Ignition system?: Anyone chime in on this problem ?

[Tom Ngan]

Setup:
SR20DET
Gt2871R .86 @ 1 bar
256 HKS St1 cams / otherwise stock head
1.6mm Greddy headgasket
Greddy IM / Greddy FMIC / Greddy BOV
550cc w/ FPR / stock fuel rail / Z32 filter / 255 Walbaro
Stock bottom end / freshly rebuilt / new bearings / seals / gaskets
NGK 7 spark plugs / gapped down
Megasquirt V2 Standalone using crank trigger pulley system running COP

Car dyno'd 258rwhp/238lbs misfiring a bit uptop @ 1 bar on a mustang dyno. We stopped the dyno, and pulled the car off to see what the problem was.


Ok so the deal here is some times the tach signal gets very wonky. It can be idling and all of a sudden 'spike' up and 'jump' around. You can imagine how this affects your driving. Big backfires are common when this happens when I'm driving.

Also sometimes it spikes DOWN, its like the car just shuts off, but it bounces back up.

Anyway, we tested the coil packs on another SR20 and it was misfiring the same way on the dyno and it had the same tach 'jumping' problem. Swapped back his original coil packs and the problem was completely gone.

I know it might be hard to diagnose since I'm running a megasquirt, and it's pretty unique, but could bad coil packs be the problem with the misfiring/jumping tach signal? The coils are setup running waste spark as well. The megasquirt isn't usually setup to run on a car with individual coil on plug setups, so we think this is the problem.

We concluded that were going to try to run dual coil packs from MSD off a SRt-4 to try to get rid of the problem, anyone see any problems with this?

Any help will be great. Thanks.

[MegasquirtCA]

A bad coil can cause the misfiring and tach bouncing. Dont forget thats how it reads rpms so if its messing up it'll also send a bad signal causing the bouncing. Try using another coil possibly the one from the guy you tested the bad coil on, since you know he has a good coil.

If that doesnt help, than using a SRT-4 coil can help, if you can try using a FORD EDIS coil, they've been proven to LOVE BOOST, offer great charging and have a more powerful spark than some of the coils out their.

Can you post up your MSQ so we can check it out. Also tell us what code your running.

[steve shadows]

Its not a bad fucking coil.

I dont understand why all you guys go out and buy fucking Ignition upgrades when you stock is fine to 500 fucking hp.

Your tuning sucks, or your tuner sucks if your having break up issues sub-400 hp with stock parts.

I tried to explain to you on FA, that its probably a grounding issue with your coils not the actual coils themselevs.

Your plug gap should be fine at .030 in fact .032 is better for making power under 20 psi.

moses and marry magdelen in a fucking three way with a goat~!

fucking tuning and propper installation guys!

slams door

[Tom Ngan]

^ hahaha

Well we were working on the grounds the other day, there was a lot of interference when my altima fans came on so we rerouted all the big grounds to the back of the trunk where the battery box is. No big difference, but a drop in the interference no less.

Anyway, i'm going to beef up and clean up the ground connections on the ignitors before buying anymore shit for the car.

But steve, I stated that when I put my original coils on another SR20DET S13 that was on the dyno, the signal broke up and it was misfiring. Once we swapped it back to HIS original coils, everything ran gravy.

Work in progress, not alot of resources out when I try to look up help for "megasquirt" "SR20" definately appreciate the replys guys. :)

[Matt Cramer]

It sounds like an issue with the coils. One thing you'll want to do is take a data log - with MegaTune, if you hit the space bar, it'll mark areas of the log for you to come back later and look at. Check to see if Megasquirt is losing the tach signal at the same time things are breaking up. If you're losing the signal there too, check for a noisy crank trigger. If you're getting a good RPM signal on the log, suspect the coils or the coil driver circuit.

[rps13drift]

I second mr shadows! Its either a grounding problem or plug problem!

[steve shadows]

^

But steve, I stated that when I put my original coils on another SR20DET S13 that was on the dyno, the signal broke up and it was misfiring. Once we swapped it back to HIS original coils, everything ran gravy.

Work in progress, not alot of resources out when I try to look up help for "megasquirt" "SR20" definately appreciate the replys guys. :)


I understand, but there was probably some sort of problem on your old ignition that needed maintenece or fixing, upgrading something everytime it goes wrong gets expensive and you usually dont correct the org problem...

as seen in this post

make sure your timing map isnt super retarded and you havent cracked the porcelin on any of your spakr plugs

feel free to post your timing map.

keep us updated im curious now

[daryl337]

you can always go through the FSM procedures to determine if your coils are good... but more than likely you do have a ground issue with the coils, possible on the connectors themselves if the problem transfers to another another car with a solid set up.

[Tom Ngan]

*Update*

Problems:

-Resetting ECU, at any rpm. Idle, WOT, whatever
-Misfiring, especially at higher RPMs, higher boost levels (1 bar)
-Bogging
-Poor gas mileage 300km/tank, minimal boosting
-Choppy acceleration, break ups



Did every possible measure to solve the problem from cheapest solution to spending money solution.


-Megasquirt data-log showed breaking up of RPM's at all levels, even when it idled.

-Upgraded all the big rounds. Battery to chassis, chassis to block, alternator to chassis. No change.

-Swapped original coilpacks for coilpacks from running SR. No noticeable change, however car that ran MY coilpacks was misfiring.

-Data log shows a drop from 15.1V to 13.7V when altima fans kicked in, ran car for a couple runs, without the fans turned on. No change

-Swapped out original S13 alternator for S14 blacktop alternator. Circuit tested and showed much less interference, and a bit smoother acceleration. However, resets were still occuring, still breaking up at higher boost/rpms

-Swapped out copper spark plugs for my friends iridium spark plugs. No change. Original copper plugs were in good shape, a bit rich.

Decided to spend some money........

MSD 8.5mm super conductor plug wires
MSD Dual coilpacks from SRT-4
Subaru Impreza External ignitor
NGK copper heat range 7 spark plugs

SUCCESS! Seems like there was alot of interference coming from the coilpacks, that was breaking up the RPM signal, and causing the Megasquirt to not run properly. We positioned the coilpack tower near the front driver side corner to move it away from noise and heat. The external ignitor also helped as well since the built in ignitiors on the Megasquirt are not that great. Also went back to using the copper plugs, seemed to work better for me. No more ECU resets, no more bogging, hesitations. Very smooth through entire powerband. I still need to go back from a touch up tune for higher boost levels. Currently boost at about 11psi. Some hiccups here and there on decel and lower rpm ranges, but the final tune should rid them.

Thanks for all the help guys, thought i'd share the conclusion for this big problem with you guys. :)

[johngriff]

Were you using the oem ignitor chip with the coil packs?

[Tom Ngan]

Were you using the oem ignitor chip with the coil packs?

Yes

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