Started new engine. Idle Hunting, slight stumbling!
 

Well. Today I started up the FD for the first time. Its a Pineapple Racing Stage 3 motor with a large streetport. We replaced the main wiring harness and all the vaccumm hoses with HT silicone hoses as well. It started up on the first try but we ran into a couple problems. Also, I'm running the stock computer till its done breaking in, after which I will be installing my AEM EMS and tuning will begin.

With the headlights off and engine warm the idle hunts between 1000rpm and about 1500rpm. With the headlights on it stays pretty steady at 2000rpm but sometimes switches back to hunting at around 1000-1500. The idle is set all the way down.

When driving it stumbles sometimes. Not really on acceleration but while cruizing at the same speed it will all of a sudden start stumbling and I have to either give it gas or let off the gas to get it to stop.

What do you guys think? I've done some searching already and found a couple suggestions, but I'm out of time and have to go to sleep. I will start work on it once I wake up again.

As a side note, I let it idle for a couple minutes and the motherf*cking AST exploded and dumped coolant all over the engine! Guess I should have seen it comeing.

Video's coming soon!! Thanks for the help.

Frustrated but happy,
Dan

Also, theres only one y-pipe and stock its supposed to be plastic right? I see a y-pipe on top of the turbo's but its metal, not polished, just dull metal. Just curious about this. Thanks again.

That how the pipe comes stock...

The car should come stock with a plastic one, that has a coupler hooking it to the lower section of the Y pipe. If its metal, and it has a couple 12mm nuts holding it on the Y pipe assembly, its a Efini Y-pipe. Wich is much nicer, imo. Sorry about the other problems. Have you tried adjusting the idle, and checking grounds? CJ

I'm a bit confused here..
You mean the Y-pipe? Or the IC-piping connecting to it?
The stock Y-pipe is made of metal (aluminium).
The IC-piping connecting to it is plastic in stock shape.

After my rebuild i had fluctuating idle for about a week before it stabilized at 900rpm.
I then put in a PFC and had fluctuating idle for a couple of days before this to stabilized..
Seems it just need some time. At least mine did.. :)

could the tps have anything to do with the idle?

as for the stumbling I know that feeling. I think that's a grounding problem. Did you put the ground back on the motor when you installed it? There are lots of grounds you could add also.

You have my dream motor there. Be careful with it. I'm sure you know to drive like a granny to break it in the first 500 miles. Then the next 500 drive like a granny who drank a sip of coffee.:D

Thanks for all the advice guys. I added a temporary ground and went for a spin and it seemed to run much better, so i'm going to add some permanent grounds and hopefully that will hopefully take care of the stumbling.

The idle seems to be working itself out. It seemed to stay steady at around 1500 on the drive, and when i pulled into the garage it dropped down to a steady 600-700, however it started smoking pretty badly. I've got about 33 miles on the new engine now, so i'm assuming this is still normal? I can't drive it till the new AST comes in, so i'll update then if anyone cares.

Dan

ummm, maybe it's just me, but please elaborate on your other mods. Just from the fact that you have a large street ported engine, you should not be using the stock ecu period, break-in or other wise.
The stock ecu is going to have a hard time setting the idle because of the porting done (and what ever else you have on there). I'm surprised Pineapple didn't caution you on that.

Here are my current mods:

AEM Programable EMS
Pineapple Racing Stage 3 Motor
Large Street Port
Hurley 3mm Apex Seals
M2 Down Pipe
Racing Beat Catback
Trust Airinx Dual Intake
3" IC Pipes
UR Underdrive Pully
Nippondenso Fuel Pump
HP Clutch
4.30 Final Gear
Short Shift Kit
HKS Turbo Timer
Silicone Hoses
Removed Cat
Removed Powersteering
Removed A/C
'99 Jspec Tail Lights
White Gauges

I was in a dilemna about whether to install, tune, and subject the engine to alot of stress right away, or hold off and break it in really easy on the stock ECU. I talked to Rob Golden at PR and he said as long as I keep the boost low, I shouldn't have a problem.

So I've been keeping the rpm's below 3k, and the throttle as low as I can get away with. Its kind of hard though, pretty much any gas at all and you can hear the turbo's start to spool!

Keep us posted. CJ