SR20DET ISSUE: Revs at low throttle, backfire/sputters under heavy throttle

[stylo1]

Let me start by saying I have searched and have not found an answer so....

K I just finished my sr swap, Its an s13 with s15 turbo, s15 injectors, rocker arm stoppers, isis intake mani, z32 maf, walbro 255 fuel pump, cx racing intercooler and bov, and an R.S Enthaly ecu tune.

THE PROBLEM: It will start and idle, and if u give light throttle it will rev all the
way, BUT under heavy throttle it will sputter and backfire and bog. pressure
tested the turbo, no boost leaks at all. IACV is good as well, and spark plugs were cleaned and re-gapped. Also assumed the maf was bad, but if u unplug the maf while running it dies, so im assuming that means its working. Now, my first step of action was emailing the company that tuned my ecu. My first guess is a bad tune, is there any way to tell? And my second step is going to a colder bkr7e plug. I have heard that might do it. ZILVIA... I NEED YOUR HELP. Please give me feedback on what you think the issue could be.
Thank you

[stylo1]

Bump, help my ass!!

[SilviaT]

Having the same issue.. Bad knock sensor at first, replaced. Bad maf, replaced. Was running in limp mode for a little bit with bad sensors until i replaced them.
Now i'm having your problem. It drove fine at first but then it started bogging under boost, cutting out. Now my idle sounds like shit but is steady at start up and had a loud backfire after i reved it..
I'm assuming our timing is off.. Check that.
Boost leak test.
Check my threads..

[NismoKnights13]

I posted pretty much the same thing. My car stops misfiring after fully wormed up. I think you should be having Heat 8 if anything for your spark plugs. I don't think any turbo car should have anything under 7. I just ordered mine, I'm getting 8. Maybe our motors are blown!?

[Phoenix4987]

Your car shouldn't die when you unplug the MAF. The ECU will detect this and go into "limp mode" and won't let you rev above 2500. But to just die? Not a good sign.

My car had similar issues, would idle fine and could rev all the way light throttle, but under wot it would misfire. Didn't matter what gear or rpm range was. But mine was fuel pump and plugs.

If you have a brand new walbro that shouldn't be an issue. Try going with the 7s. Also, what is your spark plug gap?

And yes, tuning could very well be an issue too. But try the smaller stuff before approaching something like an ECU.

[DallasTXjdm]

First things to check are the coilpacks and ECU. Try a couple of things:


Verify dizzy / coilpack (does it need timing adjustment or is it wet?)
Verify all the sparkplugs actually work (with an idle motor and disconnect coils one at a time and observe the engine reaction)
Swap out the ECU (if you have a local friend or shop that will loan you one)
Verify the wiring harness connections and ground (from the ECU to connections in the engine)
Verify your sparkplug gaps
Verify proper amperage to the fuel pump and injectors
Verify no leaks with the turbo gasket and intake manifold
Verify no boost leaks starting with the clamps on the intercooler and check all other ones

I experienced a similar issue as well but I had a bad ground on the harness plug which the pin was slightly bent and some of the other connections were loose. I did not feel like wasting my time with a faulty harness so I swapped it with a different one which resolved my issue. Hope the checklist helps.