So I've searched a lot on here the past month or so and its helped a lot I just cant seem to find the problem and I'm stumped now so I need some help. My car only misfires at idle and it threw the flashing CEL at me for #1 cylinder misfire so I ran the codes and the freeze frame on the scanner said it missed at 896 rpm at 6.2% load. It seems as long as the rpms stay above like 1100 it's fine. It pulls fine and doesnt stumble under hard acceleration, going up hills or anything like that. Right after startup the rpms do like to come down rather slowly when I coast but a couple minutes into driving it gets better. And the rpms stay around 1500-2000 when coasting until I come to a stop. IAC problem or is this normal? Brand new spark plugs gapped to spec and new coolant sensor, swapped out brand new wires and coil with no change. Timing marks line up on the cams (but I havent had the time to check the mark on the crank since I'm at school right now). I've checked the majority of the sensors that have anything to do with idle or could possibly adjust the timing (haven't checked the crank or MAP sensor yet), all were withing spec. But I was wondering about the IAC motor. According to my Haynes manual the resistance is supposed to be between 38-52 ohms and I'm getting like 53.4-54 and I was wondering if this is far enough out of spec to warrant a replacement. I did a hot/cold compression test and the numbers were rather low but consistent staying around 120psi + or - 5psi. Could I have done the test wrong? No exhaust leaks at all, idle searches sometimes but I cant find a vac leak for the life of me. Oh and my cruise control doesn't work and I know it needs vacuum to work, could this cause the idle surge?

Could it be a headgasket or rings? Because in this post
http://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=127460&mode=full
I read that if there is an exhaust leak into the coolant, the coolant will jump out of the neck of the radiator. Mine does this unfortunately. Not sure if this is related. I do go through some coolant and it's not leaking on the ground so I'm assuming I'm burning it. Sorry this is long but I wanted to cover everything I've done so far. I just need some ideas because I get a week off for thanksgiving coming up and I want to have some things lined up to check right away.

Thanks in advance everyone

IAC sounds like a red herring and I still wonder if you have spark issues, despite changing placing new items on. What plugs did you use - copper or something else? Only use the cheap copper type in our cars, they work great.

2gnt: '99 RS-T, killed by a toyota, pending rebuild...
Daily: Volt
Daily #2: '99 EVG ebike- STOLEN by PEDRO

Yea I just bought the cheap NGK plugs. Is there some wiring or something that I should check that would only affect the #1 cylinder?

No one has any ideas on what else I could do?

If your IAC is out of spec replace it, period. Make sure to clean the throttle body out as well. Often times, gunk and rust will gather where the IAC opens and closes causing further faults.

A failing IAC creates an intermittent vacuum leak at the throttle body passage where the controller is housed.

In relation to your misfire, in my experience, every time I've ever had a misfire, I ended up tracing the problem back to the crank position sensor, but you posted some really low compression numbers, are you stock internally? sorry I responded before checking your profile.

The screen name says it all

Yea I'm stock internally. I know the numbers are low but since they were all consistent with each other wouldn't this rule out HG/rings? Or am I mistaken? I guess I'll plan on replacing the IAC and testing the crank sensor next time I'm home from school. I also noticed that the 12v wire going to my #1 injector has a small slit (very small) in it that exposes the wire. I didn't know if this could somehow change the resistance. How can I check the injector wiring?

Thanks in Advance

breaks in ANY wire should be fixed immediately.

Compression numbers that low just dont seem right. I would check the seal on the compression tester and try again. If they are that low then you most likely have poor sealing valves, or timing is off on one of the cams, possibly the crank timing also as you mentioned.

Driving with mis timed crank or cams will usually give you some sort of bogging either down low or up high to the point where you will really feel its different than before, going through this right now with misalligned OBX adjustable gears I installed without researching.

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Yea the slit is just in the wire insulation but I plan on fixing it as soon as I get time. And I know the compression numbers are low but it was just weird to me that they were all pretty much exactly the same. I need to do a leak down test. And I hopes its as easy as a misaligned cam or crank but it really doesn't seem like it bogs down at all. I mean I usually shift by 5000 rpm but up until that point it seems fine. Other than having any power below like 2500 rpm likes it's always been. I just wish I had more time to look at it but schools done in 3 weeks so I'll hit it hard then.

thanks again

advancing and retarding cam,crank and ignition timing can be calculated for gains I'll say. Accidentally timing to a position that is beneficial and unnoticeable is not common but not impossible.

I am speaking with the utmost confidence when I say look to the timing for your answer.

This thread will be open, so chime in when you get into the work, everyone loves a happy ending.

The screen name says it all

Captain Caveman

96 RS Turbo 11.414 @ 119.62 MSNS, Crower 2 NA cams, BW366, 10.5 comp, UDP, 60mm TB, W/A intercooler, 3.55 tranny 567.9whp 430tq
97 RS NA 13.188 @ 103.87 MSnS powered 12.5 comp, Crower 3's and 219.4whp with 175tq
98 RS DD 12.5 comp on stock ECU, LTH, Crower 2's, Koni, GC, Hypercoil, DG hats
99 OZ 5sp Stocker 15.856 @ 85.97
99 GS stocker auto 17.7@77mph!

wiki home page:http://www.2gnt.com/index.php?d=bullettdsm

bullet, my instincts without seeing the car lead to timing simply for the 120 compression numbers, and they are consistent across the board. The only time I've ever seen numbers that low consistent was when (and I hate admitting it) I installed an AEM cam gear upside down four years ago.
The gears were in just the right position to let the car run without throwing a CEL. He said he didn't misfire after a certain rpm, mine cleared up after 1500 when I made that mistake back then as well.

I may be off, but I do think we can agree that the 120 compression numbers should be explored further. Crazy things have always accompanied terribly low compression for me, hiccups, smoke screens, leaks, cracks and funny smells haha, definitely not smooth driving.

WAIT WAIT: update: I have been racking my brain and re read the OP 1st post and I realize it is NOT clear whether or not he compression tested ALL cylinders or just the #1 with the misfire, we only assumed. Sorry OP could you clear that up for me? did all four cylinders give 120 or just all of the readings you took from the #1. If you have only 120 in cyl #1 Bullet is right about me being wrong, and things will consequently have just gotten simpler in terms of us helping you solve your problems.

The screen name says it all

Yeah, this sounds a lot like its fuel related. Start by changing that fuel filter and see what's inside of it.

Captain Caveman

96 RS Turbo 11.414 @ 119.62 MSNS, Crower 2 NA cams, BW366, 10.5 comp, UDP, 60mm TB, W/A intercooler, 3.55 tranny 567.9whp 430tq
97 RS NA 13.188 @ 103.87 MSnS powered 12.5 comp, Crower 3's and 219.4whp with 175tq
98 RS DD 12.5 comp on stock ECU, LTH, Crower 2's, Koni, GC, Hypercoil, DG hats
99 OZ 5sp Stocker 15.856 @ 85.97
99 GS stocker auto 17.7@77mph!

wiki home page:http://www.2gnt.com/index.php?d=bullettdsm

So I kind of forgot about this thread but it ended up being a really small vacuum leak on the intake manifold gasket by cylinder #1 port. Sorry it took so long for me to get back.

just out of curiosity, how did you find it? smoke trick? propane trick?

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Outside of Corona: "That sucks, peace out..." (jamie walks away)... "Sweeet, what we doin?" -Zac
Tim's garage (prior to motor install): "Im gonna smoke real quick, that way if you fuck up I am already nicotined up" -Tim

I'm not familiar with the propane trick but I used the smoke test. It was only misfiring in the #1 cylinder so I had a hunch it would have to be a vacuum leak somewhere I just had to find it. Now I've got other problems to figure out haha