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Fully functioning spark and how TCM interprets throttle angle

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Fully functioning spark and how TCM interprets throttle angle

Post by precopster » Mon Aug 06, 2018 1:43 am

Recently I had a CEL for a coil pack. I waited until the CEL remained lit as previously it was flashing under hard throttle. Cylinder 4 was the culprit as found by my $4 ELM327 scanner.

I pulled cylinder 4's coil pack and found a severely split boot and a cracked casing. I swapped it out with a used coil pack from a pick and pull.

Immediately I noticed an increase in performance back to when I had sorted all the gremlins such as VVT solenoid and failed sensor 1 on the ETM. Another thing I noticed is that the 1-2 shift became noticably softer. It was excessively harsh for almost a year. Many of you may recall that I had a blocked transmission filter last year which stopped my car from driving at all. After pushing the filter media aside the shifts were pretty good. In fact they weren't far off new vehicle standards.

Then in about 3 months after the transmission work the harsh shifts from 1-2 re-appeared. I had noticed a drop in performance but it was temperamental. Some days it was normal T5 neck straining greatness and other days it was awful with surging and un-linear performance. It was as though the car was possessed.

After the coil pack swap I'm back to that linear smoothness and great performance as well as almost perfect shifting of the auto. I also had a badly surging Cruise function which would accelerate if I set the speed and pressed the throttle at the same time.

If I had known a partially operating coil pack could have affected the transmission's shift behaviour so radically I would have investigated earlier. Just goes to show how sensitive these earlier turbo cars can be :D :D

Any similar experiences or comments welcome....
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Re: Fully functioning spark and how TCM interprets throttle angle

Post by abscate » Mon Aug 06, 2018 3:17 am

Wow. I know they are pricy but it seems like a PM model, replacing coils every 100k, might be in order.
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