Ford Cougar (1998 - 2000) - 99 2.5 v6 intermittent low rev engine hesistation

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Sun 27 Jul 2008 19:45
99 2.5 v6 intermittent low rev engine hesistation - spyceman
When i changed the spark plugs about a month ago i noticed that 1 cylinder was fitted with a short reach spark plug.This aroused my suspicion.However the car was running perfectly so i didnt worry about it.In the past sometimes when starting the engine the rev counter and speedo needles would osciliate together and the locking mechanism could be heard clickingin the doors.On several occasions the time clock had to be reset indicating the battery was loosing charge.Anyway one morning the battery packed in so replaced it.The rev counter and speedo have behaved since changing the battery.The problem now is a hesistation or misfire at engine speeds between 1200rpm to 2300rpm.I am debating whether to refit a new short reach plug to the one cylinder or to change the H.T leads.Part of me thinks the problem could be related to the faulty battery.Any ideas???Please help.Thanks!

Edited by Pugugly on 27/07/2008 at 19:54

Reply | Report as offensive | Link
Mon 28 Jul 2008 07:12
99 2.5 v6 intermittent low rev engine hesistation - Andrew Moorey (Tune-Up)
The short reach plug is wrong. HT leads problematic on these especially the rear bank as they are slightly more awkward to change. Suggest you fit a new set (come in two sets of 3 leads) and a fresh set of the correct plugs.
Depending how long its been running for with the short plug there may be a bit of carbon build up in the lower threads so you may want to use the old dodge of making a hacksaw cut along the threads of an old plug, coat the threads with grease and screw it into the hole to act as a makeshift tap to clear the thread.
Andrew
Reply | Report as offensive | Link
Tue 29 Jul 2008 02:57
99 2.5 v6 intermittent low rev engine hesistation - spyceman
Replaced spark plugs 6 weeks ago with bosch HR8.Engine was running sweet.The occasional hesistation problem only seemed to occur just before battery failure.I have disconnected the battery and left over night in order to reset the ECU.This made no difference.I thought it strange that a short reach was in cylinder 3 and wonderered if a normal plug had been fouling up.Ford told me that when these engines were first launched they used short reach. But like i said the car was running great after changing the plugs.Anyway i think i will change the leads although they cost the best part of £80 from ford but just got the feeling something else is wrong.Maybe i will find a cheaper set somewhere else!Although the fault is intermittent do you think the engine management light would come on if it was the leads faulty?Thanks for your response.Cheers mate.
Reply | Report as offensive | Link
Tue 29 Jul 2008 07:21
99 2.5 v6 intermittent low rev engine hesistation - Andrew Moorey (Tune-Up)
There are few faults which will put the light on but there well may be faults logged on the ECU memory. Always worth getting them read and cleared as a first port of call before throwing money at it. Bear in mind you will have erased any codes logged by disconnecting the battery so any codes now stored will be fresh.
Andrew
Reply | Report as offensive | Link
Tue 29 Jul 2008 09:44
99 2.5 v6 intermittent low rev engine hesistation - spyceman
Th e light has never come on but i think i will get a diagnosis scan.Thanks Andrew.
Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide

From which small car to buy at which price point to the best UK-built cars, our Top 10s have the lot. Click now for your shortlist.

Unsure of what to buy? Our Top 10s are here to help you....