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Tech Talk Technical Discussion About The Nissan 240SX and Nissan Z Cars |
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08-25-2014, 09:02 AM | #1 |
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95' Ka24DE wont rev past 4500rpm
Recently this S14 KA24DE has been feeling a bit sluggish (slower than it normally is)
Just noticed that it wont rev above 4500rpm, doesnt matter if its in gear or out of gear Engine is completely stock, about 202,000km. Recently replaced the knock sensor and secondary o2 sensor. Any ideas? Solution: Exhaust had 2 cats on it. The primary cat off the header and a secondary cat after the secondary o2 sensor. The secondary cat was almost completely plugged! Replaced it with a straight pipe and everything is fixed Last edited by Ktt88; 10-25-2014 at 12:48 PM.. |
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08-29-2014, 12:50 PM | #4 |
Leaky Injector
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so turns out i was mistaken; it actually wont rev above 5000.
Searched a bit and it might be the low grade 87 octane fuel i recently put in. Going to fill up with 91 octane and throw in some seafoam and ill report back |
08-29-2014, 02:32 PM | #5 |
Zilvia Junkie
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Why would it be the low grade octane considering the ka24de never required a higher octane?
The easiest test is always the MAF. Either borrow one to test or simply disconnect the MAF's connector and see if anything changes. If your car idles better without the MAF then your MAF is bad.
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08-29-2014, 04:45 PM | #6 | ||
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That's no really true actually.. Since without any input from the MAFs at all the car goes into limp mode. It could possibly be a bad wire, signal/ground for the MAFs. As well as many other things.
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08-30-2014, 10:12 PM | #7 |
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But will it only go into limp mode if you are on the gas? then it limits the rpm(limp mode). IF you simply just disconnect the MAF wont it just change the idle IF it was bad?
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09-13-2014, 05:51 PM | #8 |
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So heres a little update..
I had a spare MAF from a 96' ka24de 240sx that I found in a junkyard, swapped that in and there was no change (it could have been bad, not sure) I had to upgrade my fuel pump anyways since I have plans of swapping a sr20, put in a walbro 255. Also, from idle; if i give 100% throttle it limits at 5000rpm. However if i roll onto the throttle the rpm will go to aprx 6000rpm. any other ideas? this is killing my build. |
09-14-2014, 08:20 AM | #10 |
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I've seen this before, usually the speed sensor has been disconnected and the speed signal to the ecu has not been disconnected or viseversa. That is what i've seen on s13's. The other time i've seen this on an s14 was a fuel injector problem, upgrading injectors fixed the issue.
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09-19-2014, 08:31 AM | #19 |
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Had a similar issue were my maf signal and ground were crossed and threw the polarity out of wack, It seemed like it tried to ground back to the ecu.. Changed my ecu and harness, problem resolved. (it may be a fried ecu bud) try swapping them.
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09-19-2014, 08:33 AM | #20 | |
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Ill try asking a friend with a working MAF to swap his MAF into my car and see what happens. |
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09-19-2014, 09:12 AM | #21 |
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Just because you rarely drive the car doesn't mean you won't have a fried ecu. That was my issue when some dude had wired the maf wrong and fried my ecu, my harness was pretty much butchered and it was shorting things out. SINCE you are going to ask a friend to use his maf, ask to try his ecu as well.
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09-19-2014, 09:18 AM | #22 |
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Obviously it has to do with something with or in between your maf and ecu, those are primarily the two components that complete the circuit for it. I'm almost positive it's either a short in between the ecu and maf, a frayed wire, crossed wires, old beat up exposed harness, or a circuit board on the ecu is fried chicken and maf could be toast.
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09-19-2014, 09:53 AM | #23 | |
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I was having some issue's with stutering and revving so i change the maf with 3 others but as soon as i tried the 2nd one the car went into limp mode and was undrivable , so i thought it was the harness so i grounded the ground wire from the maf connection to the chassis and it helped to get me were i began... Swapped the ecu and bam! Pulled like a horse!!! |
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09-20-2014, 01:44 PM | #24 |
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So here a little update again....ugh. I went to the junkyard today. Put a MAF I found there in and theres no change, same issue.
Last night I also checked continuity of the signal wire going from the maf plug to the ecu, it was good. Along with the power and ground wires being good at the MAF. The ECU is also now throwing no codes (code 55) My only suspect now is the ecu or a hidden vacuum leak (does this make sense that it may be a vacuum leak?) |
09-20-2014, 07:17 PM | #26 | |
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