bha280 Posted April 3, 2015 Report Share Posted April 3, 2015 This started a few weeks ago, but as its not my daily I put it to the back burner. Well today my daily's slave cylinder went out and its a Saab so its a royal pain and may take a while so I need my Starion up and running well. One night on my way home the car backfired as I took off from a light then started running like crap. AFR's all over the place and rough. I pulled over, killed the lights and turned it off. After sitting for a minute I fired it back up and idled for a couple minutes. AFR's went back to normal and all was good until I turned the lights on and it started again. Made it home and haven't driven until today. With no lights on it ran fine until it got warmed up, then taking off from a stop it back fired then started missing a bit. All grounds cleaned up about a month ago, new wires on alternator and battery, and mods in sig. Just never had a car backfire and don't know where to start. Thanks. Link to comment Share on other sites More sharing options...
techboy Posted April 5, 2015 Report Share Posted April 5, 2015 (edited) Do you have a leaking injector or an injector not flowing properly? Sounds like your fuel issue .. running rich ... under hard acceleration causing it to backfire. Since electrical is involved as well, I'd check out your injector clips. Edited April 5, 2015 by techboy Link to comment Share on other sites More sharing options...
bha280 Posted April 6, 2015 Author Report Share Posted April 6, 2015 (edited) Perhaps backfire is not the right word. It makes a loud pop/bang and starts stumbling. Injectors and clips are newish and AFR's are normal until the described condition. It really only happens when fans and or lights are on. When the fans come on it is very noticeable as the car shudders hard one time. have the TEP fan kit in there with both the temp switches hooked up. I disconnected one of them and it seems a little better but I only drove like 3 miles after. Edited April 6, 2015 by bha280 Link to comment Share on other sites More sharing options...
Edde Posted April 7, 2015 Report Share Posted April 7, 2015 Sounds like maybe when your fans kick on it's robbing your ignition of current, enough to allow unburned fuel into the exahust. Link to comment Share on other sites More sharing options...
bha280 Posted April 7, 2015 Author Report Share Posted April 7, 2015 Thats what I thought, but even when fans aren't on and car is warm my AFR's start to bounce around sometimes. Usually it is more lean than anything. Beginning to think the fans are just making another problem worse. Just for the hell of it, I took the wires off the temp switches in the radiator to see if taking them out of the equation helped, it didn't. A couple things I noticed today: when I was rolling the windows down and they got all the way down, I was still on the switch for just a moment and the car stumbled hard. Also, the fuel pump was louder than normal. I can't make it start running bad, it just happens out of no where. Sometimes it just goes back to normal without shutting off or doing anything. I am very confused. Just have to test everything this weekend. Where should I look for the fan/lights drawing too much power? Like I said, I went through and cleaned all the grounds in the manual (even behind gauges) and a lot of the wires i the battery area are new. Link to comment Share on other sites More sharing options...
Edde Posted April 7, 2015 Report Share Posted April 7, 2015 Seems like all symptoms point to the same thing. I'd say weakness in the ignition circuit as opposed to a large draw. Can be pretty hard to trace for certainty. Ignition switch itself, coil, wiring to and from, etc. Actually fairly common as much of our wiring is small. I at one time could tap my brakes repeatedly and get a bouncing minor stumble. And you have a bunch of mods... Link to comment Share on other sites More sharing options...
mikec Posted April 8, 2015 Report Share Posted April 8, 2015 A whole lotta stuff is powered by the "IGN" fusible link - basically EVERYTHING that needs the ignition key to be in the ACC or ON positions. So a worn-out IGN link, poor/dirty contacts on the link or the box, or in the connector from the link box to the wiring harness (down by/underneath the battery tray typically), and a worn-out ignition switch will lead to electrical issues. The dash voltmeter reads this voltage which is why it "dances" in sync with the turn signals - they're also powered by the IGN link/circuit. As a test: while driving, flip on the turn signals and verify the car acts up... then turn the signals OFF and instead turn on the HAZARD flashers. If they can blink away without making the engine act up that's very strong evidence of issues in the IGN circuit. The hazard lights are NOT powered by the IGN circuit. Much of the fan stuff is powered by the IGN circuit too so they can affect things. The alternator's field coils & regulator are powered by this circuit too which is why the alternator struggles at low engine RPMs combined with high electrical loads. The wire from the fusible link box to the input of the ignition switch is a common sore point on cars - not just StarQuests. Doubling-up on this wire with a fresh/clean wire can make a world of difference. Worn contacts in the ignition switch are also common. Got a voltmeter? With the engine idling and the turn signals ON, measure the voltage from the ignition switch input wire (fat white+black wire) to the output wire (black+white wire) and then test input wire to the other output wire (blue+black). If you see more than 0.1 or 0.2 volts across these wires that means the ignition switch itself is not healthy. In theory you are measuring across a closed switch in this test so you should see 0.00 volts... but nothing has perfectly 0.0 ohms so any wire, any switch, any connection, will have a little resistance and thus show a voltage drop that gets worse as more "stuff" is turned ON drawing amps. I'll bet you get a few tenths of a volt on either side of that IGN fusible link too when the engine is ON and the turn signals are ON. Add the cooling fans? Watch the voltage jump even higher if the IGN link is old/worn out. mike c. Link to comment Share on other sites More sharing options...
bha280 Posted April 11, 2015 Author Report Share Posted April 11, 2015 THanks for that. I'll get on it. I did find the ground wire on that bolts to the intake mani had a melty spot on it at a yellow butt connector. So I cut that out and put a new connector and that pretty much solved my problems. Now, my AFR's will be normal for a while then out of nowhere start going crazy for a bit, then go back to normal. Love it. Link to comment Share on other sites More sharing options...
Edde Posted April 15, 2015 Report Share Posted April 15, 2015 Tim C had a near identical response to fixing that link a long while back. I've always wanted to double up the wire Mike describes as I am certain it would be wise. Link to comment Share on other sites More sharing options...
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