried resetting the computer during the race to see if that would have an affect but didn't think about it. I have not since driven the car to see if it's any better. There's a possibility that something else amiss is going on, but I haven't found anything. I will try and drive it this weekend on the street to see if it's acting more like it did at the track day before going to the dyno(fingers crossed that it is!).
CURRENT PROBLEMS:
- 1. Too rich, which should be a generally easy fix.
- 2. Unstable idle once warmed up. When cold and warming up, I can gently bring the engine to an idle speed(1000-1100rpm) and it will stay right around there pretty steady. Once it's warmed up though, the AFR will cycle from 14-18:1 and the idle will bounce up and down accordingly! I have not been able to figure this out. The car has never done this before, but it has ever since we went to running the 960 MAF and throttle body. This has also been with a different B21F intake manifold and different engine than what we had run previously. I checked for a vacuum leak with brake cleaner but it was inconclusive. We should smoke test it, but otherwise I'm at a loss and open to suggestions! [There was a vacuum leak through the throttle shaft on the 960 throttle body and we replaced it with an 850 non-turbo throttle body using the 960's shaft for proper TPS clocking and put new seals on it. Problem fixed!]
GOALS:
- 1. Dial in the injector constants so the car is using most of the map. I mostly only play with Injector Constant 1 because when I've adjusted IC4 it moves where the ECU is pulling data from on the load scale.
- 2. Dial in the fuel map and WOT switch to get an even 12.5-13.0:1 or somewhere even closer in between there. Ideally I think I want to be around 12.8-13:1 for decent fuel mileage.
- 3. Play with camshaft timing to see where it likes it best for power between 3,000-6,500rpm and see how hard it falls off above that for when we need to rev closer to 7,000.
- 4. Recheck fueling then move on to play with ignition timing. HOW?! I can easily bump up the whole map a couple notches at a time, but should I just bump little sections of the map and do a pull, listening for knock, then move onto another section of the map and check there, rinsing and repeating until I've gone through almost the whole map by 2? and then start over again?
- 5. Recheck fueling once timing is dialed in.
Any thoughts on what's going on and anything more specific about what to do when on the dyno?
Thanks in advance!
TL, DR:
- 1. We have an endurance race car running LH2.4 without an idle motor, with 960MAF and TB. What typically causes the idle AFR to bounce? [a vacuum leak! Throttle body in this circumstance, see above.]
- 2. I'm going to do my first dyno tuning session, how should I go about dialing in the ignition timing? [Dyno operator suggested dialing in the fuel first, then drop the whole map 2 degrees and see how it responds. Read on!]
Yes, I know, you will say ditch LH2.4. To that I say, once decently set up, it's been fine for us for the past 8 years we've been racing it!
SETUP:
-LH2.4 with an 012 MAF
-960 throttle body on a 90? adapter elbow with a B21F intake manifold with NO idle motor. [Switched to an 850 non-turbo throttle body with the 960 throttle shaft and new seals on both sides.]
-Orange 850T injectors
-B230 bottom end bored .030" over with 16V flycuts in b230F pistons
-405 head shaved .123"/3mm with mild(NO?) port work, stiffer springs, modified/opened up combustion chambers with a single groove on the larger quench pad.
-ENEM K13 camshaft
-"Stock" Elring headgasket.
-Combustion chambers were roughly measured as around 44-45CC which put our static compression ratio between 10.5:1 and 11:1 depending on what numbers I use for other information.
-Cranking compression with the K13 camshaft's intake clearances set to .015" is between 193-210psi(#4 is a bit low).
I did a track day in it a couple months ago and played around with the maps and fuel injector constants during the sessions. I got it to be pretty decent between 12.5-13:1 at WOT by the end of the day with Lambda feedback turned off. I can't hear detonation from the engine inside the car with the current engine mounts, so I put the ignition timing at what I felt was pretty safe based on what I've done in my street car and ran it without issue(both for the track day and the race).
After the track day I decided to bump up the IC1 one notch from 90 to 91, made some minor tweaks to the main fuel map and added some WOT switch fueling to try and help flatten the AFR curve for the next time we went out. I then turned on Lamdba feedback because usually these things lean out a little on me over time in my street car and then we went racing. It was too rich at WOT and would dip below 11:1 enough that the wideband wouldn't read above 4500rpm. I could at least let off the throttle and get it to start reading again, though.
For Sunday's race I dropped the IC1 back to 90 but when racing it was even richer! I couldn't get the wideband to read ANYTHING it was so rich, even at part throttle. I did NOT reset the computer after I experienced this, and later found it had a fault code suggesting an ECM or programming error(maybe for checksum?). I should have tried resetting the computer during the race to see if that would have an affect but didn't think about it. I have not since driven the car to see if it's any better. There's a possibility that something else amiss is going on, but I haven't found anything. I will try and drive it this weekend on the street to see if it's acting more like it did at the track day before going to the dyno(fingers crossed that it is!).
CURRENT PROBLEMS:
- 1. Too rich, which should be a generally easy fix.
- 2. Unstable idle once warmed up. When cold and warming up, I can gently bring the engine to an idle speed(1000-1100rpm) and it will stay right around there pretty steady. Once it's warmed up though, the AFR will cycle from 14-18:1 and the idle will bounce up and down accordingly! I have not been able to figure this out. The car has never done this before, but it has ever since we went to running the 960 MAF and throttle body. This has also been with a different B21F intake manifold and different engine than what we had run previously. I checked for a vacuum leak with brake cleaner but it was inconclusive. We should smoke test it, but otherwise I'm at a loss and open to suggestions! [There was a vacuum leak through the throttle shaft on the 960 throttle body and we replaced it with an 850 non-turbo throttle body using the 960's shaft for proper TPS clocking and put new seals on it. Problem fixed!]
GOALS:
- 1. Dial in the injector constants so the car is using most of the map. I mostly only play with Injector Constant 1 because when I've adjusted IC4 it moves where the ECU is pulling data from on the load scale.
- 2. Dial in the fuel map and WOT switch to get an even 12.5-13.0:1 or somewhere even closer in between there. Ideally I think I want to be around 12.8-13:1 for decent fuel mileage.
- 3. Play with camshaft timing to see where it likes it best for power between 3,000-6,500rpm and see how hard it falls off above that for when we need to rev closer to 7,000.
- 4. Recheck fueling then move on to play with ignition timing. HOW?! I can easily bump up the whole map a couple notches at a time, but should I just bump little sections of the map and do a pull, listening for knock, then move onto another section of the map and check there, rinsing and repeating until I've gone through almost the whole map by 2? and then start over again?
- 5. Recheck fueling once timing is dialed in.
Any thoughts on what's going on and anything more specific about what to do when on the dyno?
Thanks in advance!
TL, DR:
- 1. We have an endurance race car running LH2.4 without an idle motor, with 960MAF and TB. What typically causes the idle AFR to bounce? [a vacuum leak! Throttle body in this circumstance, see above.]
- 2. I'm going to do my first dyno tuning session, how should I go about dialing in the ignition timing? [Dyno operator suggested dialing in the fuel first, then drop the whole map 2 degrees and see how it responds. Read on!]
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