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breaking up in high rpm

Old 04-26-19, 10:12 PM
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breaking up in high rpm

so i have a street ported single turbo pfc ecu rx7 fd the car was perfectly fine for 6 months then out of no where in the 7-8k rpms it would break up really heavy i couldnt figure it out so i got a afr gauge to see if it was running lean and i found out its at 13.8-14afr at wot so i tried everything to fix the afr to see if thats the issue but i cant figure it out i installed new pump filter coil wires spark plugs and relay mod i just need answers sometimes after the car is sitting overnight or something i hop in and afrs read fine and theres no break up reading 11.8ish at wot but after being driven for 5mins it goes back to 13-14s if someone could help me find the problem it would be a massive help i dont know if its a sensor issue or fueling issue
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Old 04-26-19, 11:12 PM
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I would highly recommend not boosting your engine, particularly at WOT, until you have systemically gone through every system that can be causing your lean events. You are on borrowed time right now. 13.8-14 AFR's in any high boost is begging your engine to have a catastrophic pre denotation event. That event will cost you a minimum of $5000 to replace or rebuild your engine and even possibly your turbo as the pieces of apex seal goes into your turbo turbine and destroys the wheel. Many of us can help you try to solve your lean problem, but do yourself a favor and don't boost at all until this is solved.
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Old 04-26-19, 11:42 PM
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any help would help so much i dont wot anymore i only test it for a split second then let off and try something new so if you have ideas send them my way i need this fixed
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Old 04-26-19, 11:43 PM
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i dont know afrs before the breaking up when the car was perfect i installed the gauge after the breaking up
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Old 04-27-19, 09:40 AM
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What ECU are you using? Also, give more details about your setup, particularly as it relates to fuel delivery including injectors, fuel pump, fuel pressure, etc. You need to research this forum where there are threads that show people with similar problems and how they fixed them. This may be an easy fix once you find the problem or a combination of many things. Many of us can help but it may be better to take your car to any of the shops in Florida that specialize in RX7's.
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Old 04-27-19, 11:11 AM
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im running a pfc ecu i just put in a new supra pump because i thought that was the issue i have 1700cc injectors fuel pressure is 4 on idle at wot it pins at 6 ive asked all over fb and looked at fourms and i cant seem to find the problem my next step is having a tunner look at it to see if he can find anything wrong but until then i wanna see if any of you guys have had similar problems and found the issue maybe a sensor or something?
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Old 04-28-19, 02:43 PM
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Who tuned the car's fuel basemap? Has it been tuned by someone familiar with the Power FC? Is your voltage to the fuel pump good? Do you have the fuel pump rewire in place? There are so many things that can be going on and these are just a few things that can be responsible. I would take the car to someone who can go through everything in your area. This has to be done in a systematic fashion checking everything.
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Old 04-28-19, 08:57 PM
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Originally Posted by mikejokich View Post
Who tuned the car's fuel basemap? Has it been tuned by someone familiar with the Power FC? Is your voltage to the fuel pump good? Do you have the fuel pump rewire in place? There are so many things that can be going on and these are just a few things that can be responsible. I would take the car to someone who can go through everything in your area. This has to be done in a systematic fashion checking everything.
Mike
i bought the car imported already it was tuned in the uk by a good company fuel pump rewire is perfect i did the relay mod to get good voltage whats strange is if the car is sitting like over night or something and i start it the afrs are perfect but if its not sitting that long my afrs are lean
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Old 04-28-19, 09:01 PM
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Originally Posted by mikejokich View Post
Who tuned the car's fuel basemap? Has it been tuned by someone familiar with the Power FC? Is your voltage to the fuel pump good? Do you have the fuel pump rewire in place? There are so many things that can be going on and these are just a few things that can be responsible. I would take the car to someone who can go through everything in your area. This has to be done in a systematic fashion checking everything.
Mike
it was tuned in the uk i bought it imported and tuned already it was tuned by a good rotary company fuel pump is wired perfect and i did the relay mod to get proper voltage and nothing is different but what i have noticed If the car is sitting overnight the afr read perfectly but if the car is not sitting that long they are lean it's only when the car sitting for 8+ hours that the readings are normal until he gets fully warmed up then it's off again
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Old 04-28-19, 09:10 PM
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Originally Posted by mikejokich View Post
Who tuned the car's fuel basemap? Has it been tuned by someone familiar with the Power FC? Is your voltage to the fuel pump good? Do you have the fuel pump rewire in place? There are so many things that can be going on and these are just a few things that can be responsible. I would take the car to someone who can go through everything in your area. This has to be done in a systematic fashion checking everything.
Mike
it was tuned in the uk i bought it imported and tuned already it was tuned by a good rotary company fuel pump is wired perfect and i did the relay mod to get proper voltage and nothing is different but what i have noticed If the car is sitting overnight the afr read perfectly but if the car is not sitting that long they are lean it's only when the car sitting for 8+ hours that the readings are normal until he gets fully warmed up then it's off again
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Old 04-28-19, 09:50 PM
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Originally Posted by mikejokich View Post
Who tuned the car's fuel basemap? Has it been tuned by someone familiar with the Power FC? Is your voltage to the fuel pump good? Do you have the fuel pump rewire in place? There are so many things that can be going on and these are just a few things that can be responsible. I would take the car to someone who can go through everything in your area. This has to be done in a systematic fashion checking everything.
Mike
it was tuned in the uk i bought it imported and tuned already it was tuned by a good rotary company fuel pump is wired perfect and i did the relay mod to get proper voltage and nothing is different but what i have noticed If the car is sitting overnight the afr read perfectly but if the car is not sitting that long they are lean it's only when the car sitting for 8+ hours that the readings are normal until he gets fully warmed up then it's off again
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Old 05-01-19, 08:50 PM
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fuel pump is fine, tunes dont change and its pfc ecu i think its sensor related but i have no idea what it could be
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Old 05-04-19, 10:42 AM
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How do you know the fuel pump is fine? Did you check the voltage at the pump with the ignition on? What's your voltage drop as compared to your battery voltage? Did you have a fuel pressure gauge in place to check your pressures? Do you have the fuel pump non-stock rewire in place with at least 10-12 gauge wire going from the battery to the pump bypassing the lower gauge crappy Mazda wire that typically goes to the pump? Did you reground the pump in the truck with a 10 gauge ground wire? Are your main grounds good to your chassis? Did you check the resistance through your main grounds? You can see there are many things to check, and these are not all, to know you have reliable fuel delivery system.
Mike

Last edited by mikejokich; 05-04-19 at 10:43 AM. Reason: added one thing
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Old 05-05-19, 10:09 AM
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lol, you know if its too rich and misfires the wideband will read lean, right?
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