1993 nissan 240sx backfiring problem - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

puerkone · 10-25-2013, 04:27 AM

So here is the story. I traded a set of racing bride seats for the complete car because the seats were too small for me. The catch was that previous owner lost control of the car and ran the car to a lake. Pretty much the entire 240sx was under water. After getting the car out of the water, I towed it to my house and car sat for 4 months on my driveway.

I finally saved up some money and decided to start fixing it. I popped the hood and the entire engine bay was full of mud. I had a spare twin cam in my garage and decided to just exchange engines since when I opened the oil cam, I saw water and mushrooms inside the valve cover. it was nasty. So I spent this week cleaning all the mud and mushrooms from the car and got the new engine in. I replaced all electronics like blower motor, relays, super hicas or abs module, put new battery and car started perfect.

Now here is the fun part. when car is cold, car drives great and idles awesome. Once car reaches operating temperature, idle starts to fluctuate and when I decelerate, car backfires loudly. Then I get check engine code 45 which is fuel injector leak. I have my other 89 240sx with ka24de and that car runs perfect. so I thought it had a bad fuel injector or oring and decided to use the fuel injectors and orings from the other car. I installed them and didn't fix anything. then I heard the maf can also cause backfiring and well I went ahead and switched them on my other car. Sadly both mafs are fine and still code 45. Then I checked fuel pressure and I have about 34 psi with vacumm connected and 40 without vacumm. I also have new spark plugs and wires. Compression is 180 in all cylinders. spark plugs are clean. timing is 20 btdc. new air filter. car is fast. I can't drive the car after it hits operating temperature because everytime i let the car idle, car backfires , dies, and have to start it again.
so I was wondering if anyone got anything else to try. would the o2 sensor or air regulator control afr while decelerating? it seems that when I decelerate, smells like unburned gasoline. this is brand new engine by the way.

rwtf · 10-25-2013, 04:41 AM

check the cts

rwtf · 10-25-2013, 04:42 AM

also, lol at stock KA being fast.

10-25-2013, 04:27 AM	#1
puerkone Join Date: Dec 2009 Location: Sacramento Age: 34 Posts: 37 Trader Rating: (1) Feedback Score: 1 reviews	1993 nissan 240sx backfiring problem So here is the story. I traded a set of racing bride seats for the complete car because the seats were too small for me. The catch was that previous owner lost control of the car and ran the car to a lake. Pretty much the entire 240sx was under water. After getting the car out of the water, I towed it to my house and car sat for 4 months on my driveway. I finally saved up some money and decided to start fixing it. I popped the hood and the entire engine bay was full of mud. I had a spare twin cam in my garage and decided to just exchange engines since when I opened the oil cam, I saw water and mushrooms inside the valve cover. it was nasty. So I spent this week cleaning all the mud and mushrooms from the car and got the new engine in. I replaced all electronics like blower motor, relays, super hicas or abs module, put new battery and car started perfect. Now here is the fun part. when car is cold, car drives great and idles awesome. Once car reaches operating temperature, idle starts to fluctuate and when I decelerate, car backfires loudly. Then I get check engine code 45 which is fuel injector leak. I have my other 89 240sx with ka24de and that car runs perfect. so I thought it had a bad fuel injector or oring and decided to use the fuel injectors and orings from the other car. I installed them and didn't fix anything. then I heard the maf can also cause backfiring and well I went ahead and switched them on my other car. Sadly both mafs are fine and still code 45. Then I checked fuel pressure and I have about 34 psi with vacumm connected and 40 without vacumm. I also have new spark plugs and wires. Compression is 180 in all cylinders. spark plugs are clean. timing is 20 btdc. new air filter. car is fast. I can't drive the car after it hits operating temperature because everytime i let the car idle, car backfires , dies, and have to start it again. so I was wondering if anyone got anything else to try. would the o2 sensor or air regulator control afr while decelerating? it seems that when I decelerate, smells like unburned gasoline. this is brand new engine by the way.

10-25-2013, 04:41 AM	#2
rwtf Zilvia Addict Join Date: Jun 2011 Location: Maryville, TN Age: 32 Posts: 830 Trader Rating: (3) Feedback Score: 3 reviews	check the cts __________________

10-25-2013, 04:42 AM	#3
rwtf Zilvia Addict Join Date: Jun 2011 Location: Maryville, TN Age: 32 Posts: 830 Trader Rating: (3) Feedback Score: 3 reviews	also, lol at stock KA being fast. __________________