Hi everyone, I would like to pick your brains on a problem that occurred yesterday on my 91 N\A 2+2. Started running on 5 cylinders so connected up datascan and discovered it was cylinder 6 not firing. Did a diagnostic with code 55 so ok on that front. Changed all spark plugs from iridium to double platinum, changed coil pack and then swapped performance chipback to standard chip as I felt it was not running as well on current chip. Disconnected battery while performing this operation which I have done several times.

 

All back together and switched on ignition and the electric fan is coming on straight away, started up and sounds like its running on 4 cylinders and wont tick over at all, the check engine light is on. rechecked chip on ecu for correct seating and checked ecu plug and pins, all ok. Tried to do a diagnostic with the ecu dial and paperclip but it will not go into diagnostic mode at all! :cursing:

 

So thats basically where im up to at the moment, I`m wondering if the ecu has died on me? any thoughts would be most appreciated! :helpsmilie:

 

Cheers guys and girls. :dance:

 

Paulr

Ok Electric Fan shouldn't be on .. Check the 2 pin temp plug on the top front water pipe when this goes faulty it can give you a very bad running

all most like a misfire

 

but on the other hand get your engine Compression tested as Cylinder 6 is very known for Melting

 

failing that i do have a Spare NA ECU u can Borrow or buy

 

Mark

Fan running and engine light on is a sign of either corrupted ship or an issue with the chip carrier connection, have you tried going back to the first chip? you may have a faulty injector causing the original misfire, so a resistance check with a multi meter should be around 13 ohms.

 

Jeff TT

Cheers for your quick reply guys, Jeff I have gone back to stock chip and still the same. Is there any way to test the ecu unit? It won't even let me do any diagnostics?

For the original misfire, ensure the injector connector isn't full of Nissan's patented green corrosion. I've had Zeds running on 4 cylinders due to the loom. Simple listening test with a long screwdriver found which ones were down.

 

As for the current issue, definitely a corrupted chip or faulty ECU. However, I have been able to cause a CEL & fans on constantly by uploading a known good map from one car to another car with a different ECU (same type, different part number). The poor running is caused by the ECU dupming in a load of fuel. If you had a wideband hooked up, you would see around 9:1 AFR with the CEL illuminated.

Its going to sound silly but from experience this end...check the ECU blue block connector is fully based into its socket,iff it has signs of being u shapped or a slight curve in the slightest when bolted home then its not seated right:wink:

Cheers for your quick reply guys, Jeff I have gone back to stock chip and still the same. Is there any way to test the ecu unit? It won't even let me do any diagnostics?

 

Seems you had one fault and ended up with more now, not an uncommon problem with looms etc. assuming the engine light issue was not present before then something has changed, the only reasonable thing is the chip carrier where it is soldered to the motherboard pcb, remove the bottom ecu cover and check the 28 soldered pins carefully with a magnifying glass and a strong light,may be just a fracture that has opened up when swapping the chip.

 

We can do an ecu check for you in person or by post, your not that far from us either way.

 

Jeff TT

Thanks for all your help. I will check ecu. Will post or try and drop into you Jeff. Many Thx. Just a quick question, how easy are the injector plugs to get to? Do I have to remove anything to get to number 6 injector?

You will need to remove the balance bar and associated pipe work and remove the plenum or dremel down the side of it to remove the injector, it's a pita, I think Jeff at zedworld has done this job a couple of times lol.

 

Paul

Edited February 17, 201312 yr by 300_zedx

Thanks for all your help. I will check ecu. Will post or try and drop into you Jeff. Many Thx. Just a quick question, how easy are the injector plugs to get to? Do I have to remove anything to get to number 6 injector?

 

Ecu received and tested, cannot vouch for your other chip as dont have it but the ecu is fine and working with another eprom fitted, the chip is corrupted / damaged.

 

Jeff TT

That's good news Jeff! I have 2 other chips, one had same effect with engine light on and the other I'm not sure about. Can a bad loom damage a chip once connected and ignition switched on? Do you have a performance chip you could fit and send back with ecu? I can pay you through PayPal. Many Thx. :thumbup1::thumbup1::thumbup: