I bet your hesitation isn't at all related to the injector size. I highly doubt the 4% flow difference will cause your hesitation, it doesn't seem drastic enough. Clean/add grounds first - might save some $.

 

I agree. The stock s4 TII runs really rich in stock form. Most likely much richer than you running 750's with this set up.

 

jon88se and guys - I was looking for someone to tell me that the injectors weren't the problem. I am going to do the full blown grounding process, OEM and additional w/o changing the secondaries. Think you are right about the grounds as I had this before the Rtek 1.7 I'll report back progress and results..Thanks again.........chuckles

FYI - The remaining concern is another guy at the same tuner shop in ABQ, NM with a 87 TII got the v1.7 Rtek chip and then installed 750cc secondaries and has the same problem, 3200-3300 RPM hesitation.

 

i just sent my ECU out today!!! u guys got me itching to get it back already!!!!

btw, how long did u guys end up waiting for ur chip to get back to u from the day u sent it out?? i cant wait!!! although ill prolly have it before i get the car rolling anyway lol

 

I believe it only takes a day for them to do everything and they either send it off that same day or the next. Fast as ****!

 

cool ****! lol

 

Sorry this one got long (tired with 2 absessed teeth, antibiotics and painkillers).
Alright I promised to give an update. RotaryRX's Tommy and I built ground wires from #4 heavy insulated wire that I bought at Driver's Den, great stereo place in ABQ, NM. Put eyelet connectors on and soldered solid with propane torch (only way to go). Followed Rotary Resurrection's guide to Grounding, but didn't do the Hot wire installs. (Q: I haven't read that anyone else did the new hot leads from that guide. Should I?) Just did the grounds. Hesitation was milder throughout and almost non-existent from 1st to 2nd. Still felt and smelled like it was loading up with fuel when the 750cc secondaries came on. (Note: read another post in this thread that said he grounded the boost sensor to the firewall and hesitation was gone. So will build this ground also.
Bought some 720cc injectors off eBay and sold the 750s here on the forum. Hesitation is still the same, but the rich gas smell is gone! This led us to start thinking about what else could be causing the hesitation and why the 750s ran so rich even though as jon88se stated there was only an ~4% increase in fuel flow.
Check out the logic in this theory and tear it apart if flawed! My 10AE came stock from CA, sea level, without any hesitation or running rich. Albuquerque is close to 5k feet above sea level. Add 720 or 750 secondaries and you have less air and more fuel. That equals Rich status to me. Tommy's brother has a 87 TII that is streetported. He did the Rytek v1.7 and added the RC Eng. 750cc secondaries with hardly a hesitation at all. The streetport adds more air to offset the extra fuel. Guys in ABQ who buy or moved from Texas are having similar problems with hesitation and rich conditions. Do you think the streetport compensates for the difference in altitude and air? Or are we airheads and full of ****?

 

Check your fuel rail pressure.

 

Race teams change fuel setup acording to local, alt., day/night...etc. so I could see how a change in alt could affect the a/f ratios to an extent. To what extent I don't know though.

 

Hey Eveeeeeel-We added a good aftermarket fuel pressure regulator and gauge. It is holding a steady ~40-45 PSI. Is this what you are referring or is there another procedure to actually test the new custom machined fuel rails we installed (w/o Fuel Pulsation Damper or whatever you call the "thingy" (an ABQ term) that burns RX-7s up)?
Please educate me as I see you're online. This is kicking my *** and I'm tired of throwing money at it........thx, chuckles

 

i got my rtek a couple days ago!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! but it s stitting in my room still waitin on some warm weather and a couple more parts before i throw it all together!

 

Sometimes higher altitudes take their toll on a fuel system. Did you check your fuel pressure while driving during the conditions that produce the problem, or just at idle?

Yes, the removal of the pulsation damper could cause problems.

 

Only checked it at idle as we placed the gauge inside the engine compartment by the oil dipstick away from alot of heat. Should have thought about putting handrails on the fender to hold on and monitor the gauge while someone pulls 7k RPM, LOL! It would be like wind-flying on a 7! Right up your alley, isn't it?

Seriously, the PD removal could be contributing to the hesitation problem. I don't understand.

I also have a new Walbro 255, but didn't put it in, because of the steady high fuel pressure. Didn't think I needed it.

 

Um, I flew the aircraft while the passengers hung out the side and jumped out on ropes or in parachutes.

Can you attach a hose between the gauge and its fitting so that you can temporarily mount the gauge outside the hood while driving? Or maybe one of your friends has a hand gauge that you could attach between some existing fittings?

Fuel injectors meter fuel by time, not by weight or volume. The pulsations can cause more or less fuel to be injected during a given time interval, depending on the harmonics between the different injectors. This probably isn't your problem, but you may want to keep this in mind.

BTW, there is always a pressure figure associated with the volume flow rating of a fuel injector. For example, 720cc @ 45psi. This means that "720cc" injectors may or may not be comparable to "750cc" injectors, depending on the pressure at which each is rated. This also means that if the fuel rail pressure is higher than the fuel injector pressure rating, it is flowing more cc at 100% duty cycle than it is rated. Conversely, a lower fuel rail pressure will cause the injectors to flow a lower amount than rated.

I think you should check your fuel pressure while driving. At least that way you can eliminate it from your list of potential problems.

 

Thanks, Evil! Appreciate the constructive feedback. I will do as you suggest and get back with results

 

how do you know if your s4 is low or high impedence? is there a color to look for?

 

read the FAQ

 

Cough..Dust!. 4 year old thread..Zombie..(resurrected).

 

will the rtec1.8 work good with a s4 turbo with a bnr stage 2 ...t3/t4

 

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