My car will go into limp mod every time I hit full throttle. The tach needle is also going all over the place then it will sort it's self out. Does anybody have an idea what it could be an how I can fix it?
the engine light isnt on so im guessing there are no codes. i did some more thinking and realized its not limp mode. it just stops reving at certain pionts and hit another random rev limiter. the car will stop at like 4000 rpms and just bang off a limter and some times the rpm starts rising but still making the rev limiter noise.
Check the rpm signal for a stable reading first. If it's smooth it's good. The Tach. may be failing or have a loose signal wire for example. If the signal is irratic, fix the cause of that.
If it's just stopping at certain rpm's and won't rev past that (with the acception of a small amount of rpm creeping) you "could" have a slight fuel delivery issue. Try checking the fuel pressure which should read 3 bars with no vacuum at the FPR. Less under vacuum and +1lb of pressure for each pound of boost on top of the one bar (45PSI approx).
If your motor is starving for fuel because of inadequate pressure that could cause the erratic rpm limits under load.
No scrader valve available (nipple) you'll have to remove the feed hose to the fuel rail and stick a pressure guage on there with the exit hose clamped onto the fuel rail. This will basically put the pressure guage inline between the feed line and rail where you can monitor the pressure the fuel rail is seeing. You may need to run a long hose on the guage as it'll be hard to see the pressure under the hood when you have to load up the engine to see what's happening during those rpms while driving.
I've run with the guage on the outside of the windshield being held down at the hose under the windshield wiper blade so I could drive and see what's happening to the fuel pressure. Just had a "T" hose between the feed line and rail and ran a longer hose up to the guage. You can still close the hood just make sure it doesn't pinch the hose completely or you'll get an inaccurate reading.
ok thanks a ill give that a try. im just gonna change the plugs for now until i get a pressure guage. also i dont have a datsun data scan but how do i do the paperclip trick. i know you have to jump the pins and the engine light will flash. i just need to find the place to stick it in
Knock sensor is being tripped which is why your getting code 34 and it'll retard the timing very aggressively when happening but that's just the result of the ECU protecting the motor from blowing up. You'll have to find out what the underlying issue is.
With the knock sensor going off you should know that your running a lean condition on the motor which is why you have knock. Now this can be caused by a faulty MAF signal, bad fuel pressure (pump can't keep up or your regulators gone) and of course air leaks which bypass the MAF and aren't calculated for by the ECU which is why it doesn't match the right amount of fuel for air entering the motor.
Before I spend any money on a new MAF sensor, is there a quick way i can check it? If i were to open the wire MAf sensor what kind of voltages should i get through the rpms. Also i checked for some boost leaks around the intercooler piping. No boost leaks around there. So I'm hoping it's just the maf sensor.
hmm your knock sensor might just be fubar ... cheapest solution would be to buy a 7$ one on ebay(sr20de will do) and have it installed then see if you get code 34 again.
My timing was being retarded and once I took the knock sensor off, I noticed it was all cracked ... replaced it last year and its been runing strong since then.
I have an update on how my car is running. I changed the plugs and it runs better but still has this problem. I knew the plugs were not gonna fix it. But when i give it throttle from neutral or a stop it will have a miss fire then it catch up and work. until i put a big load on the ecu it will go into limp mode. Is this a sign of a MAF sensor, TPS sensor, the knock sensor, or soomething else?
I did the ecu faullt code check and i have code 34. So hopefully its a bad knock sensor. The miss fire happens when the engine is cold or hot so i don;t know if its the power transistor. And the miss fire happens when the engine is warm enough that it runs regular rpms after a cold start.
so now it will drop a cylender at idle. I have a video of my car going into limp mode. maybe the sounds can help you guys out. It starts at 14 seconds in the video when I start to accelerate. The car is shooting more flames then usually as well. I'm assuming thats because when the system is being retarded it runs rich and a lot of fuel is getting through the engine. My friends had to make a video of it...
Do you have a nissan Datascan?Have you ever made an ecu fault code check?Start from there and let mw know what is wrong.
the engine light isnt on so im guessing there are no codes. i did some more thinking and realized its not limp mode. it just stops reving at certain pionts and hit another random rev limiter. the car will stop at like 4000 rpms and just bang off a limter and some times the rpm starts rising but still making the rev limiter noise.
Check the rpm signal for a stable reading first. If it's smooth it's good. The Tach. may be failing or have a loose signal wire for example. If the signal is irratic, fix the cause of that.
If it's just stopping at certain rpm's and won't rev past that (with the acception of a small amount of rpm creeping) you "could" have a slight fuel delivery issue. Try checking the fuel pressure which should read 3 bars with no vacuum at the FPR. Less under vacuum and +1lb of pressure for each pound of boost on top of the one bar (45PSI approx).
If your motor is starving for fuel because of inadequate pressure that could cause the erratic rpm limits under load.
Less load = More rpm
More load = Less rpms
is there a nipple or someting i can do a fuel pressure test?
No scrader valve available (nipple) you'll have to remove the feed hose to the fuel rail and stick a pressure guage on there with the exit hose clamped onto the fuel rail. This will basically put the pressure guage inline between the feed line and rail where you can monitor the pressure the fuel rail is seeing. You may need to run a long hose on the guage as it'll be hard to see the pressure under the hood when you have to load up the engine to see what's happening during those rpms while driving.
I've run with the guage on the outside of the windshield being held down at the hose under the windshield wiper blade so I could drive and see what's happening to the fuel pressure. Just had a "T" hose between the feed line and rail and ran a longer hose up to the guage. You can still close the hood just make sure it doesn't pinch the hose completely or you'll get an inaccurate reading.
ok thanks a ill give that a try. im just gonna change the plugs for now until i get a pressure guage. also i dont have a datsun data scan but how do i do the paperclip trick. i know you have to jump the pins and the engine light will flash. i just need to find the place to stick it in
At the top of you this page under the right side "Popular GTiR Articles" it's the last one called "ECU Fault Code Check."
http://www.canadagtir.com/forum/engine-performance/ecu-fault-code-check
i did a fualt code check. the code i got was 34. whats that?
have a look at your air flow meter maf clean the pins or change it thats is what was up with mine a few ears back hope that helps
the green dragon
ok so i think its a knock sensor. sound right to any one?
Knock sensor is being tripped which is why your getting code 34 and it'll retard the timing very aggressively when happening but that's just the result of the ECU protecting the motor from blowing up. You'll have to find out what the underlying issue is.
With the knock sensor going off you should know that your running a lean condition on the motor which is why you have knock. Now this can be caused by a faulty MAF signal, bad fuel pressure (pump can't keep up or your regulators gone) and of course air leaks which bypass the MAF and aren't calculated for by the ECU which is why it doesn't match the right amount of fuel for air entering the motor.
Before I spend any money on a new MAF sensor, is there a quick way i can check it? If i were to open the wire MAf sensor what kind of voltages should i get through the rpms. Also i checked for some boost leaks around the intercooler piping. No boost leaks around there. So I'm hoping it's just the maf sensor.
hmm your knock sensor might just be fubar ... cheapest solution would be to buy a 7$ one on ebay(sr20de will do) and have it installed then see if you get code 34 again.
My timing was being retarded and once I took the knock sensor off, I noticed it was all cracked ... replaced it last year and its been runing strong since then.
OK :) I will give that a shot. The Canadian tire by my house has one for a g20. I was gonna get it but it cost 10$ more then what i had :p
I have an update on how my car is running. I changed the plugs and it runs better but still has this problem. I knew the plugs were not gonna fix it. But when i give it throttle from neutral or a stop it will have a miss fire then it catch up and work. until i put a big load on the ecu it will go into limp mode. Is this a sign of a MAF sensor, TPS sensor, the knock sensor, or soomething else?
does it do it from cold, or after driving awhile so its hot. if it does it after its hot, its likely power transistor or knock sensor.
but the fuel pump, and or injectors could also be culprits
If you haven't done the following
check injectors for leaks
changed power transistor or relocated and added heatsink http://www.gtiroz.net/gallery/gtir/misc/diagrams/power_transistor.jpg.html
changed fuel pump
knock sensor could also be bad and need changing
u should try datalogging with a consult cable
if ur timing is being crazy pulled but showing no knock sensor, could still be the sensor, someone else on the forum experienced the same
I did the ecu faullt code check and i have code 34. So hopefully its a bad knock sensor. The miss fire happens when the engine is cold or hot so i don;t know if its the power transistor. And the miss fire happens when the engine is warm enough that it runs regular rpms after a cold start.
so now it will drop a cylender at idle. I have a video of my car going into limp mode. maybe the sounds can help you guys out. It starts at 14 seconds in the video when I start to accelerate. The car is shooting more flames then usually as well. I'm assuming thats because when the system is being retarded it runs rich and a lot of fuel is getting through the engine. My friends had to make a video of it...
http://www.youtube.com/watch?v=6msXbY01dFk.
so let me get this straight, your ecu is complaining of a bad knock sensor
ppl have suggested u fix certain things yet u just continue to beat the shit out of your car and post videos about it while fixing none of the above
i may sound like a dick, but fix the small stuff before it becomes expensive
good luck
I rarely ever do that. And that was also at pretty slow speeds. But there one thing I need to try. My spark plugs are gapped way to big.
I doubt very much your plug gap is the culprit ... change your damn knock sensor .... you are getting code 34 dude.
My knock sensor was fucked and I never even had code 34 so count yourself lucky you are at least getting the code from the ECU.
I changed my plugs to copper and gapped them at .028. Runs like a champ now. (Knock on wood)
What heat range with a .028 gap?
Ive always found on these cars its almost always basic stuff... until boom lol
Mine isn't bigger than yours.. I just like to drive
What heat range with a .028 gap?
Ive always found on these cars its almost always basic stuff... until boom lol
Mine isn't bigger than yours.. I just like to drive