Low rev limiter and backfiring on KA24E

[metalmonkey47]

So I've found myself under the hood of a '90 S13 hatch that a friend just bought, and we're trying to sort out a few things. I'm likely going to be buying the drivetrain when he swaps it for a DOHC but I wanna sort some stuff out first...

 

The car will not rev past 4900... period. We've researched a little bit and a lot of people are pushing for vehicle speed sensor, but I wants some of your opinions first.

 

 

 

Second, everytime you shift, the car backfires loud like a sonovabitch and it's NOT timing related. We have no CEL diagnostic codes to go off of and I don't want to inherit stupid KA problems if I buy it..

[DISLEXICDIME]

vacuum leek ? whats the fuel pressure has the air filter been changed?

[metalmonkey47]

There was no indication of a vacuum leak, in fact we replaced all the vacuum lines to be sure. Fuel pressure is unknown and will be the next step.

[datzenmike]

Check the cap, rotor, wires, and the coil conections. Sounds electrical.

[DAT510]

clean the MAF sensor with carb cleaner

My friends turbo civic would do the same (because of boost) we just unplugged a sensor on the intake and that seemed to fix the problem temporarily...

[DISLEXICDIME]

could be a dirty injector. get some clear hose carbcleaner 2 hose clamp's a 9v battery a air fitting and a injector clip

turn the regulator on your air compressor to 45 pound's stick the clear hose over the injector feed tighten the hose clamp fill the clear hose with carb cleaner stick a air fighting on the other end hose clamp it on.

Hook the injector clip to the injector strip the wires turn on the compressor let it build to 45 pounds aim the injector a way from you and anything flammable. then tap the wire quickly (DO NOT HOLD THE WIRE TO THE BATTERY) you will damage the injector . look at the spray pattern make sure it is a nice even spray.

[nismo dr]

clean the MAF sensor with carb cleaner

 

I prefer using maf cleaner, this stuff is the business

 

 

First thing I do with old ka's (aside from basic tune) is to run a redundant ground to the maf ground wire. Remember you only need one strand of wire for the circuit to show continuity.

[DAT510]

I prefer using maf cleaner, this stuff is the business

 

 

First thing I do with old ka's (aside from basic tune) is to run a redundant ground to the maf ground wire.

 

Didn't even know that existed!

lol.

now I know

[nismo dr]

Does it still have its cat? If so it could be plugged. I know you checked vacuum lines, but did you check vacuum?

[metalmonkey47]

^^Great ideas guys! Didn't even cross my mind to look at most of that. We're gonna run some 8 gauge grounds from dizzy pedstal to chassis and around the motor to chassis to see if it helps a tad.

 

It's still cat equipped, but just passed emissions with flying colors so I'm not sure if that would lead us to look at cat as a possible issue.

 

 

 

I didn't measure vacuum but that's going to be the next step from here. Compression can't be too great because it does smoke a tad bit.

[Uber Deaf One]

MAF

[JakeWard]

Usually when the MAF is acting up it does something similar, but limiting it to 2500 rpm. Easy test is to see if the condition changes with the maf disconnected.

 

Also check the BIG rubber rings that seal the injectors to the manifold. Those things like to leak and make interesting problems.

[MYTE_510]

Does this still have the stock ecu? I had an issue like this when I swapped my KA-e 5spd into my 510 and I switched ecu's and it worked just fine.

[metalmonkey47]

We think we got it. About 90% sure on this one.

 

 

Some stupid ass put 3 different injectors on it before. Surprised it ran at all. The injectors were loose on the harness and all of the clips were broken off, so we're gonna have to do some repairs to it.

 

Cyl 3 injector has a crack down the side and isn't firing 90% of the time.