Miss-fire and No power!

I have a Toyota Supra 3.0 Auto Non Turbo late 1993 MK4. I've owned it for 7 years of trouble free motoring as my second car. Going to my garage to start it last weekend, it fires up immediately by has absolutely no power? It idles OK(ish?), but as soon as the throttle is pressed it miss-fires and once in gear it can hardly give enough power to move out of the garage:(. Nothings been touched on the car sinse I last used it, I've used it sinse filling with petrol, so can't think it's comtaminated fuel? HELP!

When was the last time the plugs/leads were changed?

I have to say not for some years., so I will do this. Would these cause a sudden miss-fire problem?

mine has done the same and ive found out what it was, it was an injector that was stuck open and it flooded the cylinder with fuel. take your plugs out and shine a torch down to see if one of the cylinders is wet inside with fuel. if so then you know if its fuel related. check plugs and coilpacks first and your loom mate

Do you have rodents in your garage?

If you have a standard air box, take a look inside and check that mice have not set up home in there!

Have come across this a couple of times with cars that have been standing during the winter months.

An odd occurance, but an easy fix as long as they have not chewed up the loom too.

two other possibiliys .

1. the coolent pipe thta goes too and from the throttle body leak into the plug wells

2. the cam cover gaskett can leak oil into the plug wells.

Guys,

Thanks for the responses. I'm going to order new plugs, leads, coil, fuel filter and pull the injectors for ultrasonic cleaning.

A couple of questions, what is the procedure for getting to the injectors, plus where is the fuel filter fitted and whats the best way of getting it off?

Cheers

That sounds expensive, I would have taken it one at a time.

The fuel filter is under the passengers left foot. You need to be cautious of this little job, as it is common for them to have been overtightened by Mr T. This can bell out the end of the pipe inside the filter and make it impossible to get out. Worse case scenario is need to replace fuel line.

No need to buy a new coil, if you need one, I have recently taken a perfectly good one out of mine when I replaced it with an MSD Blaster.

That reminds me, I must get it on the for sale forum.

Got new plugs and stuff today- one stupid question before I start- where's the fuel filter fitted, is it up by the engine, or at the rear of the car???

I think your car just need proper service when you are at ordering stuff, maybe it would be good to order oil. oil filter, air filter too?

Fuel filter is located underneath the car on the passenger side, protected by metal shield.

Oh and membership costs just 10 pounds, lots of info here.

Hi,

Finally managed to get to do some work on the car today, but only managed to do the plugs.

The old ones were black with soot, so in went the new ones, along with fresh oil and filter, plus new air filter.

Started the car.... but still a missfire and absolutely NO POWER! The car won't even crawl up my drive! I also noted after managing to keep it running on a rough idle for about 4 minutes, when then blipping the throttle its like a rev limiter comes in at about 3900rpm.

Once cool, I pulled a couple of the new plugs and again covered in thick black soot?!

Would this suggest I have spark, but also an overfuelling? I hadn't run the car since Nov last year and that was just letting it tick over on the drive. My wife reminded me that the car ran out of petrol doing this.

Once filling it back up with petrol, it was OK, I blasted it for a few miles and then put it away. It was then left until I tried starting it a few weeks back now with a miss-fire- hense the start of this thread. A mate thinks it could be a sticking injector??

Help Clouder:(

I had an over fueling issue with mine. Turned out to be a fuel pressure regulator problem, test it by pulling the vac hose out of the regulator to see if it makes any difference.

Hi Miko,

Thanks for the suggestion. Should I plug the end of the hose? Does the vacuum on the regulator increase the fuel pressure, hence the overfuelling?

just hold your finger over it. Only need to do it for a second or two to see if it makes a difference. Check all over for loose of split hoses too.

Hi,

Disconnected the hose, and yes the idle went up a bit, but still loads of black smoke from the exhaust when the throttle was blipped- and still no power?!?

Guys,

Swapped out the plugs, coil and also did the fuel filter (as I had a new one) about a month ago and this seemed to cure the miss-fire. Due to being ill, I didn't get a chance to use the car for more than a few miles and things were 100% good to me. I even popped into my local garage (about 12 miles away as I live in the country) and they quickly did an emmisions test on it and all things are good.

Anyway, came to drive the car today. Started fine, drove about 6 miles, perfect. Orange low fuel light comes on and I am already suspisious that the car is more thursty than usual perhaps. Within a mile, I kicked the auto down to pass another car, the engine stumbled big time and the main warning triangle comes on. Off throttle light goes off but for the next mile the car keeps going from normal, to miss-fire, sometimes to stalled! Luckly my parents house was now within about 1/4 mile so went there. In the drive I could get the engine to about 3900rpm sounding OK, but then a big missfire. Bugger. Also I noted that when coming off throttle, when the idle dropped below 1000rpm, the speedo shot up to about 30mph and then straight back to 0 ?!?!?

Left her there over night. Went back this morning, so the car was cold, with 10 litres of unleaded. Fired her up straight away on the key, but it idled at 800rpm- no cold start sequence of 1500, 1200-1000 down to 750rpm? Any ideas??? HELP!!!

Another stupid question- which plug do I use for the error code, the one under the dash, or the one under the bonnet, or does it not matter?

The one under the bonnet unless you have a (rare) OBD2 reader that does Supras.

Right,

I managed to get an hour on the car tonight.

First I fired her up, hoping the fairies may have fixed things, but still the same symptoms,big miss-fire and a fair bit of black smoke when revd.

Anyway, I then went on to look at the error codes. Following the procedure OK, until I came to the bit about viewing the engine check light for pulsing. I've only owned my car for 8 years and I suddenly realise there is a small screen of tell-tale lamps on the right side of the dash!!!! I now find that due to not having a hand book and also just leaping in the thing and driving, I haven't noticed any of these lamps being lit. They are the 'engine check', 'oil pressure', 'oil level' and 'ABS'. I have now removed the top panel of the dash and pulled out both the LH and RH indicator panels to test the lamps. All the lamps are OK on both panels, except for the SRS lamp on the LH panel.

It's too dark now to have a good look at whats going on here, but does anyone know if these bulbs have a common power, or common return that may have failed- thus all RH panel lights not working??

Finally, I did manage to extract a unit from the LH panel (the one with the odometer in) which I think could be the digital speed converter unit thingy?? I've attached a image- hopefully someone may recognise it.

Cheers for now.

Cloudder:(

The right hand panel is notorious for having problems with the solder joints inside it that attach the ribbon cable. Dabbing fresh solder on every joint with a miniature soldering iron should fix it and enable you to get the fault codes. Speedo converters are also notoriously unreliable, try with the wiring returned to stock if you get a speed sensor error. You are !10% sure none of the intercooler to plenum and turbo assembly are partly off, aren't you? A look is NOT good enough, you need to physically attack each joint and check for a part blow off, or loose clamp. The one down by the side of the battery is especially troublesome.

You are !10% sure none of the intercooler to plenum and turbo assembly are partly off, aren't you? A look is NOT good enough, you need to physically attack each joint and check for a part blow off, or loose clamp. The one down by the side of the battery is especially troublesome.

Think its an NA?

would the distributor cap and rotar arm cause the miss-fire?

Hi Guys, Yep it is an NA Auto. I'll go over all the hoses etc again, but I am beginning to think dist. cap. rotor and leads- they look like the original factory build ones still.

Right,

I managed to get an hour on the car tonight.

First I fired her up, hoping the fairies may have fixed things, but still the same symptoms,big miss-fire and a fair bit of black smoke when revd.

Anyway, I then went on to look at the error codes. Following the procedure OK, until I came to the bit about viewing the engine check light for pulsing. I've only owned my car for 8 years and I suddenly realise there is a small screen of tell-tale lamps on the right side of the dash!!!! I now find that due to not having a hand book and also just leaping in the thing and driving, I haven't noticed any of these lamps being lit. They are the 'engine check', 'oil pressure', 'oil level' and 'ABS'. I have now removed the top panel of the dash and pulled out both the LH and RH indicator panels to test the lamps. All the lamps are OK on both panels, except for the SRS lamp on the LH panel.

It's too dark now to have a good look at whats going on here, but does anyone know if these bulbs have a common power, or common return that may have failed- thus all RH panel lights not working??

Finally, I did manage to extract a unit from the LH panel (the one with the odometer in) which I think could be the digital speed converter unit thingy?? I've attached a image- hopefully someone may recognise it.

 

Cheers for now.

 

Cloudder:(

never seen that before- dont think thats a speedo con

Is there vacuum at the fuel pressure regulator pipe with the engine running and the vac pipe off? Could be a failed engine temp sensor or the wire off or broken to it.