240SX bogging/misfire/backfiring

[spcnguyen]

I can't figure out this problem. I just bought a 240SX (90 SOHC). Here's the problem. I've seached everywhere so I decided to post this up. I will PayPal $20 to the person who helps me find the correct diagnostic answer.

DRIVABILITY PROBLEM:

The car holds idle fine most of the time, but once you start driving, it'll bog out/misfire and eventually die down unless you floor the accelerator. It seems like I have a power loss somewhere in the high end range. From low to mid RPM's, the car stutters and misfires (popping noise from the exhaust). The last owner said that he had the same problem. Sometimes its better, don't know why.

transmission PROBLEM:

It's hard to shift into first and second...you actually have to go to the side a little bit. It's not grinding, it's more like it seems like the bushing is worn? Any comments? First and second is VERY hard to get into/out of, 3-5, R is normal. The shifter feels like it has a lot of slop. Pulled out the shifter with the help of a friend, the bushing is still there, but have you guys ever heard of the bottom cylinder bushing getting shaved down in diameter? Do you think a B&M shifter would rectify this problem? transmission DOES NOT GRIND THROUGH ANY GEARS.

[dkdeleon68]

the bogging sounds like your mass air flow sensor or your fuel pump, but you said it doesnt bogg if you punch it so im thinking maf or vacuum leak.

you caint go wrong with the B&M shifter.....

[spcnguyen]

CEL just popped up today finally...pulled code 33 and 45.

33: 02 sensor circuit 45: Injector leak

Code 45 is supposed to be for California models only but wth? Any ideas to diagnose this problem? I dont know why the 02 sensor circuit isn't working, the previous owner installed an AF ratio gauge and its working fine.

[InsanityInc]

All cars HAVE code 45, only CA models throw a light with the code. All cars throw a light with the O2 sensor circuit.

First, replace the o2 sensor, that won't fix your problem, and it probably broke because you have a leaky injector. Then press a screwdriver against the tops of all the injectors and against your ear at the same time. You should hear a rapid clicking noise from the injector when you do this (when the car is on). If one isn't clicking, that's your bad one. Then pull the plugs and see if any are wet with fuel or really carbon fouled (black tips). That should confirm the leaky one.

Then, pull your fuel rail off and let it sit against a towel under the hood. Turn on the fuel pump. if any fuel sprays out, then that's definitely the leaking one. Remove the injector to see if it's the Oring or the injector itself that's bad. Replace as necessary.

[spcnguyen]

thanks ill try that in a minute. but i live in texas, the car is a texas car (looked up carfax). why did a California Only code pop up?

[spcnguyen]

or would it even matter? so whatever pops up, thats the problem, regardless of what type of code?

[NISTECH]

You can get a leaking injector code if the O2 is rich biased. Meaning if the vlotage it is generating is higher then the actual oxygen content in your exhuast. The computer doesnt know the O2 has shifted and determines it has an injector leak. Now that you have an O2 code I suspect it has shifter so far the voltage has exceeded the expected spec of the ECM. The ECM has now determined the O2 took a dump. In mid range driving this could effect the drivability of the car as the ECM is cutting fuel back[leaning it out] to try and get the O2 voltage down. So there for you have lack of fuel and a lean misfire condition. When you floor it the TPS exceeds 75% of its sweep going into open loop[ no O2 fuel control] It now relies soley on the MAF for fuel input. I would start with replaceing the O2 sensorthen recheck the cars operation.

My first instinct on your trans is that shift bushing, If the bushing looked ok then my next though would be the shift rod in the transmission which has a bushing in the carrier plate between the case halfs. It could be either the rod is bent and/or that bushing has popped out of the carrier. This would require trans disassembly to repair it.

[InsanityInc]

thanks ill try that in a minute. but i live in texas, the car is a texas car (looked up carfax). why did a California Only code pop up?

It's not a california code, it just only throws a CEL on california models. Only about 3 or 4 malfunctions will actually light your CEL, the rest still have codes thrown, but you have to read them from the ECU to even know about them.