SR Problems- hesitation while cruising.

SON240sx Automotive
1

To start out, the SR runs and idles really nicely. It pulls nicely and no other complaints. It idles at 16-17 AFRs (not sure if this is normal) though and in boost its at 11-12. While in boost its good with no problems.

However, when I’m cruising at 80+ speeds, the car seems to have some sort of hesitation. It feels like some sort of hesitation like a speed/fuel cut but less abrupt. It’s more of a pulsing feel like very fast spurts of hesitation. When this happens, the wideband reads at 10 AFRs. Once I go harder on the gas it goes to 13-14 and all seems well.

I just cleaned the maf sensor but is there any other things I should be looking for?

I have a walbro fuel pump and a z32 fuel filter. Basically a stock SR setup but running at 12-13 psi.

I’m running on 94 sunoco gas.

Any help would be appreciated! Thanks

2

Forgot to mention the ECU is stock.

SR motor is an s13 redtop.

3

i have the same motor and same problem was searching but could not find anything. do you also get it coming to a stop? your ideal drops and if you try to put the gas on a little it is as if it is going to stall but give it a good amount of throtel and it is running well again?

4

have u changed the plugs

5

check for vacuum leaks…i bet its a realllly tiny leak somewhere…

6

Nope, when i come to a stop the rpms drop VERY slightly but nothing that made me concerned.

I’ve changed the plugs to ones that have around 200kms on them.

7

Cleaned the maf and ziptied any vacuum lines that weren’t tied down.

Still has the same hesitation.

When I say cruising, I mean maintaining a constant speed. Once i add a bit of gas it’s back to normal.

8

seriously i dont understand why everyone cleans there maf’s thies imported cars have verrrrry sensitive wires and the slightest bit of anything will damage them.
You really shouldnt touch your mass airflow. If anything, get your egr if you still have one cleaned out and decarb the motor…
I Know you people probably have never done this, but to pass my ka today on the dyne i poured water down the intake tube, cleaned up the valve very nicely and it passed with flying colours failing only 1 hour befor that… a clean properly working motor is your best friend

9

i know when my car did the same. my o2 sensor was messed, try unclipping yours then test drive it, see if it still acts up

10

If I unplugged the o2 sensor, that means my wideband wouldn’t read properly.

11

could be stupid like a clogged filter…

12

No no, your stock o2 sensor not your wideband. Unplug it and see if your wideband reads differently if its the same then you have a dead factory o2

13

I think I may have found the problem. When doing my SR Swap I didn’t recirculate the bov so the 3rd opening on the SMIC is completely open but I blocked off the opening on the intake side.

And yes, the car feels like it will stall at a stop. I can see the rpms drop a bit and the car shakes slightly but I never realized it since I have nismo motor mounts and thought that was the cause.