Rough Idle problem

[streetspirit7]

I just finished my SR swap, everything seems to be fine except when the car is idleing it shakes the car, not a whole lot, just enough to shake the whole car and make the exhuast rattle against somthing under the car. I can't find any vaccume leaks. It seems to have plenty of power so I don't think I have a cylinder not firing, but then agian I have nothing to base it off of. Is it possible that my motor mounts are bad, or should I be looking for somthing else?

[S13FASTBACKSR]

ya i have the same problem not a really bad shaking but enough to notice..i dont have any problems with my engine that would cause it so im almost 100% sure its a motor mount maybe even transmission mount..i have a brand new set of nismo motor mounts and the nismo transmission mount if you want them let me know i'll give you a good deal..im too lasy to put them on so i just shrug my shoulders about the shaking

[streetspirit7]

How much do you want for them?

[S13FASTBACKSR]

cheapest place I saw them is 220 shipped. I'll sell them to you for 150 shipped.

[streetspirit7]

If my ecu was tuned for a different MAF would that cause the problem? I think it's running a little rich to. The reason I ask was that my clip came with an ECU that wasn't mounted to the car, it was just sitting in the floor board, and it has a sticker on it that says KSROM.

[S13FASTBACKSR]

yes if you have a ecu not setup for what you have..injectors maf etc your car will not run how it should.

[streetspirit7]

And I'm guessing the only way to check that would be put in another ECU?

[IanS]

yah putting a stock ecu in would be a good way to check, also what spark plugs are you running and what are they gapped to, and how is the car timed electricly, mine ran rough at idle until I adjusted the spark timing.

[S13FASTBACKSR]

well first you must know what maf you are running and what size injectors..which would be 370cc assuming you stuck with stock and arent using a s15 sr which are 480cc..if you are running the stock maf and injectors then yes put in a stock ecu..or whatever ecu is compatable with your setup

[streetspirit7]

I'll check, but when I did the swap I was under the impression that every thing was stock.

[streetspirit7]

When I did the swap the turbo was siezed up and some oil was in my intercooler piping. Someone else told me that the oil was from the turbo being siezed, but could I have oil in my intercooler and that could be the problem? Also there is a bit of an oil smell when I drive it, but no smoke coming out and I'm not leaking any anywhere.

[Cyberkreig]

Oddly enough the Throttle position sensor can cause similar problems with richness and rough idle. check the voltage on that.

[S13FASTBACKSR]

... bad tps will cause bad idle, richness and misfiring...voltage at idle should be .45volts - .55volts... w.o.t. should be 4.5volts

[streetspirit7]

This probably a stupid question but I'm an idiot when it comes to electical. How should I check for the voltage with my multi meter while it's pluged in?

[S13FASTBACKSR]

while whats plugged in? your tps? yes you check the voltage of your tps while the key is on and the tps is hooke up..i think the power wire is a light green with a red stripe..should be .45volts to .55volts at idle...and set the voltage on your multi meter to 2

[streetspirit7]

Well I just found out I'm not getting spark on my #1 cylinder. I hope it's just a bad coil pack. I think I've been driving it like this for close to 1000 miles. Could I have damaged any thing because of this?

[S13FASTBACKSR]

check voltage and continuity to the #1 coilpack, also check your fuel injector to see if its putting out fuel...as far as ruining anything i think your ok but im not 100% sure

[streetspirit7]

Well, I swapped the coil packs between cyl 1 and 2. Cyl 2 still sparked and cylinder 1 didn't, so I'm assuming it's the wiring for the #1 coil pack. However I'm not even sure how to start tracking down this problem. hehe, I hate wiring.

[S13FASTBACKSR]

all you need to do is see if you have voltage at the power wire for coil pack 1 and continuity throughout the wire with a volt meter..also like i said check your fuel injector to see if its working..pull the rail out with the injectors still in and crank the engine..(unplug coilpacks before you do this)..this is a way to see if your injectors or one of them are not working properly

[streetspirit7]

I have continuity through all the wires, but I['m not sure which wire is the power wire that I should be reading voltage through? What should the voltage read?

[streetspirit7]

Ok, I'm reading 12 volts on the center wire on the clip and somthing like .327 on the other wire that is not the ground. I know it's not the injectors because I get no spark when I pull the coil out and put a spark plug in it. So where do I go next?

p.s. What are the three wires on the coil pack clip? I know the one on the left is the ground but are the other two both power wires?

[S13FASTBACKSR]

the power wire is the black wire with the white stripe IIRC and if there even is a wire with that color pattern..but i believe there is ..anyways thats the main power wire it is the power for your sensor and then the sensor sends a lesser voltage (the wire with the less voltage whatever it reads) to the ecu

and also im confused about what you said...you said that you get no spark with the coil pack out and a spark plug in? can you explain that to me ..let us know man and we'll get this figured out in no time

[S13FASTBACKSR]

just remembered..the coilpacks have a E, + , - on them...obviously the + is your positive/main powere wire..its the middle wire

[streetspirit7]

and also im confused about what you said...you said that you get no spark with the coil pack out and a spark plug in? can you explain that to me ..let us know man and we'll get this figured out in no time

I pulled the coil pack out (still plugged to the harness) with the car running and put another plug I had in it and there was no spark. I did the same thing with the coil pack from the #2 cylinder and I got the sh** shocked out of me. lol

[S13FASTBACKSR]

oh i see..another spark plug...how do you know you are getting fuel for sure? do you spark plugs smell of fuel? simple easy test smell all of your spark plugs see if any of them smell of fuel...and one more time bro..what are your symptoms..bad idle? any misfiring or richness? and what did you check so far?

[streetspirit7]

Well, I'm just assuming I have fuel going to all cylinders, I'll check that first thing tomorrow. The car runs decent aside from the rough idle and poor gas milage. I had the car running and I pulled the #1 coil pack out and there was absolutely no change in the idle, but there was a very noticable change when I did this on the other three cylinders. If the fuel injector is clogged would the ecu compensate and not fire that cylinder?

[S13FASTBACKSR]

rough idle and poor gas mileage? doesnt sound like a fuel injector is not opening but is opening too long..did you ever check voltage to your coilpacks? and one more time does your car misfire at all or hesitate while driving and what have you checked/changed so far to fix the problem?

[streetspirit7]

I checked the voltage and I have 12 volts going to the center (Power) wire. I also checked The ground wire that goes to the engine block off the back of the coil pack harness(it goes to the E on the coil pack), on cyl #2,3,4 it shows around .024-.072 mV and on cylinder #1 it reads from .024 and quickly raises to .271 mV then resets to zero and does it over. I think that could be my problem. Do you think I should try hard grounding that one alone? I don't notice any misfires, but there is a little bit of a hesitation while driving.

[S13FASTBACKSR]

you swapped your coilpacks around to different cylinders already though and the same thing happend...check continuity throught the wire for coilpack #1..also did you check for ecu codes? and how do you know your not getting spark to cylinder one does your spark plug smell like fuel...did you check your tps voltage? and also you may have a bad ecu itself..there is a l.e.d. light on the back of the ecu to check codes with..when you turn the key on the light comes on ..when you start the engine it should go off..if it doesnt then your ecu is bad

[streetspirit7]

you swapped your coilpacks around to different cylinders already though and the same thing happend...

I meant I took the coil pack off the plug for the #2 cylinder and hooked it to the plug on the #1 cylinder and it still didn't fire.

I think the problem could be my ECU, When I got my clip it had a remanufactured ecu with a sticker on it that says KS ROM. ( there are pics in this thread zerothread?id=128032 ) It doesn't have a code light on it.

Also I checked continuity on all the wires and it was good.

I also checked The ground wire that goes to the engine block off the back of the coil pack harness(it goes to the E on the coil pack), on cyl #2,3,4 it shows around .024-.072 mV and on cylinder #1 it reads from .024 and quickly raises to .271 mV then resets to zero and does it over.

Does that sound odd that my ground wire would be reading a voltage like that though?