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Missfire! Help!


Milo500

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Hi guys, I am very very desperate with this now haha.

 

I have posted a couple of times on the Facebook group, but the thread ends up dieing and I don't get too far.

 

My car is a originally twin turbo auto. I have single converted it (Turbonetics tnx) making 485hp.

 

The spec in a nutshell as follows:

 

Sard side feed 800cc injectors

Walbro 255 pump

Greddy emanage blue piggyback ecu (3 bar map sensor)

New coil packs

New coil pack connectors

New plugs (have tried -7 and -8 copper ngks)

Fmic

Decat straight through exhaust

Stock motor internals

Stock intake

Stock fuel reg

3200rpm stall precision converter

Totota aristo (40k miles) gearbox, shimmed by David P

 

 

The problem has been around before I changed the gearbox and prior to that it was tuned and ran perfectly for a couple of years.

 

The problem is when on any boost above 1.2 bar it starts to missfire...at least that is how it feels.

Link to video below:

 

 

It drives perfectly when driving off boost and anything under 1.2 bar. It's slightly better now than how it is in the video as it actually revs to red line slowly, but still makes the same missfire all the way up.

 

I need HELP desperately, as the tuner doesn't know what it is yet either...I have had the problem for 7 months and been changing parts to try and find the problem.

 

I have tested for boost leaks, one was found and sorted.

Changed the spark plugs and coil packs quite alot of times.

The ecu checks out fine, as it was plugged in and adjusted slightly on the dyno.

 

 

Please anyone tell me what you think it sounds like, as I am at a complete loss.

Edited by Milo500 (see edit history)
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Id look at the ECU. You can Data log e manage so that will give you an idea.

 

Emanage's are old hat, garbage nowadays, I had an ultimate years back that lost the injector drivers and killed my engine. You need a good quality ECU for a single build

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Id look at the ECU. You can Data log e manage so that will give you an idea.

 

Emanage's are old hat, garbage nowadays, I had an ultimate years back that lost the injector drivers and killed my engine. You need a good quality ECU for a single build

 

How do you go about data logging a emanage blue? (Not ultimate)

 

Chirst, how did it lose the drivers?

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How do you go about data logging a emanage blue? (Not ultimate)

 

Chirst, how did it lose the drivers?

 

 

You need to be connected to the ECU with a laptop that is 32bit to run the eManage software.

 

Once connected there is a logging feature where you can choose to log multiple variables. The laptop must remain powered on & connected the eManage in order to log.

 

It's as easy as clicking record, and pressing stop when done. But be warned the eManage logging interface is terrible so you will have some fun dispersing whats what.

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You need to be connected to the ECU with a laptop that is 32bit to run the eManage software.

 

Once connected there is a logging feature where you can choose to log multiple variables. The laptop must remain powered on & connected the eManage in order to log.

 

It's as easy as clicking record, and pressing stop when done. But be warned the eManage logging interface is terrible so you will have some fun dispersing whats what.

 

Ahh ok thank you.

As my tuner is 4 hours away we are planning on him talking me through what to do etc and sending the software...as all I need to know is what laptop software is 32bit, the software and what data cable it is

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1.2bar is around the stock overboost, could be a coincidence :search:

 

Good point, is there a stock overboost limiter somewhere in the ecu? Or something that will start shitting itself whenever you go over 1.2bar? As it was at 1.5bar for a couple of years and didn't have the issue.

 

Cheers

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Seems like some kind of limiter to me rather than a misfire.

Like Wez says, seems coincidental at 1.2 bar..

I would first look at the emanage then the stock ECU to see if it is playing up...

 

Yea I what I thought, isn't so much like in the video now, it does actually go past 4.5k, but does the same limiter/missfire, and does it all the way till red line.

 

How would I go about checking the stock ecu?

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Yea I what I thought, isn't so much like in the video now, it does actually go past 4.5k, but does the same limiter/missfire, and does it all the way till red line.

 

How would I go about checking the stock ecu?

 

Open it up firstly and a visual check for capacitor failure/leakage. Next step would be taking it to someone reputable to have them replaced. I dont know if it could cause this issue but it is without doubt a suspect imo. Depends on how the emanage piggybacks it and what controls what

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As a test set the boost to 1bar and check everything is OK in every gear right through the rev range ;)

 

EDIT: do you have an AFR gauge, do you know what your fueling is doing?

 

I do have an aem afr gauge/sensor... it riches out when the missfire happens... usually around 10.8

 

- - - Updated - - -

 

I'd be looking at the fuel flow and pressure ahead of tagging into the ECU. You might have one of those chinese $10 non Walbro Walbro pumps.

 

I changed the pump about a year ago, and it was £98 from walbro...and if it riches out when the missfire happens, could it still be the pump?

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An ignition misfire can show as an overly rich mixture on an exhaust gas analyser, even when the fuelling is correct. This now needs taking to someone with proper diagnostic gear that knows how to use it rather than it looking smart in a workshop but no one has a clues as to how to use it effectively ;) You could still be posting about this next year if it's some odd issue, and it could be diagnosed in a couple of hours with the right person and equipment. There's nothing special about a Supra, it works just like every other petrol engine out there :)

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An ignition misfire can show as an overly rich mixture on an exhaust gas analyser, even when the fuelling is correct. This now needs taking to someone with proper diagnostic gear that knows how to use it rather than it looking smart in a workshop but no one has a clues as to how to use it effectively ;) You could still be posting about this next year if it's some odd issue, and it could be diagnosed in a couple of hours with the right person and equipment. There's nothing special about a Supra, it works just like every other petrol engine out there :)

 

That's the thing Chris, it throws no codes up at all, and presents nothing when plugged in, otherwise I would be all over it haha

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You don't need any codes, how did people diagnose engines before a management system threw up codes?? By basic checks on timing, fuelling, spark line and suchlike.

 

Ohh haha, yea I know that, I have done all of the above. I'm more used to old school tuning compared to ecu's

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Things always seemed easier on the old cars, last misfire I had was last year in my MGB which when I popped the bonnet was a lead popped out of the distributor cap. For an old or new car that once ran well to get a misfire its cover the basics and being used to carb tuning and dodgy electrics in older cars leading to poor running its something I've enjoyed solving a few times over the years. You said its over fuelling so I'm assuming you've had that checked with a gas analyser though a misfire can deliver un-burnt fuel down the exhaust pipe. If it were my problem, I'd still want to know that the pump is delivering its designated 250l/hr and delivering the spec pressure and if that's good that the coils are all in good shape with a similar resistance across all of the coils and that they are all within spec. Then at least the simple stuff is checked and you know its a deeper solution that you are seeking which would lead me onto delving into timing and timing sensors. Failing there I'd give up and ask Chris to sort out who lives just up the road.

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I totally agree, I am used to old school tuning when I had my old Capri/beetle/Herald/land rovers...even though I am a bit of a computer nerd, I am not so good with ecu's compared to carbs etc.

 

I have an aem wideband, and when on the dyno the gas sensor for the dyno showed very accurate results compared to my wideband. So when I say it's running rich I mean on my exhaust sensor/wideband.

 

The pump is definitely on the list, it's fairly new, but could be on it's way out. But if it was that (running out of fuel/pressure) wouldn't it run lean?

 

With the coils, I have changed between my new ones and old ones, and it is the same with both of them.

 

I have taken the ecu apart...there are no signs of corrosion or a leaking component.

Edited by Milo500 (see edit history)
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Ohh haha, yea I know that, I have done all of the above. I'm more used to old school tuning compared to ecu's

 

Like chris wilson says, the basics are worth close scrutiny. For example, how have you checked your fuel pressure when under load?

An oscillascope and someone who knows how to use it properly can tell a lot about ignition etc

 

Might be worth booking it in on a dyno with someone who knows their stuff to try and find the issue. Faults like that can be a real pain to identify when it is happening under load.

 

Failing that, emanage log files may help

Edited by and1c (see edit history)
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Mines been doing this recently exactly the same thing :blink: not all the time either. Reading peoples messages saying it sounds like a limiter problem, my oled greddy BC has a limiter setting will try today to run it on 0% to see if that solves it. It’s not a misfire as much definitely more like hitting a limiter I would say.

 

 

 

Subscribe to this now waiting on your findings to figure this out.

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Mines been doing this recently exactly the same thing :blink: not all the time either. Reading peoples messages saying it sounds like a limiter problem, my oled greddy BC has a limiter setting will try today to run it on 0% to see if that solves it. It’s not a misfire as much definitely more like hitting a limiter I would say.

 

These cars are old and the plastic clips and loom plugs around the top of the engine are getting very brittle to disintegrate brittle. Maybe there is a problem with the cam position sensor connector? Its all guesswork till you know the fuel is good, spark is good and timing is good.

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The boost cut is controlled by the stock ECU at a set voltage (this varies a bit car by car) , this voltage comes from the map sensor via the emanage - the emanage acts as a voltage limiter making sure the ECU won't see the cut voltage

So a few simple voltage checks ie what's going into emanage , what's coming out of the emanage to the stock ECU ? What are the the settings on the emanage to limit the voltage ?

Things like the cam and crank sensors can also cause limiter/misfires , if the crank sensor is wired backwards ie pos to neg and neg to pos or loss of the screen on the cable - this causes high rpm misfire at the same rpm on load - again a simple con check of screen and pos neg before replacement .

These snags can be a mare and end up simply replacing components after wire checks - gets expensive and time consuming - I've chased a misfire for ages before .

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Mines been doing this recently exactly the same thing :blink: not all the time either. Reading peoples messages saying it sounds like a limiter problem, my oled greddy BC has a limiter setting will try today to run it on 0% to see if that solves it. It’s not a misfire as much definitely more like hitting a limiter I would say.

 

 

 

Subscribe to this now waiting on your findings to figure this out.

 

So I had a profec before the screen got smashed, so have replaced it with an LD Performance controller...as I also thought it was the boost controller limiter...however it sounds very different to the limiter/missfire I have...when the controller hits the limiter,it sounds like a rush off air being pushed out for a second.

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The boost cut is controlled by the stock ECU at a set voltage (this varies a bit car by car) , this voltage comes from the map sensor via the emanage - the emanage acts as a voltage limiter making sure the ECU won't see the cut voltage

So a few simple voltage checks ie what's going into emanage , what's coming out of the emanage to the stock ECU ? What are the the settings on the emanage to limit the voltage ?

Things like the cam and crank sensors can also cause limiter/misfires , if the crank sensor is wired backwards ie pos to neg and neg to pos or loss of the screen on the cable - this causes high rpm misfire at the same rpm on load - again a simple con check of screen and pos neg before replacement .

These snags can be a mare and end up simply replacing components after wire checks - gets expensive and time consuming - I've chased a misfire for ages before .

 

Quick update. I have checked the cam position and throttle position sensors, and they all check out. I have tried it without the 3 bar map sensor for the emanage, and nothing has changed.

Everything hasn't been changed since I have had It running perfectly...so things like the crank sensor being wired incorrectly etc can't be the reason as it is still probably the original, or if it was replaced, it was by a previous owner atlesst 4 years ago

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