cylinder 1 miss fire. prius 2009 1.8

start with the egr circuit cleaning, and pray it isn't the head gasket

 

Gen 2 doesn't have the egr circuit like the Gen 3 does.
Move the coil to another cylinder. If #1 is fine and now the other cylinder is misfiring,
you know it's the coil.
You could also check the plugs while you are at it.

 

First, let's figure out what you have. Your profile says you have a gen2 2007, your post says its a 2009 (still gen2) while you identify the engine as a 1.8L which was a 2010 gen3 engine. Plus you have posted in a gen3 forum.

$685 US to do a "deep" diagnosis after already ruling out plugs and coils probably means they are going to tear down the engine to check the head. You should ask "exactly" what will they do for that money and what they suspect.

If it is a gen3 1.8L (possibly built in late 2009), then it sounds like a head gasket. Which is expensive and can sometimes require another engine if it is run too long with this issue. It is particularly bad if it is losing coolant.

 

Early gen3 engines have a big problem with oil burning, egr cooler clogging and head gasket failures. It is something that is real although the root cause is questionable. Toyota changed the pistons and rings by 2015 and sometimes replaced those parts under warranty for the early years. But the engine had to lose a quart in 1200 miles during the first five years, so few were updated.

Initial head gasket problems do not show obvious coolant loss. Driving it will make it worse if it is a head gasket. You have already ruled out ignition problems. You need to go back to the dealer and ask them what they suspect and what level of disassembly will they will do for that 500 £ pounds.

 

Sounds like a 2009 build-date third gen, with 1.8 litre engine. Assuming yes:

#1 cylinder misfire is virtually WITHOUT EXCEPTION head gasket failure. Exhaust Gas Recirculation clogging the intake manifold with csrbon, thanks to a crap design, leads to clogging of the passage ways that deliver exhaust gas at each port, with cylinder #1 always ahead of the others, first to be completely clogged.

And while there’s no tested and documented correlation as yet, clogging leads to overheating leads to head gasket failure, is my mantra, fwiw.

I would call the coil swappers off and do a leak-down test. If you have compressed air you can DIY. You might even be able to DIY on the cheap with a hand pump...

 

As stated earlier, the 2009 is NOT a 1.8 liter engine.
You need to look at the vin number on the door sticker. It may say manufactured in 2009, but
it is a 2010 model year.
They switched the coil, but did they switch the plugs? It could also be a wiring problem.
And if it is a 2010, you need to clean the egr circuit. With only 130,000 miles, that could be your problem.
IF, it is a 2010. Then cleaning the whole egr system could stop the shake, and save the head gasket, if it
is not damaged.
But before anything else, you need to determine which Generation you have because the engines are different.

 

In different parts of the world the identity conventions vary. Japan and Australia in particular. OP’s in UK, and he’s verified once it’s 3rd gen and 1.8 litre. Maybe a pic of engine bay, just to put this to bed??

 

They suspect a head gasket. Most likely they have not seen a lot of these yet. While I don't recommend it, there are head gasket sealers (added to coolant) that will make it go away for a couple of months. In the US there are independent hybrid specialists who can diagnose and fix these problems for much less than dealers. You may want to find one if they exist in your area.

 

That’s a 3rd gen ornamental engine cover if I’m not mistaken.

Leak down test is better than compression test; for head gasket diagnostics. Almost easier to perform too. Is this a dealership?

Leak down test entails pressurizing one cylinder at a time, with piston at Top Dead Center of compression stroke. They then see how well it holds pressure, and where it’s leaking, ie intake, exhaust, crank case, coolant reservoir.

 

I just edited my response , added some. Hope you get this resolved. The preponderance of cases: it’s the head gasket, and fails at cylinder one (closest to passenger end of engine). Very common with neglected Exhaust Gas Recirculation, anywhere between 100k and 200k.

The preemptive cure is to thoroughly clean ALL Exhaust Gas Recirculation passages, that’s EVERYTHING between exhaust connection and engine intake ports. If this is done every 50k you’ll have no problems. Toyota unfortunately doesn’t want to acknowledge their screw up.

 

Coolant does not typically get into the oil with the 1.8L failure mode so the oil cap continues to look fine. Coolant loss is typically small because the coolant does not get into the cylinder when its warmed up, at least at first. The rattling won't happen every day. It can go weeks between rough start ups.

You can spend the time and money to clean the egr cooler, something that has to be done with the head gasket anyway (although uninformed mechanics don't know this). While they are at it, have them clean the oil out of the intake manifold. I guarantee it has a lot of oil in there.

If we did not see many of these every week, I would give you better news. I would not spend $685 US to have a dealer tear it apart just to tell you head gasket or engine. Find an independent shop. The problem is real and driving it may well cost you an engine.

 

Consider an independent shop experienced with Toyotas. The problem is not a hybrid control or electrical issue, it is an engine issue that would be handled the same way in a standard 1.8L Corolla (or whatever they call it there). It might require you to specify checking and cleaning the egr cooler, a service that is not standard unless an egr code appears. Cleaning the egr can be a many hour chore so dealers and others are likely to buy new parts, which in the US are well over $300. Some ebay sellers have new and used egr coolers which could be bought separately.

25601-37010 Lexus CT200h 2011-2017 Toyota Prius V 2ZRFXE OEM Genuine EGR Pipe | eBay

 

There's nothing special-prius-mechanical about the gasoline engine itself; it shouldn't intimidate any experienced mechanic who has a way of getting the repair manual.