Was on the ramp at the garage for 5 hours today and the problem is still there. Cylinder 5 is down.

 

To start with we changed the plugs, taking the old ones out was like a pick and mix! Anyway we put the new ones in. Fired her up, misfire is still there.

 

Got out the multimeter, absolutely no power to the 12V line at the coilpack harness on Cylinder 5, 12V on all the others.

 

Take the PTU off, clean the connectors, put it back on. The car wont start at all now! Anyway after a bit of persuation we got it started, still missing!!, we now have 3V.

 

So we take the PTU off again, and find out the voltage to the red wire doesnt change at all even if you diconnect BOTH PTU connectors! Anyway, we got it up to 6V, then 8V. Fired it up, got 8V, disconnected it, got 13V, connected it, got 0V, eventually we got it connected with 13V, and its still missing.

 

So anyway, we fetch the coilpack off a good cylinder, connect the harness from cylinder 5 onto it, chuck a plug on it, fie it up, sparking like crazy. So we then swap cylinder 3 and 5 coilpacks, the new on on cylinder 5 is sparking, and cylinder 3 is firing.

 

 

Also, when we took the old plugs out, they were dry as a bone, we fetch the new one out, also dry as a bone.

 

So we know that there most deffinatly is a spark that wasnt there before, and that the plugs are dry, leading us to believe that its an injector problem.

 

So, the only thing we could do is to put 2 cans of fuel rail cleaner in (btw this is really good stuff not redex or anything like that ), and still no difference.

 

 

So how likely is it to be an injector? How do you tell?

Where are the injectors?

How do you replace them?

 

 

thanks a lot in anticipation.

 

BTW- I did a ECU diag and it came out code 55.

 

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Sounds like you have described 2 problems. So far you would have appeared to fix one. Is it likely that it's been missing on cylinder 5 for ages ? Why don't you swap a known good injector with cylinder 5, also, have you checked the electrical connections to the injector on cylinder 5 ?

No m8, it only came on on Tuesday. It had been fine since the day it arrived. It had been out on the morning and it was running fine. But we went out to get the alarm done iun the afternoon and *WHAM!* no more cylinder 5.

 

How easy is an injector change?

Not sure, never done it, but I read somewhere about using a Dremel to tidy up the plenum castings so that you can swap them over without removing it.

Have a look here :-

http://www.300zx.org.uk/tech_06.htm

 

 

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change the ptu?