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car surges on the dyno... ignition problems?!

7K views 29 replies 9 participants last post by  grandville455 
#1 · (Edited)
OK here's what I've got... 427 Windsor 11.5:1 on pump gas I'm running a digital 6al box with a blaster coil. The box is in the trunk and the points wire is shielded. I'm running a fast xfi with a crank trigger which is also shielded. The fast and msd box are power and ground direct to the battery. The gap on the crank trigger is at .056 and the timing is spot on. The car ran fine other then a faulty TPS until about 6500. Right around there the car started surging. The AF was around 12.6. I'm thinking the coil is the problem because the car was only at 18 degrees of timing and it didn't matter where you set it, it would surge regardless. On thing I can see that might be a problem is the coil wires coming out of the msd box to the coil are really long. I added wire to them that was the same gauge and didn't read in the instructions the if i lengthened them I had to run bigger wire. I also think I'm at the limits of that coil and might have to go to an HVC 2 coil. Any suggestions would be appreciated. I'd post the graph but all I have is a print out.
One thing I did notice is that it didn't matter where the timing was or what fuel we used cuz we put 110 in it thinking that might be it but as soon as it started making around 450 HP and needing a hot spark to fire it is when it would act up.
:confused:
 
#2 ·
Blaster coil is a weak sister. One of these Ford coils will deliver much more energy to the plug with a CD box. Your local store should have an economy version of this for less than $20.

What plug heat range and gap are you using? If you aren’t using .025”, try that.

These work great, $20.00 price is right. If you search ebay there are some of the same for $12-13.00.


http://www.ebay.com/itm/Standard-FD-478-Ignition-Coil-Ford-Mustang-Bronco-LTD-Ranger-F150-NOS-Vintage-/160715325586?pt=Vintage_Car_Truck_Parts_Accessories&vxp=mtr&hash=item256b614092



This wire connector terminal plug is convenient because it has the second wire on the negative – terminal. With CD ignitions you can ground the coil negative terminal to the engine so the HV firing energy is direct to the plugs, not to the battery first and then back to the engine.



http://www.ebay.com/itm/PICO-WIRING-5712PT-Wiring-Harness-Pigtail-Ignition-Coil-3-Pin-Ford-Ea-/370573510337?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item5647e706c1
 
#3 ·
The gap is .035, I don't want to screw around the tfi coils anymore. The guy i talked to at msd said the blaster/street fire coil would fire it NA but wouldn't on spray which I plan to do next year. He said I'd need the 8253 coil on the juice so i think I'm gonna bump up my wires running to the coil and just put the 8253 on it now. As long as that even sounds like the issue. Which I can't think of anything else as of now. Everything is new.
 
#4 ·
If you have a known good TFI coil, try it for free. Otherwise, $20.00 or $200.00 …?? On the juice you should use .025” gap so do that now. What heat range plugs are you using? Have you checked the continuity of all the plug wires with an ohmmeter? A bad plug wire will make the rev limiter do strange things.
 
#6 ·
The coil I had on it at the dyno was a 5527 tfi coil. And the plugs are autolite 5924's. I had to shorten all my plug wires and I did test em with a meter after i was done. They all checked out right around 40 per foot which is what morose claims.
 
#7 ·
Two things, you said you had a Blaster coil and I meant a coil made to Ford specifications, not supplied to MSD by the lowest bidder. I would rather have a stock Ford coil than almost anything from MSD. The E-core is the difference in making the coil powerful in the secondary energy. The magnetic coupling the E-core provides is the key but the windings have to be there. A few cents of copper wire saved in each one when making thousands of coils is good economy for the manufacturer, not so good for the spark. I have used the $16.00 TrueTest version of the Standard Ignition 478 coil with an MSD 6AL on 500+ HP of bottle on a 14/1 510 BBC and get lots of spark mark on the plugs with nary a problem. In fairness, the coil and ignition box are closer to each other than yours.

No matter what coil you use, .035” is too much gap for the bottle.
 
#8 ·
I don't doubt that its too much for the bottle but isn't that just about right for my setup NA? Regardless of which coil i use going forward does it seem to you or anybody else that the coil I have now is the issue?
 
#9 ·
#10 ·
How am I supposed to tell you? I want to get some other opinions before I start throwing parts at it and take it back to the tuner not knowing if its fixed.
 
#12 ·
Yeah I agree with that one. I was hoping somebody would chime in that had a similar problem.
 
#13 ·
Just wondering when it surges what does the a/f ratio do at that time? Last year i moved my box and coil from under the hood to under the dash and re wired a bunch of it now it surges. I assume its something i did and not just the coil going bad. I went thru everything and never did find out for sure only thing i never tried was the pickup wires were loomed with some other wires not seperated. I went ahead and got the grid and coil this year and fixed the wires but havent tried yet to see if its fixed. But when mine surged going down the track it felt and sounded like i was on and off the throttle and the a/f ratio was pig rich. Just for reference it was the old holley strip annihilator and matching coil so i was due for something new but it worked flawlessly for 12yrs or so.
 
#14 ·
When it would start surging the AF would go rich. And watching the car it looked just like your describing like he was on and off the throttle. My pickup wires are routed away from everything other then where they go into the main xfi harness and its shielded wire. We watched the timing with a light and it stayed solid. We tried opening the gap on the crank trigger and it developed a hiccup like it skipped a. Couple teeth on the ring so we closed it back up a couple thousandths and that went away but the surge was still there up high around 6300 rpm
 
#15 ·
Anybody else have a clue? I'm gonna call msd tomorrow and see what they say about the difference between the two coils and how I have everything wired. I'd rather hear from people who've actually run these coils though.
 
#17 ·
Looks cleaner and its closer to the battery which according to what I've read its better to ground the box right to the battery.
 
#18 ·
The extension of the orange and black wires going to the coil from the box must be twisted like the trigger extension cord (green and purple) to provide as much EMF cancelation as possible. Those wires are transmitting and so they cannot be near the trigger wires.
 
#30 · (Edited)
So the Orange doesn't go to the + then? and vice versa, so orange to - and black to + is this for N/A Cars too? I use the shielded msd cable for my green and purple and those are reversed at the dist.
 
#19 ·
I'm not using the green purple or grey wires. Only the points and black/orange coil wires which run down the side of the car opposite any wires for the crank trigger or the xfi harness. Although I will twist the wires when i really do them in the larger size. It really doesn't seem like a wiring issue because that would be more intermittent. This only happens when the car gets high up and needs more fuel/spark. Its got plenty of fuel that's why I'm leaning more towards spark. It would be much easier if i could post the graph but all i have is a print out that they gave me. The horsepower curve is on a steady climb until about 2-300 rpm before it starts to surge at that point which is about 5800 the curve flattens completely then it starts to surge and by 6300 its bucking like hell but the really weird part is while its bucking it starts to build more power. Probably around 10-15 more.
 
#22 ·
Does this only do this on the dyno? Is it fine on the street or track? We had a similar situation two years ago on a dyno and thought it was the same thing (coil/box related). We eventually grounded the car chassis to the dyno with a heavy jumper cable and it went away. Since then the dyno owner drove a large ground stake outside the building and mega grounded the dyno. Had no issues since. I was one of a couple cars that ever did it on his dyno. I never had any issues on the street, but on the dyno it would buck and go nuts at about 5,800 rpms. I normally run 7,200 rpms at the track. I run a Digital 7 box, a HVC coil, crank trigger and FXi.

John
 
#23 ·
I ended up putting the blue hvc2 coil and ran larger wires to it from the box (10ga I believe) and the problems went away. I already had the chassis grounded in multiple places with heavy cables to welded studs but I did add grounds between both heads then to the primary ground for shits and giggles.
 
#24 ·
Windedv6... mine did it on the street also before I upgraded the coil and wiring.
 
#29 ·
Well thankfully I nor several of my friends around here that have done it have those issues. Proper routing can ensure that those things don't happen either.
 
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