Start with VE or AFR table once idling?
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
Start with VE or AFR table once idling?
Another Newbie question… on the hierarchy of tuning, which table is really the best starting point once I’ve gotten my engine to idle? I started out by messing with the req_fuel and injector open time values but I’m realizing that the proper way to adjust the mixture is to adjust the VE and AFR tables and leave the req_fuel and opening time at set values. At this point the engine idles but runs way lean at any TPS value above 0% (and that’s not even under load, that’s just revving the engine in the driveway). So I assume that once I take it out on the road it would be so lean that it’s un-drivable. So, I was going to start by 1) bringing my req_fuel and injector opening time back to where they should be 2) begin to adjust my VE table to get it back to a good idle 3) continue to adjust the VE table until the AFR reading from my WB O2 sensor remains in an acceptable level over the full RPM range. But back to my original question – should I be starting with the ARF table first? Just trying to work out the order… does the VE table dictate the AFR table, vice versa, both? Thanks!
Porsche 928 track car - Chevy 350 TPI, 24 lbs injectors, mild cam, 7-pin HEI, MSIIv3.0 2.905
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Bernard Fife
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Re: Start with VE or AFR table once idling?
kccampro,
It depends.
If you are using 'Combined VE/AFR' tables (the default), then the AFR is used only for EGO feedback, and you should tune the VE table first. The AFR table is then tuned to adjust the EGO feedback as you want.
If you are using 'Separate VE and AFR' tables (the default), then the AFR is used to also calculate the fuel pulse width (as well as EGO feedback), and you should first calibrate the VE table until the EGO correction is zero at all times (i.e. the EGO reading from the wide band matches the AFR table at all rpms and loads you run). That ensures that the VE table is correct. From then on you would tune for maximum performance/efficiency/whatever using the AFR table only.
See: http://www.megamanual.com/mt29.htm#so
Lance.
It depends.
If you are using 'Combined VE/AFR' tables (the default), then the AFR is used only for EGO feedback, and you should tune the VE table first. The AFR table is then tuned to adjust the EGO feedback as you want.
If you are using 'Separate VE and AFR' tables (the default), then the AFR is used to also calculate the fuel pulse width (as well as EGO feedback), and you should first calibrate the VE table until the EGO correction is zero at all times (i.e. the EGO reading from the wide band matches the AFR table at all rpms and loads you run). That ensures that the VE table is correct. From then on you would tune for maximum performance/efficiency/whatever using the AFR table only.
See: http://www.megamanual.com/mt29.htm#so
Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it.” - George Bernard Shaw