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View Full Version : RB20DET pulses like a helicopter @ idle? HELP!



KA24DETurbo
03-02-2006, 01:12 AM
I was trying to search but couldn't think of what key words to use except for "engine problem"

When my car is at idle it pulses like a helicopter from the exhaust......

Thought it was the spark plugs so I changed them....idles a little better.

Thought it was the fuel pump so I swaped out the stock for the walbro fuel pump ....Nothing

I ran the car and it runs ok.....but not strong like it should, I can chirp the tires from 1st-2nd gear.

Engine: RB20DET w/ 3" exhaust from turbo elbow to exhaust.

I think maybe one or more of the pistons could be bad? Bad compression? Needs tuning? Needs new Injectors? The injectors were clicking kind of loud maybe one is out?

What do you guys think?

Voltron
03-02-2006, 01:44 AM
Don't beat on the car if its having problems.

Have you tried the power balance test?

Any smoke coming out the exhaust?

Have you just finished the swap or was the motor running fine before?

mmdb240
03-02-2006, 02:03 AM
Kinda bothered me that you're name is KA24det and you have a rb swap :X

HIGHMILEHATCH
03-02-2006, 08:39 AM
My money is on one of the cylinders isn't firing. Verify that you are getting fuel and spark on all cylinders.

MusclesMagilicuty
03-02-2006, 08:49 AM
depending on how bad the fluctuation is it could be a coil pack going. Something else you might want to try to see if it helps is resetting the ECU. Unplug the negative side of the bat then press the brake pedal. Reconnect and let the car run at idle. This helps smooth out the idle sometimes. For the injectors try running some SeaFoam through the system to see it that helps. Also if you want to check the injector then use a screw driver. Place it on each injector and then put your ear on the screw driver to see which one is clicking the most. If this doesn't help then do a leak down or comp test.

KA24DETurbo
03-02-2006, 12:47 PM
Kinda bothered me that you're name is KA24det and you have a rb swap :X



Your post didn't help but if you must know, when I first joined I was working on my KA-T build up but I've done other swaps too.

KA24DETurbo
03-02-2006, 12:52 PM
depending on how bad the fluctuation is it could be a coil pack going. Something else you might want to try to see if it helps is resetting the ECU. Unplug the negative side of the bat then press the brake pedal. Reconnect and let the car run at idle. This helps smooth out the idle sometimes. For the injectors try running some SeaFoam through the system to see it that helps. Also if you want to check the injector then use a screw driver. Place it on each injector and then put your ear on the screw driver to see which one is clicking the most. If this doesn't help then do a leak down or comp test.



I'll try these things but I have a feeling it's an injector cause I had a similar problem with one of my KA setups. Is there any way to check if one of the coilpacks are bad other than buying another one?

Big_Bronze_Rim
03-02-2006, 01:08 PM
depending on how bad the fluctuation is it could be a coil pack going. Something else you might want to try to see if it helps is resetting the ECU. Unplug the negative side of the bat then press the brake pedal. Reconnect and let the car run at idle. This helps smooth out the idle sometimes. For the injectors try running some SeaFoam through the system to see it that helps. Also if you want to check the injector then use a screw driver. Place it on each injector and then put your ear on the screw driver to see which one is clicking the most. If this doesn't help then do a leak down or comp test.



I'll try these things but I have a feeling it's an injector cause I had a similar problem with one of my KA setups. Is there any way to check if one of the coilpacks are bad other than buying another one?


The quick and dirty method is to systematically lift each coilpack one by one while the engien is running and see if idle changes and if its firing you should hear it tick as the spark tries to jump to the plug. However, on sr's Ive seen coils that pass this "test" yet will break up at higher rpm.

KA24DETurbo
03-02-2006, 01:19 PM
depending on how bad the fluctuation is it could be a coil pack going. Something else you might want to try to see if it helps is resetting the ECU. Unplug the negative side of the bat then press the brake pedal. Reconnect and let the car run at idle. This helps smooth out the idle sometimes. For the injectors try running some SeaFoam through the system to see it that helps. Also if you want to check the injector then use a screw driver. Place it on each injector and then put your ear on the screw driver to see which one is clicking the most. If this doesn't help then do a leak down or comp test.



I'll try these things but I have a feeling it's an injector cause I had a similar problem with one of my KA setups. Is there any way to check if one of the coilpacks are bad other than buying another one?


The quick and dirty method is to systematically lift each coilpack one by one while the engien is running and see if idle changes and if its firing you should hear it tick as the spark tries to jump to the plug. However, on sr's Ive seen coils that pass this "test" yet will break up at higher rpm.



That's exactly what I did on my KA problem and found out that it was the injector, but on the RB the coilpacks are on a bracket that connects 3 of them together so I can't test each one individually....is there any other way to test them? Thanks for your suggestions!

KA24DETurbo
03-02-2006, 06:57 PM
A few other symptoms......

constant air flow through stock bov, when I cover it up it seems to want to die out.

when I disconnected the MAF there was no change at idle, maybe I need to rewire it?

nismonewf
03-04-2006, 01:23 PM
the coils are on sets of 3 but you can remove each coil from that bracket with the 8mm bolts on the 4 corners of the coil ...
you can also check by unhooking the clip on the coils one at a time to see if engine sound changes .. and if one dosent change the sound then its a bad coil ..
the rb coils are prone to probems .. thats why im switching to splitfires ... but you can get rid of most of the coil probelms by taking them off and cleaning them well and cleaning the graphite elect contact inside the boot of the coil to make sure its getting good contact with the plug ...

i had probelms with the coils in my skyline the other day and it turned out it was water down in one of the plug cavitys .. it was redirecting the spark away from the plug making a misfire ... hope this helps a little

KA24DETurbo
03-04-2006, 01:45 PM
I never thought about disconnecting eash....doh! I just hate taking that coil cover off......Thanks for the info......Do you know which spark plugs I can use? Thanks again

KA24DETurbo
03-04-2006, 02:49 PM
Okay I checked each coil and found that something is wrong with #3 only because when I disconnected the others one at a time the engine started to idle rough, but when I tried #3 nothing happened.

So I hope it's only one of three things:

1. Bad Injector
2. Bad Coil
3. Both are bad.

Splitfire? Hook me up with a link so I can check it out. Thanks!

Big_Bronze_Rim
03-04-2006, 05:40 PM
What does #3 plug look like? Wet with fuel? if so the injector is prob working(or leaky injector o-ring). If its dry, coil is prob good and injector is bad. Were you able to hear the arc tick as you lifted #3 coil? You can usually hear it if you have spark.

KA24DETurbo
03-05-2006, 12:04 AM
What does #3 plug look like? Wet with fuel? if so the injector is prob working(or leaky injector o-ring). If its dry, coil is prob good and injector is bad. Were you able to hear the arc tick as you lifted #3 coil? You can usually hear it if you have spark.



Okay it's not the injector, I tried starting it and checked out the spark plug and with was wet with fuel. So I'm assuming that my problem is due to a bad coil. Unless you can tell me what else could cause this problem? I won't know 100% until I can order a replacement coil.....too bad autozone doesn't carry spare RB parts! Unless I can use a coil from a US counterpart? Suggestions?

Yellow4g63
03-05-2006, 01:22 AM
The coil packs from the Q45 can be used. #1 and #2. If your looking for RB info search Nico or 240sxforums or Team Race Bread.

KA24DETurbo
03-05-2006, 01:33 AM
The coil packs from the Q45 can be used. #1 and #2. If your looking for RB info search Nico or 240sxforums or Team Race Bread.



LOL Thanks I actually just got done reading about that on NICO just now........

MusclesMagilicuty
03-05-2006, 10:15 AM
I have quite a few RB coil packs if you need one. Just let me know....

HIGHMILEHATCH
03-05-2006, 10:30 AM
I had this same thing happen to me with a Toyota 7MGTE. No spark on number 3, verified the coil was bad, installed new and ran like a champ. Glad to see you figured it out!

KA24DETurbo
03-05-2006, 07:15 PM
HELL YEAH I WANT ONE! Let me know how much! Thanks! E-mail me VegasDrift702@aol.com

KA24DETurbo
03-05-2006, 07:19 PM
I had this same thing happen to me with a Toyota 7MGTE. No spark on number 3, verified the coil was bad, installed new and ran like a champ. Glad to see you figured it out!



I owe it all to FA & it's members! http://forums.freshalloy.com/images/graemlins/party.gif If it weren't for these boards I would be stuck on a lot of my past problems! I'm telling you if ever win a lot of money I'm donating some of it to FA!

nismonewf
03-14-2006, 07:44 PM
sorry for the long delay in reply .. BCPR6EIX. is the plug number and splitfire coils are about 700usd for the set but are useually not recomended unless runnign large ammounts of boost because they seem to like to eat plugs and stuff lol .. ill get you a link and post it ..

thanks
clet
nfdriver.com

Yellow4g63
03-15-2006, 08:19 PM
You can get them at Nugen.com for around $400. Splitfire coils that is.