Well my KA S13 hatch is bogging pretty badly. So I’ll open the throttle all the way, in 1st, 2nd, or 3rd gear and i get a lot less acceleration than a n/a ka is supposed to get. But if i open it very gradually, it gets better, but not good acceleration. When i say bogging, i mean excessive shaking from the engine and the rear end as if i weren't giving it enough gas.

So my diagnosis is that there is something wrong with the ignition system. Ignition coil, cap/rotor, spark plugs, or wires. But what I don't understand is that if i rev the motor from the throttle body under the hood, or just while I’m in neutral, there is no bogging. So it only acts up while the engine is under load. Does that mean I have a transmission problem?

 

sounds like the fuel pump...you're adding too much air and your fuel pump can't produce enough pressure to keep the mixture good. check for a clogged fuel filter, clogged FPR, or your fuel pressure (right after the pump)...and that will help you narrow it down.

 

is that consistent with the car being able to rev perfectly fine when its in neutral? < not trying to be argumentative, just trying to learn>

 

anyone have any other ideas?

 

just check your fuel pressure...thats the easiest way to rule that out. It doesn't really make sense that it will revv fine in Neutral, i can't say in all the years of working on various brands of cars that i've seen this condition, but its most closely associated with a fuel pressure problem.

 

im having the same problem too!!

 

WOW!

It seems that all S13's have this common bogging problem casue mine has it to but I have replaced:
Fuel Pump
Fuel Filter
Spark Plugs
Spark Plug wires
O2 Sensor
(Advancedautoparts.com) Coolant Temp sensor
Knock Sensor
Checked all grounds


I also did this recently to the car:
Removed Emissions
Converted to S14 dizzy,(I re-shielded some wires)

Now when I first started having the problem, I had no CEL. But I decided to check for codes anyhow. Turns out I had code 34(Knock Sensor) and 13(Coolant Temp Sensor), so I replaced those two things first and it helped a little but the bogging was still there. Now after replacing all the listed part above I'm thinking it can be the MAFS or the distributor? Those are the only two thing I can think of that could be affecting the bogging?

 

the idle on my car is nuts also. sometimes it idles great and then tonight i stalled twice while in neutral. i dont know whats up? ive had my 240 for three years now and it seems like one thing after the other.

 

Yea, after you've changed all that stuff I would stop stabbing in the dark. Take it to a pro and find out what is wrong cuz there are a million things that could be wrong with it. Just have a good mechanic diagnose it, then do the repair yourself.

 

they had a recall on the 3.4 to just replace the fuel pressure regulator to raise the fuel pressure, so the injectors wouldn't get clogged as often (thats GM for ya )...but i also sell a BG flush with that, so i don't get fucked with warranty pay. Just check your injectors...they're the best sign (if you don't have a wideband) to tell how your engine is running. DTC check is easy...if you know how to cycle the lights on the back of the ECU...just do a search if you don't know how...i don't feel like typing it all out.