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Old 07-15-2008, 01:40 PM   #1
fastenova
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Default rough idle after installing Delta street cams

I know this has been somewhat documented in places, but I dropped in the motor I've been working on this weekend. It's got Delta cams with the street grind, LW ACT flywheel, and LW Mr. Josh pulley.

Upon driving the car a little, I first got a P1507, Idle Control System Malfunction. I checked the IAC solenoid and valve and they looked OK, I used the lower mileage one. I cleared the code and reseated the vacuum lines going to the IAC. After driving the car a bit more, I am getting intermittent misfires on three cylinders around 2000 RPM. I need to go pull codes again to see if it's consistent (I only have data from two misfires).

The idle is pretty rough. I expected a little bit of a funky idle from the cams but not this bad. What's wrong?

I'm using the intake manifold, plug wires and coil from my '97 motor, with the heads and block from the '98 motor. I read somewhere that the length of the plug connectors could be slightly different... Should I swap the coil and wires?

Or is the combination of cam, LW flywheel, and LW pulley too much and the ECU is just confused? Or should I look at valve clearances again? I was pretty anal when I adjusted them. Timing was dead on as during the install but I guess it could have skipped a tooth, I've heard of it happening before.

Thanks!
Aaron
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Old 07-15-2008, 04:43 PM   #2
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Quote:
Originally Posted by fastenova View Post
Or is the combination of LW flywheel, and LW pulley
That's my guess. But it's not a super educated guess, so hopefully someone else will chime in.
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Old 07-15-2008, 05:11 PM   #3
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Have you tried retuning and resetting your ECU?
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Old 07-15-2008, 05:21 PM   #4
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my guess would be the lw flywheel and pulley and/or valve clearances slightly off.
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Old 07-15-2008, 05:25 PM   #5
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I had the LW flywheel and pulley on before I did the motor swap (identical motor, only without cams) without a single CEL.

So if it's related to those, it's only because of some change in the cam.
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Old 07-15-2008, 05:26 PM   #6
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Quote:
Originally Posted by ronoverdrive View Post
Have you tried retuning and resetting your ECU?
The battery was disconnected, so the ECU was as reset as it would get. It is a stock ECU so there is no tuning involved (yet!).
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Old 07-15-2008, 09:55 PM   #7
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If I were you, I would throw the stock crank pulley back on and see if that helps your misfires.



~Josh~
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Old 07-15-2008, 10:04 PM   #8
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I dont see how a pulley and flywheel could cause a miss. They are not part of the air, fire, fuel triangle, and there are no sensors monitoring them. You really cant mess up the install on them.
I would bet the cams are off a tooth, probably the intake side on the (r) side of the motor looking at it. I have seen that a few times, as it is hard to get all the slack out of the timing belt prior to setting the tensioner. Pull the covers and check, it only takes a few minutes.

Also check the big IAC hose that connects to the intake, and make sure all the cam, crank sensors are connected. The coolant sensor will make it run like poo as well. Probably something forgotten or the above mentioned cam timing prob.
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Old 07-16-2008, 09:55 AM   #9
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So I checked out the IAC motor last night and it looked good. I swapped the 83K mile one onto my intake manifold and got rid of the 200K mile one.

The car died about 4 or 5 times last night when returning to idle. It revs fine. I know that seems to point to an IAC, but it's not consistent, and doesn't explain the misses at low rpms.

I rechecked all of my vacuum lines, they look good. I'll put the stock crank pulley on tonight and maybe remove the timing covers temporarily to see if I can figure anything out.

Any other ideas?

Thanks,
Aaron
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Old 07-16-2008, 10:29 PM   #10
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Quote:
Originally Posted by iluvdrt View Post
I dont see how a pulley and flywheel could cause a miss. They are not part of the air, fire, fuel triangle, and there are no sensors monitoring them.
They don't actually cause a misfire, the ECU just thinks there is one (or several). Something about revs dropping too fast or something like that.

Last edited by Counterfit; 07-16-2008 at 10:30 PM. Reason: ninj4r
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Old 07-16-2008, 10:37 PM   #11
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The way the ECU determines a miss is by counting the crank and cam teeth. If the time between one set of teeth is long than the other by enough the ECU calls it a miss fire.

Now with your setup missfires at idle would be normal. However missfires at
2k would not be. Check your manifold gaskets too.

Exactly how did you time the motor? Did you go by teeth count or the timing ticks? The ticks can mess timing up by a tooth.
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Old 07-17-2008, 09:11 AM   #12
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Default Partially Resolved

So I pulled the timing covers off and sure enough, the timing was off. It's irritating to me that although I've done the timing belt on the EJ25 DOHC a half dozen times, by the book, I can still be off! I suppose it's possible that it skipped a tooth but I'd be more inclined to blame it on human error.

Anyway, still have a strange idle, it's "searching" for a good idle speed, between 600 and 800 RPM and you can hear the motor actively revving up and down, slowly. I'm going to swap back to the original IAC motor now that the timing is accurate. Also I'll run some injector cleaner through the system. I need to clear the CEL from the timing-related issues then I can have a fresh start.

What other things could cause an unstable idle?

Aaron
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Old 07-17-2008, 11:33 AM   #13
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Well just from reading you mentioned that you had the flywheel and pulley on before and the engine was running fine.

All of the issues you are listed are coming after the cam install. You mentioned that you have done the timing belt several times, but it looks like the cams are still off.

check the cams again, if one cam is off then the engine idles like crap.
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Old 07-22-2008, 09:38 AM   #14
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So I'm still getting a CEL. Codes are misfire, cyl 1, and misfire, cyl 3. No other codes so far. I occasionally get a flashing CEL while I'm driving but it doesn't feel like it's misfiring AT ALL.

Here's what I've done in trying to fix the problem, without any results:
- Reinstalled the stock heavy crank pulley
- Swapped out the throttle position sensor
- Swapped out the idle air control solenoid
- Installed a new (upgraded) ignition coil with different plug wires
- Swapped out the ignitor
- Replaced the ground from transmission to pitch stop mount on firewall (was broken?)
- Checked the timing AGAIN, seems right on.
- Checked for vacuum leaks, everything looks perfect

Freeze Frame data when I pull the codes suggest misses around 2500 RPM, but based on the still slightly rough idle and flashing CEL, it seems like it may be doing it all over the RPM range.

I'll be getting a OBDII scanner with live data availability in a couple of weeks, so I may be able to learn more with that by looking at my ignition advance and O2 levels, but if anyone has ideas in the meantime I'm out of them myself.

Last edited by fastenova; 07-22-2008 at 05:02 PM. Reason: clarified acronyms
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Old 07-22-2008, 04:50 PM   #15
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What heads are these? Stock? If so, did you re shim the valves? If not...do so. If so, check the clearances again. Did you follow proper cam break in instructions? If so, your idle will be messed up cuz it never got a chance to find it on it's own. If not, check the lobes for wear which would throw off your clearances.

Reset the ECU and let the motor run AT LEAST until the cooling fans come on before you start fiddling with the gas pedal. Let the ECU have a chance to find a good idle speed.

I highly doubt it's the flywheel, crank pully or any other lightweight bits you got hanging on the motor. Those ECU's aren't as picky over misfires....unless the clearances are off.

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Old 07-22-2008, 05:01 PM   #16
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Jay-

Thanks for the response. These are stock EJ25D heads. I did re-shim the valves per Subaru spec. I was able to reuse several of the shims but ended up getting 8 new ones, and swapping places with them all.

Upon getting the motor in the car and starting it, I ran it at 1500-2000 RPMs for ~20 minutes per instructions from Delta.

I of course used cam installation lube on the valve lifters, both sides of the shim, and the lobes and bearing faces of the cams, so I would not *expect* any funny wear on the lobes. I suppose I can take the valve covers off and check though, and check my clearances again at the same time.

The ECU has been reset several times since then, but I haven't let it idle on its own until it reached operating temp.

What do you think would cause misfires at 2500 RPM?

I am going to install a fresh set of NGK plugs tonight, one step colder (BKR6E-11). I have alternated between 5 and 6s in the past but I'm wondering if with the cams (and a different motor) the 5s are too warm. It's also especially warm lately, in the 90s during the day. I'll post back if the plugs look abnormal.

Thanks,
Aaron
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Old 07-22-2008, 05:05 PM   #17
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I also want to mention, just in case I am missing something, that the long block is a 2.5 from 1998 while the ECU is from '97. Sensors are mostly from the '97 as I used that intake manifold and associated electronics.
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Old 07-23-2008, 02:35 PM   #18
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I checked the timing again last night, just to be 100% sure that it wasn't off. Looks like I'll be checking valve clearances again this weekend. The dealer quoted me about $200 to check and adjust one side (the side with misfires), I may do that as I'm getting kinda tired of screwing around with it.

Sometimes I think HLAs would be better.
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Old 07-23-2008, 03:00 PM   #19
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Wow, I hope I am not running in to the same problem.

Granted I only get misfire on Cyl. 2, but I read it was due to the cams. I reset the ECU let it idle and all, but once I am driving at a constant speed, poof CEL on
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Old 07-23-2008, 04:12 PM   #20
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I talked a little more to the service guys and they said they'd charge me the same amount even if they don't do any adjustment.

He said to take the VC off and measure takes a lot of time, but to install new shims takes 10 seconds I know they have a special tool but it would mean they'd need the correct replacement shim in hand, and they have to remove the old one and measure it too. I am pretty sure they just use a feeler gauge to measure it. To me, it would take about 15 minutes to pop off the VC and measure each lifter. It would take a lot longer to actually replace all the shims.

Can anyone tell me, in detail, how YOU would measure tappet clearance? I measured it and felt like I did a good job, but I would love to hear a detailed explanation from somebody with lot of experience doing it, especially on this motor.

Should I just bite the bullet and pay them to recheck and fix my work?

Thanks,
Aaron
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Old 07-23-2008, 04:42 PM   #21
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FWIW, with Cobb "street" cams and a lightweight flywheel I routinely got misfires on 2 or 3 or 4 cylinders for 4 or 5 years (until I pulled that engine to be upgraded). I got the flashing CEL every great once in a while, but never felt anything abnormal when I did.

As long as I had a way to pull the codes and reset the CEL (I used a Pocketlogger), it didn't really bother me.

Pat Olsen
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Old 07-23-2008, 06:53 PM   #22
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Quote:
Originally Posted by sebtarta View Post
Wow, I hope I am not running in to the same problem.



Granted I only get misfire on Cyl. 2, but I read it was due to the cams. I reset the ECU let it idle and all, but once I am driving at a constant speed, poof CEL on
Quote:
Originally Posted by Patrick Olsen View Post
FWIW, with Cobb "street" cams and a lightweight flywheel I routinely got misfires on 2 or 3 or 4 cylinders for 4 or 5 years (until I pulled that engine to be upgraded). I got the flashing CEL every great once in a while, but never felt anything abnormal when I did.

As long as I had a way to pull the codes and reset the CEL (I used a Pocketlogger), it didn't really bother me.

Pat Olsen
How was your idle quality?
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Old 07-23-2008, 08:00 PM   #23
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Fastenova,
Your idle sounds fine. Cams often produce a "lumpy" idle with a bit of hunting. 600-800 rpms is a fairly tight range and right in the zone of stock. I think your car is fine and you just need to start driving it.

As Pat said, the missfire codes could be false and just something you have to live with. If you have no other indication that there really is a missfire, start driving the car and just pay really close attention to it. If there is something bigger wrong, you will catch it pretty quickly once you are running around in your car.
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Old 07-23-2008, 08:09 PM   #24
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Originally Posted by Matt Monson View Post
Fastenova,
Your idle sounds fine. Cams often produce a "lumpy" idle with a bit of hunting. 600-800 rpms is a fairly tight range and right in the zone of stock. I think your car is fine and you just need to start driving it.

As Pat said, the missfire codes could be false and just something you have to live with. If you have no other indication that there really is a missfire, start driving the car and just pay really close attention to it. If there is something bigger wrong, you will catch it pretty quickly once you are running around in your car.
Matt, I don't mean to argue, nor do I doubt your experience with these motors. I know that you have spent a lot of time with this engine, so I appreciate your input. However, I was told by John at Delta that the idle quality would not be affected with these cams. I can deal with a rough idle, but the car shakes a LOT. The car has died at a stop. That seems like something is wrong to me. Or, is that just something I have to deal with?

It seems to me that even on a moderately modified motor, it should be reliable and smooth enough that at idle there are no adverse effects. If I had known I'd have idle issues I'd have gone with the more aggressive cams, so I'd get more performance for the sacrifice. The idle was VERY rough last night, around 500 RPM, enough that the motor was shaking pretty bad, even with stiff motor/tranny/pitch mounts... Wonder if I should put the warmer plugs back in.

The other problem is that when I clear the CEL that pops up often, it resets the OBDII readiness which means I won't be able to pass DEQ when I need to.

I am also ONLY getting misfires on cylinders 1 and 3, which, as you know, are on the same side of the motor. Is that indicative of anything?

EDIT: And I have about 500 miles on the motor so far, it seems like other than the idle it drives perfectly. Once it's up above ~1000 RPM, it's smooth, and doesn't seem to miss at all. I guess I just want to make sure the motor is running as smooth as it can, I've put a lot of money and time into this and want the best results I can expect to get.

Thank you!
Aaron

Last edited by fastenova; 07-23-2008 at 08:20 PM.
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Old 07-23-2008, 08:18 PM   #25
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The car pulls fine? Does the power band feel like it's coming earlier or later? I'd suspect that the timing on a cam is off by a tooth somewhere.
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