Looking for a point in the right direction

[CharlesE221]

Hi all, I have an issue with no spark on my 85 Conquest (5spd, only mod is MSD Blaster 2). I've read through many of the other posts on here about no spark and tried all the solutions offered. Still nothing helps. I've combed through the FSM manuals and still don't know what to do. So far I've:

• Changed ignition coil
• Changed distributor
• Replaced Knock box with another 85
• Confirmed every grounding point is good
• Confirmed ECU is getting power
• Replaced distributor cap, rotor, and spark plug cables
• Replaced Spark plugs

I for sure wasted money on unnecessary replacements but I am really itching to get this car working and this is one of my last major hurdles. This problem only appeared after I changed the head gasket. While I had the head off I was messing with the relays to figure out another issue with my headlights I'm putting off, but I'm confident I put everything back how it was before I messed with them.

I probably made a dumb mistake that I can't for the life of me figure out. Any advice or point in the right direction would be much appreciated. Thank you for any advice.

 

[tux]

Visible no spark?  Did you try hold plug wire near bear metal while someone else cranks?

If no spark, make sure you  have wires on the correct terminals of the coil and all the wires are there 

[CharlesE221]

2 hours ago, tux said:

Visible no spark?  Did you try hold plug wire near bear metal while someone else cranks?

If no spark, make sure you  have wires on the correct terminals of the coil and all the wires are there 

Yeah, that's how I've been testing to see no spark. I even got an inline spark plug tester to confirm and that doesn't have spark. I'll double check to make sure I have the wires on the correct part of the coil. I hope it's something as simple as this haha

[tux]

Inline spark testers have been hit or miss for me

[mikec]

Do you have a basic multimeter?  They are pretty much a necessity to diagnose a StarQuest.  The ignition circuit is one of the easier things on this car fortunately.  The schematic diagram fills a full page - and is chock full of wires - but only half of it is really necessary; the rest is stuff to/from the ECU that tweaks the fuel delivery.  The ignition system itself will operate independently of the ECU - no ECU signal to the ignition system is required.

Basic operation: when the ignition key is in START, or when the ECU "sees" pulses from the ignition system (same pulses that drive the dash tachometer), the "ECI Relay" is turned ON.  This relay is what supplies power to the fuel pump, fuel injectors, and ignition system.  That relay is underneath the dash... screwed to bodywork below the windshield "A" pillar and next to the glove compartment so I doubt it was any of the relays you messed with during the head gasket job.  Two fusible links - those inverted "U" shaped wires near the battery - are involved however and are common "sore spots" on these cars.  Those links, the box they are in, and the beefy wires coming from the box to a 3-pin connector a few inches below the box, are common electrical trouble spots on these cars.  The first/#1 link should be red and is specifically for the ignition system and everything powered by the ignition switch ON and ACC positions, the second/#2 link is the "ECI" link that handles the majority of the fuel system and that ECI relay.  Link #3, another red link, feeds things in the car that work without the ignition key in the ON/START/ACC positions such as the brake lights.  So any of those links could be an issue.  With a multimeter set to read DC Volts, you can probe each side of the link, relative to the battery "-" post, for +12 volts.  On a typical "analog" multimeter (those with a mechanical needle pointer) the scale will be something like "15V DC"; on a digital meter it will generally be "20VDC" or "20V DC."

Next, with the ignition key in the ON position, use the meter to look for battery voltage on the "+" post of the ignition coil, again relative to the battery "-" post which is also ground.  That ignition terminal should have a black+white wire attached to it.  No voltage?  Then the wires from the battery to the fusible link box

With the key ON and the engine not running, you should also have +12 volts on the "-" ignition coil post (which should have a blue+white wire on it and a wire feeding one of those radio noise suppression gizmos that is screwed to the chassis) as well as the center high-voltage output post.

Still no joy in Mudville?  Look at the EGR valve and the clip below it: that clip should be holding a connector from the distributor.  Open that connector.  Inside you should see two terminals on the connector side going to the distributor.  Put your multimeter on a resistance measuring scale that measures up to 2000 ohms.  On digital multimeters that will be a "2000 ohms" or "2K ohms" scale, "ohms" may be listed by a greek Omega letter.  On an analog meter, look for settings like "x1000" or "x10000" which means "multiply the ohms scale on the meter display face by 1000 or 10000 to determine the resistance."  Touch the two multimeter wires together; the display should read close to 0.0 on a digital meter and swing all the way to the right on an analog meter.  If not... you don't have the meter configured correctly for reading resistance.  Once the meter is configured properly, touch the meter probes to the two posts inside that connector from the distributor.  You should see a reading in the 1000 ohms ballpark.  If so, the "pick-up coil" inside the distributor (aka "Distributor signal generator" in Mitsu's service manuals is likely okay.  Re-connect that connector.   One one of the two screws holding that clip you should have a black ground wire running towards the fender and the general direction of the ignitor box...

Last: when you re-assembled the cyl head, you did get the stubby extension shaft on the front of the camshaft and cam drive sprocket re-installed, right?  That's what drives the distributor and the pick-up coil.  There is a small metal roll pin, aka shear pin, that connects this shaft to the camshaft and chain sprocket.  That little pin should be brand new; trying to re-use an old one can cause problems as old ones may not fit as tightly as they should and could easily slide out... and fall into the engine somewhere.  Without that pin, the timing chain may not drive the distributor properly.  Take the distributor cap off, unplug that connector from the pick-up coil, and have a buddy try starting the car.  Can you see the distributor rotor spinning?  If not... you've got a mechanical issue with the timing chain, that roll pin, etc.  Re-connect that connector before you forget it again.  Did you do anything with the timing chain during the head gasket job?  I can't remember if there is a Woodruf key or index pin locking the crankshaft to that sprocket (most engines have such things, StarQuest engines have Woodruf keys on the balance shaft sprockets); if the sprocket was removed or even slid out of position a bit that key/pin may have fallen out so the entire timing chain stuff fails to rotate with the crankshaft.

That's really all that is required to "get spark" on these cars.  If those tests pass I would strongly suspect the ignitor module.  I know you said you tried a second one... but how do you know it is functional? 

mike c.

For the total rookies out there: the ECU does not trigger spark on these cars; instead the rotation of the distributor shaft induces tiny voltages in the pick-up coil.  The ignitor triggers off those pulses.  The ignition timing is set by the distributor, by the centrifugal advance mechanism inside the distributor (those odd weights and springs), and the vacuum advancer mechanism... just like a 1970s carbureted car with "electronic ignition."  On more modern cars the ignition is handled by the main ECU... StarQuests are "tweeners" in the engine world: somewhere between old-style carburetors with basic electronic ignition and modern fully-computer-controlled fuel plus ignition systems.  The StarQuest ignition system is a 1970/s1980s electronic ignition system with a few enhancements; the StarQuest fuel system is best thought of as an electronic carburetor.

[CharlesE221]

I looked at the ECU links and the #1 was good at the bottom, but the top one had massive fluctuations in the reading. I made a new wire link and the readings are back to normal. Unfortunately my ignition coil isn't sending a spark. I have the distributor end of the wire up to a suspension post and I'm not seeing any spark like I have before. I've double and triple checked the diagrams and your post to make sure the wiring is correct, I went back to a coil I know worked at one point and still no spark.

My dash is currently being worked on so the only test I've seen for knockboxes are to see if the coil is sending a spark to a post, which it isn't. I might try opening one up to see the condition inside but it looks like I need to find a new knockbox? Might be worth trying to upgrade to an 89 but I've heard I need do some wiring work since it's not a direct fit. Wouldn't be to hard I would just need to know if the wires were color coded 1-1 between generations.

Thank you so much for the information, it looks to be a massive help in getting the car back in order.

[TexasQuest]

2 hours ago, CharlesE221 said:

I looked at the ECU links and the #1 was good at the bottom, but the top one had massive fluctuations in the reading. I made a new wire link and the readings are back to normal. Unfortunately my ignition coil isn't sending a spark. I have the distributor end of the wire up to a suspension post and I'm not seeing any spark like I have before. I've double and triple checked the diagrams and your post to make sure the wiring is correct, I went back to a coil I know worked at one point and still no spark.

My dash is currently being worked on so the only test I've seen for knockboxes are to see if the coil is sending a spark to a post, which it isn't. I might try opening one up to see the condition inside but it looks like I need to find a new knockbox? Might be worth trying to upgrade to an 89 but I've heard I need do some wiring work since it's not a direct fit. Wouldn't be to hard I would just need to know if the wires were color coded 1-1 between generations.

Thank you so much for the information, it looks to be a massive help in getting the car back in order.

If you do decide to upgrade the knock box, I have a spare pigtail for it.

[CharlesE221]

I might be interested in doing so, is there a thread that gives a good explanation on how to wire the new ones up to an old harness?

[GoldStar]

1 hour ago, CharlesE221 said:

I might be interested in doing so, is there a thread that gives a good explanation on how to wire the new ones up to an old harness?

EDIT: Missed the part where you said yours is an 85, so the below info may not be 100% accurate:

It's really straight forward, the wires/pinouts are 1-1 except for 2 end wires on the 88+ connector; they're for the wastegate that the 87s don't have. See:

Some advice from personal experience; make sure your car runs before soldering/crimping the white wires. There are 2 in this connector, and if you cross them, it won't start

Edited December 6, 2022 by GoldStar