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1G Dim dash lights, and lean

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GSXftw

10+ Year Contributor
381
78
Dec 16, 2009
Medford, Oregon
So I've had an ongoing problem on my car for quite some time now. First was I noticed I was overworking my stock ignition system what seemed like pretty early, about 26 psi on HX40 pro/E85 the trusty .024 BPR7ES started not being enough. Went to non protruding plugs, ARC2 CDI box, went to a .018 gap, was able to run 30psi occasionally, but the spark just went downhill from there. Went from not being able to do pulls, to not being able to drive at all! In a matter of weeks anything over idle and the spark gets drowned out.

Another condition I noticed was some of the dash lights started to go dim. I have no doubt they are related, as the driveability got worse the lights just got dimmer.

Here is where we are at today
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I have tried another coil pack, igniter, no CDI box, all the same. I show good voltage at the "gauges" fuse, and although the dash light goes out when its pulled, the car still runs so doesn't seem to be the common factor.

I Tested/bypassed ignition switch, no change. The MPI relay checks out good. Not really suspecting a component since the lights are so dim at the exact same time, and they are that way all the time, even KOEO. Suspected a ground but I have checked/cleaned every underhood ground point. Have beefed up with 0ga the battery to body, firewall to intake 8ga, 96a relocated Saturn alternator with upgraded charge wires, the exhaust to body strap is in place, ECU grounds 101/106 are upgraded. The only ground I haven't tested is the one in the upper right dash area that requires the dash out, which I may look into doing if its worth it.

I do seem to see low voltage on the yellow wires going into the CDI which would normally plug into the coil. Are there any electric gurus that can tell me where I should look? I've been staring at diagrams looking for something, tried very hard to help myself here and am just stuck.

Thank you for any help
 
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Yes I see 90a on a load test. I was showing good voltage during pulls, and 14.0 at idle. But if I Unplug the small alternator plug the lights go out of course. With a battery charger on it and alternator unplugged I still get the weak spark issue. Still need ideas such as what to check from here
 
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The low voltage on the wires going to the CDI shouldn't be a problem that would cause a weak spark. The actual main power for the CDI should come from the big power and ground, which should be directly attached to the battery.

You tested the MPI, but did you look at the voltage there, compared to the battery? Does the car seem like it has a battery drain, so that the battery voltage is dropping with the engine not running?
 
My apologies guys.

I went ahead and did a lot more troubleshooting and made some discoveries, which put this in a totally different direction. After pulling/replacing spark plugs, testing spark a lot better, and also experimenting with supplemental fuel added, I realized the car has a healthy spark.

I thought since the wideband was reading lean it was due to extra oxygen from bad spark, but it IS actually lean. So first thing I did was fuel flow test, on the return side, flows fantastic. My first thought was the old E85 blackbeard, so I drained the tank of the E85 and went to premium to clean things out. It was momentarily better, since gas takes LESS fuel than E85, it was drivable on light throttle again but still fell on its face with too much.

I figured I would just run this tank of premium through, it would right itself and improve as I went through it. Well turned out quite the opposite, AFRs went from 15s, 16, 17s and so on as I drove. One thing very notable that I discovered is, I could actually tune out the problem at first. Note my global settings are correct for 2150s and have worked up until this point, but if I increase global from say -60% to -30%, the car perked right up!

This showed me that mechanically the car had the ability to deliver enough fuel/light it off, something just wasn't right. It drove great was able to lightly creep into boost a bit with no lean AFRs. But the condition worsened. After a short drive it got leaner and leaner until I limped it home basically at idle.

I attached a log to show. I see nothing that sticks out or looks odd. I had another brand new from ECMlink ECU on hand, I tried that, no change. I pulled injectors, they are clean as a whistle, they were brand new in may so wasn't surprised there. So if you were me, where would you go from here?

Does this sound like anything familiar or possible at this point? I was thinking verify 12v at injectors, and either with a noid light or waveform viewer, look at injector pulses. Sorry for the misdiagnosis guys, I went ahead and edited the thread title to be relevant
 
The low voltage on the wires going to the CDI shouldn't be a problem that would cause a weak spark. The actual main power for the CDI should come from the big power and ground, which should be directly attached to the battery.

You tested the MPI, but did you look at the voltage there, compared to the battery? Does the car seem like it has a battery drain, so that the battery voltage is dropping with the engine not running?
I did look at voltage/ground, backprobed with car on. Saw 11.7v KOEO which matched the rest at that time. The car has been sitting for weeks and still fires up so Im not suspecting a drain
 
interested to see if you made any headway with this issue?
 
But the condition worsened. After a short drive it got leaner and leaner until I limped it home basically at idle.

Have you checked to make sure the fuel tank is venting correctly.
Can you monitor your fuel pressure and make sure that it remains = base + manifold?
 
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