Toyota D4

andyb2, Apr 5, 3:07am
Hi, I have a 1999 corona with the D4 engine. Runs a bit rough on idle and when accelerating from a stop. Done decent mileage and a bit baggy all round so not keen on pouring money into it. Spark plugs seem ok. Engine light doesn't come on, but don't think it works anyway ha ha. Any ideas please.
mugenb20b, Apr 5, 3:21am
I would start by cleaning out the throttle body. D4 engines also suffer from carboned up intake manifolds, so that too may need removing and cleaning and if you do end up doing that, don't forget to clean the ports in the head as well.
gammelvind, Apr 5, 4:39am
Remove the manifolds and throttle body, give them a really good clean with carby cleaner. I do it every year with mine, everytime it runs a bit ropey, easy to do and a cheap fix.
petal_91, Apr 5, 5:57am
Try Seafoam engine treatment. Spray it through the intake manifold as described in various Youtube videos. It will clean your DI engine right up. Sea Foam is sold on here and I think I might have seen it at Repco too.
gammelvind, Apr 5, 6:30am
Sorry petal, used two cans of the stuff to clean mine, waste of money on a D4, the stuffs quite expensive and no doubt good on a normal engine that is a little clogged but you would go broke trying to declog a D4.
Pull it apart and use cheap carby cleaner.
andrewph, Apr 5, 7:42am
Try 2 cans of mr muscle caustic oven cleaner. The green spray can. With the engine at operating temperature pull the breather hose off the inlet manifold and spray it in while hold the revs at about 1800 rpm that will some times achieve the desired effect. Take it for a drive and do it again. That usually works if its not to clogged up. The only other alternative is ti pull the manifold off and clean it and the ports by hand. The mitsi gdi engines are even worse.
melonhead1, Apr 5, 7:47am
Get yourself a tin of that CRC throttle body cleaner. Its the real deal, it cuts grease like nothing else can.
andyb2, Apr 5, 7:57am
Thanks for the advice guys. Have been around cars many years ago and can't help thinking it is more an electrical issue. When it is playing up it seems a very consistent miss, not Quite running on 4 but better than 3. Thoughts please ?
intrade, Apr 5, 9:02pm
Are you sure you have a D4 because it would change everything diagnosing wise and if its a D4 then carbon and stuck egr valve is the number 1 reason for causing problems just like it does cause problems on any diesel. D4 are direct injected petrol engines the egr problems come from the direct injection crank gas ventilation and egr system.
andyb2, Apr 5, 9:12pm
Yes, it is a D4, thanks.
skull, Apr 6, 1:08am
Maybe Intrade is confusing D4 with D4D engines?
andyb2, Apr 6, 1:25am
D4 petrol engine
kimbo88, Apr 6, 1:56am
They do suffer from the carbon buildup, and a large amount of that is caused by running them on 91. While it may be electrical, it normally is the "carboning up" issue. If the throttle body needs a cleanout - I would recommend running it on 95 octane from that point onwards, I've had and got Toyota D4 petrol engines that have never had a problem, but I've always run them on 95 octane the whole time I've had them. Never had any issues at all. The extra few cents a litre is worth it to not have to deal with the issues over time.
intrade, Apr 6, 5:31am
In 1998, Toyota's D4 direct injection system first appeared on various Japanese market vehicles equipped with the SZ and NZ engines
D4 is petrol d4d the secound d stands for diesel i would assume and the first for directinjection
topgear01, Apr 6, 6:05am
I could be wrong, but I think the 4 stands for 4 stroke, which seems a bit obvious to most.
zooki007, Apr 6, 7:59am
They also have issues with the HP fuel pump failing. Carbon is a big issue regardless of fuel used. When real bad the build up on top of the pistons can actually touch the valves and cause a knock. I know of someone trying a methanol/water injection system in their vehicle.
gammelvind, Apr 6, 9:37am
Is the miss worse running about the 70 - 80km area with the green Eco light on? If you put your foot down enough to turn that light off, the miss goes away? If this is the case, carbon build up is you cause. Feels electrical though. I run mine now only on 98 and only use synthetic oil, changing to these has certainly extended the period between decokes.
andyb2, Apr 6, 10:14am
Hi gammelvind, much what you say except at take off/lower speeds.
De-coke looks the way to go.
robotnik, Apr 6, 10:27am
How about a walnut shell decoke. The service is offered at some Volkswagen dealerships, as their Direct Injection cars are plagued with carbon build up issues.
gammelvind, Mar 25, 11:15pm
You may have an electrical issue as well, but decoke it first and go from there. I have decided that I will live with a slight occasional miss as any car with a D4 engine really has no value, but as mine has only done 150km I will just drive it till it dies, guessing I have at least 100km left in it, maybe more.