Do you have the Secondary Transition stumble?
 

There are hundreds of Rteks in the field but a handful of you are experiencing some sort of stumble at the transition point. If you are experiencing this, please answer the following questions. Please don't post anything but answers to these questions in this thread.

Rtek Version: 1.5/1.7/1.8/2.0/2.0.1
Engine conditions: hot/cold
RPM of occurance:
Load: heavy throttle, light throttle or in between (TPS factor)
Boost: high, right around 0 or other
Occurance frequency: Does it always happen
Severity: severe/mild/ barely noticable
Did the car have 3800rpm stumble before: yes/no/slightly
Did the stumble change with the Rtek: better/worse/same
What year is the car, 87/88:
Block: TII / NA
Rotors: TII / NA
Port work:
Injector size (pri/sec):
Injector Impedance (pri/sec):
Resistor blocks: no/ yes (specify value of resistors)
Other mods to car: Please list
Hesitation description: (describe the hesitation and how/when it happens)


UPDATE:
I just wanted to thank everyone for the reports. It has helped greatly in searching for the problem. Henrik is hot on the trail of the possible cause due to a bug in the original Mazda code. We hope we will be able to solve it quick and release it as part of the 2.1 update. Again, only reports in this thread please!

Rtek Version: 2.0
Engine conditions: All
RPM of occurance: 3800, stumble improved a lot when staging raised from 3500
Load: only at ~half throttle
Boost: ~0 psi
Occurance frequency: 80%
Severity: mild
Did the car have 3800rpm stumble before: yes, with rtek1.7, dont know about stock ecu
Did the stumble change with the Rtek: same with 2.0
What year is the car, 87/88: 88
Block: S4 TII
Rotors: S4 TII
Port work: stock
Injector size (pri/sec): happened on both 750/1000 and 550/720 combos
Injector Impedance (pri/sec): high/low
Resistor blocks: yes, 6.2 ohm (stumble got a little better when switching from 10 ohm)
Other mods to car: no emissions, no rats nest, 3" exhaust, cone intake, fmic, bov, boost line restrictor, slightly vertically angled AFM
Hesitation description: only happens around 0 psi, at staging point. No problems at WOT or low throttle

Rtek Version: 1.7
Engine conditions: hot & cold, more @ cold
RPM of occurance: 3500 +- 100
Load: light throttle
Boost: right around 0
Occurance frequency: Always. Can reproduce.
Severity: mild
Did the car have 3800rpm stumble before: barely slightly
Did the stumble change with the Rtek: worse
What year is the car, 87
Block: TII
Rotors: TII
Port work: none
Injector size (pri/sec): 550/720
Injector Impedance (pri/sec): Stock, low
Resistor blocks: no
Other mods to car: TID, 3" racing beat turbo back, FD alt, Blitz BOV,
Hesitation description: Light steady throttle while reaching 0 psi, engine stumbles. Mostly in 2nd and 3rd gear. According to my WB, A/F #s climb high, 15-18 :-( Once I pass 0 psi or 3600 ish A/F return to safe levels. Hard throttle A/F are fine and no stumble.

I could make a vid and sent it to you.

Rtek Version: 1.5/1.7/1.8/2.0/2.0.1: Rtek 1.7
Engine conditions: hot/cold: Both
RPM of occurrence: 3200-3500
Load: heavy throttle, light throttle or in between (TPS factor) : medium to heavy
Boost: high, right around 0 or other: right around zero or low boost
Occurrence frequency: Does it always happen: Any time the engine is under load at 3200-3500 rpms.
Severity: severe/mild/ barely noticeable: Very severe
Did the car have 3800rpm stumble before: yes/no/slightly: slightly
Did the stumble change with the Rtek: better/worse/same: worse
What year is the car, 87/88: 88
Block: TII / NA: TII Block
Rotors: TII / NA: TII Rotors
Port work: Mild street port
Injector size (pri/sec): 550/720
Injector Impedance (pri/sec): high/high
Resistor blocks: no/ yes (specify value of resistors): No

Rtek Version: 1.7
Engine conditions: Cold/initial start more often with some hot events
RPM of occurance: 3400-3600
Load: Light throttle
Boost: Right at Zero mark
Occurance frequency: Running cold more often and sometimes during 78-82mph highway cruising.
Severity: Most of the time slight but if everythign goes right it's very jumpy
Did the car have 3800rpm stumble before: Yes
Did the stumble change with the Rtek: Extreme bucking with the 1.7. My 1.5 did not have that issue.
What year is the car, 87/88: 88
Block: S4 TII
Rotors: S4 TII
Port work: None
Injector size (pri/sec): 550 High impedance
Injector Impedance (pri/sec): 720 Low impedance
Resistor blocks: two 6.8 Ohm x 10 watts
Other mods to car: Walbro fuel pump/ Aeromotive FPR 1:1 rising rate set to static psi of 38/S5 turbo running 12psi
Hesitation description:
Most often it's just a slight lag/bump. On the highway at zero vac/light throttle I have had it start to buck violently in which I either have to gun it or let off the gas to make it go away.

--------------------------------------------
I live over on deer valley and 91st ave and will be buying a 2.0 from my buddy soon. So if you need me to give you any sensor readings I can do it in a week or two.
-Corey

Rtek Version: 1.7
Engine conditions: Cold and Hot
RPM of occurance: 3200
Load: light throttle
Boost: zero or low boost
Occurance frequency: all the time unless I use heavy throttle
Severity: severe
Did the car have 3800rpm stumble before: Just a little
Did the stumble change with the Rtek: yes
What year is the car, 87/88: 88 Jspec
Block: TII
Rotors: TII
Port work: stock
Injector size (pri/sec): 550/720
Injector Impedance (pri/sec): low impedance
Resistor blocks: no
Other mods to car: RB Down/Fd pump/intake/no cat/emission removal
Hesitation description: Basically the car bucks and with the BOV vented to atmosphere and its pretty bad. Everything is fine until 3200.

Rtek Version: 2.0.1
Engine conditions: hot
RPM of occurance:3400-3800
Load: medium, tps 94%
Boost: 0-2 psi
Occurance frequency: occasional
Severity: barely noticable
Did the car have 3800rpm stumble before: i don't know
Did the stumble change with the Rtek: i don't know
What year is the car, 87
Block: TII
Rotors: TII
Port work: street port
Injector size:720 pri, 1000 sec
Injector Impedance:low,low
Resistor blocks: yes stock
Other mods to car: walbro 255, bnr stage 3 turbo
Hesitation description: an occasional loss of power at the transition point

Rtek Version: 1.7
Engine conditions: hot
RPM of occurance: Right around 3400
Load: Light throttle
Boost: Right around 0
Occurance frequency: Always happens at light throttle
Severity: Severe at light load, not noticable at hight load
Did the car have 3800rpm stumble before: No
Did the stumble change with the Rtek: yes
What year is the car, 87/88: 88
Block: TII stock S4
Rotors: TII Stock S4
Port work: Stock
Injector size (pri/sec): Stock 550 / Titan 720 (rochester)
Injector Impedance (pri/sec): low/low
Resistor blocks: Yes, 7.5 ohm 10 watt
Other mods to car: 3" DP, intake, emissions removal.
Hesitation description: (describe the hesitation and how/when it happens) Only around ~3400 RPM. A little tweaking with the TPS and got it down to a single miss when transitioning through the secondary staging. The lighter the load, the more severe the miss. WOT has no stumble. The big problem is cruising about 80 on the freeway, when the cruise control tries to accellerate up a hill it stays right at the secondary staging RPM and stumbles alot.

Rtek Version:2.0
Engine conditions: hot/cold
RPM of occurance:2800
Load: light throttle
Boost: no boost(never happens under heavy load)
Occurance frequency: about 50% of the time
Severity: mild
Did the car have 3800rpm stumble before:no
Did the stumble change with the Rtek: worse
What year is the car, 86
Block: TII
Rotors: TII
Port work: large street port on intakes and larger than rb race port for exhaust
Injector size (pri/sec):
Injector Impedance (pri/sec): 720/1000
Resistor blocks yes
Other mods to car: twin t25s,aeromotive fpr and braided fuel lines,bosch 300lph pump,aem wideband,3" exh
Hesitation description: bounces between lean and rich when cruising in and around the transition rpm

Rtek Version: 2.0
Engine conditions: hot/cold
RPM of occurance: 2-3k
Load: light throttle or in between TPS 53%-67%ish
Boost: only between 16 in hg - 5 in hg
Occurance frequency: 90% of the time but like clockwork
Severity: light bucks, but stumbles pretty good(but i always goose it or let off to avoid it)
Did the car have 3800rpm stumble before: not before the rebuild, but i have no idea now.
Did the stumble change with the Rtek: n/a
What year is the car, 87
Block: TII
Rotors: TII
Port work: kevin landers streetport so i dont know
Injector size (pri/sec):720/1000
Injector Impedance (pri/sec): low/low
Resistor blocks: yes, stock resistor box
Other mods to car: BNR 1 (s5) : Greddy Comp tube : 3"dp/full exhaust : Walboro 255 : Fmic(big) : Apex i twin chamber bov : cone filter : 2.5 piping : all emissions and rat nest removed : tb mod: battery relocation
Hesitation description: at cruising throttle my narrowband goes bouncing back and forth from low stoich to lean (i have video). its bucks and stumbles. but let off or gas it and it fixes it self

Rtek Version: 2.0
Engine conditions: hot
RPM of occurance: 2800k
Load: light throttle
Boost: No boost, hppens under high vacume
Occurance frequency: Always at 2800k on light throttle
Severity: severe/mild
Did the car have 3800rpm stumble before: yes
Did the stumble change with the Rtek: THis is whats wierd. The (very light) 3800 stumble went away, shortly after the 2800k stumble appeared IIRC.
What year is the car, 88
Block: TII
Rotors: TII
Port work: Street Port
Injector size (pri/sec): 550, 720
Injector Impedance (pri/sec): HIgh
Resistor blocks: no
Other mods to car: In Sig
Hesitation description: (describe the hesitation and how/when it happens)

It is a constant hesitation around 2800k. You can see in my log below where it ahppens.

You may remeber Turbo2ltr, I called about this many months ago. You and I had a long phone conversation about a wierd stumble I was getting. It is good to see this thread, because it gives me hope. Until today, I was still looking for the damn stumble. Today I will stop until I see more about it.
Thanks,
Chris

Rtek Version: 2.0
Engine conditions: hot
RPM of occurance: just off idle to 4k
Load:light to medium throttle
Boost: right around 0 and vacuum
Occurance frequency: only when hot
Severity: severe (i mean real bad)
Did the car have 3800rpm stumble before: no
Did the stumble change with the Rtek:worse
What year is the car, 87/88: 88
Block: s5 TII
Rotors: s5 TII
Port work: streetport
Injector size (pri/sec):720-720
Injector Impedance (pri/sec): high imp
Resistor blocks:no
Other mods to car: hybrid to4b, aftermarket manifold w/ext wg, walbro fp, greddy fmic, 3" exhaust
Hesitation description: most of the time when i try to leave off the line the rpm are hard to get up. after they are up when i start going it bucks real bad. as soon as im in boost it goes away. when the car is cold it runs PERFECT.

Rtek Version: 1.7
Engine conditions: hot/
RPM of occurance:3000 range
Load: , or in between (TPS factor)
Boost:, right around 0 or other
Occurance frequency: like the sun comes up
Severity:severe/mild/
Did the car have 3800rpm stumble before: idk
Did the stumble change with the Rtek: idk
What year is the car, 87/
Block: TII /
Rotors: TII /
Port work: none
Injector size (pri/sec):550/720
Injector Impedance (pri/sec):stock
Resistor blocks: no/ yes (specify value of resistors)none
Other mods to car: racing beat twin exhaust, gredy bov
Hesitation description: (describe the hesitation and how/when it happens)it happens like when it gets to 3800 or around there it it just stutters real bad. once it mad my car stall, but once i get to 4k or get into boost its perfect

Rtek Version: 1.7
Engine conditions: hot/cold
RPM of occurance: 3500
Load: light load
Boost: vacuum up to 0
Occurance frequency: always happens
Severity: very severe
Did the car have 3800rpm stumble before: no
Did the stumble change with the Rtek:worse
What year is the car: 87
Block: TII
Rotors: TII
Port work: none
Injector size (pri/sec):550,750
Injector Impedance (pri/sec): low
Resistor blocks: no
Other mods to car: full exhaust, intake, flywheel, all emissions removed, throttle body mod, denso high pressure fuel pump, apexi NEO
Hesitation description: when cruising right below 3500 i am not able to gently accelerate to 3600. the car bucks and shakes violentley during this transition. if going past this point at full throttle, the car is fine.

Thanks again to everyone here that helped us come up with a fix for this problem.

Upgrade!
https://www.rx7club.com/rtek-forum-168/stumble-elimination-stage-1-x-update-s4-tii-now-available-691209/

Damn, I just saw this thread, and never thought it was the Rtek stumble issue. I got the 1.7 and having exactly the same problem, I tore down and checked everything else, and haven't drove my car, since it get so lean at partial throttle and couldn't tune it out with a SAFC. I got a BNR stage 3, 720/890, Jspec S4. I was planning on getting a Haltech but now I am waiting the 2.1 coming out. Hope it will work good.