Difficulty starting and dodgy idle

[Joe87]

Hi there,

I had a thread going about this in the old forum, but still haven't come much closer to sorting this problem.
Basically, when starting from cold, it takes 5-10 seconds of the engine being turned over before it gradually splutters into life. Once idling, it is a little unstable and if I rev the engine and then let go quickly the idle drops very low and often stalls. Once the engine is warmed up it is completely fine, apart from slight backfiring when i let off the accelerator - for example of the car is in gear and moving along without my foot pressing on the pedal, but I'm not sure whether this is related to the starting problem or not.

I've tested the auxiliary air valve as suggested in the Haynes Manual by disconnecting it, starting from cold and pinching the supply hose to it. The engine speed drops, which according to the Manual it is supposed to do. Once it is warmed up, I reconnect the air valve and pinch the hose again, and the engine continues to run normally, again as it is supposed to according to the Manual.

The only thing I have discovered is that it starts much more easily when the fifth injector is disconnected. If i unplug the power connector to it and start the engine from cold, it still takes a few seconds before it starts (but still starts more quickly than with the fifth injector connected) but the idle problem is not so bad - it doesn't stall if i rev the engine and let off, and the idle is more stable. This suggests to me that the fifth injector is working fine, and also that perhaps the engine is running too rich or something - perhaps it is being over-choked by the fifth injector?

The only other thing I noticed is there is a little round-ish box type thing bolted on near the top of the off-side suspension with a couple of air pipes going to it, and if i disconnect it whilst the engine is running the speed drops slightly. I've no idea what this is and it doesn't appear to be mentioned in the Haynes Manual. Not sure if it could also be related to the problem?

If anyone has any ideas please let me know, this problem has been bugging me for months...

Cheers.

EDIT: Sorry forgot to mention, it is an '87 GTX 1.8 injection.

[bluestreak56]

Im still having the same problem as Joe with my 16v KR conversion.

Interesting difference with me is that when I removed power to the 5th injector the car wouldnt start.

If I remove power to the WUR then I get a perfect start but the idle fluctuates more around the 900rpm mark..

Do you also have a fair amount of petrol smell Joe? I got a bit of water from the exhaust today (when starting) but seemed fine after the run.

[Joe87]

Hmm very strange...
What is the WUR?
Haven't noticed much of a petrol smell, I do sometimes get a bit of water dripping from the exhaust but I'm told this is normal...?

I'm thinking it could be a leaky injector after having a look at it today. However, I don't seem to be able to remove any of the injectors - the Hayne's Manual says they just pull out but I can't get them to come out. They rotate in the socket easily and I WD-40'd them a bit but they seem to be stuck. Is there some kind of technique to getting them out?

[bluestreak56]

Hmm very strange...
What is the WUR?
Haven't noticed much of a petrol smell, I do sometimes get a bit of water dripping from the exhaust but I'm told this is normal...?

I'm thinking it could be a leaky injector after having a look at it today. However, I don't seem to be able to remove any of the injectors - the Hayne's Manual says they just pull out but I can't get them to come out. They rotate in the socket easily and I WD-40'd them a bit but they seem to be stuck. Is there some kind of technique to getting them out?

It's the Warm Up Regulator - not sure if the 8v's have them actually. I havnt really tried pulling the injectors but I think mine are the same as yours..

Alot of the smoke / water issues / petrol smells can be down to leaky injectors but ive never removed them before. Im sure one of the more experienced members will be able to help out..

[markh]

The small round box your talking about is the idle boost valve. It's meant to pick up the revs when things like air con is switched on or the cooling fan kicks in. Sounds like your car has the same problems as mine(88 GTX 1.8i) I've changed the AAV, the WUR, the idle boost valve and it's control relay , cleaned out all the breather pipes, changed the vacuum pipes and inlet manifold gaskett all with no improvement. All that's left now is the injectors or the metering head.

[Joe87]

Hmm strange...I don't have air con. As far as I know... :s
I'm gonna test the injectors at the weekend. If I can get them out.

And something else I've noticed is that when starting from cold, not all of the cylinders seem to fire straight away until I give it a bit of gas. So it idles without all cylinders firing properly. Not sure if it sorts itself out on its own, didn't want to leave it doing that for long as I can't image it's very good for it.

Any idea if this is also a sign of a leaky injector?

markh - out of interest, what does yours do if you start it without the fifth injector connected? Does it make it start easier and idle better? Or does it make it worse like bluestreak?

[skattrd]

No help here I'm afraid, but I have the same problem as well ... it must be contagious.

I've not tried to sort it on mine yet, but was going to check the things you guys all ready seem to have done, so don't know where to start now

[Joe87]

Hehe well it's probably worth trying all of the things we have just in case, cos one of them still might be the solution for yours :p At least you've got a handy list of things to try :D

[craigm]

i think you'll find the culprit is the warm up regulator .it controls the fuel mixture right through the rev range both when the engine is hot and cold .it is not just a cold start device .inside the warm up reg there is a spring which maintains a certain gap which sets the control pressure .this control pressure is pushing down on the air flap all the time the engine is turning .the higher the air flap lifts the more fuel the injectors will get .if you make the control pressure higher the flap doesn't lift so high so you get a weaker mixture and if you lower the control pressure the flap will lift higher and you get a rich mixture .this spring inside the warm up regulator has a bimetallic strip pressing against it ,when the engine goes cold the strip presses harder against the spring and increases the gap ,this in turn will lower the control pressure (more fluid passes over the air flap plunger and through the bigger gap) ,the air flap lifts higher when you start the engine and you get a richer mixture .(like a choke).As the engine warms and the heating element makes the bimetallic strip go flat the spring reduces the gap and the mixture weakens to normal .if the strength of the spring weakens over time or the bimetallic strip doesn't bend as much(or too much)or the heating element stops working then your fueling will be affected .if your engine runs fine when up to temperature then your control pressure is probably ok its the bimetallic strip is bending too much over fuelling the car .(put a thin washer under it).hope this hasn't totally confused you .

[markh]

I've tried two different WURs and it's made no difference. I get the misfire sometimes for a couple of seconds and I'm convinced that's down to a leaky injector. I'm hoping to get the injectors ultrasonically cleaned week after next,so il let you know if things improve.

[Joe87]

I've tried two different WURs and it's made no difference. I get the misfire sometimes for a couple of seconds and I'm convinced that's down to a leaky injector. I'm hoping to get the injectors ultrasonically cleaned week after next,so il let you know if things improve.

That's exactly what I get. Do you get backfiring when the car is in gear and moving with your foot completely off the clutch? As this also suggests a leaky injector to me - extra fuel not burning and igniting in the exhaust pipe instead.

craigm - cheers for the info. Where abouts is the WUR, and is it easy to remove? I'll try the washer thing you suggested.

[mikeki]

Hi guys

I don,t know if this helps, but I am in the process of sorting out my storm Mk1 which has been going through the same sort of problems as you have been getting. The trouble with the Kjet is that it is wonderfully reliable when everything is pressurised and electrics working as they should. I have narrowed my problems down to the fuel accumulator, but this usually helps with starting the engine when it is hot. If I manage to narrow it down any further I will let you know.

Regards

Mikeki

[d_jay1]

i've got this problem on my new scala. i've just swapped the WUR but still have issues. gonna take a look at the injectors and see if it is an over fuelling issue. need to double check the timing too. if it was an over fuelling issue would it be over fuelling even when it's running fine?

[p in phcas]

I've had this for many years. I disconnected the 5th injector and have left it disconnected and it starts/runs fine. After speaking to a friendly Bosch FI place in Guildford, the chap there (many years in the business and probably the only one around here who knows the pressure measurements of the DX engine off the top of his head as well as has the mercury gauges to test them) said that would be the cause.

His exact statement was "that you could replace it, but in a few years it would go again as modern fuels tend to eat the older grade alloys used in these type of injectors." Effectively, it opens out the injector hole causing it to over-fuel. Once the injector is turned off (warm up regulator I believe does that too) all is fine and dandy again.

[d_jay1]

surely leaving an injector disconnected isn't ideal though is it? aren't you losing power and throwing all sorts of things out?