Badly misfiring F4R - Sounds like a scoob

[Anonymous]

I pulled out of a T-junction the other day and had to gun in as cars were approaching then suddenly it just started misfiring and sounds almost like an AK47 when its trying to pull away!

Swapped the coil pack with one in I had and its still the same!

Its fine if I just touch the throttle peddle very slightly, but if I press it more then 10mm or so it just bogs down and sounds like a Scoob lol

Also low rpm reversing mainly but also moving offf at low rpm it makes small pop's almost backfiring but are feeble efforts!

Sounds fine on idle just a bit more burbly

Any ideas?

 

[jenic]

Sounds like mine before ti got worse, turned out to be an injector. Mine was only intermittent to begin with.

I tested it by seeing which cylinder had a fault code on the rstuner, then swapping a couple of injectors around and seeing if the problem moved with it. Can also try swapping ht leads around (both ends remember) and plugs.

 

[Anonymous]

here's a wee vid

[video]http://s73.photobucket.com/albums/i201/smokey182/?action=view¤t=08102010001.mp4[/video]

 

[Brian172]

Video link doesn't seem to work.

 

[Anonymous]

how about this?


http://s73.photobucket.com/albums/i201/smokey182/?action=view&current=08102010001.mp4

 

[jenic]

Yeh that works, and sounds exactly like mine did

 

[MattyD.]

i had the same problem with pre cat lambda sensor, are you getting any lights up?

 

[Anonymous]

That's what I thought it was and have a spare lying around, just cant shift the one on the car, may have to take it somewhere in the morning and get them to swap them over for me!

Not getting any lights at all btw

 

[skiptontweed]

.

 

[jack_davey]

start simple and get the ht leads checked etc then worry about compression test etc once you've outruled the basic things

 

[172Ben]

injector

 

[my leige]

Have you tried disconnecting and replacing each HT lead in turn at the coil pack whilst the engine is at idle? It should start running like a pig when you remove the spark to a cylinder. If there's no change or a noticeably different noise on one cylinder compared to the others you should be in luck.
This tells you if you have a plug, HT lead, fuel delivery or lack of compression issue.

Test the HT lead/ plug by removing the HT lead (both ends) from the suspect cylinder and swapping it with a lead from another cylinder. If the suspect cylinder comes good the swapped cylinder will go dead and the problem is a duff HT lead. If swapping the HT lead with another make no difference (same cylinder still dead) you know that the leads are good and it's the the plug, fuel delivery or lack of compression.

Test the plug of the suspect cylinder by removing it from the head. Then reconnect the HT lead to the plug, hold it with some insulated pliers just above an exposed metal part of the engine (cam cover) and get someone to crank the engine. You should see and hear a good regular spark. No spark = plug is duff. Spark = ignition system not at fault and so it must be fuel delivery or compression.

Test fuel delivery by removing the injector from the suspect cylinder, reconnect the cable, aim the injector into a cap from an aerosol (or similar) and get someone to crank the engine. No fuel = injector is duff. Uneven fuel pattern = mucky or sticking injector, so clean or replace injector. Good pattern = fuel delivery ok.

If ignition and fuel delivery checks out then you need to do a compression test (remove all plugs before testing). All cylinders should be within a few PSI of each other. If one or two are low then, remove the tester and using and give the low cylinder a couple of pumps of engine oil from an oilcan and redo the compression test on those cylinders. If the readings improve it's probably piston/ bore wear. If the readings stay the same it's valve related. If this isn't conclusive try a leakdown/ cylinder decay test (or take it to a garage and get them to do it).

I hope the above is useful (i'm not sure of your level of experience).

 

[my leige]

To remove the lambda sensor: give it a good wipe over, spray the nut with WD40 and go for a drive. Round the block will be enough. Give it another squirt of WD40 and let the exhaust cool enough that you can comfortably grab it with your hand.
Then try and remove it (if you don't let it cool you risk stripping the threads - not funny).
If it won't shift try a good fitting spanner and gently push it with your foot. Mine was stuck solid but came straight off using this method.

 

[KJD78]

i had the same problem last week,got new leads and it solved the problem