engine running but can't idle

[fabio420]

First, I want to apologize for the size of this thread, but I just want to give all the info possible for whoever can come up with a solution. So here it is: 2 months ago i blew a piston. So I replaced the pistons, and reasambled the engine. Now, the head had work done to it(port n polish, 3 angle valve job,dual titanium springs, .5mm oversized nitrited valves) and I used a metal head gasket on the rebuild. I also installed an oil pressure gauge. Now for the current situation. The car is running. When it's still cold it runs better. However, It won't idle if the ac is not on (it brings the RPMs to about 1000) After running for like five minutes, it starts to act rough and it "hickups" in cycles. Whenever it does this, the oil pressure drops and the vaccum jumps. If I am not moving, the car idles almost fne in neutral with the ac on. If I have it in drive, the car stalls out. btw, it's an automatic. I checked for vacuum leaks with starting fluid, and found nothing. I'm not really sure what it could be. My oil pressure drops to about 20 psi when it gets hot, but I can't tell for sure, since I've only driven the car for about 20 miles in 10 minute intervals. I've tried to adjust the timing, but I don't know if I'm using the timing gun correctly. The car is turboed, but I don't think this is the issue, since it was boosted before with no issues, and I haven't touched the turbo parts and I'm tring not to boost ( keeping it below 3500 rpms for a while). The plugs are NGK gapped at .040. I'm kinda stumped as to what it could be. The car will run with the ac on and if I have it neutral when standing still. If the ac is off (RPMs below 800) the car stalls. Sometimes, if I'm in drive and not moving, the car will stall. The car is drivable, but it shouldn't run like this. If anyone has any ideas for me to try, I'd love to hear it. I'm not to the point of taking it to a garage yet, being that I assembled this engine myself, and feel like I can do most work on it. I JUST DON'T KNOW WHAT TO DO WITH IT! Please help me!

[Structure240sx]

figure out how to use the timing light correctly

make a boost leak tester. a sorta of PCV cap to put in the intake and a source of air pressure into it. air compressor works bike pump can. this will pressurize the system making vaccuum and boost leaks much easier to find

[Jookmasta]

might as well lower the gap..............the gap u currently have wont cut it for boost (but i assume u already know this)

[240SicknessX]

Well fabio, I havnt written a novel about my setup yet. But i have 550cc injectors controlled via safc2, autotragic s14 t3\t04e 60trim. Our cars have identical charictoristics. With the a\c on the idle raises because the IACV opens more to accomidate for the load generated by the a\c compressor. My car idles at 1000 also like this and i dont have a problem with the car stalling with normal driving and basic boosting. When you have the car in park or neutral the converter is disengauged from the engine. When you put the car in any gear the converter partially locks so when you release the brake the car rolls foward \ backward. The extra load simply lowers the rpms and at 6-700, the car can stall. My vacumm jumps like yours when the engine misfires, My misfires are due to excessive retarded timing. This could be your case also if you are running a piggyback w\ retarded base timing. I do not have any vacumm leaks, my stalls happen because of a misfire. The condition that you describe after sitting a while the car will surge and idle irradically after being in the normal operation temprature range; i belive the Coolant temprature sensor in my case is the culprit. I have monitored the coolant temprature via a snapon scanner and at 190degrees F the car starts surging and ideling as if i have a vacumm leak, its the ecu seeing a high coolant temp and is adding more fuel then usual at idle attempting to cool the combustion tempratures. I am also watched the wideband read a few points more rich at the same time.

I am unable to get an accurate base timing at ~700 rpm because the car misses and cant hold that idle, ive adjusted my timing based off plug condition and wbo2 displays (5000 miles, not 1 psi dropped in a cylinder).

bwt my total timing at 11psi is 22-23btdc WOT.

Dose the car hold a solid idle for a few seconds then drop and fluxuate all over the place until it stabiliizes again?

post your fuel\engine management, becuase if you are on a tuned ecu my whole retarded timing theory is out the window if you are properly timed.

[fabio420]

my fuel managment is only an SAFC II. I have a very hard time figuring out how to use a timing gun. Our problem sounds very similar. Does your car stall out while you are standing still on drive? Have u fixed the issue. I just need to figure it out to have the car be able to drive evryday. Our setup is very similar in that I have t3/t04e but with a 57 trim. My injectors are 370 cc's (from an SR20) gotta get new ones. We should try to meet up, being that we are so close. I go to school at Nova. hit me up

[240SicknessX]

this weekend i took the turbo and manifold off, replaced a missing exhaust stud. Huge exhaust leak fixed, now my idle dosent surge and poses the same charictoristics as a vacumm leak. I have a wild idea of how an exhuast leak could cause an unstable idle pre turbo but im probably wrong. Dose your car have a exhaust leak? Retarded timing is part of a unstable idle.

[fabio420]

I had a horrible exhaust leak because of the manifold. Since it came with a flange for a t3 or a t4 it had holes for 8 studs. No problem , right? But all those 8 hole went all the way into the manifold. I had to plug up 4 of the holes with studs and shave them down. Now I only have an exhaust leak on the downpipe. (gotta get someone to staighten out the weld on the flange. And I don't know how to use the timing gun. ( I mean the angle from which to poit and the angle from which to read)

[Kenrik]

my fuel managment is only an SAFC II. I have a very hard time figuring out how to use a timing gun. Our problem sounds very similar. Does your car stall out while you are standing still on drive? Have u fixed the issue. I just need to figure it out to have the car be able to drive evryday. Our setup is very similar in that I have t3/t04e but with a 57 trim. My injectors are 370 cc's (from an SR20) gotta get new ones. We should try to meet up, being that we are so close. I go to school at Nova. hit me up

Dam Nova is expensive how can you afford to keep your KA-T running when you're paying that much for school :O lol BCC is the shiz.. $56 a credit hour :P

[240SicknessX]

so there arnt any other exhaust leaks pre turbo right now ? bump the idle up to 900-1000 w\ a\c off normal operating temp. Double check for boost\vaccum leaks, make a boost leak tester from homedepot. get a pvc end cap the same outside dia or close to your silicone hose on the intake side of the turbo, drill a hole in the center or where ever so that a valve stem will fit in there. I dont know the exact size because i havnt made one yet, if you still get a small leak around the valve stem you can try some rtv silicone around the stem, let it dry and try again. To help find leaks if your pressure drops, a bottle of soapy water will make leaks bubble.

Do you have your distributor almost all the way retarded? or if you can figure it out what your base timing is at.

[fabio420]

I think it's retarded all the way, but I don't really know for sure. I have a timing gun, but don't know how to use it properly. If u could help on ur spare time, I'd be more than happy to drive to you so you could guide me.

Dam Nova is expensive how can you afford to keep your KA-T running when you're paying that much for school :O lol BCC is the shiz.. $56 a credit hour :P

With lots of academic scholarships and diy car work.

[240SicknessX]

i have not been able to get a base timing reading because of my unsteady idle. The timing marks on the crank pulley would move all around, never got an accurate reading. If your idle isnt rock soild i wouldnt be able to get a timing reading off your car either. I check my plugs to determine if i need more or less timing, being cautious and conservative since last january plus 5000 miles of ka-t whoop *** at drift events and 1\4 i have not dropped compression in any cylinder, 180psi. Dont get the idea my car dosent know what the revlimiter is either.
Modified by 240SicknessX at 6:04 PM 11/8/2005