StewyN Posted October 15, 2014 Report Share Posted October 15, 2014 So my engine has a bit of a sputter/backfire under load, itll run smooth when im at higher rpm's, but when it at lower rpm's it has a bit of a hic-up every now and then. Any ideas? oh and its a z24 with a stock carb Quote Link to comment
supererogator Posted October 16, 2014 Report Share Posted October 16, 2014 Sounds like timing to me. The "under a load" is what keys me off. Can you start off in 2nd or 3rd and get the sputter? Then it is definitely timing.Fuel could be an issue, and that stock carb has seen many days on this earth. Might be something to look into soon. Quote Link to comment
StewyN Posted October 16, 2014 Author Report Share Posted October 16, 2014 alright ill look into it, thanks. Ive been thinking about a carb swap, ive seen a lot of webbers, are there others? and does it hurt anything to swap to something like that? Quote Link to comment
datzenmike Posted October 16, 2014 Report Share Posted October 16, 2014 Timing is 3 degrees. Two things.... I would check the hot valve lash at 0.013". A tight valve does not close properly and under load it can sneak back into the intake and pop. Check the cap, rotor and plug wires. There are 8 plug wires on a tiny cap with very little space between them. Check the underside for carbon tracking, cracks, moisture. Under load it takes more voltage to fire a plug and it will try to find an easier path to ground... maybe another wire. If the wires cap and rotor are unknown just replace them. Quote Link to comment
StewyN Posted October 18, 2014 Author Report Share Posted October 18, 2014 so come to find out its only firing on the exhaust coil, does this just mean the intake coil is bad or? Quote Link to comment
datzenmike Posted October 18, 2014 Report Share Posted October 18, 2014 Replace the first fuse on the far right LEFT in the fuse box. (closest to the driver's door) The coil high tension leads are swapped, probably by accident but the intakes are wired directly from the ignition switch while the exhaust are powered from the fuse box. It will run just fine reversed as the coils fire together at the same time. Likely the fuse is blown. The engine is timed to run with both coils firing. If one is not working the engine will be running severely retarded and lack power and give crappy mileage. Quote Link to comment
StewyN Posted October 18, 2014 Author Report Share Posted October 18, 2014 replaced fuses didnt even check them but no luck there, found out i had the coils swapped so its the exhaust thats not firing now. Quote Link to comment
StewyN Posted October 18, 2014 Author Report Share Posted October 18, 2014 i checked the coils too, both read right around 11000 Quote Link to comment
datzenmike Posted October 18, 2014 Report Share Posted October 18, 2014 Check power to the positive side of coil, if fuse is good should be about 12 volts. If there is power to the coil, briefly ground the negative side and you should get a spark. If there is spark the coil is good and possibly the wire to the distributor is broken or loose, or the ignition module has failed. No spark then the coil is bad. Quote Link to comment
StewyN Posted October 18, 2014 Author Report Share Posted October 18, 2014 im not sure i understand what your telling me to do, ground it to the body when checking or? Quote Link to comment
datzenmike Posted October 19, 2014 Report Share Posted October 19, 2014 Key on.Is there power to the exhaust coil + terminal?If NO, then find out why and fix this. Power should be supplied by the first fuse on the exterme left side of the fuse box, sorry I guess I did say right my badIf YES, briefly ground the - negative coil terminal and release. Coil should spark. A length of wire touched to the battery negative post or the engine block and to the negative terminal of the coil will work. When removed, the coil should spark.NO spark, the coil is bad.YES there is spark, wiring between coil negative and the distributor is broken or loose, or the ignition module in the distributor is bad. Quote Link to comment
StewyN Posted October 19, 2014 Author Report Share Posted October 19, 2014 ok so i have power and it did spark, so where shoud i go from here? Quote Link to comment
StewyN Posted October 19, 2014 Author Report Share Posted October 19, 2014 i hook a meeter up to the ignition control module an i get a reading where the intake wires hook but nothing for the exhaust, does this mean its toast? Quote Link to comment
datzenmike Posted October 19, 2014 Report Share Posted October 19, 2014 Check your wiring harness to the distributor. Does it have a three wire harness with a separate light or White color wire with it's own plug, like this...See the Black plug with the White wire?If it does, unplug the single White wire and try the coils again. Quote Link to comment
bryant2482 Posted October 19, 2014 Report Share Posted October 19, 2014 i would do the carb swap first and see what happens Quote Link to comment
StewyN Posted October 19, 2014 Author Report Share Posted October 19, 2014 No mine has a single wire that hooks to the distributor itself and a 4 wire plug red, white, blue, and black. no extras with eyelets like in the pic Quote Link to comment
CrazyHawaiian760 Posted October 19, 2014 Report Share Posted October 19, 2014 I had the same problem ...It's not the carb I had the wires crossed at the dizzy! Hook up a timing light like you where going to time it ....hit the button get the strobe going if the light goes out when the engine sputters its a ignition problem. I did that and sure enough the light went out every time the motor sputtered .So I started looking and noticed the wires where backassward. I so thought it was the Carb...I took the weber apart 7 times thinking there was something stuck in it! I even dropped the tank and cleaned it! Needless to say I got schooled this week:) Quote Link to comment
datzenmike Posted October 19, 2014 Report Share Posted October 19, 2014 so come to find out its only firing on the exhaust coil, does this just mean the intake coil is bad or? i would do the carb swap first and see what happens A carb swap cannot possibly fix an ignition problem, except to add more problems.. No mine has a single wire that hooks to the distributor itself and a 4 wire plug red, white, blue, and black. no extras with eyelets like in the pic Later models may have incorporated the white wire into the main harness. There is a spark shut off function where grounding the white wire turns off the exhaust coil. Maybe the vacuum switch that controls it is stuck on, maybe the wire is pinched and grounded...? Try and disconnect it. This is the last easy cheap check, if this does not allow the coil to work then the module in the distributor is most likely bad. Quote Link to comment
StewyN Posted October 19, 2014 Author Report Share Posted October 19, 2014 replaced icm with a junkyard one and the wire ends, had to they fell apart, and both coils firing now. Thanks a lot guys Quote Link to comment
datzenmike Posted October 20, 2014 Report Share Posted October 20, 2014 That works too. If my questions and answers dragged this out, I was diagnosing a problem from a distance. Those modules are well over $300 at the dealer. Auto supply are usually about half that maybe less. It's in everyone's interest to exhaust all possible (easy and cheap) fixes first, is all. Seen some, with a charging problem so they change the alternator (usually a totally inferior made in China unit) and it doesn't work, so they change the battery, doesn't work. Then the ignition switch. They come here and its a $7 fusible link but it still won't charge because the new alternator is a piece of shit and they turned in their perfectly good one for the core. Shit gets expensive. Quote Link to comment
StewyN Posted October 20, 2014 Author Report Share Posted October 20, 2014 yea it sure does, but thanks a lot for your help. i was really lost Quote Link to comment
bryant2482 Posted October 20, 2014 Report Share Posted October 20, 2014 from what he was saying it definetly sounded like the same issues i was having, and thats why i suggested the swap. hopefully you get it fixed Quote Link to comment
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