Misfire and no hot start
03-12-22, 07:32 AM
#1
Misfire and no hot start
Finaly got the the new 7 runnig but having issues with missfire on idle and it wont start when hot, doesent seem to flood because once its cooled down it starts.
So background story, Brought it with issues hunting idle and hot start issue.
Previous owner had the engine rebuilt by a renowned builder 2017. engine sat until 2020 when the installed it, crushed a ecu connector on install and that was replaced. when they got it running the idle was all over the place.
Everything is stock exept for catback and 3mm apexseals. Car is a 1996 JDM
I have replaced: coils,sparkplugs and wires, ignitor, 02-sensor, throttlebody, adjusted tps, fuel filter, installed apexi pfc.
Fuelpressure is good but drops when engine is off.
That resulted in more stable idle and less missfire,
Compression is low and not sure if it is due to not breaked in yet? 074/076/073 @252rpm
Also speedo is dead, pfc wont read manual switch and a/c switch
Video of hot and cold start
So background story, Brought it with issues hunting idle and hot start issue.
Previous owner had the engine rebuilt by a renowned builder 2017. engine sat until 2020 when the installed it, crushed a ecu connector on install and that was replaced. when they got it running the idle was all over the place.
Everything is stock exept for catback and 3mm apexseals. Car is a 1996 JDM
I have replaced: coils,sparkplugs and wires, ignitor, 02-sensor, throttlebody, adjusted tps, fuel filter, installed apexi pfc.
Fuelpressure is good but drops when engine is off.
That resulted in more stable idle and less missfire,
Compression is low and not sure if it is due to not breaked in yet? 074/076/073 @252rpm
Also speedo is dead, pfc wont read manual switch and a/c switch
Video of hot and cold start
Last edited by rovers; 03-12-22 at 07:39 AM.
03-12-22, 07:44 AM
#2
RX-7 Bad Ass
iTrader: (55)
First off, not sure why a builder in 2017 would use 3mm apex seals. That's a 20 year old way to go. They will drop your low end compression.
Can you generally drive the car or does it want to stall? Does it hold an idle?
Does the car drive OK or is it driving terribly?
Stock ECU? What year is the car?
Also get a picture of your PFC commander on Sensor Check with water temp and air temp up. Also just look at them. At a cold start they should be about the same, ambient air temp. As the car warms up, coolant temp should go up and air temp will only go up a bit. If not you may have something up with those sensors. I'm also wondering why fuel temp has a high voltage - possible you have swapped connectors?
Dale
Can you generally drive the car or does it want to stall? Does it hold an idle?
Does the car drive OK or is it driving terribly?
Stock ECU? What year is the car?
Also get a picture of your PFC commander on Sensor Check with water temp and air temp up. Also just look at them. At a cold start they should be about the same, ambient air temp. As the car warms up, coolant temp should go up and air temp will only go up a bit. If not you may have something up with those sensors. I'm also wondering why fuel temp has a high voltage - possible you have swapped connectors?
Dale
03-12-22, 07:49 AM
#3
First off, not sure why a builder in 2017 would use 3mm apex seals. That's a 20 year old way to go. They will drop your low end compression.
Can you generally drive the car or does it want to stall? Does it hold an idle?
Does the car drive OK or is it driving terribly? It drives fairly good, i can feel some hesitation when cruising at highwayspeed
Stock ECU? What year is the car? Yes. 1996 so 16bit
Also get a picture of your PFC commander on Sensor Check with water temp and air temp up. Also just look at them. At a cold start they should be about the same, ambient air temp. As the car warms up, coolant temp should go up and air temp will only go up a bit. If not you may have something up with those sensors. I'm also wondering why fuel temp has a high voltage - possible you have swapped connectors?
Wtr temp volts goes up, need to double check airtemp. those might be swapped around yes, will check
Dale
Can you generally drive the car or does it want to stall? Does it hold an idle?
Does the car drive OK or is it driving terribly? It drives fairly good, i can feel some hesitation when cruising at highwayspeed
Stock ECU? What year is the car? Yes. 1996 so 16bit
Also get a picture of your PFC commander on Sensor Check with water temp and air temp up. Also just look at them. At a cold start they should be about the same, ambient air temp. As the car warms up, coolant temp should go up and air temp will only go up a bit. If not you may have something up with those sensors. I'm also wondering why fuel temp has a high voltage - possible you have swapped connectors?
Wtr temp volts goes up, need to double check airtemp. those might be swapped around yes, will check
Dale
03-16-22, 02:34 PM
#4
Have you compression tested the motor? Hot starting issues are very common with low compression motors. Could also be the tune or one of the temp sensors throwing it off. As Dale said, check you fuel temp connector. It is possible to swap it with the coolant temp sensor and that would definitely cause an issue as there are map corrections based on temperature.
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