Timing Getting Retarted Into Negative

nighthawklude99 · 01-06-2008, 06:57 PM

Ok so I have been trying to figuere out why my car runs like crap sometimes, but for the most part it runs great. The problem is that sometimes, and its never predictable always just at random times it will bogg and cause a huge loos in power. I alwayse thought it was because it was retarding the timing and finaly tonight I had my data logging laptop hooked up and was logging when the problem occured. When i get into any kind of boost, decel, and sometimes right when i got on it (then it would quit and run really strong, others it would continue to bog) it would pull timing all the way down to -14 at times but usualy -5 to -10. The tricky thing is that it only happens sometimes, not all the time and its never predictable. It also seems like it does it when its extreme hot (hotest days of the summer) or extreme cold (night like tonight mid to high 20's) this has been the first time it has done it since the hot summer days. What do you think could be causing this, my thoughts are knock sensor or mass. Does anyone know how I can logg knock to see if this is it? Timing is dead on 15 btc. Its really annoying, it makes my car non consistant and i cant stand that.

Thanks Jason

Car is a 1989 240sx hach w/ red top sr20det, front mount, 2.5 cold pipes, 3 hot pipes, apexi avc-r, tomei ecu(had stock sr ecu and did the same problem) 3 down pipe, 3 exhaust cutout.

PhorB13 · 01-06-2008, 07:07 PM

I'd clean the MAF if anything. Sometimes they get messed up from running rich, don't ask my why, but when they go bad, it's almost outta no where. The knock sensor, when it goes, things run like CRAP. Which is why I am wondering WHY you're car has it's moments where it's GREAT, and others when it just sucks. I'd get that checked also. Last thoughts would be getting the ECU tuned again, but that part is just a guess. Good luck bro.

nighthawklude99 · 01-06-2008, 07:53 PM

Thanks for the info. I know the computer has a good program, i got it from a guy that was running it in a similar setup as mine. What really puzzles me is that it does it in extreme cool and heat conditions. I was also kinda thinking the same thing about maybe the mass is giving a bad reading causing there to be to much or not enough fuel and activating the knok sensor.

Anyone know of a good way to logg knock, or check for it? That might further help me out.

Thanks jason

CovertRussian · 01-14-2008, 06:31 PM

Interesting, subscribing.

My knock sensor code is showing, the code is P0325. I think mine is also going bad...

I think I will be buying a new knock sensor, good thing ebay has them half priced here

DC Scotty · 01-14-2008, 11:26 PM

Ive had this problem off and on for over a year now... I have been trying to isolate the cause. Replaced the knock sensor and swapped to a known good MAS..

Knock sensor will throw a CEL when going bad but not until its really bad.. The IACV/AAC or Air Regulator will also cause this problem with symptoms like a bad MAF. Ive also replaced them and only got temporary relief.. Your 15 btc timing is being maintained by the ECU... The question is::::: What input is the ECU using? and What adjustments is it making to maintain the A/F mixtures & Timing?

But my latest testing is pointing to engine temperature.. Believe it or not... The engine temperature plays an important role by the ECU in determining A/F ratios and timing.

About the same time my random problems started to occur, I changed the temperature sensor, engine coolant flush, new thermostat, new radiator hoses, new short intake mani coolant hoses and added Water Wetter to new coolant.

My engine temperature is always rather low now and the fans dont come on as much, due to the addition of water wetter. And it takes a long time for the car to warmup to normal operating temperature on cold days and my winter heater temps kinda sucks.. Note: This also have negative results on my gas mileage. I will post my findings as I change the coolant mixtures.