Not firing on #3 cylinder?

Turtle_Wax · Post by **Turtle_Wax** » Sun Apr 02, 2006 7:10 pm

Hey guys I could do with your help please. I bought a cheap Lanos 8valve but it is not firing properly on number 3 cylinder. I checked this by pulling the leads from each sparkplug in turn as the engine was idling. The engine revs drop when I pull the leads to cylinder 1, 2, & 4 but make no difference when I pull number 3. I changed the plugs and there is spark at the leads. I did a compression test and number 3 was low @ 140 psi where the others were around 170 to 180 psi. It starts first time and surprisingly drives ok for a car not running on all 4 cylinders - but at idle it is chugging. Any ideas welcome. Thanks.

MMamdouh · Post by **MMamdouh** » Sun Apr 02, 2006 7:38 pm

the drop in comprerssion is within the allowed range, if the lowest piston is lower than 75% than the average of the other 3 then you are in trouble.

MMamdouh

Turtle_Wax · Post by **Turtle_Wax** » Sun Apr 02, 2006 8:36 pm

Cheers bud. Yes it looks like the compression is within the 25% range so shouldn't really affect it too much. Any idea what else could be causing #3 not to fire. If I remove the lead from the sparkplug it makes no difference to the engine when idling? I changed the plugs and tried a different lead to #3 cylinder but didn't make any difference. There is a good spark coming from the lead when I hold it to the engine block so I assume the coil is working ok.

To test the coil I swapped number 2 & 3 wires around as they fire at the same time. If I pull #2 wire the engine revs will drop to nearly stall. If I connect #3 wire to #2 sparkplug the revs will rise again (so that means #3 coil & wire are definitely working). But if I put #2 wire onto #3 sparkplug it doesn't make any difference to the engine?

The car had not been used for several weeks so I was wondering if it could be a sticking valve or something - but would a sticky valve have shown up on a compression test?

Thanks for the advise.

Daniel · Post by **Daniel** » Sun Apr 02, 2006 8:57 pm

So if your cables, plugs & coils are right look at injector #3. Maybe is it clogged or has a bad electrical connection. Check if plug #3 is wet or dry.
I would have a go for injector cleaner in fuel.

My 0.02ct.

Daniel

Turtle_Wax · Post by **Turtle_Wax** » Sun Apr 02, 2006 9:53 pm

Hi m8, I tried unpluging each of the injector connections with the engine running and the same thing happens. Number 1, 2 & 4 drops the revs to nearly stall but removing #3 makes no difference. #3 sparkplug is dry (no unburnt fuel or wet oil). I did try swapping over #3 injector connection onto #4 fuel injector and it increased the revs (so #3 electrical connection must be working ok) but putting #4 injector connection onto #3 made no difference.

Is it easy to remove the injectors and can you swap them around into different cylinders? That should tell me if it's an injector problem if the same thing happens to a different cylinder?

I'm all done in for one day so will take another look tomorrow. Thanks for the help guys.

Audacity Racing · Post by **Audacity Racing** » Sun Apr 02, 2006 9:55 pm

the fuel rail is removed with only a few screws (4 i think)...

once the rail is free, you can pull the injectors as you see fit and swap them around. just be sure to relieve the fuel pressure before working on the rail!

Turtle_Wax · Post by **Turtle_Wax** » Sun Apr 02, 2006 10:20 pm

Cheers man, that doesn't sound too bad. Once the fuel rail is off do the injectors simply pull out or do they unsrew? Is there any seals or O rings I need to be careful of? Thanks.

Daniel · Post by **Daniel** » Sun Apr 02, 2006 10:47 pm

It looks that the ECU is all right too!
Before removing injectors can you test their electrical resistance with a multimeter, connectors removed? Sould be aroud 11-12 Ohms temperature depending.
Otherwise there are O'rings. Check the "How-To" section and www.daewootech.net .

Daniel

MMamdouh · Post by **MMamdouh** » Sun Apr 02, 2006 10:59 pm

their is an article for removing injectors and fuel rail in the how to section.

it could be a dead injector at cyl. 3 so swaping injectors is a good test.

MMamdouh

Aneab · Post by **Aneab** » Mon Apr 03, 2006 2:54 am

MMamdouh wrote:their is an article for removing injectors and fuel rail in the how to section.

it could be a dead injector at cyl. 3 so swaping injectors is a good test.

MMamdouh

+1

here's the link to what MMandouh is talking about. http://www.daewootech.com/forum/viewtopic.php?t=2900

~kyle

Turtle_Wax · Post by **Turtle_Wax** » Mon Apr 03, 2006 7:48 am

Thanks for that guys. I will swap the injectors over later today. I did check the resistance with a multimeter and they appear to be equal.

1 12.6ohms
2 12.4ohms
3 12.5ohms
4 12.2ohms

I'm hoping it is a blocked injector. Will let you know what happens. Thanks again.

Aneab · Post by **Aneab** » Mon Apr 03, 2006 7:48 am

Turtle_Wax wrote:Thanks for that guys. I will swap the injectors over later today. I did check the resistance with a multimeter and they appear to be equal.

1 12.6ohms
2 12.4ohms
3 12.5ohms
4 12.2ohms

I'm hoping it is a blocked injector. Will let you know what happens. Thanks again.

Good luck.

Turtle_Wax · Post by **Turtle_Wax** » Mon Apr 03, 2006 3:04 pm

Looks like I'm back to square one again.

I swapped around #3 & 4 injector but unfortunately #3 is still not firing. I checked the compression again with the engine at normal temp. With the plugs removed and throttle fully open the readings are;

1 180psi
2 180psi
3 140psi
4 160psi

I put a teaspoon of oil in #3 to see if it increased compression but it stayed the same. I also tried a different coil pack from a known good lanos and still #3 is not firing. This has got me completely baffled. If I have compression in the cylinder and a spark at the plug and a known working injector what else could cause #3 not to fire? There is no CEL light on

Daniel · Post by **Daniel** » Mon Apr 03, 2006 5:27 pm

Intake valve #3 not opening properly??????????

My 0.2ct Ooooooooooops
Daniel

Daniel · Post by **Daniel** » Mon Apr 03, 2006 5:27 pm

Intake valve #3 not opening properly??????????

My 0.02ct

Daniel