hey All, had this for a while on my mk2 16v.....Sometimes, not always (from a cold start can be fine) when you start the car, maybe after a run and its been sitting, u start the car and its very very shakey to start off with...never stalls, just if u apply a bit of gas its very very lumpy.....after about 5 sec....job done, revs fine, freely and works fine... Its not a problem, just more annoying and makes the car sound like a tractor when you start it sometimes.......its like its not feeding petrol through properly.....just for about 5 secs of so......then its fine and idles fine.. Car has been set up properly....Jody at Midvw seem to think it was a hose not connected properly at back of block, but it still runs poo currently and i can't seen any loose hoses and all pipes are blocked off after the mk3 dash install... Any ideas??? Rich
I know of a few valvers that seem to fire up on 3 cylinders & need a bit of a rev to clear their throats... Not sure what causes it. Maybe one of the resident valver experts can enlighten us
yeah its odd....just a very very shakey....hard to explain kind of start....can imagine it right now, just hard to explain... thought i might be the injectors...maybe???the car has done near enuff 195,000 miles now..... the fuel pump and all that was changed a while back but the problems were before that.. it seems ot happen when the car has been out for a run and heated up and then left for say couple of hours......it never stalls or anything.......just shakey then once its cleared revs fine...
Could be leaking injector (the main 4 or cold start), recommended intervals for changing them are 80k and they do wear out eventually. Cheeck the throttle closed microswitch and also the co reading and idle with engine hot (with the red/black coil wire disconnected) any problems with any of these will cause problems.
mine does this too, i was told it was the injectors as they have over 122k on them now, but im changing the engine soon so im not too bothered
same as mine. get it nice and hot (after doing a ton for an hour on the m1) then park up and head to the shops later and its all lumpy sounding. ive resolved to forget about it personally. my valver has done a meer 85k and has done it since i bought it with 79k on the clock; hence i dont think its manky injectors (tho i may be wrong!). as you said, it never stalls from it. maybe relevant; i was "hanging out" in the waiting room at c&r and was reading a reprinted roadtest of the 16v when it was first released - even back then, the reporter noted that they "hunt" on startup. and as you said, it only lasts for 5 seconds or so...
Hmmmmmmmmmmmmmmmmmm someone must know what it is though, how about Phatty? or 800g's?????? It defo isn't right though, as its REALLY REALLY lumpy.......like a TRACTOR and it sounds AWFUL to anyone outside... anyone... [:^(]
My 91 16v is exactly the same, it seems to be random more than anything. I was told by a friend that this is a problem with all valvers. But i dunno how true that is.
Nothing to do with the valvers, they should all start on the button and idle fine unless something is broken. I'd check all the cold start stuff and as Keith says could be a leaky injector. Otherwise, could be very old plugs maybe taking time to clear all the crap off them when first fired up. Joe
have all of you had the WUR tweak done? Since i had this done my cold starts have been cack, lumpy as hell and sounds like a lawn mower for about 30 secs if not longer on cold days.only just reached 80k. though never happens when hot
Mine does this sometimes, I was planning on taking the ECU out and cleaning all the connectors on there as I hear this can affect it? Seems to make sense as my ECU spends a large amount of time under water due to poor drainage of the scuttle tray area!
could be the cold start injector, it's very crude in operation and you can sometimes get all of the extra squirt of fuel on startup going into one cylinder (depends on what position the engine stopped in) and preventing a clean burn, after a rev or a few seconds the plug cleans up and it runs fine. My KR did this for ages and there was no sign of any injector problems on the 3 times I had it rolling roaded. David.
which one is the cold start injector? is it worth replacing this one then??????? It can't be the ECU as 16v's don't actually have ECU's effectively?
Ecu could cause electrical missfires but on all cylinders. The cold start valve is on the nearside of the inlet manifold, so cylinder 4 cold get quite a gulp of fuel occasionally!
hmmmmmmmmmm its not just mornings though thats the point, its after a nice drive and u been out for lunch at work and as soon as u start it....bang... it started fine this morning no probs... 16v's don't have an ECU though? there mechanical fuel injection surely?
gotta be a dodgy cold start valve......exact symptoms me thinks! Take it out, chuck it into a jam jar and start the car... does it squirt? if not, there is your problem!
my car valver does this also, except its worse in the mornings, or wen i come out to it from work. I have had the cold start injector sat in a jar of cleaner to see if i can free the internals up a little, but it started no better after that. Somebody has mentioned to me th 'thermotime' switch. Could it be this. Is this what controls the cold start injector. Can't believe so many people have this problem, but nobody knows what it is yet, weird problem.
Yes, the thermotime switch controls the cold start valve. It should be closed for 5 seconds "worth" of cranking the engine and then become open after that. Then when the engine is started, it will become closed again while the engine is still cold (below a threshold temp). The cold start valve is then used for cold acceleration enrichment when the diaphragm pressure switch detects low vacuum (i.e. high load) in the inlet manifold. It may be that the spray pattern has become very poor from the cold start valve so tends to only supply 1-2 cylinders? Joe
