KA24De Running on 3 after Fuel Injectors Replaced - ECU?

[thomasjamal]

So I recently replaced my fuel injectors and seals in my KA24DE (205k) hoping that this was the source of my oil burning issue (washing out rings...).

After I put in the fuel injectors I started the car and it ran like normal for about 2 min. Then I turned it off and started it again and it was running like crap.

The 3rd cylinder was not hitting. I checked the plug and was getting spark so I thought the injector was bad. I got another injector and replaced it and it started and ran strong for 5 minutes. Again, however, when I started the car the 2nd time the 3rd cyl was out.

I took all the fuel injectors out again and checked all of the o rings and seals and reinstalled them all. I check all of the connections of everything I had touched and everything is like it was before.

So I started the car again and the 3rd cyl was out and now the 2nd cyl is barely firing.

The only similar problem I have read about on NICO was ecu related and involved rain leaking in and getting the ecu wet. So I checked the ecu and there is no sign of moisture.

Check engine light is not on and I haven't changed anything else.

Need help!

[3Q Jay]

what is pedigree of the injectors? OEM new from Scottsdale?

chech hot/cold static resistance of the injector coils and report back. also look at your FI wire harness for signs of age/heat deterioration.

[thomasjamal]

So it was a bad spark plug connection.

The plug was still sparking but apparently the connection was poor and it was coming and going. So I replaced it with a new plug with a slightly longer connector and it started right up.

[thomasjamal]

Just kidding. I changed the plugs and it ran perfectly for almost exactly one day.

Then it started idling like crap again, started smoking and went back to running on three.

Except this time a DIFFERENT cylinder is out. That makes all four cylinders that have gone at at various times.

Could this be something simple like a bad distributer or am I looking at a more complex problem?

[3Q Jay]

distributor is a good place to check. on the transverse (my U13's), the distributors are known for leaking and slinging oil with age. does something similar to what you are describing.

i thought, though, that the 240 longitudinal mount with front distributor did not have this problem. check with the 240 guys to be sure.

what about moisture in the plug wells?

[thomasjamal]

Replaced distributor cap and rotor, made no difference.

Results of cold FI resistance test: 11.7, 11.8, 11.8, 11.7.

[3Q Jay]

FI (static) resistance is fine, doesn't completely rule out bad transient response from FI's, but unlikely at this point. I would still check the hot FI static resistance for comparison.

yeah, more subtle than cap& rotor. those looked fine on mine, then i pulled the little dust donut off the sharft and there was major tracking where the inductive coil is that would be where the old breaker points would go 30 years ago.

what about the moisture under the plug wires? I can't tell you how many times that has got me after a lil motor cleaning.....

[sir420]

I just recently had the same problem and like you tested and replaced components that I thought it could be. But after testing everything all the way back to the ecu there was only one thing left. Luckily I had a spare ecu from another 240sx of the same year and switched them out and now she runs beautifully.