Car running on three cylinders

[Gavin Waddell 18]

I did a coolant flush the other day

and to bleed properly I let the car idle run up to temp and let the fan kicked in. The car was running normally.

 

went back to it today and it now only wants to run on 3 cylinders. It starts and runs albeit on 3 and smells really rich. I checked for spark and they are all there when I pull the plugs they are all dry so can’t tell which isn’t firing and if I unplug the leads it doesn’t really make a difference to the noise. 

 

I know that if there is no sos ark there is no injection but that’s all good

 

I was thinking maybe a sticky injector? 

 

I also rebuilt the loom this winter so i know that all good and no crusty connections.

 

running out of ideas as what it could be .

 

gavin 

[karabas 21]

Hi, did you try pulling the injectors wiring plugs one by one?

And also you can try to hear the injectors click sound with the screwdriver test.

[Gavin Waddell 18]

That was what I was going to do next just need an assistant ( which is my 7 year old but she had a play date) to turn the key on and off so I can listen through a swrew driver.

[PhilNW 40]

At what engine speed did you take take the leads off? if it was tick over then you may not have noticed a substantial change in noise, trying doing at higher revs to get a high difference in engine speed/noise.

 

Do the listening of the injector with screwdriver with engine running, not when switching ignition on and off, you should hear a definite ticking sound.   

[Gavin Waddell 18]

I took the leads of at idle. I did give it a bit of revs and it sounds like a lawnmower.  

 

From my understanding On the ignition  side the injectors batch fire and only if they receive signal from the coil/spark. As the injectors all share the same feed wire and earth wire if oneisfaulty theyre all faulty. But an injector could be closed. But Why is it pouring out rich petrol smoke from the exhaust? More like its over fuelling 

 

its more like one of the plugs isn’t firing? But I did the old stick a screw driver test in the ht lead and There’s  a decent arc from all the leads.

 

could it be running super rich as the plugs are quite black and it’s blowing out a plug with a rich mixture? I know that if the écu temp sensor is faulty it will run rich. I did Unplug it to see and It

didnt start. Lesson learnt from previous experience, but it could be faulty giving a false reading and it’s  chucking in a to much fuel?

 

its all I can think of really.

 

 

Gavin

[PhilNW 40]

Take the plug leads whilst holding engine at higher revs (say 2000) to see which ones causes a change in revs/noise.

 

From memory - The earths from the individual injectors join together under the inlet manifold, I had a similar problem and turned out to be one of the earths before the join.

 

Might just be a bad spark plug, best to establish which cylinder is bad first.

Edited April 23, 2021 by PhilNW

[Gavin Waddell 18]

When I did the coolant flush I also did plugs with NGK bcpe6, I didn’t do leads as they were changed about 5 years ago

and the car has driven about 200km since then.  I know that they can degrade over time  but they haven’t really seen any heat cycles.

 

im going to get or find my feeler gauges so I can check the plug gap and make sure they’re good and maybe order some new plug leads so I can rule them out.

 

will so do as you said and pull the leads off at high rpm. I’m guessing that at higher rpm when I pull the ‘’ good’’ leads the car will run on 2 cylinder ?

[PhilNW 40]

You can get a bad plug but very rare but not impossible.

 

Rather than buy new leads straight away , put a old plug in the end of the lead and earth against the engine, start engine and see if there is a spark. Leave the plugs screwed in the cylinders (risk of petrol vapour being shot out of the cylinder and igniting).

 

Engine should still just (badly) run on 2 cylinders, if it does not you know that that cylinder it good.

 

. 

 

 

[Gavin Waddell 18]

Like I said before I did the screw driver test and all where sparking, whether or not they were strong can’t tell. But will try with a plug

 

I changed the coil yesterday and that hasd no difference. 

 

Could a really rich mixture blow a plug out? Could it be the pressure regulator related ?

 

will have a play on tuesday

[Gavin Waddell 18]

So I went back to the car today I. I pulled each plug out whilst at 2000rpm  with no real difference in engine noise. 

 

Soni ni then decide to see what the spark was like using an old spark plug  in each lead I tried to start the car and each had a decent spark.

 

so I then decided to check the injectors, with the car running had a listen to each injector with a screw driver and they were all clicking merely away . 

 

So got spark and fuel. Grounded the ignition amp still no change.

 

i un plug the AFM to have a look and that’s when I saw that 2 pins on the AFM plug had been pushed back. Reseated then and hey Presto running again on all 4s.

 

case closed thanks for all your help everyone.

 

gavin 

[PhilNW 40]

  Happy days