Is this normal??? Cold ping issue.

[BaroidEngineer]

i have a '96 240SX with a KA24DE Motor. Turbocharged with a T3 turbo, 8.8:1 pistons, JWT tuned for a stock MAF and 370 injectors. Car runs fine after it is warmed up. Problem is that when it is first started up, the engine pings if I hit the gas. i have to baby the throttle until it warms up. One thing that I do notice is that the Air Fuel gauge is very sluggish while the motor is warming up. Once warmed up, the meter starts sweeping normally, the pinging stops, and the power is up to normal. Acts like the sluggish power and pinging is related directly to the O2 sensor. Is this normal? Is my O2 sensor going out? It isn't that old, maybe 8 or 9 months old. I used a Bosch generic sensor, wired in and working correctly. The TPS was recently changed, reading 0.5 ohms with the throttle closed, timing is set at ~ 18 BTDC / Idle at ~ 750 rpm. The timing seemed to minimize the ping a bit when cold. Any thoughts would be appreciated.
Thanks,
JT

[BaroidEngineer]

<laughing> Yeah, I'm scratching my head also. Seems the O2 sensor is a little more sluggish than usual when getting the motor warmed up. Don't know if replacing it will help or not. Seems to work fine after ~ 5 minutes. Thanks for all of the views. I find this place extremely helpful when researching issues with my car. You guys really know your stuff!
:bowdown:

[RedtopTech]

O2 is sluggish at idle because it needs to be warmed up before it gives accurate information. That is why All sensors now have a heater circuit. Dont trust the O2 till its warmed up. Also keep in mind that the computer doesnt even look at the sensor until it reaches closed loop so it couldnt be causing your drivability issues.

[orion::S14]

^^^ Good reply, exactl what I was goin to point out regarding the O2.

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When you set the base timing, was it on a warm motor, with the TPS unplugged? You mentioned ~750rpm, so that part is correct.

If not, then that could be your issue.

- Brian

[BaroidEngineer]

I did warm up the motor prior to setting the timing, TPS was unplugged, that all went fine. (I learn a lot here and spend more time searching for my questions than anything else. You guys are a wealth of information! Correctly setting the timing was one of them, along with where to get a FSM.) I can accept the O2 sensor having to warm up for it to work correctly. I'll just take the necessary time to let things warm up prior to heading out of the driveway. No quick runs for me! Thanks a million for your replies, they are greatly respected and appreciated. You guys have a great new year!
Regards,
JT

[F3600]

maybe your coolant temp sensor is broken, or the wiring is bad.

Did you check error codes in the ECU ?

try to use a new one its only 15$ or just test the wiring and your old sensor with your FSM.

good luck

PS: i read your post wrong .i was reading cold start issue.. anyway check your code ! it could help you find the problem.

[burnsauto]

im guessing you use high test fuel? (just thought i'd bring it up...even though you would rocking a T3..)

[BaroidEngineer]

Yeah, premium only with the occasional octane booster. I try to use Shell most of the time. Seems to be the best premium in the area. No ECU codes at present. I replaced both of the temperature sensors a while back, shouldn't be any issues there. The ECU isn't throwing any codes outside of the rear O2 sensor once in a while. Shouldn't have any bearing on the engine management from what I can tell. She runs pretty darn good most of the time. I push ~ 13 psi (it floats a bit 12-14 psi) and she runs like I stole her! I am killing my automatic! <laughing> I have a 5-speed set-up and will probably swap that out when I upgrade the turbo, injectors, ECU, etc. My goal is 300-350 everyday driving & ~ 350-400 at high boost if I can get it. Looking forward to working on her this spring, will probably use a JWT set-up, it runs a bit rich but pretty much seems to operate without too many issues. Might fine tune with a S-AFC II once I put a wideband on it. All in all, I think the care runs fine, just hate to hear the ping at start-up.
Thanks,
JT

[jkjunior]

Had basically the same problem, my timing was a bit off, i adjusted it and it seemed to help a ton. Keep us posted