Can Trouble Codes set during cranking mode?

[dr69]

Before I get into detail of my "no start" dilemma, can any codes be set during the cranking process? The ECM is only giving me the "all systems OK" code of 55. Must the engine run for a certail amount of time before a code will set?

'95 240SX SE, manual, 110K miles

More detailed info soon....just wanted this info up front for now.

Thanks!

[PMan_S13]

pretty sure the car has to be running to throw codes

its possible it could throw some without running though.. for example, the ecu could detect if you had the ignition on and the MAF wasn't hooked up. That would through the AFM code, I believe.

What exactly is the problem? Its pretty hard to get a KA series motor not to start. I have had a motor set with 20 degree retarded timing and 40 degrees retarded valve timing (don't ask) and it still started, ran, and idled.. not to mention it still boosted itself.

The ecu is designed to let the car start in almost complete sensor failure. So I'd start looking to the mechanical settings you have. (Namely, I'd look at the ignition timing.. too advanced or too retarded and it will never start.)

Remember, if a motor has spark, fuel, air and compression... it HAS to run. Just weed out what you know you have and og from there.

[dr69]

What exactly is the problem? Remember, if a motor has spark, fuel, air and compression... it HAS to run. Just weed out what you know you have and og from there.

Well, it all started when the water pump puked, caused the engine to overheat and blew a head gasket. I replaced the pump, gasket(s), had the head machined and pressure tested for leaks, did the routine tune-up and car ran GREAT!

Stupid me didn't torque the cam gears to the correct 115ft-lb and had the circular "ridge" (keeps the gear centered on the cam) of the exhaust cam shear off. This happened about a week afterwards.

Pulled the front covers, oil pan (what a PITA!), replaced head gasket again - since there was no way the front cover could have gone back w/ the head still on, cleaned everything up, changed oil, filter, etc.... Also, found an exhaust cam fom a '93 at a local salvage yard.

Put all back together (@ TDC of course) w/ fresh new gaskets (timing is DEAD ON! I marked everything there was to mark when disassemling - rotor position to dist, dist position to block, cam gears, compression stroke confirmed, etc...) I have verified SPARK, using a NOID light I have verified fuel delivery, compression is @ 130psi, but not firing up!!!

It's strange that the first try of the day, there is some hope...it kinda fires up, but runs a bit crappy then stalls. From then on, it shows no signs of life. Had a neighbor come over and turn dist as I was cranking, but not finding the sweet spot (even though I agree w/ you that there shound't be a "spot" but rather a "range" in which it will run)

All grounds are connected, all harnesses are connected, vacuum lines in place, battery fully charged, plug wires correctly routed, etc...

How can Spark, Fuel, and Compression NOT fire-up consistantly? It will always "kinda" start on the initial try of the day (it's been three days now) but then just quits afterwards.

No Trouble codes in the ECM (but as you stated, it may not throw any until it runs), but ECM sending signal to allow SPARK, and Fuel Injector Pulses.

This is making me MAD!

Thanks for ANY ideas!!!!

[s13sr20chris]

timing is good but compression is a little low...

its not flooded is it?

some codes will set right at key on. they are the open/short codes. nissan calls them "normality" codes.

[dr69]

timing is good but compression is a little low...

Thanks for the info guys, I really appreciated it.

I have seemed to have found the culprit (myself!) After looking VERY closely at some pics I believe I found @ Jim Wolfe Tech, I noticed that my cam timing "dots" might just want to be advanced one more tooth clockwise. So I took off the upper cover and removed the chain, then reinstalled with cams in slightly new position, buttoned everything up and she fired right up!

Not that it really matters now, but could this have been from the install of the '93 exhaust cam (car is a '95)? Since I marked the cam locations precisely prior to disassembly, it must have run in the original position I used.

I wasn't sure that 130 compression was good or not, just assumed that since they were all pretty close, it must be OK....What is GOOD compression?

Thanks again...I always learn from your replies - this forum ROCKS!

[PMan_S13]

Perfect compression is like 180 or 182 or something like that.

Its still in spec if it is about 153ish though.

Most important is consistant readings across all cylinders. If you get 180, 175, 165, 125. This is not good. It is normal for there to be like 10% differences between cylinders.. but a drop of ~50psi in one cylinder is not from wear alone.