Dcrasta

restricter pill in boost line to boost sensor?? - Grounding of injectors?

88rxn/a

iTrader: (6)

check the boost today, im getting around 3 LBS. then it hesitates (3K ) then the boost increase to about 5 LBS. and stays there until the secondaries come on...then it boosts and runs fine...all the way to 14LBS. of boost....

now that I think about it...im using the N/A pressure sensor line which makes me wonder? would that make a difference? is the TII pill the same as a N/A?

88rxn/a

iTrader: (6)

im sure all the other TII's that have this problem have the TII boost senor pill/line though??

IDK!!! LOL

turbo2ltr

iTrader: (1)

The majority of the people having this hesitation issue seem to be NA conversions..

88rxn/a

iTrader: (6)

i really think im the only N/A conversion..erik is using N/A rotors in a TII hosing but the rest (I THINK) are TII's??

winter39

Mine is a TII with original engine...no emmisions removed at this point. I still need to check the TPS this weekend if I get lucky. I would like to check that sooner then later but my wife and 3 kids are keeping me away from my 10 minutes a month with my car...lol. Oh the married life!

Henrik

One other thing that seems to be in common is that you're all 88's and as such need to run external resistors for the 720's. So a theory:
Digging through some of the posts, I see that 88rxn/a and eriksseven are using 10
ohm resistors. In an 87 model, the resistors are 5-7 ohms so your running a fair bit
more resistance than people with 87's are. On my 87, my resistor block measures
at 6.4 ohms. My injectors measure at 2.5 ohms. So in total, the ECU in my car, like
other 87's will see 8.9 ohms. You'll be seeing 12.5 or so. Higher resistance will
mean less current which will mean slower opening times. It may only be a fraction of
a ms but at light throttle at cutover to secondaries the pulsewidths will be very low
already. At higher rpms and/or heavy throttle the pulsewidths are much longer and
a fraction of a ms will be much less significant, if at all. Could one or more of you try
running 5-7 ohms (you can put two 10ohm in parallel to get 5).

One thing that doesn't fit is the reports of hesitation a 3000rpm. At this rpm range, the
1.7 will operate exactly as a stock N332 ECU and on primaries only.

-Henrik

88rxn/a

iTrader: (6)

thats what has me stumped as you say nothing was altered with the primaries?
but my secondaries are fine.....if needed i can maybe try what you are saying...now did you measure the resistance at the injector clip to get your readings?

Digi7ech

iTrader: (1)

Just to add but not blame.
I'm running the 1.7 now as well. I can't fully blame the rtek for this but the hesitation was deifntely less pronounced/existant when I had the 1.5. With my mods there could be other problems causing this so I'm not blaming rtek yet.

I do get a nasty buck/hesitation at mid to light throttle at the 3500 point.

WOT boost below that runs fine and I'll feel a bump and then it passes over and gets to normal.

I am also running 10ohm/10watt reistors on the secondaries.

88rxn/a

iTrader: (6)

yeah, def. no blame to the Rtek but from what i KNOW about the 7 this is the only thing i know left that could be the culprit....i thought it was dirty injectors (primaries) but they were cleaned before my build up (1 1/2 yeasr ago) and i havent driven really all that much....i noticed today i have the hesitation at light to mid throttle also....with still hesitation at WOT...

Henrik

Yep, below the secondary rpm threshold, its stock operation. The other thing
that confuses me is that you mentioned that it started after the weather
got warm. You sure you don't have any vac leaks?

I measured at the clip. What brand 720's is everybody using? Mine are ND.

88rxn/a

iTrader: (6)

i thought the weather had a part in it but i dont think it was because i really didnt get to drive it in colder weather......i am going to look for more VAC leaks...

i greatly app. the help and time you put into helping me!!
thanks again!
ill let ya know the outcome!

winter39

I have 720 ND injectors for my secondaries.

Digi7ech

iTrader: (1)

Mine are from TLF performance. An Ebay company.
The injectors came in a Venom injector box so I assume Venom did something to them and TLF was just a seller an not manufacturer.

Henrik

No worries. There's one thing I'de like to try if you don't find any vac leaks.
I can send you a stock N332 rom to see if there's any difference with the
3000rpm hesitation. pm me and we can work out the details.

88rxn/a

iTrader: (6)

OK, i been a little busy so i havent had time to check for the leaks but ill let ya know soon!!!
ill do it before the weekend...
thanks.

winter39

Well, I finally got around to changing my TPS and now the hesitation has changed significantly. The hesitation seems to be right about 3500RPM when the secondaris come on (I was feeling it from 3400-3600 rpm on the tach). If i cruise in that range I can feel it. Before the hesitation range was much larger. I did a diagnositc check on my car and it seems that my O2 sensor is not functioning. Here is a theory, is the hesitiation happening while I am crusing because I am in open loop (because the 02 sensor is not working). I dont feel any hesitation at all when I accellerate through this zone only while sitting in this small range. Anway, if you can shed some light here maybe I can get this thing smoothed out a bit more.
Thanks
Jeff

Henrik

At light throttle the secondaries won't be used at all. You need to have postive pressure in the manifold and be above the staging point before they will be enabled, so if you have hesitation under light throttle (ie no boost), then its not secondary injector staging. The O2 sensor could be contributing here. Try disconnecting/reconnecting the sensor a couple of times (to clean the contacts on the connector, the underhood one. I've noticed on my car that this connection looses connectivy for me sometimes, likely moisture and/or corrosion)

gxl90rx7

iTrader: (1)

sorry to bring this old thread up, but has anybody tried henrik's idea of ~6 ohm injector resistors?

Im trying to track down my staging hesitations once and for all. Heres the list of stuff ive tried:

Cleaned all engine grounds & relocated battery to bin
Regrounded ECU
Cleaned boost sensor connector
Tested TPS
New spark plugs & wires
New O2 sensor
Replaced injectors (new RC Eng, flow tested 750cc/1000cc)
Added restrictor pill in boost line (1/32" hole)
Raised staging rpm to 3800

the car drives hella nice now, lol no more jumpiness (old primaries must have been dirty or something), but the hesitation still occurs at the staging point, under 0 vacuum. Under wot, no problems at all, only under part throttle

The next thing I wanted to try is replace the 10 ohm resistors on the secondaries (primaries are high-imp) with 8ohm/20w resistors (found them at radioshack) per henrik's earlier post. Has anybody tried this, any positive results?

arghx

iTrader: (3)

I am also interested. My problem is that the car goes WAAAAY lean when I hit my secondary injector transition! I have the 1.7 . On my wideband it will go from like low 11's to 13's during transition at WOT. under part throttle boost it might hit 12's. Under WOT when the boost gets over like 10psi (I run ~12-13psi with a FMIC on stock turbo) it always goes lean until the boost falls off. I am going to try to clean and reground my boost sensor first.

I am not sure what resistors I have for my secondary injectors but I may consider changing them.

RotaryEvolution

iTrader: (30)

i think you are on the right track with the injector resistors, 10ohm's work fine if you have matched 720's but when mixing 550's with 720's they can cause a seam in the transition point.

here is a thread with some food for thought though it deals with some large gaps in the injectors it still has alot to do with injector resistance and transition point variances.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/hesitation-after-1600cc-injector-install-591282/

i suggest someone try using 3-6ohm resistors and see if it helps with the transition point seam.(only problem is these resistors are not as readily available at the 10A/10ohm resistors)

RSVampire

I have a rebuilt motor and tranny and also have 1.7 rtek.

it was also a TII so don't think I built it from an N/A or something

I have a hesitation problem when my secondaries kick on. When I'm under vacuum it doesn't hesitate, when I'm at ~0~ or around 1-3 I get a slight hesitation and if I run like 8 lbs+ it's a huge hesitation and sometimes it backfires at that RPM too.

gxl90rx7

iTrader: (1)

well im still trying to confirm if the pre-87.5 resistor packs were actually 6 ohms, i am almost positive that is what is causing the near 0 vac hesitations. waiting arghx's feedback to see if they worked..

Digi7ech

iTrader: (1)

So, I'm trying to think.
reducing the impedance should make the injectors open longer? or will it affect the duration at all and just pass too much voltage through it possibly shortening the lifespan of the injector/injector drivers?

gxl90rx7

iTrader: (1)

reducing the impedance will pass more current to the injector (and increase voltage it sees), which will shorten turn-on times. the long turn-on delays can cause hesitations, well thats the theory anyway.

the lower the impedance, the better injector response, but if the impedance is too low, it will draw too much current from the ecu, overheating its injector drivers. The question is.. how much current are the ecu's injector drivers rated for??