240SX Need Help!

B

bilracer

New member
I have ran my 89 240 in ITA for 2 seasons with very few problems that I call "serious".
During my winter teardown, I noticed that #1 piston was actually starting to burn. I rebuilt the engine, checked everything that I could think of and started this season off.
At VIR in may I burned #1 completely through. I was having some fuel pressure problems so I changed the pump and had my injectors cleaned and blueprinted to be safe. After installing a spare engine, I went to another race last weekend and now have the same problem. The spark plugs show that the engine in NOT lean and I watched the fuel pressure very carefully - that was not the problem. Does anyone know of a distributor or ecu timing problem that exists here. ANY HELP AND INPUT WOULD BE APPRECIATED.

thanks
 
Billy, Jim please share with all of us. Thats all I need this season is a problem like that. Would love to prevent it before it happens.

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Tristan Smith
Buffalo's Southwest Cafe
ITA Nissan 240sx #56
 
Billy, The first thing is to check the TDC mark on the balancer is correct. #1 seems to be the first to go in the 3 valve when they burn pistons. I have found in the past the timing marks on the balancer to be off by as much as 5 degrees. You mentioned fuel pressure issues? Pump? Injectors? Do you run a cell or a stock tank? Also what fuel are you running? What Pistons early 89?

[This message has been edited by Joe Harlan (edited June 26, 2003).]
 
Tristan,
I shared with Billy a little personal experience resulting from a crappy wiring harness. The harnesses on these cars seem to deteriorate quickly and I didn't catch a bad injector clip on #3 prior to Sebring race a couple years ago. The clip was vibrating. At idle, it ran fine. Under race conditions and rpm, it intermittently lost contact. It expanded a piston too much and beat a rod bearing to death.

I don't know if this is Billy problem or not.

Billy,
I failed to mention that I ALWAYS run a mix of high octane race unleaded and 93 street fuel just to be safe. Bob Stretch and Doug recommended I do it, so I just listened and spend the money when it is fill up time.

Jim
ITA240 for sale
(or going back to Daytona in august)
 
Good thoughts from Jim and Joe. Thats what I need - some input!
No I can't say I have checked the TDC mark, and Jim, I've always ran 93 octane. Thats what JWT recommended for the ECU settup they gave me.
I am runing a fuel cell, with an aftermarket pump from NAPA designed to pump fuel for a fuel injection system standing alone (designed not to need a secondary in tank pump). I tried to run a bosch pump like a VW runs but they give up after awhile because they don't have a prepump. I learned that this year. I'm 95% confident (don't know if your ever 100 % sure) that I don't have a pressure problem anymore. The first time I burned a piston it was with the bosch pump. This pump is for people who put a fuel injection system on a car that was formerly a carb. model and is designed to "pull" the fuel out of the tank. The bosch pump is designed to "push" fuel because it has a prepump in the tank to deliver fuel to the pump. I've heard rumors that excessive heat will cause the distributor to go nuts. I can say that I've never had this problem when its cool weather. The only thing about this theory is why is it always #1 or #2 piston. Seems like if distributor was going faulty , it would be all cylinders. Anyway, thanks again guys! Any more thoughts are welcome. Like I said, I did not have these problems for 2 seasons - why now?(Don't misunderstand - I had other problems - just not this one)
 
Joe talk to us more about the timing mark being off, how did you check that. I have a JWT computer and it seems to produce real high advanced timing at 4000rpm. thanks for any help. dave
 
I run 100 octane unleaded. Not because I think the car needs it but purely for the "cooling" factor that all that unburnt gas can help provide. I am sure it is actually robbing me a bit of power, but again, provides just the tiniest safety factor.
Jim, what are you planning to run after you sell the 240sx?



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Tristan Smith
Buffalo's Southwest Cafe
ITA Nissan 240sx #56
 
<font face=\"Verdana, Arial\" size=\"2\">Joe talk to us more about the timing mark being off, how did you check that. I have a JWT computer and it seems to produce real high advanced timing at 4000rpm. thanks for any help. dave </font>
Click to expand...

Dave use a dial indicator to find TDC #1... Look at timing mark and make sure it lines up. I have seen these mis-marked and also the rubber in the balancer gets old and the outer ring turns.

The other thing is when using a fuel cell with out a surge tank. Could you be drawing a little air into the system from time to time in different corners. This could cause a temporary lean mixture that would not show up in the EGT or O2 sensor...If my memory is correct on the 3 valve the number 1 injector is the first inline to get fuel so any air is going to go through that injector first? Just more to think about. I know on the stock tanks you need to run them on the top side of 3/4 to keep them from drawing air on the S14's. The S14 has a knock sensor so they don't seem to burn pistons from lean but they do eat the aluminum out from behind the exhaust seats when this happens. I have 2 really nice 4 valve heads that are junk from this. We call it a lean extrude hone job
smile.gif
 
Billy, did you ever figure out what the problem was? I for one (and I'm sure I'm not the only one) would like to know if there's anything I should be watching out for.

Thanks

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Earl
ITA 240SX in process
 
So far so good. I was told that when the distributer gets hot, sometimes if causes the timing to go haywire so I put in another one. I also put a heat shield between the distributor and the header. I am running 100 octane now instead of 93. I set timing down to 13 degrees. I put new connectors on the injectors so that they can't short out. I ran at Road Atl. last week and it seemed to be ok. Time will tell I guess.
 
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