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Bad misfire since going single, really need some help


Mk4Gaz

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Hi all, many of you would've seen my going single thread, and this has started since putting it all back together.

 

Today I turned the key for the first time, since fitting all the single bits.

 

It's misfiring badly on throttle, but idles ok.

 

I've checked the plugs, coil packs and wiring, and all seems fine. Checked the ignitior plug, and that's fine - although I haven't touched that through all of this, and the car was perfect at jae

 

I've got error code 14 for ignition signal, and code 78 for fuel pump control signal.

 

I've got 3 bar fuel pressure while the engine is running, so not sure why that's popped up - unless it's to do with the relay wiring for the 450lph pump. I used the blue/red wire from the fuel pump ecu to the pump, cut it and used the ecu side to trigger the relay, then the other side to continue to the pump

 

I've got an fcon gold ecu, that's been base mapped to the factory settings, but allowing for 650cc injectors.

I've left the mines ecu plugged in, as I thought it would be easier to keep that - rather than have to install a separate sld and fcd.

 

I've checked all the vacuum lines, and pretty sure I've got no leaks. There are two very small lines at the bulkhead, on the exhaust side - next to the water pipe that goes from the thermostat housing, to the heater matrix. I've just looped a piece of hose across these two pipes, if that's correct?

 

The port on the back of the inlet manifold, pointing towards the bulkhead, is being used to go to my ssqv if that's correct?

 

Apart from that, there's nothing else I've changed

 

Could anyone please help, with any ideas or advice, as I'm booked in for mapping on Thursday afternoon, and really need to get it running properly.

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Was the fcon on the car before the single install? Possible its that, might be worth dropping the stock injectors and ecu back in to try obviously only run off boost.

Also if you have any cracked coilpacks its worth replacing those before mapping.

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Thanks for the reply bud.

 

Problem is, to swap the injectors, I'll need to take the inlet manifold back off and refit the stock rail with everything to go with it - big job :(

 

I've removed the mines ecu, and fitted a stock one. It was still much the same, but after idling for about half an hour, it seems much better - although still quite a nasty misfire on throttle.

 

Everything ran beautifully before starting the conversion, so I can't imagine anything has failed, and upon inspection, all the ignition components look good.

 

Code 78 has now gone, but still got 14 back on the stock ecu, indicating a misfire. Could this be caused by the fcon?

 

The fcon wasn't on the car beforehand. I bought it, and took it to have a base map installed, with the new injector values loaded in, so I could drive it to the dyno.

 

Also got my overdrive light flashing on the dash, which wasn't like it before!

 

Went for a light drive round the block, and the misfire is quite evident. It does pick up speed, but it's not very smooth at all. The gear changes also feel quite harsh, and its revving higher before changing.

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Cheers Lee, in your experience what's the best way to do it?

 

I've re checked the spark plugs, all look good. No cracking on ceramic, gaps look good, a nice tan colour.

 

Wiring all looks good, I fitted new coil pack plugs a few months back, and they still look perfect.

 

Coil packs have no cracks that I can find, and all the springs are still in place inside.

 

Done a compression test, and got 175 psi on all cylinders, which is reassuring.

 

Shame you're not closer Lee, I'd bring it down!

 

It's so odd, because it was perfect last time I drove it, which was coming home from jae. It's been in bits since then, and I haven't even touched the ignitor!

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Ignitor gets a feed from the ecu though

 

First thing I would try is another ignitor, if its the same then has to be the wiring

 

If you have just fitted an f con check the wiring harness and also the stock plug to make sure a pin hasn't come out

 

Cheers Lee, in your experience what's the best way to do it?

 

I've re checked the spark plugs, all look good. No cracking on ceramic, gaps look good, a nice tan colour.

 

Wiring all looks good, I fitted new coil pack plugs a few months back, and they still look perfect.

 

Coil packs have no cracks that I can find, and all the springs are still in place inside.

 

Done a compression test, and got 175 psi on all cylinders, which is reassuring.

 

Shame you're not closer Lee, I'd bring it down!

 

It's so odd, because it was perfect last time I drove it, which was coming home from jae. It's been in bits since then, and I haven't even touched the ignitor!

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Gary Kee kindly came over and we've been messing about swapping bits over.

My coil packs and ignitor seem fine, so it must be a wiring issue.

I've checked the coil pack plugs, and they all check out good.

 

Check the wiring harness down by the ecu

 

Make sure no pins got pushed out when you plugged the adapter harness in

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No mate, stock cams went back in. Only removed them to change the valve seals.

 

All I've done, is remove the stock twins, and fitted the single. Removed the inlet manifold and fitted a ttfr with injectors, and put it back together.

 

And plugged the fcon in.

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Right, I've turned the fuel pressure up to 4 bar, with the engine off, and the fp point in the diagnostic port connected to the battery, to force the pump to run.

 

The misfire has now almost completely disappeared! There's a tiny misfire and a little bit of hunting on the revs, but it's very minor.

 

With the engine running, it sits at just over 50psi, or 3.5 bar.

 

Other things happening:

 

Od light is flashing on the dash, but if I switch overdrive off, it just illuminates "o/d off' constantly as you'd expect. No error codes for the speedo (42?), and I'm pretty sure it's not my converter. But, although the od light flashes, it still goes into 4th when driving

 

Also, whilst driving, if I let off the throttle and coast for a few seconds, the Mil and eml light up for a couple of seconds, then go off again. This happens pretty much every time I coast to a stop, or let off whilst rolling. The only error code stored is 14 to indicate a misfire still, even after resetting the ecu and going for another spin.

 

I've checked the wiring at the ecu plugs, and can't find anything wrong with it.

 

Does this sound like it could be just fine tuning of the map needed?

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hang on one minute your misfire stops when you turn the fuel preasure up ?

if so what you are doing is putting more fuel in but the problem with that is the stock ecu will trim that fuel out over time if you still have the o2 sensor still plugged in do you have the stock o2 still in?, my thoughts are that you have 630 injectors and have set the ecu to compensate for 650 making you lean and probably det if you have been making boost / driving it on boost.

what afr are you getting from your wide band o2 sensor ?

if you dont have one then this is a must or at least the sensor to go into the fcon if you have the software to see what value it is ?

as mark says you just cant put an ecu in and expect it to work this seriously needs to be looked at and never driven on boost

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Yes mate, I know I can't just plug it in and expect it all to be perfect, I had a base map installed on the fcon so I could start it at home after the build, to check for leaks etc, then drive it to the dyno for mapping.

 

I haven't driven it on boost, I wouldn't even attempt to without mapping - I know that much!

 

The stock o2 sensor is plugged in still, and my wide band seems to be playing up. It kind of says around 16 on idle, then resets itself - it's an aem one.

 

I know how mapping and building engines works, I done enough in the mr2 world, but supra are new to me. Hence asking the questions, and for help.

 

I don't have the fcon software, but as I said, it's getting mapped on Thursday, so I want to get it running as best as I can before I take it down there..

 

So far I've only driven it around the block a couple of times on light throttle, to make sure it's running alright.

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