Not firing on all cyls??

[Shauns GT]

1991 2.3 na dual plug head
new wires and coils
newer plugs

My car seems to have spark issues, runs a bit rough at idle. using a timing light and hooking up to each individual wire. find that cyl 2 and 4 fire perfect but 1 and 3 the spark seems to cut out as the rpms increase. by spark im refering to the strobe from the timing light. swaped plugs with cyl 1 and 2 and still stayed a mis on cyl 1. anybody have any idea?

 

[stykthyn]

try unplugging your IAC and re-setting your idle.

 

[Stinger]

Does the tach also sometimes show "half" of the actual rpm? It is most likely an ignition module failure.

 

[Shauns GT]

No tach reads ok. The only other possibly related symptom is that the idle jumps up and down right when you first start the engine cold. How is resetting the idle performed? Does the ign module on the intake separate cyls or just controls coil operation in general?

 

[stykthyn]

unplug the battery for 20 minutes
unplug IAC
connect battery with IAC unplugged, start the engine and use the set screw to adjust your idle. I like mine around 850-900.
turn engine off and plug your IAC back in.
start your car and it should run fine.
after I had a vacuum hose break my car idled like crap even after I fixed it. it didnt clear up until I did this.

the ignition module tells both the coils when to fire. a jumpy tach is often an early indicator that one is malfunctioning. they tend to go without notice. could be tomorrow or a year from now. If you can get the idle cleared up then I would just drive it until the module fails altogether.

 

[Stinger]

If you write down the plug wire locations on the coils, then switch the coil locations and see if the dead cylinders move with the coil or stay in place. Moving means the coil is bad. Not moving means most likely the ignition module.

 

[Shauns GT]

well i thought id try and swap the ign module with a spare that i got off of my junk 2.3 ranger engine. bolted it on and plugged it in, car no start. must be bad module. put my original module back on. bolted and plugged in, again car no start.
took both modules to Napa today and tested and both sides of each coil failed. assuming we tested them right with the machine. so ordered a new module gonna try it tommorrow. did i do something wrong or did i fry the module by unbolting it?

 

[Shauns GT]

Installed new module. car starts now. however still back to original condition that i was trying to fix by switching the modules in the first place. so car has new ign module, one new coil (for rh bank plugs) new wires and found that swaping plugs between cyls changes nothing. cant even check timing with number 1 plug wire as it hardly flashes. Is it possible that the spark plug wires are mixed up? I have tried switching a few with worse results but the engine was replaced and almost completly disassembled a while ago? im stumped!

 

[stykthyn]

have your checked your IAC and TPS???
also a vacuum leak can cause erratic idle. check the vacuum tree on the firewall

 

[Ponycar]

Check thread - Did the mechanic screw me? Need my car help! - 01-13-07, 09:07 PM
I posted a diagram of the correct firing order

 

[Shauns GT]

ok getting mad now.
The new module that i installed seemed to be working. All of a sudden after
2 days of driving the car is stalling, losing spark on me on the highway when engine is under load, like at the first gradual hill down the road from my house.
Anyways car all of a sudden halfway up hill tach jumps around and the car starts losing power fast so i give it more gas, no good loud bang and car stalls. pull over to see if muffler still in one piece. look under hood no oil on ground. get back in and on second try car starts and seems to run ok back to my house. when i came home from work later i started the car, which cranked for longer than usual but started, i drove it into the shop and pulled off the new module. got another module from napa and now the car wont start at all. I have 2 used modules and 2 new modules and wont start with any. swaped in another crank sensor but that made no change. Please help ive been trying this on my own for 4 days now i cant figure out why no spark. lots of fuel pressure and cranking power just no spark?

 

[Stinger]

All of that sounded exactly like the ignition module dying. Just because you bought a new one doesn't mean it works. Brand new "parts store" modules are known to be faulty from time to time. I'd take it back.

Did you put the white grease under the module when you installed it? It is necessary, otherwise the module overheats and dies.

 

[Ductape91]

my car was having feeling like it was losing spark so i had the icm tested and was told it was bad(it wasnt). couldnt afford to buy a new one anyway so at the time i put the old back on but noticed how dried out the grease was on it(from the intake getting hot many times) after cleaning the area and module i applied new grease and havent had a problem since, 2 months later(knocks on wood)
also noticed the module was installed upside down (from when my brother owned the car)but not sure if it matters
like stinger said dont forget to use the dielectric grease on the module, and to clean the mounting surface too.

 

[Shauns GT]

ok. I installed new module #3. cleaned off intake and applied a coat of dielectric
grease and plugged in. still no spark. i have spark tester on in place of #2 plug.
the coils both show power at the 3 wire connectors at each coil. now unless im mistaken spark occures when coil power colapses, which means coil has to loose either power or ground. i believe that ground is supposed to be switched on and off to do this. this is suoopsed to be done by ign module. so my question now is what controls the ign module? My guess is crank sensor. however i have swaped my crank sensor with that off my parts engine. does anyone have a way to test and see if the crank is sending a proper signal. I got a diagram of the wires from another thread "help car wont start" but it doesnt say what each of the 4 wires does or goes. The manual i have here is haynes and doesnt have proper wire diagram for 91-93 dual plug engines!!!!!

 

[Shauns GT]

Success!!!!! Car runs again turns out it was a bad connection at the ign module for wires 7-12. (the grey plug on the bottom of the module. I will start a new thread with my findings so as others might be able to slove there no starts in this same manner but in ALOT less time! Thanks for your help everyone!