Hi,

I have a 1986 Accord EXi that's impossible to start unless you use a block heater even in summer, and it's bogs down and dies unless you press the accelerator VERY gently. These problems go away when I apply vacuum to the outer vacuum hose coming off of the distributor.

The shop manual says to replace Thermovalve B, but I can't find it. There are seven different vacuum line diagrams, and none of them match my car sold in Sweden:




I saw a video on how to repair the Thermovalve, but it's for a carburated engine with the valve clearly visible on the back of the intake. On mine, both hoses go from the distributor to the orange thing, and end up directly in the intake, with no visible "valves":






Does anyone know where it's located, or how to fix this issue?

 

I only have the Honda manual for the civic, yes the carbureted model has a thermovalve B, on the intake, but the fuel injection model of the 1.5L engine does not mention a thermovalve B. In fact my thermovalve B has failed some years ago and it is not available anymore, so I did a bypass and connected a vacuum hose from another source to get the proper high idle speed.

For the fuel injection model you should have the computer under the passenger side with 4 LED diagnostic capabilities.

Fuel injection relies usually on the computer increasing the idle speed and controlling the timing for cold weather conditions

Here are some pict, they may help

 

Thank you so much! I really appreciate it. This led me down the right path. Some more googling with the new information in mind led me to this picture of the Ignition timing control system.:



Along with this text: "For 1985-87 models, the distributor has two separate vacuum advance diaphragms which operate on manifold vacuum. Vacuum is applied directly to diaphragm A, while vacuum to diaphragm B is controlled by an inline cold advance solenoid valve. This valve is operated by the control unit which receives signals from the engine coolant temperature, engine speed and manifold vacuum. When the solenoid valve is open, it sends vacuum to diaphragm B to improve cold engine performance. No vacuum advance is used on 1988 fuel injected models. Ignition timing is directly controlled by the ECU."

I figured that orange thing on my car must be the "Cold Advance Solenoid Valve," which of course doesn't show up anywhere if you google it. I checked the 1987 supplement service manual for Accords too, just in case they missed it in 1986, and there it was! How to inspect the valve, (for those who find this thread in the future):




Doing this test, mine had a slow vacuum leak without connecting the battery, which was unaffected by applied voltage. Since googling for the valve gives no results, I looked in the parts catalogue and this thing is called "VALVE ASSY., IGNITION SOLENOID (#150-B)" with part number 36161-PH2-004, which I can only find for sale on a Ukrainian site:https://razborka-ua.com/ru/honda-acc...-4-36161ph2004

Seems like 650 грн is about $15, but it's unclear if they ship to Sweden. Does anyone know if there's an equivalent part that would do the job?

Interesting, do you think that would work for me too? One of the two hoses going to the solenoid valve has constant vacuum, so I could in theory just plug it directly into the distributor. But I don't know how it would affect the engine when it's hot, and I'm fixing this car for an elderly gentleman, so it has to "just work" without any extra manual input.

 

you can try to buy the parts from Ukraine, not too sure about shipping charge to Sweden

Otherwise as the part seems easily accessible, you could substitute another vacuum switch from a different vehicle/brand... you can get these switches on ebay, use "vacuum switching valve" search, the electrical connector might need a little modification

I used this one, no longer on dabay


and use a manual switch, easy and cheap, you may find something at your local junkyard, toyota and most cars have plenty of similar items

 

Thank you! This was really helpful I'm gonna try to get a hold of one somehow, since it did make it run better and start easier. However, now that the weather has been colder, the car won't start at all with or without vacuum to the distributor, unless I use a block heater:-/

With an inline spark tester, I managed to discover that all the brand new plugs spark outside the engine, but not when they're installed. Do you know what could cause this? It's really driving me nuts. Like, why would the coolant temperature affect the spark? I tested the ignition coil and wires according to the manual, and all values were within spec.

 

When the weather is cold, may be under 50F or 8C, I will suspect that the engine management resort to added ignition timing and more gas (for carburetors) and less air for fuel injection.

As for the spark plug issue, I have no real ideas, AI answer is as listed below:

A spark plug not working in the engine block, while sparking outside the engine, suggests a problem with the spark plug's ability to fire under pressure or within the combustion chamber's environment. This could be due to a faulty plug itself, or issues with the ignition system, fuel delivery, or even engine mechanical problem

Are the spark plug being used the recommended specs on the manual of the hood sticker?

Many many years ago (before the internet) I installed cross referenced spark plugs on a Honda wagon... started fined, but as soon as we had steep uphill, the engine was bucking... so I dropped the car at the Honda dealership, and was told that I did not use the right spark plugs... problem fixed