Dropping #1 Cylinder on 4afc

**ra65** · 18-09-2010, 03:34 PM

Hi Guys,

I am dropping number 1 cylinder on 4afc in a 1990 corolla. Have so far replaced:

Cap
Rotor
Plugs
Leads

Will always be dropping at idle, car is low on power, getting around 250km per tank of fuel driving around.

What else should I look at? Any ways to easily narrow down the problem?

**kickstartRA28** · 18-09-2010, 04:06 PM

Do a compression test on the engine might have a burnt valve, blown head gasket or something along those lines........

**allencr** · 18-09-2010, 04:06 PM

What's the compression?
Pulling the injector or plug wire to find out which one?
Swapped injectors?
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Thanks RT40Corona4AGTE.

**RT40Corona4AGTE** · 18-09-2010, 05:23 PM

Originally Posted by allencr

What's the compression?
Pulling the injector or plug wire to find out which one?
Swapped injectors?

are we talking 4afc here or 4afe? as the title states 4afc, but this post makes me think otherwise?

**ra65** · 20-09-2010, 08:44 AM

Its carby. Pulling lead to test.

**Tweak** · 20-09-2010, 09:47 AM

Maybe a cracked piston or a burnt valve
Had any bad pinging lately?

**RT40Corona4AGTE** · 20-09-2010, 12:44 PM

+1 for compression test. . . . . please let us know what you find?

(if you get poop readings here, try the oil down the spark plug hole trick and repeat test) this would indicate worn rings/piston damage. If readings dont increase after oil, check out the valve train and perform a leak down test.

**ra65** · 20-09-2010, 07:20 PM

Would it be worth changing out the coil?

If its piston / valve / any other big job I don't think it will be worth fixing. How much does a compression test set you back?

**RT40Corona4AGTE** · 20-09-2010, 08:59 PM

whereabouts are you in QLD, I have a comp tester!

One would think the coil would make all cylinders miss and carry on, not just one of them.

**ra65** · 21-09-2010, 05:09 PM

Originally Posted by RT40Corona4AGTE

whereabouts are you in QLD, I have a comp tester!

One would think the coil would make all cylinders miss and carry on, not just one of them.

I am in Brisbane, Taringa.

Yeah I was thinking that, changing all the ignition components (except coil and ignitor) actually seemed to make it slightly worse.

**TERRA Operative** · 21-09-2010, 05:45 PM

You've tried pulling the ignition leads of one by one to see if it makes a difference?

**banana_socks** · 21-09-2010, 07:03 PM

Think about the basics: fuel, air, compression, spark.

Fuel: Its a carby, so any problem is gonna affect all cylinders, not just one. Rules this out.

Air: It's possible there could be an issue with the intake valve. Easy to check if it's opening/closing properly, turn it over by hand with the cover off. Anything else would affect all cylinders.

Compression: the most likely suspect. Compression gauges are like 30 bucks from SCA, and are very useful. A problem in the head is easier, a problem in the block would probably be terminal in your case.

Spark: Already checked out the plug and lead. Make sure the dizzy contacts are all good. Coil and other stuff will affect all cylinders.

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