L20 spuddering

[Dimerforlife13]

My 620 has recently developed a misfire. It doesn't feel like a dead miss in one cylinder, it spudders. really feels like an electrical issue. I had an extra cap/rotor/wires, that changed it a little. It doesn't seem to do it as frequently. Its mostly under lower rpm load(under 2k). Do the EI dizzy's start going bad or do they just die? I have a 200sx EI I can put on there. I just recently had my plugs out(they looked fine) to do a compression test and it was 160-155-155-160 cold, so definitely no problems there. I'm running a DGV if anyone wants to know. Some help would be appreciated.

 

-Brett

[MicroMachinery]

You said you changed your cap, rotor, and wires.. Did you say there's an EI Distributor on it, or you just had one that you were thinking about installing.. if it's not EI, did you replace your points? What about the condenser? If you're doing all that, you may as well replace the plugs(I recommend NGK) with a fresh set, just so you know it's all new.

 

After a complete Tune-Up, if you're still having the issue, then you can start questioning other parts.

 

By the way.. if you DID switch to Electronic Ignition, did you also install an Electronic Ignition Coil? If you use just a normal points coil, it will fail.

[banzai510(hainz)]

Look like the compression is good but just to ck the valve lash. Maybe a lash pad fell out. Im not sure if one can have a good reading if lash pad fell out or not.maybe ck in case whn it goets hot the lash changes just enough

 

ck for loose rotor shaft but you say its good at higher RPM so I think that good.

 

make sure the carb 2nd barrel is closed( a little spring keep it closed untell the mech pushes it open.

 

ck vacuum adv and time it again.Maybe just the dist plate is loose and it moved.

[hang_510]

spuddering? does it smell like french fries when it backfires???

 

Do the EI dizzy's start going bad or do they just die?

usually die, unless its a poor ground, which would affect all cylinders.

 

check that the rotor (not the plastic to the cap) is is good shape.

i had a chip missing on one before

[banzai510(hainz)]

are you saying it has a point sytem right now?

was soemthing changed? was anothe coil added in there? If you running points a point coil is needed. or if you removed the ballasty resisitor can cause the coil to get hot. If its not HOt then its most likely OK.

 

 

olddatsuns.com

[Dimerforlife13]

No, it already has EI, I just did the valves within the last 200 miles. I switched the cap/rot/wires off of my other EI(from a Z20 on my 510). Everything is in good shape and has been inspected. I'll check on the ground. Like I said, I already have EI in it, its a 78 KC. The 2nd barrel is closed also.

[banzai510(hainz)]

run some carb cleaner thru it .

 

most time the ignition will cut out at higher RPMs .Thats when they draw more current.

I would look more at the carb

 

maybe trypulling out the dizzy and make sure the shaft spins EZ. I had a dizzy where the weights and springs blew apart. It was more or less a blender under the contack plate

[Dimerforlife13]

I'll look into it Hainz, thanks.

[datzenmike]

I assume you changed the dizzy to coil wire?

 

Check the coil where the high tension wire plugs in. Look for cracks or carbon tracking. Carbon tracking is where poor insulation on the nipple has allowed voltage to leak and it has arced to the negative wire terminal or outer case and has burned a track in the insulator.