Guest 73Turbo240z Posted January 7, 2006 Share Posted January 7, 2006 alright, we got a wideband on the motor, i'm running 10:1 under WOT, rich as hell i know, but i'm keeping it that way untill i find out this problem, safe and slow, rather that stoich and sorry. the motor will run up to about 5krpm FAST, then it cuts up bad, the AFR's stay in the 10:1 rich zone, so it's not lean conditions, i'm going to get a spare cowl panel to bolt an FPR too and see that in real time, but for now i have no reason to suspect that it's wrong, it's 41psi @ base idle off the rail gauge. so now were looking at spark as a possibility, the system works obviously, since the car does in fact drive/run. but were thinking about if it's weakened or going out... the ignition is a second hand MSD Digital 6+ and a MSD HVC coil. currently we did readings for the setup, the D6 box gets it's voltage from the battery directly, battery is charged, alternator is giving good charging voltage, and it continues to do so under load, so we ruled out lack of voltage to the box. at the coil measuring with the ground on the ground terminal, the negative battery post, and a strut bolt, never wavered, and the positive only residing on the positive terminal of the coil, we got .03v with a fuctuation of mininal proportions, which we assume to be the coil charging and collapsing repeatedly. that voltage seemed shockingly low, so we compared it to boostin280zx's coil last night at a car meet, he too. shows .03v with minor fluctuation. all readings were taken w/ the cars idling, i'm thinking next i'm going to put a pair of clamp lead's on the coil and go hit the 5krpm and see what it does while my ampremeter is hooked up. but i'm really starting to get frustrated with this, i don't have a shelf of spare parts to swap in and out to diagnose this, but so far everything i'm seeing is pointing to ignition related issues. anyone got some ideas? or do i need to start looking for a MSD 6AL box? Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted January 7, 2006 Share Posted January 7, 2006 What's your plug gap? How are your plugs? Plug wires? Maybe ohm them out, check for damage. Mario Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 7, 2006 Share Posted January 7, 2006 checked the wires, not bad... plugs are new gapped at .035 (down from .050) 2 days ago. plug tips were a brown color. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted January 12, 2006 Share Posted January 12, 2006 Check the other side of the coil, the positive side should have ~12v Quote Link to comment Share on other sites More sharing options...
240hoke Posted January 12, 2006 Share Posted January 12, 2006 Hey, I am running SDS and i had the exact same problem as you are decribing. My motor would cut up horrible like the ignition was cutting out or there was somehting bad wrong. I tried everything trying to fix it. New hall sensor braket, , new hall sensor, plug wires, even sent my ecu to SDS to have it checked out. Ended up i had a bad rich spike around 5K. Around 10:1 i didnt find it till i got on the dyno and ran a motec wideband on teh car. Once the rich spike was pulled out it pulled all the way to redline no problems. i would try and get your car back up around 12:1. Anyway I felt like an idiot, but my curves were linear it was jsut somthign wierd that happened. And what threw me off was my stock tach when used with hte SDS signal would cut out at 5K and then pick up hte signal again at around 5.5-6K. -Austin Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 12, 2006 Share Posted January 12, 2006 I have a simple coil/distributor set-up, but I get 12VDC on + side, and about 8-9 VDC on the distributor side with everything hot. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted January 13, 2006 Share Posted January 13, 2006 I have a simple coil/distributor set-up, but I get 12VDC on + side, and about 8-9 VDC on the distributor side with everything hot. is this with the car running, engine consuming gasoline, etc... or with the car in full auxillary position, motor not running? and by simple coil/dizzy are you reffering to a stock setup w/ no aftermarket ignition computer in the mix at all? Hey' date=' I am running SDS and i had the exact same problem as you are decribing. My motor would cut up horrible like the ignition was cutting out or there was somehting bad wrong. I tried everything trying to fix it. New hall sensor braket, , new hall sensor, plug wires, even sent my ecu to SDS to have it checked out. Ended up i had a bad rich spike around 5K. Around 10:1 i didnt find it till i got on the dyno and ran a motec wideband on teh car. Once the rich spike was pulled out it pulled all the way to redline no problems. i would try and get your car back up around 12:1. Anyway I felt like an idiot, but my curves were linear it was jsut somthign wierd that happened. And what threw me off was my stock tach when used with hte SDS signal would cut out at 5K and then pick up hte signal again at around 5.5-6K. -Austin[/quote'] alright, i'll try leaning the upper curve 10% and see if it moves. Quote Link to comment Share on other sites More sharing options...
getZ Posted January 13, 2006 Share Posted January 13, 2006 The coil voltage is not a constant DC voltage so it can't be measured with a multimeter. The coil is only "on" when it gets a signal from the computer. I had to use a digital o-scope to capture the signal and it is a series of pulses. A higher frequency of pulses will make a multimeter read a higher voltage. Also, coils do not like a continuous dc voltage on them. I made the mistake of hooking my msd blaster up directly to 12v over lunch while working on my car. When I came back a couple hours later, the coil blew up and all the oil in the coil went everywhere. As far as the output of the coil, I wouldn't recommend trying to hook your meter up to it. It says it's supposed to put out 50,000 volts (reality is more like 20,000), but it is still way to much for your standard multimeter. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 13, 2006 Share Posted January 13, 2006 Quote:Originally Posted by blueovalz I have a simple coil/distributor set-up, but I get 12VDC on + side, and about 8-9 VDC on the distributor side with everything hot. is this with the car running, engine consuming gasoline, etc... or with the car in full auxillary position, motor not running? I have a Uni-lite distributor with a coil, no iginition boxes or added circuitry, and this was with the engine running. Quote Link to comment Share on other sites More sharing options...
getZ Posted January 14, 2006 Share Posted January 14, 2006 There is usualy always 12 volts present at the + side of the coil but not across the coil. If you measure with a meter from the positive part of the coil to ground you will measure 12 volts, but it is not what the coil is seeing. You have to measure from the positive terminal to the negative terminal, then you should see nothing unless the engine is running. Be careful it is the ground path via the ignitor that switches not the 12 volts. Quote Link to comment Share on other sites More sharing options...
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