Switching to a single plane intake!
Safety Car
Joined: Nov 2009
Posts: 3,973
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From: Adelaide South Australia
have you checked condition of o2 sensor ?
it will have those symptoms as the computer disregards o2 readings and uses a set fuelling graph under WOT .
although some aftermarket computers can tune at WOT as long as they have wideband o2, does your autronic do this ?
it will have those symptoms as the computer disregards o2 readings and uses a set fuelling graph under WOT .
although some aftermarket computers can tune at WOT as long as they have wideband o2, does your autronic do this ?
Thread Starter
Instructor
Joined: Apr 2005
Posts: 228
Likes: 0
From: Göteborg
Ignition problems that create misfire shows up as lean when looking at a wideband, will prob look into this as a first step. Maybe the old msd6 box or coil is the root cause?
Last edited by bogor; Jun 15, 2014 at 08:38 AM.
Safety Car
Joined: Nov 2009
Posts: 3,973
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From: Adelaide South Australia
your ecm operates in open loop mode all the time ?
what is the specific temp that it starts leaning out ? if its temperature related could it be a vacuum leak ? or is that specific temp affecting the msd or wiring ?
what is the specific temp that it starts leaning out ? if its temperature related could it be a vacuum leak ? or is that specific temp affecting the msd or wiring ?
Thread Starter
Instructor
Joined: Apr 2005
Posts: 228
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From: Göteborg
Well, still misfire
I have now
-changed MSD box
-changed ignition coil
-changed distributor cap
-changed spark plugs
-changed fuel filter
-searched for vacuum leaks "everywhere"
-increased fuel pressure from 40 to 55 psi (to reduce risk for vapor lock)
-added alot of heat protection to the fuel lines
-checked all spark wires for damage
-tested numerous tunes
-checked PCV valve and brake booster
Running out of ideas. Been fighting this for almost three weeks now and I wants to use the car before summer ends.
Maybe switch back to the old superram intake ?
I have now
-changed MSD box
-changed ignition coil
-changed distributor cap
-changed spark plugs
-changed fuel filter
-searched for vacuum leaks "everywhere"
-increased fuel pressure from 40 to 55 psi (to reduce risk for vapor lock)
-added alot of heat protection to the fuel lines
-checked all spark wires for damage
-tested numerous tunes
-checked PCV valve and brake booster
Running out of ideas. Been fighting this for almost three weeks now and I wants to use the car before summer ends.
Maybe switch back to the old superram intake ?
Last edited by bogor; Jul 1, 2014 at 04:42 PM.
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
I will suggest it again (seeing as you have tried just about everything else), have you checked the o2 sensor is operating properly ?
Does your setup use an intercooler ? Could it be a temperature thing related to that, i.e. intake air being too hot ?
Does your setup use an intercooler ? Could it be a temperature thing related to that, i.e. intake air being too hot ?
Thread Starter
Instructor
Joined: Apr 2005
Posts: 228
Likes: 0
From: Göteborg
Meth inj- no intercooler. Intake air temp is normal when it happens. Also tried cooling spray on the IAT sensor.
Misfire on bank or cylinder: dont know, how do I go about finding this out?
The old sparkplugs all look the same.
Last edited by bogor; Jul 2, 2014 at 01:24 AM.
Safety Car
Joined: Nov 2009
Posts: 3,973
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From: Adelaide South Australia
could be a fuel problem, if its going lean then it must not be getting fuel,
are you running a knock sensor ? if so the leaning out must be activating the knock sensor and causing the misfire (it will cause the ecm to "kill" the engine),
maybe the knock sensor is too sensitive ?
maybe your fuel setup is sensitive to fuel load in the tank ? How much fuel was in the tank when the symptons happened ?
are you running a knock sensor ? if so the leaning out must be activating the knock sensor and causing the misfire (it will cause the ecm to "kill" the engine),
maybe the knock sensor is too sensitive ?
maybe your fuel setup is sensitive to fuel load in the tank ? How much fuel was in the tank when the symptons happened ?
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Thread Starter
Instructor
Joined: Apr 2005
Posts: 228
Likes: 0
From: Göteborg
could be a fuel problem, if its going lean then it must not be getting fuel,
are you running a knock sensor ? if so the leaning out must be activating the knock sensor and causing the misfire (it will cause the ecm to "kill" the engine),
maybe the knock sensor is too sensitive ?
maybe your fuel setup is sensitive to fuel load in the tank ? How much fuel was in the tank when the symptons happened ?
are you running a knock sensor ? if so the leaning out must be activating the knock sensor and causing the misfire (it will cause the ecm to "kill" the engine),
maybe the knock sensor is too sensitive ?
maybe your fuel setup is sensitive to fuel load in the tank ? How much fuel was in the tank when the symptons happened ?
Im running a standalone knocksensor (http://www.jandssafeguard.com/8ChInt...terceptor.html) and if it command retard (ignition only) it is displayed -however no sign of knock retard.
Last edited by bogor; Jul 2, 2014 at 04:05 PM.
Team Owner
Joined: Mar 2001
Posts: 30,856
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From: Boston, Dallas, Detroit, SoCal, back to Boston MA
To find a misfire you need to pull the injector connector one at a time and see which one doesn't make it worse
could be the meth injection not getting distributed correctly
could be the meth injection not getting distributed correctly
Burning Brakes
Joined: Mar 2005
Posts: 1,082
Likes: 115
From: Richmond Hill Ontario
This is my analysis and recommendations and the reasons for.
You are running in open loop and using a Wideband O2 in the exhaust just to monitor AFR so this has no relevance to symptoms. You have already checked and or replaced anything to do with ignition such as plugs, wires, distributor and coil. If it was caused by an ignition misfire this would cause raw fuel to be dumped into the exhaust which will definitely cause backfire or popping in the exhaust – which you do not mention of having.
I would recommend that you concentrate your efforts on a faulty injector, injector connector or wiring, or possibly an intermittent injector driver when it gets hot. A misfiring injector will cause your wideband O2 to read very lean.
You can try to run the car until the symptom happens then pull over and with an Ohmmeter measure each injector’s resistance value to see if anything seems abnormal on any one of them.
Hope this gives you some direction to troubleshoot.
You are running in open loop and using a Wideband O2 in the exhaust just to monitor AFR so this has no relevance to symptoms. You have already checked and or replaced anything to do with ignition such as plugs, wires, distributor and coil. If it was caused by an ignition misfire this would cause raw fuel to be dumped into the exhaust which will definitely cause backfire or popping in the exhaust – which you do not mention of having.
I would recommend that you concentrate your efforts on a faulty injector, injector connector or wiring, or possibly an intermittent injector driver when it gets hot. A misfiring injector will cause your wideband O2 to read very lean.
You can try to run the car until the symptom happens then pull over and with an Ohmmeter measure each injector’s resistance value to see if anything seems abnormal on any one of them.
Hope this gives you some direction to troubleshoot.
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
A misfire will be displayed as a lean condition so I think its still up in the air if its ignition or fuel related.
Im running a standalone knocksensor (http://www.jandssafeguard.com/8ChInt...terceptor.html) and if it command retard (ignition only) it is displayed -however no sign of knock retard.
Im running a standalone knocksensor (http://www.jandssafeguard.com/8ChInt...terceptor.html) and if it command retard (ignition only) it is displayed -however no sign of knock retard.
Thread Starter
Instructor
Joined: Apr 2005
Posts: 228
Likes: 0
From: Göteborg
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
Thread Starter
Instructor
Joined: Apr 2005
Posts: 228
Likes: 0
From: Göteborg
Im currently adjusting valve lash and looking into the wiring to the injectors.
Maybe it is an internal problem with the ECU (despite lack of error codes) after all...?
Last edited by bogor; Jul 4, 2014 at 06:44 PM.
Safety Car
Joined: Nov 2009
Posts: 3,973
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From: Adelaide South Australia
keep at it bogor, you will find it eventually Im sure 
is there any chance that some grit has found its way into the fuel system during the build and found its way into some injectors ?
do you have another set to try, or can you get that set cleaned ?
a bad injector clip or wiring could do it, I know gerard always talks about bad injector wiring that took him over a year to find, and he nearly sold the car cheap he got so sick of chasing the problem.
do you have another ecm to swap in and see what happens ? I had issues with my timing recently, it was going all over the place and pinging (i thought at first my 11:1 compression was too much), no fault codes came up, someone in the club gave my another ecm, I put my chip in, and now it runs like a champ, you just never know with them sometimes !
is there any chance that some grit has found its way into the fuel system during the build and found its way into some injectors ?
do you have another set to try, or can you get that set cleaned ?
a bad injector clip or wiring could do it, I know gerard always talks about bad injector wiring that took him over a year to find, and he nearly sold the car cheap he got so sick of chasing the problem.
do you have another ecm to swap in and see what happens ? I had issues with my timing recently, it was going all over the place and pinging (i thought at first my 11:1 compression was too much), no fault codes came up, someone in the club gave my another ecm, I put my chip in, and now it runs like a champ, you just never know with them sometimes !
Thread Starter
Instructor
Joined: Apr 2005
Posts: 228
Likes: 0
From: Göteborg
I guess it is possible for some contaminats in the system. I checked the cost for cleaning and flowing the injectors and it was quite steep so I would like to look into some other things first.
I measured resistance between the big ECU connector and the injector clip and resistance was between 0,3 and 0,4 Ohms for all eight clips. I visually inspected the wires and they looked ok.
A good idea to try another ecu box, unfortunately dont know about anyone usingthis particular one but I will have this in mind.
I have another theory about a failing component I will check when Im back frpm a vacation trip next week.
I measured resistance between the big ECU connector and the injector clip and resistance was between 0,3 and 0,4 Ohms for all eight clips. I visually inspected the wires and they looked ok.
A good idea to try another ecu box, unfortunately dont know about anyone usingthis particular one but I will have this in mind.
I have another theory about a failing component I will check when Im back frpm a vacation trip next week.
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
it can be hard to find some things sometimes,
I had a problem where my engine would run rough when it was warm, after checking so many things couldnt find it, I used tunerpro and the only thing that showed up was "low coolant" and I thought that was because i had only just started it and running it in the garage, i did a check after driving it on the road, it showed "low coolant" again,
I checked the sensor and connector clip with the voltmeter and they tested ok,
I replaced the sensor (at $60) no difference, it was only when i was putting the connector clip back on i noticed the connector was broken on the underside and as i pushed it on the pins were pushing back and not going into the sensor, put a new connector on ($6) and problem fixed,
must have taken 2 months to find that one !
I had a problem where my engine would run rough when it was warm, after checking so many things couldnt find it, I used tunerpro and the only thing that showed up was "low coolant" and I thought that was because i had only just started it and running it in the garage, i did a check after driving it on the road, it showed "low coolant" again,
I checked the sensor and connector clip with the voltmeter and they tested ok,
I replaced the sensor (at $60) no difference, it was only when i was putting the connector clip back on i noticed the connector was broken on the underside and as i pushed it on the pins were pushing back and not going into the sensor, put a new connector on ($6) and problem fixed,
must have taken 2 months to find that one !