96 240sx Idle / Run / Fuel Problems

[slc240sxse]

Hi everyone, thank you for your advise and help in advance.

I have a 96 240sx se, automatic, with 138k on it. I have been experiencing some very strange problems with my car's operation. About 1 and a half months ago, I went out to start the car, nothing. Further research indicated that the fuel pump was not functioning. I removed the fuel pump, jumpered it on the battery to see if it was truly dead. It was not. I then reinstalled the fuel pump into the tank, drove it down to a friend's shop, and sure enough it was dead again. From that point I went to Checker Autoparts, and purchased a new fuel pump. I installed the new fuel pump, and it seemed to operate correctly again. Well, about a week ago, the car started running terribly, with the idle dropping down, and sometines killing the engine. At the same time the car started blowing a great deal of white smoke from the tailpipe, it also started doing this starting out from stoplights. Gas mileage also became horrible. So, 2 days ago, I go out, ready for work, and sure enough the new fuel pump is dead. Nothing. I smacked the top of the unit a few times (not too hard) with a large screwdriver, and up she fired. I replaced the fuel pump again (lifetime waranty) yesterday, the car seemed to be running fine. Not so unfortunately. Once again, the car has a terrible idle at times, and dies. It is quite intermittent, and the vehicle seems to run better when it isnt so hot outside. I don't however see any white smoke this time though. Today, I drove over to the Nissan dealer, and purchased a new Fuel Pump Relay. The car as of now hasnt died again, but the idle will bounce from time to time, and prefomance is not up to par imo. The exhaust from the vehicle does not smell proper either. It doesn't smell like sulfer however, I replaced both Oxygen Sensors this past March.

I replaced the O2 Sensors after I recieved a code from the obd2 "System too Lean".

I cannot run the ac for very long without the car exhaust smelling.

I do need to replace the front main seal as it is leaking. I have cleaned the MAF off with some high content 98% i believe alcohol as best as i could. I changed the airfilter. I have a new PCV Valve, but those are a pain in the butt to get to.

Any suggestions as to what it could be? I have also replaced the fuel filter.

Any help is much much appreciated.

Thank you!

[NISTECH]

check your coolant temp sensor connector for corrosion If ok check the coolant temps resistance values make sure they are in spec.

[slc240sxse]

I'll check that for sure. Also, I tried your advice for the carb cleaner on the #4 / #3 intake runner. When i spray it back there the car idle goes down, and almost dies. Does this indicate that the gasket is faulty, and needs to be replaced?

[NISTECH]

You must of read on on the Altima. On your car it is likely the EGR base plate gasket which is also in the general area of where you sprayed.

[slc240sxse]

I took your advice, and checked the Coolant Temperature Sensor. It appeared faulty, so I replaced it. That fixed the idle problems that I was experienceing. Once the car would start, it would go right to 500rpms. Now the car goes right to 1000rpms (if cold) or if warm, the car starts up, goes to about 650rpm. Throttle response is good.

I am still having the intermittent problems with the car running horrible, I am still unsure as to what is causing this. What will happen, for no reason whatsoever that i can tell, the car will be running great one minute, and then the next it will be hesitating very badly, not like it is missing, just like it is bogging down. The car will eventually flood out it seems, just die. It will however start up every time, but if i don't give it gas, it will die. The car also runs very rough durring this time. It happens both in the city, and on the freeway at high (80 or so MPH) speeds. My coolant was low, so i topped it off this morning. I experienced the same problems today, however it does not appear to be blowing as much vapor or smoke out of the tail pipe when it runs horribly.

Any other ideas? Is the part that I need to replace the plenum to intake manifold gasket? Would that small of a leak, or perhaps not that small of a leak there at the intake cause my intermittent problems?

Once again, I appreciate your help, I'd take ya to sushi if i could! lol..

TY --

Damon

[NISTECH]

I'd take ya to sushi if i could! lol..

Yea you could do that if you wanted me to hurl in your lap ..lol

I can't stand that sh*t it is nasty.

I think you are still having connectivity problems with your coolant temp harness every once in awhile it see's a full cold signal and fattens up the mixture. try bending the female pins in the connector a bit better and see if that solves the intermitten problem.

[slc240sxse]

No time to write as of late. I took your advice and bent those connectors up, it doesn't seem to make much of a difference. The car is running better, but it still will start running quite bad, and dying. When it starts to run poorly, the exhaust will smell quite bad, and then the car will die. It seems to be acting like the fuel is cutting out. Any ideas?

Car seems to have very poor power when it runs bad like this, i step on the accelerator but it doesnt pick up like it should, and seems to be a bit "boggy".

Thanks again for your help!

[ShifDown96240SE]

Im no tech, but maybe theres a vacuum leak. You could also clean the EGR out. Reset you ecu after that too.

[NISTECH]

check your connections at the MAF and at each of the injectors make sure there is good contact and no corrosion in them. That year uses a newer style connector that is not usually suseptable to corrosion but give them a look any how.

[slc240sxse]

Yesterday was a big day. I decided that it was high time to start on the major work on the 240, I took the week off to get this done. I started by changing out the front main seal (the one that goes around the main damper). Well, as I started this lovely job, I decided that it would be in my best interest to bust out the power washer and clean the holy livin' crap out of the engine, and the engine underside. Easier said than done! Because this has been leaking for so very long (over a year), there was more caked on oil then I have ever seen. The alternator was basically encased in this stuff. So, 3 cans of Gunk Degreaser, and about and hour and a half later, I was ready to start pulling the radiator etc. Everything came out nicely. I also decided to replace the thermostat, as last winter the car was overheating (it was toast i believe). This time around I used Nissan parts from the dealer. Good idea. I managed to get the front main seal out, replaced it, and it appears to be leakfree. So, to get to the end of this. After fixing the front main, replacing the thermostat, and filling everything up with new fluids, the car appears to be doing well! So, a few questions Mr. Nistech: (And I know, no mention of sushi .. lol)

1. Could the alternator being caked in oil been part of my problem?

2. Due to the oil pressure not being consistant, could this been part of my problem?

3. What does the grey wire on the alternator do the one with the standard Nissan Plug? I forgot to hook it back up for a while, the lights ran dim, but the car ran fantastic. I hooked it back up, and the dropped the idle back down to about 650-700.

4. The intake (throttle body) was very encrusted in carbon, I cleaned it up with some Goofoff, and i also noticed that there is a large amount of carbon/oil buildup from the throttle body to the intake. Would it be in my best interest to pull the intake and clean it out, and if i do, what should i use?

I sincerly appreciate all of your help. For all I know, this could be just a faulty wiring harness, but at least im not leaking oil like a Harley!

slc240sxse

[NISTECH]

lets take a few steps back and recheck that place where you sprayed the carb clean and it effected your idle. I kinda skimmed through the thread and caught that did you ever address that? If not try spraying there again if it affects the idle try finding the vaccum leak in that area.

[Rhoad Racing]

hey guys.....keep this thread going. I have the exact same problem slc240 has.

here's the thread about mine:http://www.nissaninfiniticlub....+leaki believe i worded mine a little different, but the systems are very identical.

[slc240sxse]

NISTECH: "lets take a few steps back and recheck that place where you sprayed the carb clean and it effected your idle. I kinda skimmed through the thread and caught that did you ever address that?"

Well, I am finally at a loss really. I pulled the plugs, omg, what a mess. I replaced them with new NGKs from the dealer. I fear that I have a vacuum leak toward the back of the intake, under the intake. It is either the plenum gasket or its the hoses back there. Car still dies, runs like its rich, gas milege is god aweful, full tank in 250 miles! Throttle is unresponsive at times, car bogs down, seems to hit an area and power is back. Im going to run it into the dealer i think. Although i hate being defeated! =(

Any Ideas Nistech?

[180fan]

Did you replace all your vacuum hoses? It's a PITA but if you haven't done that yet, you haven't tried all your possibilities. About the carb cleaner, where exactly did you spray? Between the runner/block at runners 3 and 4?

[slc240sxse]

You are correct, I have as to yet replace my hoses. And to answer your second question, that is also correct, right between em. My knock sensor is also shot (coded) the main error code I het from the OBD is "SYSTEM TOO LEAN". Which could be a vacuum leak, or a faulty plenum gasket, correct?

Oh.. and the idle will bounce sometimes. Especially if i am runnin the AC and i toss the car into park.

[NISTECH]

It certainly sounds like a vaccum leak with all thoses symptoms. Try unplugging the Vaccum brake booster hose from the intake manifold and plug its port. see if the idle problem goes away. That hose is right there in the back.

[slc240sxse]

Checked the booster line, seems fine. Car is doing better now for some reason, but there is still a loss of power, and car will experience idle death randomly. Exhaust still foul smelling. Gas mileage is better, but not the best. Can someone point me to an area on this site to instructions on reading ECU Codes, how to reset etc? I've never checked it for codes either. Thanks

[slc240sxse]

Well, I figured it out, found the link out on 240sx.org. It is: http://www.240sx.org/faq/artic...h.htm for those of you that needed to know as well. Just a few questions: After I replaced the coolant temp sensor, was I supposed to reset the computer? Because I didn't, to follow are the codes that I was given by the ECU:

98 - Coolant Temperature Sensor115 - A/T 3rd Signal13 - Coolant Temperature Sensor34 - Knock Sensor

I can't seem to find anything about that transmission code? Know what it is? Why would I get 2 Coolant Temperature Sensor readings? Does this mean that the new sensor that I purchased is faulty? Perhaps it is a wiring issue. What would you suggest to clean the contacts with? I purchased some electrical connector cleaner at radio shack, and I've used it, doesn't appear to have done the trick. I'll check the new sensor's resistance.

Thanks a ton, once more.

[NISTECH]

You would have needed to erase the code when you did the work prior. You should now clear the codes and drive it and see which come right back.

[slc240sxse]

So, I replaced the CTS with one from the dealer as opposed to the one that I purchased from Checker. I cleared the codes, and it ran great for a while. Now its back to the same ole stuff. Spraying carb cleaner between runners 3 and 4 still does the same thing. I managed to get the Nissan Service Manual for the car, but guess what? It's for the Japanese model! lol. I can't win sometimes.. haha.. Filled her up with some 91 octane and some cleaner, still no diff... any other ideas?

[NISTECH]

what codes came back up after you cleared it?

[slc240sxse]

Only one that came back this time was the knock sensor. 34.

[slc240sxse]

Think I figured it out. My MAF Connection is faulty. There is a short in the connection! I still however have that vac leak. As long as I stay up on the connector, she runs great now. Very Very frustrating.

[Rhoad Racing]

slc240....prior to replacing the MAF connector, did you pull it off the MAF while the car was running. If so, was there a difference in the idle? Also, did you replace the connector itself and that fixed the problem (other than the vacuum leak)?

[slc240sxse]

Definately. The car will die. I have noticed if the car starts missing, I pull over, and "Jiggle" the maf connection, applying pressure toward the connector. Once i do that, you can hear the engine start to run better. It seems that it goes into this crap mode of running, if you will, if i hit any bumps. Unfortunately for me, the roads here in Utah blow goats. lol. TY! =)

[Rhoad Racing]

lol...interesting. the symtoms of your car are very similar to mine. However, I replaced my MAF and the MAF connector but still have the problem. And the ECU is throwing a MAF codeI had a mechanic look at the vacuum lines but didn't see anything out of the ordinary. No sure if he checked the manifold though. I'm going to try the carb cleaner trick and see what I come up with.if you have any secrets regarding the matter, I would love to hear them.thanks man

[slc240sxse]

From what NISTECH said, it is a common problem. If it isn't the intake plenum, it is some of the vac lines or something under that nice hard to get to pos area there. If things go well, I plan on getting an s14 front clip, dunno yet though. As long as all the wiring is there, and everything else i need.. 3500 bucks isnt a bad deal in 1 way at all imo. Does your car loose power, lurch, and feel like it is "Surging"? (missing)

[Rhoad Racing]

yep...that's exactly how it feels. I should check the vacuum lines again huh?

[slc240sxse]

We've tried everything under the sun it seems. I'd say yes.

[NISTECH]

Rhoad If your car is throughing a code for the maf you need to check the voltages at it while its running. Battery voltage at one wire, signal input at the other, and most important here, less then .02v on the ground wire. It is throughing the cade coase it sees a bogus voltage on it.