I bought a 91 car not running. It has been down for around 8 months the previous owner has some one work on it and they changed the computer and dis module and it did not fix it, it left the shop not running. I got the car home and checked the connections and tried to start, very weak spark. Installed a 89 dis from a friends car and it started right up it ran for about 3 minutes and died. Tried again no good. Changed back to the orginal dis and it started right up and ran for 10-15 minutes started running well idiling good and just died. Has not started since around a week. I tried the dis modules on my friends car and they both ran fine. I changed the crank sensor and still no start. Dis is grounded pin 7 case and bolt. My V-bat are good. I checked the crank sensor pip at pin 4 on dis by back probing and it is strobing on dmm it ranges from 6-12 vdc. The spout pin 5 seems to fire the same as pip from pin 4. The c1,c2,c3 pin 8,9,11 fire they have 12 vdc with key on and strobe 6-12 when key is in start position. v-bat is good on coil pack, replaced with good coil and still no start, when I use the led test light on the coil input wires they seem to strobe weak. All test were done back probing. Any suggestions would be greatly appericated.
just bought 91 wont start no spark
- Thread starter boss2553
- Start date
Have checked the balencer it is tight with no wobble, what is the best way to check out put to the coils from 8,9,11 on the dis, what will the voltage ranges be from 0 to 12? What is the best way to check the crank sensor out put. I have been reading the post and the dis digrams poated here but do not understand how they are actually checked.
thanks Mike
thanks Mike
Vince_Hayduk
Registered User
The EEC (computer) controls the spark, so yes a bad computer could prevent the car from running. That doesn't mean that a bad computer will automatically have no spark or that a computer with spark is good.
I would start from the beginning... especially since we know the car obviously had suspected electrical problems in the first place at the shop:
a) Try reading codes from the computer. Even if you just get a pass, it's good to know that at least the computer thinks it's healthy.
b) The crank sensor controls spark timing and the cam sensor controls fuel timing. Did you check the crank sensor wiring? I believe it has been known to fail mechanically.
c) Check all grounds; there are several. You can always put a jumper wire to a known good ground (- battery terminal) to eliminate it. Concentrate on the IRCM, DIS, coil pack and EEC.
d) Check all Vbatt wires under load. A corroded or damaged wire might show +12 with no load, but once there is current draw, it's no longer +12. In this case, check the coil pack voltage for sure while trying to start the engine. The coil gets power from a fuse. Check that as well to make sure it's properly seated.
e) Put a timing light on it and see what the timing looks like. If it's consistent and reasonable, that goes a long way to narrowing things down.
f) Check the ignition switch. I kind of doubt it, but they are known a separate (fall apart) and cause all kinds of havoc.
Can you describe how it quit when it was running? Did it just slowly die or was it instant?
As to running it without a S/C belt: yes it will run.
Vince
I would start from the beginning... especially since we know the car obviously had suspected electrical problems in the first place at the shop:
a) Try reading codes from the computer. Even if you just get a pass, it's good to know that at least the computer thinks it's healthy.
b) The crank sensor controls spark timing and the cam sensor controls fuel timing. Did you check the crank sensor wiring? I believe it has been known to fail mechanically.
c) Check all grounds; there are several. You can always put a jumper wire to a known good ground (- battery terminal) to eliminate it. Concentrate on the IRCM, DIS, coil pack and EEC.
d) Check all Vbatt wires under load. A corroded or damaged wire might show +12 with no load, but once there is current draw, it's no longer +12. In this case, check the coil pack voltage for sure while trying to start the engine. The coil gets power from a fuse. Check that as well to make sure it's properly seated.
e) Put a timing light on it and see what the timing looks like. If it's consistent and reasonable, that goes a long way to narrowing things down.
f) Check the ignition switch. I kind of doubt it, but they are known a separate (fall apart) and cause all kinds of havoc.
Can you describe how it quit when it was running? Did it just slowly die or was it instant?
As to running it without a S/C belt: yes it will run.
Vince
Vince,
I got the car not running, the owner said it was at a drive through and they were waiting in line it died and never ran again, no issue before that the had the car for about 5 years with no issues. They were not able to make run again new computer and dis, I got the car after the parts were changed. The car ran for me just about 15 minutes after a dis swap 3 minutes on friends dis and 15 minutes with the dis that came on the car. Had weak spark when I started working on the car after crank sensor swap I have no spark, I will have another new crank sensor in tomorrow. You said check the timing do you mean hook up and turn over motor is this to see if anything is goung through wires.
I have been checking grounds most are under 1 ohm. I will try to check v-bat while cranking and start ringing out wires, I can get a computer from a friends car but it is a 5 speed and mine is an auto a assume it will work to start the car.
Checked the codes 111,114.116.
thanks for the help
I got the car not running, the owner said it was at a drive through and they were waiting in line it died and never ran again, no issue before that the had the car for about 5 years with no issues. They were not able to make run again new computer and dis, I got the car after the parts were changed. The car ran for me just about 15 minutes after a dis swap 3 minutes on friends dis and 15 minutes with the dis that came on the car. Had weak spark when I started working on the car after crank sensor swap I have no spark, I will have another new crank sensor in tomorrow. You said check the timing do you mean hook up and turn over motor is this to see if anything is goung through wires.
I have been checking grounds most are under 1 ohm. I will try to check v-bat while cranking and start ringing out wires, I can get a computer from a friends car but it is a 5 speed and mine is an auto a assume it will work to start the car.
Checked the codes 111,114.116.
thanks for the help
Vince_Hayduk
Registered User
Yeah, use an inductive timing light to see what the actual timing is. This won't tell you anything about the quality of the spark, but it will help eliminate things. If the timing is right and constant, then we can eliminate the crank sensor and EEC. I've seen parts fail that cause the timing to be all over the map. When simply checking for spark (via a spark checker or spark plug), it looked "ok", but once we put a timing light on it, it was very obvious that the timing was jumping around all over the place.
The manual computer should work; at least to test it. I doubt the computer is bad, but you never know.
Those codes are interesting. 111 is pass, so no memory codes. 114 (ACT out of range) and 116 (ECT out of range) occurring together raises a flag for me. It is possible that these caused by the engine being cold when the test was run, but I doubt it. I'm betting that there is a wiring issues somewhere that is affecting these sensors as well as the ign circuit. Take a very careful look at the engine harness for obvious damage. Unfortunately, I don't have an EVTM (vacuum and electrical manual). If you can get the relevant pages from someone, it should show exactly how the sensors are wired as well as where they are grounded.
Vince
edspringer
Registered User
Try This!
I would check your EEC power relay. It controls everything. The relay is located in the power junction box under the hood. I just had an incedent with my SC thinking my problem was fuel since I had no fuel pressure. I replaced the ignition switch, IRCM, inertial switch and fuel pump assembly. About a $160 worth of parts, minus the IRCM that I already had. Finally determined the EEC relay was bad by swapping it with the, I believe, Fog Lamp relay. Anyway they were side by side and after I swapped them, my SC started everytime and now runs great. I took the bad relay apart and the contacts were burnt with minor pitting.
Ed
’94 SC Red Auto: 110,000 Miles, Headers, No Cats, Pro Torque 2500 Stall Converter, TRANSGO Shift Kit, 10,000 Lbs Auxiliary Tranny Cooler, Tranny Fluid Temp Gauge, 3.73 Gears, 70mm BK Throttle Body, 76mm C&L MAF with Gold Tube, A/F Ratio Gauge, Raised SC Top, Teflon IC Seals, ’90 XR7 SC Pulley, ARP Head-Rod-Main Studs, Scorpion 1.73 Rockers, Solid Motor Mounts, Iridium Plugs, Live Wire Plug Wires, Screamin’ Demon Coil, 36# Accel FIs, Custom Air intake, K&N 9” Cone, Royal Purple Synthetic Lubricants and Optima Yellow Top.
I would check your EEC power relay. It controls everything. The relay is located in the power junction box under the hood. I just had an incedent with my SC thinking my problem was fuel since I had no fuel pressure. I replaced the ignition switch, IRCM, inertial switch and fuel pump assembly. About a $160 worth of parts, minus the IRCM that I already had. Finally determined the EEC relay was bad by swapping it with the, I believe, Fog Lamp relay. Anyway they were side by side and after I swapped them, my SC started everytime and now runs great. I took the bad relay apart and the contacts were burnt with minor pitting.
Ed
’94 SC Red Auto: 110,000 Miles, Headers, No Cats, Pro Torque 2500 Stall Converter, TRANSGO Shift Kit, 10,000 Lbs Auxiliary Tranny Cooler, Tranny Fluid Temp Gauge, 3.73 Gears, 70mm BK Throttle Body, 76mm C&L MAF with Gold Tube, A/F Ratio Gauge, Raised SC Top, Teflon IC Seals, ’90 XR7 SC Pulley, ARP Head-Rod-Main Studs, Scorpion 1.73 Rockers, Solid Motor Mounts, Iridium Plugs, Live Wire Plug Wires, Screamin’ Demon Coil, 36# Accel FIs, Custom Air intake, K&N 9” Cone, Royal Purple Synthetic Lubricants and Optima Yellow Top.
supercoupe519
Registered User
Im having the same problem, THE ACT AND ECT temp. sensors are FINE dont change them, itll cost you about 80$ to change both of them and there fine. I did the same thing, i changed both sensors and i still got the code, it IS due to the fact the engine is cold. Other than that, i have no help for you other then not to replace the sensors because its a waste of time. A class A mechanic is comming to look at my car sometime this week to see what the problem is seeing that i replaced already the Coil pack, Ignition switch, Sparkplugs and wire, EEC, Crank Sensor, Cam sensor, DIS, and the 2 temp sensors, and still not running. My fuel pump runs strong and my injectors pulse and give out fuel and my timming is right on.. FAST CARS BUT FORD HIRED A BUNCH OF KINDIGARDEN KIDS TO DESIGN THESE CARS... UNLESS you totally rebuild the engine with stronger parts your as*s fu**cked..
got some time on car to night
worked on car for a bit,
changed back to orginal coil and cam sensor reseated the dis
before i had 6-12 vdc at coil for some reason not dropping to 0v
now only 9vdc at pin 1 on dis and c1,2,3 and voltage at coil, restiance at pin 7 on dis 6 ohm, unplug dis and 12vdc at pin 1, cleaned an reseated dis still 9 vdc used silver fox from radio shack. cleaned screws and everything still v drop loosened an got 11vdc with screws loose but v drop to around 8vdc at crank, battery stays at 12 vdc when cranking. I will try another dis, can you put to much silver fox on the dis plate. I will start tracing back the vbat and see if i find something if the dis change does not help. any suggestions would be appreciated
worked on car for a bit,
changed back to orginal coil and cam sensor reseated the dis
before i had 6-12 vdc at coil for some reason not dropping to 0v
now only 9vdc at pin 1 on dis and c1,2,3 and voltage at coil, restiance at pin 7 on dis 6 ohm, unplug dis and 12vdc at pin 1, cleaned an reseated dis still 9 vdc used silver fox from radio shack. cleaned screws and everything still v drop loosened an got 11vdc with screws loose but v drop to around 8vdc at crank, battery stays at 12 vdc when cranking. I will try another dis, can you put to much silver fox on the dis plate. I will start tracing back the vbat and see if i find something if the dis change does not help. any suggestions would be appreciated
Any is too much - despite the trend to use it where it doesn't belong.
Dielectric grease is what the factory uses, repair manuals recommend and what's been used on similar modules in the past. These things have enough problems without introducing others
I had one SC lately act like a bad camshaft/crank sensor was the problem...pulled the DIS and found a bunch of heat-sink paste. Cleaned it off, applied dielectric and reassembled. Problem gone.
Really, I don't know where the urban myth to use heat-sink paste (which transfers heat into the module - ouch) came from, other than someone having it on hand instead of dielectric grease, but with some owners having to install multiple DIS modules, it wouldn't surprise me to learn the wrong material is related to their problem(s).
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Vince_Hayduk
Registered User
KMT: Dielectric grease is an insulator and not a great conductor of heat. What would be the purpose of putting it on the back of the DIS? The whole point of mounting the DIS to that bracket it to prevent it from overheating and to provide a good ground (via the mounting screws). Dielectric grease does neither. Do a search... if you run a dis module without bolting it down (to transfer heat away) it will fry. I beg to differ about putting heat into the module from the engine. I'm pretty sure the dis runs hotter than that bracket under normal operating conditions and as such, the bracket acts like a heat sink. People have reported temps up to 300F on the dis. They obviously run too hot, which is why they were relocated. If they didn't need heatsinking, then they wouldn't have the nice machined back. That being said, yes it is possible to go overboard with HS compound. A nice even thin layer is all that is needed.
Back to the issue at hand:
I think you're on the right track in trying to figure out why you don't have 12VDC @ pin 1. I'm just speculating here, but my guess is that 9 Volts isn't enough to drive the transistors in the DIS fully on which is giving you the 12 Volts to 6 Volt drop at the coil instead of 12 Volts to 0 Volts.
When measuring resistance at pin 7: Did you measure from 7 to ground with the dis plugged in? If so, that should be close to 0 Ohms. One (or more; I can't remember) of the mounting screws on the dis should have a metal "eye" that is used to ground the module via the screw. Run a small jumper wire from there to a known good ground (like battery -).
Vince
Back to the issue at hand:
I think you're on the right track in trying to figure out why you don't have 12VDC @ pin 1. I'm just speculating here, but my guess is that 9 Volts isn't enough to drive the transistors in the DIS fully on which is giving you the 12 Volts to 6 Volt drop at the coil instead of 12 Volts to 0 Volts.
When measuring resistance at pin 7: Did you measure from 7 to ground with the dis plugged in? If so, that should be close to 0 Ohms. One (or more; I can't remember) of the mounting screws on the dis should have a metal "eye" that is used to ground the module via the screw. Run a small jumper wire from there to a known good ground (like battery -).
Vince
Vince
Vince,
thanks for the info.
yes 9v is just a bit two low to drive the transistors. they fired once last night to the plug. it would throw a weak spark at the end of cranking when i let off the key, i need to check the ingnition switch also.
At first i had with key on 12v at all c1,2,3 to coil when crank then drop to 6v to 12v.
I changed back to orginal cam sensor and coil no impact to problen i think.
reseated dis and get 9v with key on and 0v to 9v when crank. cleaned and reseated still the same.
checked restiance at pin 7 it was around .7 ohm, before it was almost 0 which makes sense with the v change except dropping to only 6v.
Vince,
thanks for the info.
yes 9v is just a bit two low to drive the transistors. they fired once last night to the plug. it would throw a weak spark at the end of cranking when i let off the key, i need to check the ingnition switch also.
At first i had with key on 12v at all c1,2,3 to coil when crank then drop to 6v to 12v.
I changed back to orginal cam sensor and coil no impact to problen i think.
reseated dis and get 9v with key on and 0v to 9v when crank. cleaned and reseated still the same.
checked restiance at pin 7 it was around .7 ohm, before it was almost 0 which makes sense with the v change except dropping to only 6v.
Vince_Hayduk
Registered User
How does the car crank? I mean, is it nice and fast like it is supposed to or does it "drag"? Have you checked voltage (while cranking) at the fuse box? Maybe the main batt cable has gone bad and the whole system is dropping to 9V while cranking?
Definitely check the ign switch at this point. They are known to go bad and once that happens... who knows.
I wouldn't worry about 0.7 Ohms; that's negligible.
The 0 - 9V: is that @ c1,c2,c3? If so, that sounds right. Now you just need to get that to 12V instead of 9.
I was also going to suggest pulling the fuel pump fuse or tripping the inertia switch in the trunk to prevent flooding. If you've had fuel all this time, you might need to change the plugs before it will start (once you get the ignition problems figured out).
Vince
Definitely check the ign switch at this point. They are known to go bad and once that happens... who knows.
I wouldn't worry about 0.7 Ohms; that's negligible.
The 0 - 9V: is that @ c1,c2,c3? If so, that sounds right. Now you just need to get that to 12V instead of 9.
I was also going to suggest pulling the fuel pump fuse or tripping the inertia switch in the trunk to prevent flooding. If you've had fuel all this time, you might need to change the plugs before it will start (once you get the ignition problems figured out).
Vince
Young-SC-Owner
Registered User
Id say check grounds and cables,
they will corrode on the inside causing a HUGE voltage drop
they will hold voltage but little amperage
they will corrode on the inside causing a HUGE voltage drop
they will hold voltage but little amperage
v drop
thanks good sugestion on the fuel it is flodded now the oil smells of gas, how do you change the plugs on these things,I can only see 1.
The battery holds good v when cranking. and the 0 to 9v is at the c1,c2,c3 at the coil and out of the dis, i have sweing pin probed in my harmess for check points.
I might get 2 AA batterys and add to pin 1, just joking I work on some 24vdc drive stuff and have biased them with 3 9v batterys. I will start looking from the battery out to find a drop. I am sure it is a simple problem ones like these always are, I tell you robots and maching equipment is alot eaiser to work on, good prints and room to work on.
thanks good sugestion on the fuel it is flodded now the oil smells of gas, how do you change the plugs on these things,I can only see 1.
The battery holds good v when cranking. and the 0 to 9v is at the c1,c2,c3 at the coil and out of the dis, i have sweing pin probed in my harmess for check points.
I might get 2 AA batterys and add to pin 1, just joking I work on some 24vdc drive stuff and have biased them with 3 9v batterys. I will start looking from the battery out to find a drop. I am sure it is a simple problem ones like these always are, I tell you robots and maching equipment is alot eaiser to work on, good prints and room to work on.
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Vince_Hayduk
Registered User
I'm not surprised it's flooded Once you've got spark, change the oil and sparkplugs before you fire it up. There is tons of info on this site about changing sparkplugs; do a search. Here is one for starters:
http://www.sccoa.com/forums/showthread.php?t=76189&highlight=sparkplug
Put the ignition switch and main relay as the first items on your list to check.
I agree that electrical problems on vehicles are a real PITA. Especially when people try to be cheap by using the body as a ground.
Vince
Once you've got spark, change the oil and sparkplugs before you fire it up. There is tons of info on this site about changing sparkplugs; do a search. Here is one for starters:http://www.sccoa.com/forums/showthread.php?t=76189&highlight=sparkplug
Put the ignition switch and main relay as the first items on your list to check.
I agree that electrical problems on vehicles are a real PITA. Especially when people try to be cheap by using the body as a ground.
Vince