CEL code 73

[nsxter]

Hi guys
Hope someone can help. Today I got a CEL and TCS lights on. Car stumbles, and runs rough. I pulled the code using the blue connector (I wish I had an obd2 reader). Code 73 (cylinder 3 misfire). I swapped the coil packs and reset the ecu, and restarted, threw a CEL. Checked it and it was still 73 (seven long and 3 short blinks) What to check next? Oh yeah, its a 1997

 

[pgilliam1]

Cylinder 3 is the rear bank drivers side - right?

If not the coil, maybe the spark plug?

A bad TPS (throttle positioning sensor) will cause it to run sluggish and hesitate (it usually seems like it's affecting more than 1 cylinder though). Most of the time this will get worse in higher gears (4th-5th-6th).

Good Luck!

 

[nsxter]

Yes drivers side rear, I pulled the plug, looks good, gap and electrodes all good. Would a bad tps cause a cell code?

 

[pgilliam1]

TPS could throw code #7 or #40, but if it's marginal (intermittant) it may not. Take your car out and accelerate in 5th gear and see if the hesitation seems worse.
Good Luck!

 

[Larry Bastanza]

Find another NSX and swap the ignitor.

HTH,
LarryB

 

[nsxter]

Find another NSX and swap the ignitor.

HTH,
LarryB

Anybody have a spare one they can loan me?

 

[nsxter]

TPS could throw code #7 or #40, but if it's marginal (intermittant) it may not. Take your car out and accelerate in 5th gear and see if the hesitation seems worse.
Good Luck!

I am getting cel code 73.

 

[nsxter]

Well this is wierd, I bought a obd2 reader, read the codes, cleared the codes, started the car threw the cel again, read the code (still cyl 3 missfire) turned car off, repeted the above sequence a couple of times over the morning, well I went out and did it again this afternoon, and poof... no cel code runs smooth. I have done nothing mechanical since yesterday, it just sort of fixed itself.....at least for now. :biggrin:
Any ideas on an intermittent fault?

 

[warrenw]

http://www.nsxprime.com/forums/showthread.php?t=145195&highlight=ignitor

read post #12

 

[nsxter]

Now all I need is a loaner igniter to test it:wink:

 

[nsxter]

The car worked fine this morning, went to go out at lunch....bam back to cell code 73 and runs rough. I tried a used igniter, cleared the code started it and within a few minutes....Cel 73 is back, so must not be the igniter, any other ideas? bad gas maybe? clogged fuel injector? Any ideas are always welcome.....
Here is what the odb2 tool readings are
DTCFRZ P1203
FUELSYS1 CL
FUELSYS2 CL?
LOAD_PCT (%) 61.2
ETC (C) 160
SHRTFT1 (%) 27.3
LONGFT1 (%) 0.0
SHRTFT2 (%) 0.8
LONG FT 2 0.0?
MAP (KPA) 18.3
RPM (MIN) 2578
VSS (KMH) 24
IAT 111
TP (%) 24.3

 

[pgilliam1]

Have you tried driving the car (when it's running bad) with the TCS off to see if it makes a difference? In the original post you said you also had a TCS error.

 

[nsxter]

Have you tried driving the car (when it's running bad) with the TCS off to see if it makes a difference? In the original post you said you also had a TCS error.

not yet, the cel code happens first then a minute or so later comes the TCS light

 

[nsxter]

Could the main relay be the problem?

 

[pgilliam1]

Could the main relay be the problem?

The main relay controls the fuel pump. It is a known failure on these cars but when it goes the engine stops because the fuel stops. It can be intermittant because the failure is bad solder joints on the relay board, but you wouldn't get just a cylinder #3 misfire code. There is also a fuel pump resistor (above the fuel filter) that allows the fuel pump to run at a lower pressure below 4000rpm. If your problem goes away above 4000rpm then that might be your cause. The consistant cylinder #3 misfire code has me puzzled. Have you swapped spark plugs with another cylinder? Check the wiring connector to the #3 coil for loose wire or spread connector.

 

[Daedalus]

Ohm the injector. A consistent error on one cylinder is almost certainly due to the spark plug, the coil or the injector. Plug was inspected (though spark not verified), coil was swapped--now ohm the injector. It's the low hanging diagnostic fruit here.

 

[nsxter]

I'll ohm the injector, is there a way to do it quickly? or do I have to remove it to test it.

So far this is what I have done
1. swapped the coilpack - no change
2. Remove and inspect the plug -
3. Swapped the igniter - no change

Next to check
1. OHM the injector
2. Swap the sparkplug with one from another working cylinder
3. ?

 

[pgilliam1]

I'll ohm the injector, is there a way to do it quickly? or do I have to remove it to test it.

You should be able to ohm the injector in place (I have no idea what it should read though?).

 

[Daedalus]

You should be able to ohm the injector in place (I have no idea what it should read though?).

Not sure either for a '97 injector. If no one chimes in with the right value, I would measure all 6 and see if the #3 seems out of character with the other 5. I seem to recall there's a single harness that can be disconnected and probed. If not, disconnecting all injector connectors isn't a big deal relative to the work already done. Agreed, no need to remove the injectors.

 

[nsxter]

I could not find my multi-meter to measure resistence (my garage is a mess) so I "listened" to the injector expecting to here clicking while the engine was running....but no clicking. Other working injectors were. Now I need to backprobe the wires (when I locate my tool), or replace the injector.....We shall see.....

 

[nsxter]

Checked the ohms across the injector as well as known good ones. All the same reading about 1.75
Looked in the service manuals, no indicated electrical test for the injectors, I can only assume that even if it were bad, they would all have the same reading? Now I will move this injector to a different cylinder to see if the cel code moves with it. If it does not, It would have to be the ECM or a short between the ECM and the injector, I don't think my leeds are long enough. I will keep everybody posted, moving the injectors is a little bit of work.

 

[nsxter]

I want to thank everyone who contributed to finding the answer. I especially want to thank Jeff at SOS (Brian too). They have been very helpfull. It was a bad/clogged injector. The suggestion was to lightly tap on the injector to see if perhaps it was stuck or clogged with some dirt. Sure enough when I tapped it ........ boom back functioning. Now I know this injector needs to be replaced and the old one cleaned/calibrated. I will do the swap tomorrow.

 

[Larry Bastanza]

Get a bottle of Techron Fuel injector cleaner, add to fuel tank, and you are done.

Regards,
LarryB

 

[Quix-Draw]

Sometimes my engine will "pause" from a cold start and I start driving right away... I'll get a CEL and TPS immediately. When I pull the codes I'll get a 1201...1202...1203... all seemingly misfires, but once I clear the codes, it'll go fine. Probably take Larry's advice and run a bottle of fuel system cleaner through her...since she is my daily (love) driver... (I'm sure she wishes I'd have an affair and give her a little break...