Author |
Topic: misfiring badly at 50 mph (Read 7334 times) |
|
pedropedro
Full Member
Posts: 677
|
 |
misfiring badly at 50 mph
« on: Sep 15th, 2011, 1:03pm » |
 Quote  Modify
|
2.3 recently sorted wiring issue edis/ecu.........now has a problem at 50mph +/- 5mph I can feel the engine sort of jerking.. missing a beat if that makes sense ..almost feel a jump. like drive train backlash
drives perfectly at all other speeds; doesnt miss a beat at 70 plus...idles perfectly...could it be coil packs/injectors ?? but if it were would it run smoothly at 70 and idle ok ..dont know where to start ....any input appreciated
|
|
 IP Logged |
|
|
|
Scorpio_Mike
Senior Member
Jeep Grand Cherokee 3.0 V6 & 2.8 Sierra XR4i 4x4
Posts: 2354
|
|
Re: misfiring at 50 mph
« Reply #1 on: Sep 15th, 2011, 1:07pm » |
Quote Modify
|
Sounds like coil packs or wiring 
Have you cleaned the MAF ?
|
|
IP Logged |
Star sign is Scorpio !
Sierra XR4i's are great...especially when fitted with 4WD 
|
|
|
pedropedro
Full Member
Posts: 677
|
|
Re: misfiring at 50 mph
« Reply #2 on: Sep 15th, 2011, 1:29pm » |
Quote Modify
|
yes cleaned maf...tks for comments
|
|
IP Logged |
|
|
|
Mike H
Senior Member
Renault Clio
 
Posts: 2594
|
|
Re: misfiring at 50 mph
« Reply #3 on: Sep 15th, 2011, 1:47pm » |
Quote Modify
|
Mine used to do that as well, cleaned MAF, no difference; new MAF, sorted, as if by magic. 
The "acid test" to double-check if MAF is the problem, try driving it with the MAF unplugged.
(PS: it also needed new cat, exhaust and filters as were all very bad, but still pretty sure jerking was mainly the MAF)
|
|
IP Logged |
Mike H
|
|
|
pedropedro
Full Member
Posts: 677
|
|
Re: misfiring at 50 mph
« Reply #4 on: Sep 15th, 2011, 3:44pm » |
Quote Modify
|
ok will give it a go tks
|
|
IP Logged |
|
|
|
pedropedro
Full Member
Posts: 677
|
|
Re: misfiring at 50 mph
« Reply #5 on: Sep 15th, 2011, 8:29pm » |
Quote Modify
|
well I am pleasantly surprised...disconnected the maf and it runs perfectly...also a gearbox flare I had 2-3 seems to have gone.....happy days !
thanks for advice
|
|
IP Logged |
|
|
|
Mike H
Senior Member
Renault Clio
Posts: 2594
|
|
Re: misfiring at 50 mph
« Reply #6 on: Sep 16th, 2011, 9:10pm » |
Quote Modify
|
Terrific, so now we know what's doing it
Amazing what effects it causes, mine couldn't hold 4th properly, as though the lock-up clutch was burnt out, finally resulting in flashing O/D light
|
|
IP Logged |
Mike H
|
|
|
Mike H
Senior Member
Renault Clio
Posts: 2594
|
|
Re: misfiring at 50 mph
« Reply #7 on: Sep 16th, 2011, 9:19pm » |
Quote Modify
|
PS: so what's the plan now, try another MAF?
|
|
IP Logged |
Mike H
|
|
|
pedropedro
Full Member
Posts: 677
|
|
Re: misfiring at 50 mph
« Reply #8 on: Sep 16th, 2011, 10:05pm » |
Quote Modify
|
ordered a new one...but runs fine without !
|
|
IP Logged |
|
|
|
Mike H
Senior Member
Renault Clio
Posts: 2594
|
|
Re: misfiring at 50 mph
« Reply #9 on: Sep 18th, 2011, 1:13pm » |
Quote Modify
|
Fuel consumption might be worse though, as it can't measure the precise amount of air coming in so has to resort to a more basic fuelling map. Just guessing...
|
|
IP Logged |
Mike H
|
|
|
pedropedro
Full Member
Posts: 677
|
|
Re: misfiring at 50 mph
« Reply #10 on: Sep 23rd, 2011, 12:09pm » |
Quote Modify
|
put new maf in and it does exactly as before with original maf ie erratic at 50mph...maybe maf makes fuel leaner and shows an underlying fault elsewhere...could blocked injectors do this??
really bad exactly at 50mph all other speeds fine so earlier idea coil packs ..if they were bad would that produce those symptoms...also with no maf engine died a couple of times when idling..maybe to be expected any help greatly appreciated
|
|
IP Logged |
|
|
|
Mike H
Senior Member
Renault Clio
Posts: 2594
|
|
Re: misfiring badly at 50 mph
« Reply #11 on: Sep 23rd, 2011, 1:21pm » |
Quote Modify
|
When you say "new MAF", brand new or 2nd hand?
If it seems to be perfect without, can't be much else seriously wrong.
|
|
IP Logged |
Mike H
|
|
|
pedropedro
Full Member
Posts: 677
|
|
Re: misfiring badly at 50 mph
« Reply #12 on: Sep 23rd, 2011, 1:38pm » |
Quote Modify
|
brand spanking new £103 worth ..there is something underlying 100% which i need figure ...it died on me twice without maf maybe a clue...i think no maf its running richer and masks the problem ...
|
|
IP Logged |
|
|
|
Mike H
Senior Member
Renault Clio
Posts: 2594
|
|
Re: misfiring badly at 50 mph
« Reply #13 on: Sep 23rd, 2011, 5:33pm » |
Quote Modify
|
Possible, inlet manifold air leak or idling control valve sticky?
|
|
IP Logged |
Mike H
|
|
|
singlefin_scott
Newbie
I'm a YaBB newbie!
Posts: 18
|
|
Re: misfiring badly at 50 mph
« Reply #14 on: Sep 23rd, 2011, 8:23pm » |
Quote Modify
|
Hi,
Just a thought i may be completely wrong, but i have heard that a faulty/ broken fuel shut off loom can cause these kind of probs !
Could this be correct
|
|
IP Logged |
|
|
|
pedropedro
Full Member
Posts: 677
|
|
Re: misfiring badly at 50 mph
« Reply #15 on: Sep 24th, 2011, 9:05am » |
Quote Modify
|
think if manifold leaking it would run leaner and problem would get worse would idle control valve affect 50 mph speed ? ...its not loom recently replaced but thanks for input
any help would be appreciated as its quite bad...guess can disconnect the maf again but need a resolution
|
|
IP Logged |
|
|
|
Mike H
Senior Member
Renault Clio
Posts: 2594
|
|
Re: misfiring badly at 50 mph
« Reply #16 on: Sep 24th, 2011, 2:00pm » |
Quote Modify
|
Have to confess I'm a bit lost now
When was last time plugs were looked at? Also, albeit if wiring is good, how about cracked coil packs (?)
|
|
IP Logged |
Mike H
|
|
|
Cosray
Full Member
8th Scorpio, 2nd Cosworth: currently '95
Posts: 569
|
|
Re: misfiring badly at 50 mph
« Reply #17 on: Sep 24th, 2011, 4:11pm » |
Quote Modify
|
Hi Pedro, I had a Scorpio doing this and it turned out to be bad wiring related to the EGR Differential Sensor.
So at certain speeds it would confuse the EEC/V by erratically opening-closing the EGR/Valve injecting exhaustgasses when it should not.
If you follow the 3/wire loom from the EGR Diff Sensor downward it sprouts from the main engine compartment loom where. Do inspect it for brittle, bad isolation.
While I write this it could also be the vacuum management of the EGR System as a whole, rattling or leaking causing instability at certain speeds.
There´s a good writeup on the website here http://www.fordscorpio.co.uk/egr.htm
Do you have OBD/II capability? That could give a clue perhaps
HTH
Ray
|
|
IP Logged |
|
|
|
pedropedro
Full Member
Posts: 677
|
|
Re: misfiring badly at 50 mph
« Reply #18 on: Sep 24th, 2011, 4:34pm » |
Quote Modify
|
Hi Ray...that sounds plausible.......will check out that wiring,.,,yes have obd2 peppers no codes though ,,,,guess i could do a journey record a session and see what comes up ..tks for tip john
|
|
IP Logged |
|
|
|
Mike H
Senior Member
Renault Clio
Posts: 2594
|
|
Re: misfiring badly at 50 mph
« Reply #19 on: Sep 24th, 2011, 5:02pm » |
Quote Modify
|
Good article that, note e.g. paragraph:
"My vehicle suffered from a persistent misfire under very light throttle conditions ...."
Actually, my EGR has seized up a couple of times along with all the other things that weren't right up until it all got fixed last year, it would need an overnight soak in summat to get it working before it would pass an MOT test
|
|
IP Logged |
Mike H
|
|
|
|
Home
Help
Search
Members
Login
Reply
Send Topic
Print