Sr20det weird misfire/detonation

ONLY for ADVANCED technical discussion about the 240sx!
Paytons13
Posts: 6
Joined: Thu Dec 17, 2020 8:57 am
Car: '89 Nissan SR20DET swapped hatch

Sr20det weird misfire/detonation

Postby Paytons13 » Thu Dec 17, 2020 9:42 am

I have a sr20det swapped s13 a weird miss accrued in cylinder 1 followed after by detonating. I unplug coil pack one detonation goes away and miss stays the same

Tried brand new injectors
New plugs
New coil pack
150ish compression across the board

No matter what I do miss and detonation stays on cylinder 1
I am just confused on what could cause this


User avatar
the converted
Posts: 3443
Joined: Wed Feb 21, 2007 7:14 am
Car: 99 M3 6.0l
88 Celica All-Trac (somewhere in Cali)
2020 Taco
Location: Boston

Re: Sr20det weird misfire/detonation

Postby the converted » Fri Dec 18, 2020 6:07 pm

I'd check the coil pack sub-harness connectors as well as the connectors right at the coil. It's going to be that or a bad wire somewhere.

Paytons13
Posts: 6
Joined: Thu Dec 17, 2020 8:57 am
Car: '89 Nissan SR20DET swapped hatch

Re: Sr20det weird misfire/detonation

Postby Paytons13 » Fri Dec 18, 2020 8:09 pm

Will check that tomorrow thank you

*also replaced fpr, fuel filter, and igniter

Paytons13
Posts: 6
Joined: Thu Dec 17, 2020 8:57 am
Car: '89 Nissan SR20DET swapped hatch

Re: Sr20det weird misfire/detonation

Postby Paytons13 » Tue Dec 22, 2020 7:51 pm

the converted wrote:
Fri Dec 18, 2020 6:07 pm
I'd check the coil pack sub-harness connectors as well as the connectors right at the coil. It's going to be that or a bad wire somewhere.
Sub harness is fine, is reading 30 psi of fuel pressure swapped a known working walbro 255 no change, unplug coil pack miss stays the same unplug coil and injector car sputters and dies

Paytons13
Posts: 6
Joined: Thu Dec 17, 2020 8:57 am
Car: '89 Nissan SR20DET swapped hatch

Re: Sr20det weird misfire/detonation

Postby Paytons13 » Tue Dec 22, 2020 7:55 pm

Has spark and injector pulse cylinder 1

User avatar
VStar650CL
Posts: 1616
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

Re: Sr20det weird misfire/detonation

Postby VStar650CL » Tue Dec 22, 2020 8:07 pm

With the detonation, sounds like maybe some sort of crossfire issue. Is it possible you swapped-up the 1-2 coil connections or 1-2 injectors? Or if not, have you checked the harnesses for possible shorts between cylinders?

User avatar
the converted
Posts: 3443
Joined: Wed Feb 21, 2007 7:14 am
Car: 99 M3 6.0l
88 Celica All-Trac (somewhere in Cali)
2020 Taco
Location: Boston

Re: Sr20det weird misfire/detonation

Postby the converted » Wed Dec 23, 2020 8:43 am

I think that the fuel pressure should be in the 45 psi range with the vac line disconnected.

If there's no change when you disconnect the coil that is calling out bad ignition to me. I'd move the coil to another cylinder and the spark plug to a third cylinder and see if the issue follows it.

Have you looked at the plugs or done a compression check on the engine?

User avatar
Lobo240sx
Posts: 779
Joined: Wed Dec 01, 2010 7:39 am
Car: 1991 Nissan 240sx Coupe SR2.35DET Redtop Build
Location: Austin, Texas USA

Re: Sr20det weird misfire/detonation

Postby Lobo240sx » Tue Dec 29, 2020 1:43 pm

As stated above check the 1 and 2 , and 3 and 4 coil harness. It's very easy to get 3 and 4 reversed. I ran into that issue. If I tried to start it, it would back fire very loud, or run extremely rich.

If that is the issue, Mark the coils with a permanent marker. Also, check your timing and coils.


Return to “240SX Technical Forum”