[MatthewP]

Our 2l EFI Surf (Australian) is only running on two cylinders straight from startup, which to me sounds like "limp" mode, but I'm trying to figure out the cause. I'm going through a tedious process of elimination and I've reached a point where I'm not sure what the next step is. Can anyone help?

So far:
Swapped injectors to see if it was them. Injectors check out OK.

Replaced spark plugs.

Swapped coils around to see if it was them. Coils check out OK.

Replaced ECU (and recoded keys). No improvement.

Can anyone suggest more tests/rule-outs to do??

Any help appreciated.

Matthew P
Brisbane, Australia.

 

[Blogson]

Welcome, Matthew! When you swapped the spark plugs, injectors, and coils around, were you able to determine whether the same two cylinders were the ones which were working when you restarted your RAV?

 

[MatthewP]

Yes, always the same two, the Middle ones (2 and 3 I assume).

So: I started the car.

Removed coil lead to Cyl 1, engine dies

Removed coil lead to Cyl 2, no change to idle.

Removed coil lead to Cyl 3, no change to idle.

Removed coil lead to Cyl 4, engine dies.

Swap plugs 1 and 2, and 3 and 4, same effect.

Swap coil heads 1 and 2, and 3 and 4, same effect.

Swap injectors 1 and 2, and 3 and 4, same effect, always Cyl 2 and 3.

So, my belief is that 2 and 3 aren't getting spark signals at the coils, OR not getting signals at the injectors, OR there is something wrong with the cylinders themselves (BUT the engine passes a head gasket gasses test).

Any clues??

MP

 

[Blogson]

That's a bit of a scratch-one's-head situation, but at least you know which cylinders aren't working properly. It should be possible to test for ignition problems by using a timing light and connecting in turn to each of the spark plug leads. If the light doesn't illuminate when connected to a lead then there is no current flowing to that spark plug. On the other hand if all of the connections result in the light illuminating then the ignition system most likely is fine and the problem lies elsewhere, possibly with the fuel system. You mentioned that the engine passes a head gasket gasses test - does that mean that it passes a compression check test for each of the cylinders? If the engine passes the ignition check test and a cylinder compression check has not been done it would be important to perform that check.

 

[skitter]

Have you run a code scan to check for diagnostic trouble codes?

 

[MatthewP]

Thanks guys!

I'll definitely check the cylinder compression, as it's possible that the head gasket has failed between these two. I'll check the timing light, I thought they were a no-go due to the fact I don't have spark plug leads (the coil packs sit on top of the spark plugs and are triggered by a wiring loom). I'm thinking I may be able to test this loom with a multimeter.

Now, I did think about fault codes, but I had assumed that when a fault is thrown, the Engine light comes on. (Mine is not on). Do you happen to know if that's always the case?

Matthew P

 

[Clydeb]

This would be bank 1 on my CAT converter and I assume yours is the same. If so, don't rule out Air/Fuel sensor (top) and Oxygen sensor (bottom). Swapable bank to bank.

 

[MatthewP]

Thanks for that excellent observation! I'll swap these over tonight and let you know how I get on.

One thing that continues to worry me is the absence of an engine light on the dash. Are there some types of fault that aren't sensed/reported? Is it worth doing a code read, EVEN if the engine light isn't on?

Matthew P

 

[skitter]

Maybe these links will help. They discuss how a dtc may not cause a check engine light.

https://www.quora.com/When-a-diagno...rn-on-the-Check-Engine-Light-on-the-dashboard

https://www.scantool.net/forum/index.php?topic=6933.0

 

[MatthewP]

Thanks guys (and girls?) for the excellent suggestions so far. Just an update in case anyone comes across this in the future.

Last night I identified all four Oxygen sensors pre and post Cat converter.

I removed, then attempted to swap, the two pre-cat sensors, but found that the plugs are actually different, and when you order this particular part, you actually specify Bank 1 or Bank 2. The bottom two sensors (post Cat) are however the same, and are interchangeable.

I know I could take a punt and snip the wires and join it all up with bullet connectors, but I've decided to just take the punt and order the Bank 2 Pre-Cat sensor, and see what happens.

INTERESTINGLY (and I cannot explain this with logic), once I have the pre-cat sensors swapped (but not plugged), the car started and ran like it had before swapping. Removing a plug for a BOTTOM sensor, however, caused the car to immediately die.

I'll let you know what happens when the part goes. I will probably, while waiting for the part, do the compression test on the cylinders, in case I have a failed head or head gasket.

Thanks for all your terrific help so far!


Matthew P

 

[Dr. Dyno]

Can't really explain your O2 sensor findings but I do think you're outsmarting yourself or at least getting in way too deep before checking the simple causes. Once I determined the middle two cylinders weren't contributing at idle my FIRST test would have been compression for a blown gasket between them. Since the gap between the cylinders is so small, maybe 1/4", the gasket can fail there w/o any other symptoms.
And no, there isn't a code for "head gasket failure."

 

[MatthewP]

Thanks Dr, good advice. I'm getting my hands on a compression tester today, I must admit I'm a bit mystified how I get the neck of it way down that deep spark plug recess! But I'll cross that bridge when I come to it.

Matthew P

 

[Dr. Dyno]

Thanks Dr, good advice. I'm getting my hands on a compression tester today, I must admit I'm a bit mystified how I get the neck of it way down that deep spark plug recess! But I'll cross that bridge when I come to it.

Matthew P

You have to use a gauge equipped with a hose. My Craftsman one has a hose about a foot long with a fitting that screws into the spark plug hole. The cheaper ones are short and have to be held against the hole while someone else cranks the engine.

 

[MatthewP]

Wow, this vehicle has me stumped!

So my compression tester came today, and while I don't know what "correct" compression would be, I do know that all cylinders were the same reading at 150. So blown head gasket seems unlikely now.

I also swapped out the pre-cat Sensor on Bank 2. No change to symptoms.

I put a thin block of wood across all cylinders without spark plugs in, and all seem to be getting fuel of similar quantities (from the spray marks).

The one LAST thing that I'm not 100% sure how to check is if all the spark plugs are receiving spark. Naturally I've swapped around the plugs AND the coils so I've ruled them out. Does anyone know how I can check the messages going to the tops of the coils with a multimeter??

At this stage, ANY suggestions appreciated!!

Matthew P

 

[Dr. Dyno]

To test for spark you can simply lay an extra spark plug on top of the engine while it's attached to the coil and cranking or running the engine.

 

[FixIt]

I've been following this since its inception, and haven't posted because others have the same ideas. This is perplexing.


Something simple is being overlooked. Has another set of eyes looked it over?


I have been in so deep on a vehicle that was fighting me that I couldn't see under the hood, sort of like couldn't see the forest because of the trees.


I've been wrenching for almost 40 years, and have had my share of diagnostic nightmares that kept me awake at night. Every one of them was solved, provided the customer did not run out of money first. I never shotgun, and test twice, and if that repairs the problem, I'm not done. If the part is easily accessible, I reinstall the old part and if the problem returns, I can be confident that part was the cause. Sometimes with electronic failures, the failure will correct itself momentarily, and you will think you fixed it, when in reality it rolled over in the grave once.


150psi is decent. I like to see about 165-175 on an engine that has been maintained.


You can take both center coils out (leave the spark plugs in), put spark plugs in the boots, ground the shell, and start it up. If you have no spark, you could have a bad 2/3 coil driver in the PCM, but I have never heard of that. If it comes down to PCM replacement, then replace both coils with the PCM.

 

[Dr. Dyno]

150psi is decent. I like to see about 165-175 on an engine that has been maintained.

Agreed, the main thing is they are equal meaning all cylinders should be contributing the same power. It's possible they are reading low due to not holding the throttle open during the test, an easy mistake to make. In any case a failed head gasket and other issues such as valve related problems are ruled out.

 

[FixIt]

It's possible they are reading low due to not holding the throttle open during the test, an easy mistake to make.

I never hold the throttle open when doing a compression test on all cylinders. All the spark plugs are out, so air is flowing freely through the other cylinders. However, when I am checking compression on a single dead cylinder, I only remove the spark plug for that cylinder, and I do hold the throttle open for better airflow.


We are assuming he cranked it for at least 4 revolutions. Dr. Dyno is correct in that we are looking for cylinder 2 and 3 to be lower than 1 and 4. If the head gasket was blown between cylinders 2 and 3, the readings would be somewhere between 80psi and 100 psi if the other cylinders are 150 psi.


How about spraying carb cleaner around the intake manifold gasket? It is extremely flammable so have a class ABC fire extinguisher nearby.


Do you have a noid light to check the signal at the injectors? That would rule out the driver in the PCM if the light flashes at the same intensity on cylinders 2 and 3 as with 1 and 4.

 

[Dr. Dyno]

I never hold the throttle open when doing a compression test on all cylinders. All the spark plugs are out, so air is flowing freely through the other cylinders.

Yeahbut the only air flow that contributes to compression is any particular cylinder has to go thru its own intake valve. You must be assuming that with the spark plugs removed air flows backwards thru the other intake valves into the manifold thus bypassing the closed throttle plate.