K Series Cold Running issue
 

Right, at my wits end with this, but can't bring myself to go as far as replacing the engine wiring loom as I've had suggested elsewhere.


Every time when starting from cold, the car will misfire until it fully warms up. Most of the time it will start OK, and then develop sometimes to the point of stalling, however every now and then it will stumble into firing up and have a miss from the instant it starts.
The severity of symptoms isn't consistent - sometimes it will be a little fish-bite misfire, other times it will stall 3 or 4 times before it runs. Does seem to be worse in the cold/wet though. And finally, sometimes when driving it feels a bit down on power for the entirety of the trip - not enough to say there's definitely something wrong, but enough to feel like its struggling a bit. Other times once it's warm it's completely fine.



It's a 1.8 non-turbo, VVC inlet manifold and ported cylinder head but both Kmaps and DVApower have said they've never come across something like this before from the inlet/head work alone.


I've done quite a bit of diagnostics/code reading/parts cannon but I don't want to start off by listing it all in case it leads people down the wrong path/into the same trap I seem to have fallen into.


Thoughts and suggestions of what to do welcome, please!

Considering the work that has been done on the head, this may seem obvious but.....


Is there any signs of coolant on the spark plugs?


regardless, I would imagine that one spark plug will be a different colour to the other three unless you have a random misfire going across all cylinders.

No signs of coolant in the cylinders/on the spark plugs.
Plugs all look the same as well, so I'd reached the conclusion that it's a random misfire across all cylinders, which is supported by no cylinder-specific codes, only P0300 (random misfire) and P0316 (misfire excess emissions).


So from that (plus a compression test that showed all cylinders to have similar, normal pressures) I've ruled out anything mechanical.
EDIT: Should also add that I've done the obvious cam timing check as well.

I would look for an inlet leak.

That was my next thought, I've lost count of the amount of times I've sprayed brake cleaner around it looking for a leak - nothing.

Even the couple of garages it's been in can't find any evidence of a leak. Plus I don't think that would explain it not starting smoothly sometimes.

What plug gap have you?

Sent from my moto g(7) power using Tapatalk

Plugs are at 0.8mm, it's even worse at the book 1.0mm!


And it's not the ECU either as Marinabrian has very kindly swapped that already.

By way of a bit of a bump.

My next thought was a TMAP or coolant temp sensor issue, so these were both replaced with no effect.


Does anyone have any thoughts on a fuel pressure problem? It's had FFS and the clip fitted, but wondering if the pressure being slightly low, but enough to run on, would do this?

When I had FFS, I just fitted an orange clip and the problem wasn't fixed. It was caused by the old and dodgy o-ring. They tend to leak once disturbed and I had opened up the filter to check it inside. Basically, it's an expensive error. Never open up the filter unless you plan to replace everything inside. Just a thought.

Thankfully I didn't open the filter up, just screwed it back up and fitted the clip.
The FFS episode made no effect on the running issue - just as bad both before & after, so I'm confident it's not the filter.


When I said low pressure, I was thinking more along the lines of "what if the pump is a bit weak?"

It's very unlikely to be the pump, but I guess everything eventually wears out.

Maybe try reducing the spark gap further? I set mine at 0.7mm.


TC

You've probably gone over this but have you tried alternative ignition coils? I would be tempted to replace the inlet manifold gasket and check that wonderful little "jiggle valve" while you've got access to it.

Good luck.

I've not tried new coils, but they are only a couple of years old, and produce a good strong spark on a spark tester. Plus I'm not seeing any of the more typical signs of failing coils.


IMG gasket is fine - especially being the flat VVC type - and so is jiggle valve.

So the past two days it has been noticeably more reluctant to start (I took a video yesterday and no, it didn't need any throttle to eventually start) but running OK when warmed up.
Then today driving it felt like it was bogged down and running rich all the time.


I'm thinking it might be best to focus on the starting? And that might be a quick way to an answer.
Have ruled out:
Compression
Plugs/coils/leads
Cam sensor (was swapped for a new one and then back to original)


There can't be many more things 'required' for it to start? The crankshaft sensor springs to mind but that's about it.

I think I'd take a closer look at the inlet manifold seal. You said earlier that spraying brake cleaner around it failed to indicate any problem. I'm not sure that proves anything really, so in the light of the ongoing symptoms, I'll suggest fitting a new IMG/seal. Get the black/Viton version. I note you've got the VVC version. Is the poor starting coincident with that?

TC

maybe have a check of any o2 sensors .
Had a faulty o2 and did all sort of things, ran fine at idle but started missing etc as soon as i put the accelerator down.
A faulty brand new sensor!!

T-Cut - the VVC manifold doesn't use an elastomer seal, it's a more traditional flat paper type affair.
The cold running problem did start at the same time the VVC manifold was fitted, but then the ported cylinder head also went on that day too, so can't point the finger definitively anywhere. The starting is a more recent development, at first very intermittent but gradually becoming more regular. I have noticed that unless I wait for the fuel pump to time out, there's absolutely no chance of the car starting; it'll just crank and crank. Not sure if that's normal or not?



genpk - a good suggestion, but the O2 sensor has already been changed twice - once for aftermarket, and once for OEM - no difference.

You say it gets worse if you open the spark plug gap up.

Therefore it has to be spark related.

The voltage increases as the plug gap increases and gets less as the plug gap decreases. This might indicate faulty plug leads that start to break down at the higher voltage and will allow the spark to track through the casing to earth. It can also indicate a break down in the coil windings with an internal break down to earth.---:eek:

Or it could just be that the spark gets drowned more easily at the larger distance.
As it's two different sets of plugs I'm using (Bosch/NGK) I don't think we can directly conclude it's an ignition issue.


If it was spark related, I'd expect to be seeing issues at higher revs/hard acceleration which there just aren't. I also find it hard to imagine that I've got 2 failing coils, especially as they're only 3-4 years old.

Are the plugs sooty when you check them ??

You think it's running rich. Normally a rich mixture is necessary to start a cold engine but your engine is harder to start from cold. Odd.

Large plug gaps normally make an engine easier to start but the spark can fail to jump the gap at high revs and cylinder pressure. It just tracks down the electrode surface.

The standard gap should work perfectly at all revs.

Your need to modify the gap could mean the mixture is too weak or too strong so I guess you need to find out the cause of the varying mixture.

Best of luck with it.---:}

I Remember a few of us looking at options at Gretna. The uneven firing pulses through the exhaust at the time suggested cam timing to me, was this rechecked and ok, has that stopped? The oxygen sensor obviously wasn’t working in current data but you’ve now fitted a genuine one. I’ve just seen the mention of the head and manifold being changed at the same time the fault started. Was the ported head your original or a replacement? I’ve seen an issue on the K series where the symptoms were similar to inlet manifold gasket failure but not caused by the gasket. You have a VVC manifold so can discount the gasket. It was a 400 tourer and I found on removing the head there was a very small mark on the head by the fire ring, upon testing it was a hole. Once the car had been parked up overnight the coolant would leak into the cylinder and the car would start with a misfire for a few seconds then clear. There was no indication of wet plugs and this was in the days before borescopes. The head was drilled threaded, a threaded plug fitted and skimmed level and the result was instant. It was my own car so nothing to lose as it potentially needed a new head anywhere and the fix lasted a good 12 months before the car was traded.

Yes, after Gretna I completely stripped the cams down and put the originals back in. Turned out that the offset dowel on the inlet cam had rotated, so was retarding it rather than advancing - leading to too much cam overlap. How that happened I have no idea, but the dowel is now completely wedged in the cam and will need drilling out.


Anyway, that plus the o2 sensor has it running properly when it's warm, can see the sensor working on the live data now too.


The head was a new one that went to DVA power for building up. Other than some of the valve guides being slightly oversize there was nothing noted (and even then, Dave's words were "not suitable for a race engine but more than OK for normal use").


We're not talking a few seconds of rough running here, like you get with a coolant leak, but several minutes - before lockdown, my normal routine was to start the car, go in and have breakfast, and then it would just about be running smoothly by the time I'd eaten (around 10mins probably).

Heat seems to cure you cars engine performance so what is it that heat can cure ???----:shrug:


Perhaps the sensor to the flywheel gap changes with heat ??? Only a good signal when all the surrounding parts expand with heat.--and the gap closes.

I have wondered that, the crank sensor is one of the few that I haven't changed.


The other option I considered is it being in closed loop control - but then it's not like it suddenly runs fine, it's a very gradual improvement.

Bit of a bump, any suggestions/ideas other than possibly replacing the crank sensor?

Well, bit the bullet and ordered new crank and throttle position sensors. Don't know what else to do if its not that.



Felt very bogged down below 3000rpm driving to work today, not sure if that's me not being used to it or if it's real.


As always, if anyone has any ideas...shout up!

Well, new crank and throttle position sensors haven't made a difference.

Completely stumped for what to do or where to go now.

Is the earth lead to the engine intact?

Yes, earths are all connected tight and in good condition.

Walking the cat home a bit, have you checked the throttle body & air filter housing - something similar from years ago on a friend's car was down to this area. My K is a dizzy spark rather than coil packs so the occasional damp starting issue I have is different to yours.

Have you tried swapping out the fuel injectors? I've had one fail on a K Series years ago.

Also if you can get hold of a Colourtune plug try fitting that to each cylinder in turn and see what the mixtures are like.

A really nursery school suggestion but I'd consider either a new set of plugs or try one new one, one at a time to rule out a faulty plug.

:shrug:

I've tried different sets of plugs, no difference - so I'm content it's not them.


An interesting idea about the injectors, I've not really considered them as there's been no cylinder-specific codes. Think it's unlikely more than one would fail at once.


I will be splitting the manifold when I get chance, see if there's any clues there. It seems to have a propensity to collect condensation on the outside which I find a bit strange - why the moisture prefers that to the rest of the engine I don't know.

Me too - to be honest it sounds like air getting in the manifold until the engine warms up and seals the gap, but you have checked that out.

As for a Colourtune plug they can be really useful, as you can see inside each cylinder and check whether you are getting a spark, and if so, running rich or lean.

When you fitted the VVC IM, did you swap the sensors for your old ones or use any that came with it?
You need the old ones.

TC

All the sensors and injectors are the originals. Caused a big disagreement when the nearest T4 garage insisted that only the higher capacity 135 injectors could be used!


The smell of the exhaust indicates it's running rich, not something I'd expect from an air leak - if anything, I'd expect the opposite, a high idle rather than the low/drowning I'm experiencing. If I crack one of the breather hoses off, it is low on vacuum when it's struggling but it's impossible to tell if this is because of the low engine speed or a leak. It pulls good vacuum at hot idle.

Split the inlet manifold this afternoon, after the car's been sat on ramps for the past week while I painted the rear subframe.
All looks fine, some oil misting on everything as you'd expect but nothing excessive and no sign of condensation.

I then tried to start it to move off the ramps it turned and turned with no attempt whatsoever to fire up. Oh bu**er.
Pulled the spark plugs and they were soaked as well as quite sooty #4 was possibly slightly better than the rest. Quick spray with brake cleaner and under the soot they looked fine. Let everything dry out before refitting and...still nothing.


It eventually stumbled into life after about 10mins of on-off cranking, but would just die below 3000rpm. Finally after the 3 or 4th restart from it dying, it was just fine (well, I say fine, certainly not running as smooth as it should have been, but able to keep an idle on its own).


Started it twice since then and it's started fine and back to the usual bogging down after a couple of seconds.



Thoroughly stumped now.

Although I haven't quite gone for the full dark night approach, I have done similar and found no sign of any problems on the HT side.
I've also been round every plug and sensor I can think of and checked them, again with no apparent problems.


If I had any faith it would solve anything, I'd swap the entire engine loom over to the spare that I bought, but at the moment I can't convince myself its worth the effort.

Hello Mike,

As you've not found the cause of your problems yet, and they do match fuel starvation, would you consider attaching a gauge to the fuel line? Your engine needs 3.5 bar.

Simon

I have thought about doing that, but I'm not sure what type the connection on the end of the fuel rail is? Had a quick look and it didn't look like a schrader type?

I disagree that it's fuel starvation, if anything I'd say its the complete opposite, as it stinks of unburned fuel when it's running rough, and generally feels bogged down at low revs when driving - but is fine at higher revs.

Regardless though, I do think fuel pressure is a good one to look at if I can work out how.

Does this help?
So do you think it's an ignition problem then? I see that you haven't tried new coil packs. Misfiring is a classic symptom of a failing ignition module and it would disguise itself as a rich mixture.

Simon

Thanks Simon, that link is helpful - will need to acquire a pressure gauge with tube but that's no hardship.


I don't think it's an ignition issue, as everything feels normal higher up the rev range. It feels very choked up below c. 2500rpm then frees up. Just about everything I've read suggests weak/failing coils would show up more at high speed when there's less charging time and cylinder pressures are higher. Coil packs aren't actually that old, 5years max, and were fine until the ported head/metal manifold went on.

I've reviewed the whole thread to try to get a clear picture. You have a VVC manifold and a replacement head which has been ported. You've also been struggling with this for a month.

How about putting the engine back to standard? Can you refit your factory cylinder head and inlet manifold? i haven't seen any mention of changes to the exhaust system or fuelling to complement the modified head and inlet manifold.

Simon

I've actually been battling with this for nearer 18 months Simon, initially with a set of 135 cams fitted which were then removed to eliminate them.
While I do still have the original head, it's pretty much scrap having been skimmed multiple times, and needs all the valve stem seals replacing - so I'd rather not put it back in.


Having spoken with the well regarded K-series tuning experts like DVAPower and KMaps, they're all in agreement that porting/manifold alone would not cause this issue, and when they tune they stay away from adjusting idle settings (other than idle speed and properly setting the IACV/ HOTDPOS value in T4).

It also wouldn't explain the intermittent reluctance to start, nor the gradual worsening of symptoms.




I will have a go at exploring the fuel side of things - but again, it doesn't seen to really fit the bill for fuel starvation. Yes it can struggle to start, but will then be fine at high revs which surely necessitates a higher fuel demand??

I had a quick scan through your posts and you haven't mentioned changing the plug leads. I've had several cars where the leads have broken down over time. The graphite leads tend to harden and crack, forcing the spark to have to make several jumps before it gets to the plug. May be worth a few quid to eliminate them? I've found cars to be transformed by this simple swap!:shrug:

Thread revival!


I've given the car a good solid 3 weeks of going to work every day (or in other words, I haven't had time to do anything), and the codes I've read off just now are
P1300 - Boost Calibration Malfunction
P1316 - Misfire increase emissions
P1590 - ???


Plus 2 not relevant ones
P0501 - speed sensor (suspect one of the rear wheel bearings/ABS)
P1520 - every K-series has this dummy error.


So not much to go on...if anyone has any bright ideas I'd love to hear!

Boost sensor is a strange one as yours is an 1800 nasp isn’t it? I suppose it could be map related but I’d expect a map related fault over boost. Are you running the correct ecu? What are you using to read the codes? My gut feeling allthough a lot of work is to refit to standard and try

:wot:
Michael, I thought you'd like to know RAVE's description of these codes:

P1300 = misfire detected sufficient to cause catalyst damage
P1316 = misfire causing excess emissions
P1590 = not listed

They don't really help you do they. :o

Simon

I'm using a pscan tool to read the codes. Interesting that it lists P1300 differently to RAVE, but that's irrelevant really as it still doesn't help give any direction!


For now, reverting back to completely standard (bearing in mind all we're dealing with is porting/VVC manifold) is out of the picture - it's just too much work while still needing the car as a daily 5+ days of the week.


Interestingly one of the mechanics commented when it was in for MOT (which it passed by the way with flying colours on the emissions!) that at idle it sounded/felt like a fuel delivery issue, so I'll definitely be looking to explore that when I get chance - I know you've mentioned it before Simon, I just haven't yet had chance.

I've mentioned this a couple of times but seeing as you haven't made much progress, worth mentioning it again. You can buy a Colourtune plug for about thirty quid, and then you can see directly into each cylinder and whether you are getting a consistant spark, running rich, running as it should or running too lean.


Very helpful for pointing you in the right direction. :}


https://www.minimobracing.com/store/...8-02-0012b.jpg

Right, digging this one back out as I know people like updates.

Unfortunately I still haven't solved the running issue, but I have fixed the reluctant starting by replacing the fuel filter.
Decided to take the tank completely off while it was in the garage for the tank straps to be replaced, opened up the filter housing and boy was it choked up! I know the filters go black, but you shouldn't be able to scrape the gunge off them with your finger!!




That improved the running in general for a couple of days - it wasn't perfect but I figured it would settle as the fuel trims readjusted. Sadly that hasn't been the case and its gone back pretty much to how it was. It has crossed my mind that I may have a weak/failing fuel pump - perhaps the excessive black gunk is the insides wearing out (I know that's pretty much unheard of, but this car seems to love coming up with new, never before seen problems - like the auto 'box sump rusting through!).

I doubt it Michael. The fuel pumps on petrol engined cars are extremely reliable.

I've just looked back at earlier posts and you have fault codes for misfiring. I mentioned coil packs around that time which can cause this. How about a T4 session to find out which cylinders are affected?

Simon

Codes are for cylinders 2 and 4, so to me that rules out a failing coil pack. It was interesting though that last time it was on livedata the misfire counts for 2/4 were going through the roof but 1/3 remained at 0 - not sure I believe they were completely unaffected to be honest.

Re the misfire, it might be worth looking closely at the wiring in the area underneath the throttle body and multi connector. It can chafe leaving bare wires exposed and the wiring for the coil packs is among the wires in that area and can be affected. Re the cold running problem, if it has a standard stat as opposed to a PRT it might be worth checking it to see if it has been drilled. The stat which came with my Rover 25 had two holes drilled in it both of which were about the diameter of a six-inch nail. It rendered the stat useless and it may as well have not been fitted at all. It caused running problems and overfuelling, the engine never got up to temp and the heater did not work as a result making the car cold and dangerous to drive in the colder months. Might be worth testing the stat if it shows no sign of having been tampered with.

Mbonwick, just a quick question, when you start the engine from cold, does it misfire straight away ? Or after 20 or so seconds ?

Pete.

I ask because I have a ZR and TF with the same problems. The TF is slightly worse. It starts fine, then after 20 or so seconds starts to chug, you can hear it from the exhaust, it will stall at junctions and doesn’t like restarting. But drives fine once up to temperature.
The ZR misfires under load under 2500 rpm, but not straight away, after a couple of minutes, then when the engine is hot, it’s fine.
I have a T4 and nearly everything has been changed, to no avail.

I’m starting to wonder if it’s a sticking valve that expands after a couple of minutes, causes the misfire, then when the whole engine is hot, stops sticking, or an injector problem. We have ethanol fuel here in France.

Pete.

Initially, it would be perfectly fine then start getting worse after 20secs or so. Over the past year though it's morphed into a slight misfire at initial start that then gets worse. There seems to be less "flare" now as the engine catches - used to easily get over 1500rpm as everything fired for the first time, now its somewhere around 1250rpm usually.

It's so inconsistent with how severe the miss gets (and if the car stalls), but seems to be slightly better when there's more than 1/2 a tank of fuel. I am beginning to wonder if it's a fuel pressure/injection problem too

Hi,

did you ever get to the bottom of this problem ?

Pete.