My evo has been breaking up a bit at light load between 2000-3000 RPM for a while now and seemed to be getting worse, so I swapped new plugs in it last night. Seemed to help quite a bit, but I left work today it suddenly went to complete **** as I exited a corner at light throttle and low (4000) RPM. It started backfiring/popping/breaking up at all RPMs and at idle. Limped it to the garage and pulled the plugs but they look fine. Swapped out each of the coils with a spare but no change. I checked all couplers and intake tubes. Any ideas?

 

Pulled the valve cover and checked the timing chain. Everything appears fine; it had stretched a few weeks ago and I had to replace it. Thought maybe I dicked it up but that doesn't seem to be the case.

 

What are the plugs gapped to? When you repulled them, were they all the same gap still?

 

Plugs are gapped ~.021-.022, just checked them a sec ago

 

Fuel relay? Any codes?

 

Fuel relay seemed to be working fine. I do not have a way to pull codes ATM, still have my <!> from the timing chain stretch (need an MUT) and the S-AWC pump rebuild message.

I took everything apart a bit ago, cleaned connectors, and checked the MAF. Started it up and it was back to normal. Still have the hesitation issue from 2000-3000 that I have been trying to fix. None of the connectors appeared very corroded but who knows...

 

I had something like this back on my IX when the clutch/brake fluid was getting gross. Clutch wasn't staying fully engaged but wouldn't slip. It was triggering high knock counts which was pulling a lot of timing despite no real knock.

I figured it out after realizing it happens on the 2nd time I start my car. First drive of the day would be fine. 2nd drive (warm/warmer start) would occasionally have hesitation right after a 1-2 shift at ~2200rpm. I was able to stop it by simply putting it in neutral and pumping the clutch pedal a few times similar to when bleeding. (First I tried changing the tune but the high knock was always there, eventually I figured out it wasn't real knock.)

After pumping the clutch quickly 3-4 times, the next 1-2 shift would be fine for awhile, and I'd just pump the clutch again next time it did it. Went away *completely* after changing the clutch fluid. (I also tried bleeding first, no go)

Mine wasn't popping though so it may very well be some kind of spark problem in your case. Just try pumping the pedal a few times when stopped, then see if it still happens. If not it was a simple and free 2 minute test at the very least. Good luck man

 

Then go to just about any car-parts place and have them fetch them for you (for free).

This game of "let's try to guess the problem when a device can tell us in ten seconds" is getting old. At least, it is for me.

 

I never had a code pop up when it was doing this before. In Feburary my AWC pump went out and my timing chain stretched. I had the following codes pulled at the time:

P0012 - Camshaft position- timing over-retarded
P0134 - Heated oxygen sensor (front) circuit no activity detected
C161E
C161F

Nothing pops up when the hesitation occurs...

 

My bad.

It surprises me that no codes are being thrown. The only thing that comes to mind that would cause bucking/hesitation at part throttle and won't throw a code is the way the wastegate and CBV are controlled. It's rather annoying how a partial lift, just to get the tail to come out, can cause the car to become very upset when the wastegate and/or CBV do their fluttering thing.