Backfiring and hesitation under load

[Drain2]

Hello all! Had to create a new account and decided a new thread would work as well

I have replaced spark plugs, coils, distributors, caps, rotors. And all 3 sensors and plugs with them on the cams and crank. I had a code 31 but that was resolved with new plug for MAF

Sc400 has code 13 hesitates under load and will not rev over 2000 in neutral or it backfires through exhaust. However the engine idles perfectly fine and seems like nothing is up until revved.

Any help? Thanks!!

 

[ivan129]

Pull the plugs to see if you can identify a bad plug / cylinder not firing correctly. Also do a comp test. You might have a sticky / stuck valve. A misfire when you rev the engine is a sign of 1 or more cylinders not firing due to spark or being lean. A valve stuck partially open will cause this.

 

[Drain2]

Already tried replacing with new plugs, it helped but didn’t solve the backfiring. I will do the comp test but the valves should be good as I just got the heads serviced. I think it is a fuel delivery issue. Occasionally when I start the car it takes multiple seconds to crank as the idle slowly revs back up to notmal

 

[P Bateman]

Code13 with log when the crank signal drops out (even momentarily) or when the logical pulse count from NE, G1/G2 is out.
When you clear the code, does it reappear immediately?

What has happened with the vehicle in the immediate days before this fault occurred?
How long ago did you have the heads serviced? Has there been any other work done recently?

Having replaced almost the entire ignition system and the sensors, if you still have a Code13 then I would suspect wiring.
I would start with resistance+wiggle tests on all sensor wires back to the ECU.

 

[Drain2]

Code13 with log when the crank signal drops out (even momentarily) or when the logical pulse count from NE, G1/G2 is out.
When you clear the code, does it reappear immediately?

What has happened with the vehicle in the immediate days before this fault occurred?
How long ago did you have the heads serviced? Has there been any other work done recently?

Having replaced almost the entire ignition system and the sensors, if you still have a Code13 then I would suspect wiring.
I would start with resistance+wiggle tests on all sensor wires back to the ECU.

The heads were serviced pretty recently I just got the whole engine put back together and have had it started and drove a couple times, albeit with the code 13 the car still started.

Code 13 appeared initially after rebuilding engine then went away as I replaced most of the ignition system. Then it came back

The code would re-appear immediately even after disconnecting battery or efi fuse. Today I got a setup for a fuel pressure test ready but then the car wouldn’t start, still had the code 13 so I cleaned up the crank sensor and now that code is gone, along with both sub o2 sensor codes. However now I have a code 12 and only 12