[RichardR66]

216 R8 Honda D16 Engine pre-cat. Engine wants to stall when attempting to move off or change up a gear when driving, when it is warm/hot. It is possible to drive the car using high revs when warm/hot. But the engine works perfectly when cold. I have recently fitted new Ignition Coil, Igniter Module, Distributer Cap, Spark Plugs and Leads. But I do not think that this is an ignition related problem. I think this is a fuelling problem, because the ECU gives the engine extra fuel when it is cold, so the Fuel Injectors are working correctly, and the Fuel Pressure is ok. When warm/hot, the engine ticks over correctly at idle. It then wants to stall when the accelerator is pressed slightly and the throttle opens slightly. Could it be a problem with the MAP sensor? But this seems odd to me because it works fine when the engine is cold. Any help would be greatly appreciated. Thanks.

[g259fsg]

I don't know anything about this engine, but the symptoms sound like the mixture goes too weak when you open the throttle. On carburettor cars, that's usually because there is a blocked jet. It could be the MAP sensor is telling the ECU the wrong thing as the throttle opens so it doesn't respond with more fuel from the injectors. I agree, it doesn't sound like ignition. May need to put an analyzer on the ECU to look for faults.

[StubbornPatriot]

Did this problem start immediately after you fitted all the new ignition components, or did it run OK for a while and then start exhibiting this problem?

[RichardR66]

The problem started immediately after fitting only the new Ignitor Module, but it was not evident until the engine warmed up.
I had an even bigger problem beforehand which prompted me to fit the new Ignitor Module: the engine was missfiring very badly, so that I could only drive the car at walking pace. Fitting the new Ignitor Module appeared to fix the problem, until the new aforementioned problem occurred.

[StubbornPatriot]

When the engine is warm, does it rev OK when the accelerator is depressed? Or does it only stall when it's under load? Sorry, lots of questions. Despite the symptoms appearing to be fuel related, I would still be a bit suspicious that this has happened immediately after you replaced all those ignition components. As a matter of interest, did you also replace the rotor arm? Some of these aftermarket ignition parts are not of the highest quality and I just wonder if one of your new parts is a bit duff. Maybe the coil? Have you tried just cleaning up the dizzy cap contacts? Did you make sure the spring bit of the dizzy went back in clean? This is guesswork though, still rather in the dark at the moment.

[g259fsg]

I agree. I've had quite a lot of problems with aftermarket ignition parts, particularly rotor arms which seem susceptible to electrical breakdown when they get hot. This leads to a weak spark which can cause misfiring under load. If you still have the old ignition parts you took off, maybe you can try changing them back to see if the problem persists. Interesting that the car seems to drive OK when it's cold. Is that correct? The low engine temperature measured by the sensors tells the ECU to inject more fuel. The fact that the engine idles OK even when hot, is maybe not that relevant to this problem. The fuel required for tick-over is minimal and the ECU is controlling the air supply using a stepping motor (assume that is the same as the 1.4 K-series). In that case the MAP sensor isn't playing a big part.

[RichardR66]

Thank you for taking the time to ask these questions.
When engine is warm it revs, but stalls under load, however it goes when using high revs.
I replaced the Ignition Coil a year ago which cured a similar missfire to the one I have now, but was also when engine was cold.
I have only driven the car once, so I will have to test it again when cold.
The previous owner replaced the Dizzy Cap, Plugs and Leads 2 years ago, but not the Rotor Arm.
The car has only covered 1000 miles in 2 years, the Dizzy Cap Contacts look like new.
The next step will be to check the ECU Fault Codes.

[RichardR66]

Yes, the car drove well when cold. But I have only driven it once. Will have to check that again.
Replacing the Igniter Module cured a much worse missfire, so the old part is no good.
Replacing the Ignition Coil also cured a bad missfire, so that part is no good.
The Rotor Arm has not been replaced, so a new one is worth a try.

[Johnny 216GSi]

A low-cost thing to try is to clean all the PGM-FI flexible pipework to make sure it's all completely clean all the way through. Removing each piece and then something like a pack of pipe cleaners or if you have a compressor, blowing them out. You should start with the flexible tube to the MAP sensor first, and see if this makes a difference.

It does sound like a fuelling problem, however whilst the logical thing would be to suspect the MAP sensor or it's air feed, you have to remember that several sensors contribute to the fuelling of the vehicle. E.g. the air temperature and coolant sensors (one at the back on the RHS of the manifold and one at the front of the engine on the LHS). I'd say the O2 sensor too if your car has one fitted, as some earlier ECUs had a CO2 adjustment potentiometer fitted and so whilst it's not true closed-loop, I believe it is taking the O2 signal and the potentiometer setting to achieve a steady CO2 output.

The other thing that affects fuelling is engine timing. The TDS sensor is in the distributor on SOHC cars or it's a separate unit on the other cam shaft on DOHC cars. The ECU takes that pulse and varies the time delay it is subjected to according to engine speed and other parameters, to create the trigger pulses for the igniter (spark amplifier) and coil pack. Mechanical alignment of the distributor matters though. On the distributors I've worked on, I could clearly see where the spark amplifier had been triggered just a millimetre or two from the tip of the rotor at one end, demonstrating the ECU time-delayed switch on. The pattern you see is a spark eroded edge with carbon deposits, but the edge is clean for the first millimetre or two.

You may find that you'll have to track down other replacement sensors to fix the problem, which may be a blessing in disguise if a temperature sensor can be sourced as an aftermarket part and it fixes the problem, as I believe a replacement MAP sensor would have to come from a scrapped vehicle.

[GTiJohn]

It still might be the ignitor...

The new one might be better but it still might not be good when hot.

I seem to remember that some ignitors (maybe OE ones) came with a sachet of conductive grease to put on the back of it to give it a good heat sink.

It might be worth seeing if you can get another one or find some conductive grease. Jon will probably be able to point you at some