Hesitation under load - How to cure (1 solution).

The mgf (mk2) is like the TF and has two coilpacks above the spark plugs. Each coilpack serves two cylinders.
Ours had been misfiring occasionally under load. Absolutely fine at tickover and normal driving, just accelerating from low speed.
Replaced the plugs, that made it slightly worse! Changed the two Plug leads, but that was no better. Damn!!
As Mk2 MGFs and all Tfs are OBD2 compliant I got myself a cheap OBD2 reader off Ebay and plugged it in to the diagnostic socket(above the fuse box under the steering wheel). It showed only one fault code - Cylinder no. 1 misfire.
Now you mightl know that cylinder no. 1 has a coilpack sitting on top of it, but a faulty coilpack would mean two cylinders misfiring so I was stumped for a while. So I had a cup of coffee and thought about it.

Aha! It had to be the connection from the coilpack to the spark plug underneath it.

So I removed the coilpack and eased off the rubber cover exposing the spring connector.
Mmm! Where the steel spring is attached to the bottom of the coil(alloy) there was a substantial amount of corrosion-No real surprise when you consider that you have alloy and steel in close contact with electricity running through them!

Any way, I removed the spring, and cleaned it up. then I cleaned away the crap off the alloy and tightened up and refitted the spring. Put the rubber cover back on, and refitted the pack.
Just to be thorough I cleaned up the other coilpack as well before I put it all back together, and guess what? -Mgf running beautifully, no hint of a misfire! Even trying to accelerate from 20mph in 5th.

I suggest that anyone with these symptoms investigate your little springs before resorting to buying new coilpacks.
I hope this is of help to someone.

David

P.s. Be aware that the rubber covers under the coilpack can become fragile with age and engine heat. One of mine broke in half and I had to create another from the old plug leads.

This hesitation under load began to happen again. The OB Diagnostics showed Cam Sensor fault.
I changed the Cam sensor And the hesitation has gone. :broon:

You need to be aware that a misfire can throw up a camshaft sensor fault, so if you also show a misfire code on OBD, there may actually not be a faulty sensor. In my case the cam sensor fault kept reappearing after clearing the faults.

Hi David it was more than likely it was the cam sensor all the time

Hi David . Just thought I would say thanks for the 'Hesitation How To' Just applied it to my TF after its winter hibernation as I noticed the very same type of 'Miss' when the car was pulling in higher gears . It was a spot on diagnosis, as a mass of corrosion was found on the lead to No 1 plug at the coil pack end. After some careful and lengthy cleaning , re fitted the lead and road tested with excellent results . Top man ! Thanks, John

thanks very helpful