Weird AFR and Lean condition on low throttle. Videos included.
I have a 1987 S4 TII. I have weird problems with AFR running lean on low throttle. Below are YouTube videos of each of the problems I am about to address, and I will have a description on each of them, followed by a summary and relevant information at the end. Grab some popcorn, may be a long read. Any insight is greatly appreciated.
https://www.rx7club.com/2nd-generati...-889547/page4/ MOD LIST
Tps/Timing As mentioned before, I have set the TPS and insured there are no dead zones. My timing could be slightly off, as I was not able to get the car to idle down to 850 at the time of setting it, but it is in the exact same spot as when the engine was removed before rebuild. Rich at WOT The car runs very rich at WOT, lower than 10 AFR, and the car is hesitant, I tuned this out with the Apexi NEO, and it runs better at WOT, 2 stage throttle pedal thing Just for future reference, what is this called, where it is lighter to press at first, then gets a bit harder. Anyway, my car does it, hope its normal. Vacuum issue I recently hooked up a smoke tester and fixed any vacuum leaks I had, the main one was because I forgot to i install the diffuser under the injectors. These issues were happening before this. Other notes The low load lean condition may have started happening at the same time my AFR gauge started acting weird on startup. I can also hear my fuel pump. If this issue is caused by my filter or pump, why would I be rich at WOT? Overall, Im confused and annoyed. The car runs well with decent power, these are just the only issues that dont make it run perfect (Except my diff that has slop, but that's for another story) |
No thoughts? The car is still going to 17 afr under light load, sometimes bucking like a mofo. Tested the afm, turned out good.
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I think (regarding the strange pedal feel) that what you're describing is the secondary butterflies. Unlike most cars the Rx7 has a primary butterfly that cracks open first, then two secondary butterflies that open when you press the pedal further. At WOT they are all completely open. So this is not unusual per se.
Regarding the AFRs, I feel like the TPS is the likely candidate since it seems to be load-related. I know you have adjusted with the resistance method, have you tried the voltage method? Personally the two-lamp method has always given me the most reliable results, but that requires a bit more setup. |
Originally Posted by WondrousBread
(Post 12523843)
I think (regarding the strange pedal feel) that what you're describing is the secondary butterflies. Unlike most cars the Rx7 has a primary butterfly that cracks open first, then two secondary butterflies that open when you press the pedal further. At WOT they are all completely open. So this is not unusual per se.
Regarding the AFRs, I feel like the TPS is the likely candidate since it seems to be load-related. I know you have adjusted with the resistance method, have you tried the voltage method? Personally the two-lamp method has always given me the most reliable results, but that requires a bit more setup. |
Originally Posted by Stussy
(Post 12523908)
Thanks for the response! I’ll try a different method, and make sure the butterfly’s are clean.
Since you have the S-AFC, can't you just add fuel at the appropriate areas of the map to fix the lean condition? At least as a temporary solution for safety. |
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