sr20det not running right, coil problem?

[hastin09]

Soooo I just swapped my 91 240sx with an SR20. It starts up but idles badly at first till warmed up. It drives and holds boost fine at 7psi with no boost solenoid hooked up, holds around 20psi vacuum at idle. The motor shakes badly and it almost sounds like its running on 3 cylinders. Shakes bad enough that I already have an exhaust leak at the turbo exhaust outlet. Driving on the road it feels as if it boggs at lower rpms and pulls a little better when it gets in boost. First checked all the wiring connections and they seem tight. Pulled the coil packs and plugs and found this?

http://i77.photobucket.com/albums/j41/hastin09/2012-09-30163646.jpg

http://i77.photobucket.com/albums/j41/hastin09/2012-09-30163452.jpg

The coil pack on cyl #2 is different. The sparkplug for the cyl looks fouled which leads me to believe that coil pack is bad? The other three coil packs have the number 162 printed on them and that one has 171? Also the 162 coil packs have electrical tape wrapped around them? The motor was swapped into another 240 and I bought the full swap from that owner. He checked the compression before I bought it and it read 150psi across the board and the motor has no ticks or knocks while running.


Any help is greatly appreciated!!

[hastin09]

Did a little more detective work. Put all the packs and plugs back in, started up the car, and pulled the plug on #2 cyl... and exactly as I thought, the cars idle didnt change. That coil pack isnt firing and the car is running on 3 cylinders. Now how can I check if its a bad coil pack or wiring for the coil pack?

[Relentless240]

UUh. how about u switch coil pack....

[K3MPS]

yep, switch the coil packs around..

[hastin09]

dont know why i didnt think of that lol, went full retard for a second. Switched them arround and still the same thing. #2 cylinder isnt getting spark. Must be a wiring problem with that coil pack. Pulled the coil pack sub harness and seems to be intact looking. I can tell this must have been a pre existing problem and thats why the previous owner replaced that coil pack thinking that coil was the problem.

[lowrider260]

I would do a compression test. If #2 has a broken ring or ringland, the lack in compression will cause the miss/ oil usage that could foul the plug. Since you swapped the coil packs around and it didnt pick up it would be the easiest thing to do, before you start unwrapping loom.

[Relentless240]

1st Pull out coil pack #2 and make sure if u have spark or not, then what he said^^^^.
And if compression checks out.
CHeck wiring.

[hastin09]

checked for ecu codes and got (55 - Other Malfunction. CONSULT Terminal Required)....

[hastin09]

thanks for the advice guys will compression test tomo

[shift_down]

How do you know that cylinder isnt sparking? Did you test for spark? It could definitley be sparking but not getting fuel.

1. Check spark
2. If there is spark, then your fuel injector may be bad.
2a. Switch fuel injectors around and see if the problem is still on C2
2b. If fuel injector Orings are torn, replace them and try again.
2c. If fuel injector Orings are good, replace cylinder 2 injector

[hastin09]

Did a compression test and 155-160 across all four cylinders, which is a sigh of relief because now i know the motor is at least healthy. Got a multimeter and am checking the coil pack sub harness as we speak. Then going to check the injectors. If it comes down to the wiring harness I'm thinking I may just buy a wiring specialties harness and save the hassle of sorting through that mess plus it will clean up my bay a bit.

[K3MPS]

^^^what? :mepoke:

[rwtf]

spam....

msglngth

[hastin09]

Sub harness had good continuity. The diagram in this post differed from mine though?http://forums.nicoclub.com/s14-sr20det-coil-pack-wiring-harness-t369726.html
The 12v power was not in that pin location? Now going to see if it is getting power. Maybe check the ignitor and CAS? I hate electrical problems...

[joey200sx]

I ran a new earth to the coil pack loom from the back of the engine. Sorted my problem.
I'm also making my own harness like the YF one.

[hastin09]

You only had 3 cylinders firing? looked at the grounds on it and they checked out

[joey200sx]

was missfiring its tits off.
Sounded like a scooby. I changed plugs. New coil packs
Hardwired fuel pump
New Fuel pressure regulator
Gapped Plugs
Re-earthed coilpack loom. Fixed it.

[hastin09]

No miss fires just cylinder number two not firing it seems

[hastin09]

ok so i checked if the injectors were working via a screw driver. Could hear a definite firing of all injectors and even unplugged cylinder number 2 injector to see if i could hear a difference between plugged in and unplugged and I could definitely hear the injector working. That mixed with the the evidence of the plug being fouled leads me to believe its a sparking problem. Checked if the coil pack was getting power and it was reading 12.4v not running and 11.2v running, and showed the same across all four coils. I wasn't sure how to check the signal wire because I know its a n alternating current, but I was getting much higher reading on cylinder number 2 coil plug than the rest? don't know what this means.

[hastin09]

I really want to buy a new harness cause thats what I am thinking it most likely is but I dont want to waste 300 bones and it turn out to be another problem, really wish I had a definite answer.

[godsmack]

Get the fsm and test continuity from the sub-harness back to the computer. Make sure that everything is not arching. Also did you actually hook up the #2 coil pack to a good plug and make sure that you're getting good spark there?

[hastin09]

so pulled and checked the injectors and o rings and they all looked good. And switched the injectors around to make sure it wasnt a bad injector. Also checked for spark by pulling the plug and grounding it and nothing... missing something here. The coil plug was getting power when i tested it. I got a power reading from the signal cable but Im not sure what reading is correct?

[shifts13]

Remove valve cover and check for broken rocker arm.

[godsmack]

If you're getting signal and no spark then you have a bad coil pack. If you hook that coil pack up to a different cylinder plug and ground a good spark plug with it do you get spark?

[hastin09]

problem does not follow the coil when I switched coils as i stated. The coil is getting power, and the signal wire is giving off a reading, but im not sure what the correct reading is.

[ansemenoff]

check the continuity of each wire in the coil harness to a ground if you are getting continuity on any of the wires (other than the actual ground) then you have a short. also check the ohm load between the coil ground and chassis ground it should read 0

[hastin09]

good idea I will try this. And ohm load between the ground was within normal limits, like .03 or something.

[hastin09]

Problem solved. Bad wiring harness

[jesteratc]

How did you find out it was a bad wiring harness? Did you end up just buying a new one, and putting that in and bam it worked. or did you trace it to find your problem?

thanks,

Having the EXACT same issue.