knock sensor?

[solarized]

Got a spare coil sat in me shed if ya want it GTIrl, ya can have it for the price of postage if its any use to ya?

[GTIrl]

thats a very kind offer solarized,. im taking my car to a friend on wednesday to do some tinkering, and also to get mot'd, so if it looks like it could be the coil then i may take you up on your offer. thankyou!

[GTIrl]

sorry, a bit of misinformation, apparently i dont have a misfire! i thought maybe thats what the unburnt fuel pop was, but the engine is firing on all cylinders, so maybe its not the coil after all. wednesday am getting a new knock sensor and blue coolant sensor so will see if that helps...

[monzablue16v]

Try changing your earth straps guys so many problems caused by those little blighters cheapest and most overlooked part imo!! try your hall sender + connections from the dizzy if they have it on 8v sure they do.

[GTIrl]

just out of interest.. ive got a new knock sensor and a new blue coolant sensor, new inlet manifold gasket and exhaust manifold gaskets,and fixed all earth straps and timing checked yet again... and its still not better!!! am losing my mind over this, but now wondering if i need a new brain! is it possible that it could be the brain?what else can it be???please help

[Rain]

you dont mention if you have changed dizzie rotor arm ht leads and plugs recently had a simular problem and it was just a warn rotor arm.

just a quick check list of things that will bog ya engine down and cause power lose

fuel filter not blocked
air filter not blocked
dizzie plugs etc...
ignition leads and earth leads test this by spraying a light mist of water while the  engines running spray a mist over connections and look for archs
compression test for a blow head gasket
only things that this leaves if that didnt work is the igntion/distributer or the fuel injectors

[GTIrl]

thanks rain for your suggestion. yes it has new ht leads and plugs distributor cap and rotor arm, they were new about 10 months ago. it is an intermittent problem so cant really be mechanical can it?
also new fuel filter about 2 months ago
compression is slightly down in the middle two cylinders apparently, but nothing worth worrying about.
unfortunatley the bad running is not bad enough to point to something specific, you just notice while driving that it is slightly down on power and it sounds loud when the engine is under load especially around 3000 rpms. it still goes strong and doesnt missfire, its just as if the timing has gone slightly out, and get back pops and a jerky throttle -like when you take your foot off the accelerator it is like putting on the break.these are all things that arent there when its running well..
thinking about a faulty airflow meter now...and  am just going to look up what symptoms that would produce

[wellfan]

My airflow meter went a few months ago, however, when it goes it is not an intermittent fault. The poor running remains until you replace the meter. The symptoms when mine went were a distinct lack of power and rough running. My son's Corsa had the same problem with the same symptoms. They are very expensive to buy new, try and get a second hand one from a breaker for about £20. May be your ECU, these can be bought very cheeeply on ebay, I tend to buy one when they are going for a few quid to keep as spares. However, I am not convinced that is your problem, still sounds like an intermittent electrical problem. My problem seemed to disappear after changing my coil, however, it soon returned. I believe I have a loose connection somewhere near my coil. I have since put back the original coil and it is running well again. My problem will undoubtedly return unless I check my wiring.

[Rain]

if its lack of power all round then its likely to be mfa but if your car is down on power and very loud at 3000rpm is you exhaust ok? mine does something simular because they fit badly and it blows between the joins this causes lose of power when its wide enough but other sysmptoms are popping and rumbling and very loud zorst sounds good but gets on your nerves after a while it also caused my car to shudder and act up maybe the air flow changing as you drive along its worst examining especially if you have just had it fitted recently.

[GTIrl]

yeah my exhaust sounds horrible, its a stainless steel magnex system, and seizes periodically around the ball jointy bit that should allow for movement, and then it makes the next joint up fluff, anyhoo thats getting off the subject a little, my exhaust is fine now, all fixed and defitnitely not fluffing or leaking anywhere. my friend who has been helping me with this, well actually doing it all while i stand around passing tools to him, has just suggested that it may be sticking exhaust valves, but ive not to get my hopes up too much incase it isnt. but that would possibly explain why its not got a ryhme or reason and why maybe the electrical route has not borne fruit yet. any thoughts on this?
thanks again for all your help