Help, Engine Light And Error Codes P0300 And P0301

[DC-MR2]

My (2000) roadster started having problems the other day. The idle was very rough and the power seems to have gone. The engine light came on and started flashing then went off 10 mins later then came on again etc......at the same time the power was coming and going with the light. The engine light is now permanently flashing and I have now managed to read the error codes which are P0300 and p0301. I believe these are P0300 Random/Multiple Cylinder Misfire Detected and P0301 Cylinder #1 — Misfire Detected.

Does anyone have an idea what I can do to fix this....ie spark plug change?

[cfc1]

A few things can cause this.. so instead of me doing all the typing I'll use the old copy n paste thing ;)

P0300

Symptoms may include:

* the engine may be harder to start

* the engine may stumble / stumble, and/or hesitate

* other symptoms may also be present

A code P0300 may mean that one or more of the following has happened:

* Faulty spark plugs or wires

* Faulty coil (pack)

* Faulty oxygen sensor(s)

* Faulty fuel injector(s)

* Burned exhaust valve

* Faulty catalytic converter(s)

* Stuck/blocked EGR valve / passages

* Faulty camshaft position sensor

* Defective computer

Possible Solutions

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap

, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

P0301

Symptoms may include:

* the engine may be harder to start

* the engine may stumble / stumble, and/or hesitate

* other symptoms may also be present

Causes

A code P0301 may mean that one or more of the following has happened:

* Faulty spark plug or wire

* Faulty coil (pack)

* Faulty oxygen sensor(s)

* Faulty fuel injector

* Burned exhaust valve

* Faulty catalytic converter(s)

* Running out of fuel

* Poor compression

* Defective computer

Possible Solutions

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Other Reading

[DC-MR2]

Thanks, look like I have a bit of checking to do. Looking at the engine from the back, what cylinder is #1 ?( left or right).

i will change the spark plugs first as it will be easiest, then will look at the rest. Are the coils the parts on top of the sparks plugs and how do i test them?

cheers

[cfc1]

I would start with some injector cleaner.. might help if the injectors are dirty.

Next I would check the hoses for a vacum leak.. most likely the hoses after the maf and before the throttle body, give things a check and tighten any loose hose clamps, also check the hoses for splits in them, especially the one from the throttle body to the engine breather as I've heard this can be prone to splitting. (maybe just cars with a turbo though)

iirc cylinder one is the one nearest the drivers side.

P0301 means that cylinder one is the problem, to find out if this is the case swap the coil pack with say cylinder 3, clear the code from the ecu (if you don't have a code reader just disconnect the Battery for a few minutes) if you get the light coming on again and it's P0303 then you have found the faulty coil pack.

You can also visually inspect each coil pack for signs of burning.. like electrical arcing?. If you see anything replace the coil pack.

If you understand this and have a scope.... got this from another forum, I can't help further with this method.. sorry.

Here's their wiring:

1) Black with red stripe, constant power (with key in IGN)

2) Black / yellow, ignition feedback, this should give a signal every time the coil fires

3) Black, ignition control from ecu, this triggers the coil to fire

4) White / black, constant ground

If you have a scope with two channels, monitor pins 2&3 and see if the feedback signal goes missing at some point. That indicates a bad coil. I guess you could also monitor only the feedback pin and watch out for any abnormality in it.

If you have a friendly mechanic.. get a compression check too.

[GIDDLEPIN]

Hope it is something simple and not too serious ;)

A word of warning to anyone else with a CEL (Check Engine Light)

Light comes on and stays on...............Check error codes ASAP

Light comes on and flashes.................Stop immediately, this means a serious fault and travelling any distance will possibly cause more damage.

[curriedb]

Well done Davy for taking the time to supply such a comprehensive response...let's hope it's just the spark plugs! Fingers crossed.

[Bob Brown]

Hope it is something simple and not too serious ;)

A word of warning to anyone else with a CEL (Check Engine Light)

Light comes on and stays on...............Check error codes ASAP

Light comes on and flashes.................Stop immediately, this means a serious fault and travelling any distance will possibly cause more damage.

Does the CEL ever come on for servicing? Mines overdue a service and has recently come on (less than a tank of petrol ago <200miles) She's being booked in for a service, but is the light unrelated?

[curriedb]

Apologies Bob...I was that busy whinging about the caliper I missed your posting. It's a warning light NOT service light.

I've owned an MR2 since 2003 and believe the CEL comes on when it feels like it (well almost ).

Nevertheless it also comes on when there IS A SERIOUS problem. Les's advice is spot on. Don't ignore it!

Sometimes a dirty MAF can cause the light to trigger - so you could say this is 'service related'. The MAF is very delicate - but a gentle clean with carb-cleaner and a new air filter might help - as your car's service is overdue.

Personally, I think the car's ECU is oversensitive to data transmitted from some sensors. That's just my opinion. So, don't ignore it...invest £25 in an OBD2 reader - and you will be able to read the code number which has triggered the CEL - and find out the likely problem area. Even if you are not a DIYer you can then impress the service manager at your garage!!

Here's an example of where to buy a code reader. There are plenty of other places!!

http://www.amazon.co.uk/CAN-Bus-Trouble-Di...r/dp/B001CBBY7O

Regards

Dave C

[Bob Brown]

Thanks Dave, will get it read ASAP. I booked a service using the Toyota website but haven't gotten confirmation yet. I know a guy that Fits stuff Kwik so hopefully he can read it for me this weekend if I don't get a service confirmation that is soon.

[Bob Brown]

Well I got the code read.... and there was no error there to be read. Cleared the memory anyway, and the light is off and hasn't come back on. All ok I guess! Still needs that service though.

[cfc1]

Is your car a UK spec car (MR2 Roadster) or a Jap Spec car (MR-S / MR2 Spyder)?

If you have a Jap spec (jap import) then it isn't easy to get the codes read as UK spec readers can't communicate with the Japanese ECU, you would need to find someone or somewhere who can read it for you.

I'm only stating the above because I find it strange that there are no codes stored even although the light is on, I'm not sure what message you get, if any, when trying to read a code from a Jap spec ECU with a UK spec reader.

[curriedb]

Good point Davy!!

[Bob Brown]

MrT read it no problem when servicing her and I don't see anywhere that she is Japenese. I would have thought the code reader would throw a fit if it was Japenese, also though, this was kwikfits code reader a friend used for me, so it should support many, many cars, it was an industrial one made by Bosch.