ill pop in here and add myself to the list of happenings.
3500 rpm, low throttle, near 0 boost, and my afrs go off the lean side. ive got 750cc rc engineering secondaries, and an AFC neo leaning them out, but around 3400-3600 ive got it set super high, to compensate for the lean spot.
im not much help here, but just another statistic. at least we know its a common problem.

 

if you are getting a lean spot only in transition i can bet you it is a too high of a resistance issue with the secondaries, still waiting on confirmation if running 3-6ohm resistors fixed it.

 

oh btw I forgot to add that my car is a '87 Turbo II

so it's not an '88 with the high impedance injectors


anybody got any tips?

new motor, new tranny, no vac leaks, new TID

my weird problem is that I have to "prime" the injectors. I'll get a hesitation but after it hesitates once or twice it just goes away and it's not noticable anymore.

 

Hey guys I put in the 6 ohm resistors and had some good results. A 20 minute test drive showed no hesitation, although there was perhaps still a slight lean spot according to the wideband. Maybe resistors with less than 6 ohms would improve this further, like 4 or 5 ohms.

See my thread in the second gen forums: https://www.rx7club.com/showthread.p...=1#post6687947

 

6.2 ohm, 25w resistors did not fix my hesitation. it is better, doesnt happen as often, but it is still there

 

I swapped over to 6.8ohm x10watt resistors about 2 weeks ago from 10hm by 10watt.

Did not really notice a difference but the climate has also changed so the test conditons are not the greatest.

 

Bringing this thread back. I just purchased a 1.7 from another member on the forum and am having the same problem. Using 6.2 ohm 10 watt resistors and TMS 720cc injectors, which appear to be a rochester style injector. At first I thought my problem was with the injectors since rochester injectors have absurd dead times, but it seems that people with higher quality injectors are having this problem as well. Has anyone who has had this problem find a cure for it?

 

I am pretty sure it is the injector resistors causing it. 6 ohm resistors definately helped mine, but it still happens. Your only options are to go with lower impedance resistors (3.2ohm?) and risk frying your ecu, or get a low impedance injector driver.

if all you are using is 720's, RC engineering sells a high-imp 750cc injector that is drop-in


edit: this is gxl90rx7, forgot to logout my brothers SN lol

 

I'll try different resistors, but it seems that the problem is more hardware related than anything else. Before the 1.7 I was just using a stock ecu and an SAFC to adjust for the larger injectors and had no problems.

 

Anyone with the "secondary transition stumble" please read and post your answers to this thread:
https://www.rx7club.com/rtek-forum-168/do-you-have-secondary-transition-stumble-666391/