Slight hesitation when boosting? S5 TII

[skillzilla]

Hey hey, new rotary owner here, and of course I am working through some bugs in the new car. Its an S5 TII with a JDM swap done fairly recently.

Basically whats going on is a slight stumble any time the car starts building boost, or less vacuum I guess. It occurs at any RPM, any gear, under load or just revving. When the car is idling it is pulling good vacuum, and I couldnt find any obvious vacuum leaks. From an idle, when the throttle is pressed, it hesitates for just a second before revving. At that point it revs freely and builds boost fine.

It also happens when driving, whether the car is in boost or vacuum, just a slight hesitation right when the throttle is pressed. I'm no expert, but it seems like the car is running rich and the excess fuel is causing the hesitation, once it burns off the excess it runs fine.

Possibly related, the car doesnt like to idle when the throttle is lifted, it wants to stall out almost like a car with an atmospheric BOV would. I dont have much rotary experience at all but these two problem seem textbook for a boost leak, although I havent found anything yet. The car has the IACV, air pump, and BAC removed so that could definitely play a part also Im sure.


Anyways, just looking for ideas, I bought this car mainly to learn more about rotaries and its helping so far

[David88vert]

Clean out the BAC, set the TPS. Check the grounding of the computer and the battery.

Go to teamfc3s.org and learn more.....

[skillzilla]

Read my post BAC is removed.

I regrounded the main ECU ground and the firewall ground, and checked all the other major grounds in the engine bay. They are all good. TPS was checked but I am checking it again tomorrow, I used the multimeter method before and am going to try the LED light method now. Also going to change plugs and re-time it. I'll let you know.

[skillzilla]

Bump, no ideas?

[Spektrewing386]

definitley check out your ignition components. I sorta had the same problem with my mr2. would be super super slow even when my foot was planted, then about 4 seconds later it would take off like a rocket. I think it was either a boost leak that I couldnt find or some sort of grounding issue. I couldnt figure it out and wasnt passing emissions from it.... and it was frusterating... so look my sig and thats what im hoping will solve it.

Anyway, new ignition components can only help.

[David88vert]

Either something is sticking a little (like the AFM), or ignition. I lean towards the ignition at this point. Is everything on the ignition side fairly new and not worn out (plugs, wires, etc)?

[Five*Star*]

Im with David. it sounds like ignition if its not in the air metering.

[sc0rp7]

Like stated above, Check your TPS.

The BAC valve being removed will be your most likely culprit on not wanting to idle well, did it also have the dashpot on the back of the TB removed? This stops the throttle from immediately slamming shut when you let off of the throttle.

The car model and the motor model do match, correct? (S5 to S5?)

Almost all rotaries run rich on the stock ecu. If someone else did the swap, I would be sure to check and make sure the correct injectors are in the vehicle also.

Just a few tips. If you need to know how to set the TPS, ill link the FSM for ya.

- Chris