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Formula ignition failure? by David Hambleton
Started on: 07-06-2014 04:05 PM
Replies: 7 (106 views)
Last post by: David Hambleton on 07-09-2014 09:44 PM
David Hambleton
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Report this Post07-06-2014 04:05 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Factory stock Formula 5 speed ignition failure - no codes - 25,000 km (15,500 mile)

I was driving along a highway at about 100 kph (60mph) when the engine started to miss severely; the tach needle was bouncing around some.

It lessened if I decelerated; if I accelerated it would backfire & shake. I went off at the next exit & limped home along the adjacent service road. It would run well enough some of the time, but I kept having to slow down.

It seems to idle ok & can accelerate gently but even with no load, opening the throttle will usually result in significant missing.

What should I suspect first?
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RWDPLZ
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Report this Post07-06-2014 04:07 PM Click Here to See the Profile for RWDPLZClick Here to visit RWDPLZ's HomePageSend a Private Message to RWDPLZEdit/Delete MessageReply w/QuoteDirect Link to This Post
Sounds like it's not running on all cylinders. Likely ignition, possibly fuel but unlikely. Start with the two fuel injector fuses, a visual inspection, and inspecting the spark plugs and wires.
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Patrick
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Report this Post07-06-2014 04:45 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by David Hambleton:

ignition failure

What should I suspect first?


ICM.

Read about my experience HERE.
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Jason88Notchie
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Report this Post07-06-2014 04:52 PM Click Here to See the Profile for Jason88NotchieClick Here to Email Jason88NotchieSend a Private Message to Jason88NotchieEdit/Delete MessageReply w/QuoteDirect Link to This Post
Plugged cat can cause similar issues.
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Patrick
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Report this Post07-06-2014 04:58 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Jason88Notchie:

Plugged cat can cause similar issues.


In my case, it was a plugged cat that ended up cooking the ICM.

In my experience, a plugged cat (by itself) will not cause misfiring. The engine just won't rev past... oh, 2000 RPM... as it can't breathe.

[This message has been edited by Patrick (edited 07-06-2014).]

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phonedawgz
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Report this Post07-06-2014 06:30 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by David Hambleton:


It seems to idle ok & can accelerate gently but even with no load, opening the throttle will usually result in significant missing.


and the tach flakes out during this.

Bad ignition coil. It does this more when there is more air in the cylinders requiring more voltage to jump the gap. The high voltage jumping to the primary of the coil will kill the ICM if you keep it up.

High resistance in the spark plug wires or too large of a gap will cause the spark to jump from the secondary of the ignition coil to the primary. Once the coil has had voltage jump from the secondary to the primary the insulation of the ignition coil is bad.

How is your pick up coil while you are dealing with ignition problems. if it looks like crap, is falling apart, replace it now unless you like getting stranded.




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Formula88
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Report this Post07-07-2014 12:57 PM Click Here to See the Profile for Formula88Send a Private Message to Formula88Edit/Delete MessageReply w/QuoteDirect Link to This Post
Only 25,000 km on your car? Does it still have the original plugs, wires, coil, etc? If so, I'd go ahead and replace them all due to age, even though the mileage is low.
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David Hambleton
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Report this Post07-09-2014 09:44 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanx for all the replies. A + for Phonedawgz - he called it!

The coil was working enough to get me home; after the engine cooled, it wouldn't start at all.

I tried the coil from my broken, swapped out '86 2.5L - it looks the same & has the same connections - '85 & '86 2.5L coils are the same number in the parts catalogue as the '85 to '88 2.8L.

I was surprised the two engines used the same coil... and the Formula is purring again!

[This message has been edited by David Hambleton (edited 07-09-2014).]

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