Cascade Crew

iansane · Posted: Thu Jun 26, 2008 5:27 pm Post subject: Constant Stumble?

A couple days ago I went out to my car in the morning to start it up and go do some errands and the idle was pretty erratic and stayed at about a grand. It'd stumbled like hell when I tried to pull it out of the garage. The WB read a bit lean but not enough to make me wonder. I checked the plugs and #1 was BLACK. I swapped out plugs started her up and hooked up the laptop. All the sensors seemed to reading normal; coolant was up to temp after a bit of idling, 02 seemed like it always does, spark wasn't retarding or advancing more than usual. I popped the cap and rotor off and realized I haven't changed them in well over a year and they were pretty corroded. I had an MSD pair that has been sitting around for a LONG time so I put those in and it seemed to smooth things out but it still feels like I've got a miss. Idles funny and the car shimmies a bit more than normal and it'll almost diesel when I pull away from a stop like it's running on seven cylinders. I'm going out now to check resistance on each plug wire but they're not too old MSD units as well.

Suggestions? I still think it's ignition related but I don't know where to start looking. Coil? Ignition module? Aren't those things that usually just fail and not run like crap?

Twilightoptics · Posted: Thu Jun 26, 2008 5:34 pm Post subject:

Sounds like a vacuum leak maybe. Look at the wires real close?

iansane · Posted: Thu Jun 26, 2008 6:51 pm Post subject:

I borrowed a long plug wire from work and put it on the fouled cylinder and it didn't run any better. I'm popping a new wire set on it tomorrow as a maintenance thing, maybe it'll help.

I'm not getting much different reading on the map sensor than I remember, but then again I don't remember a lot.

I wonder if it's something with the IAC or TPS? I didn't check either of those...

I just tried dousing the engine bay with carb cleaner to see if there were any apparent vacuum leaks and the motor didn't do anything. This is bugging me.

DBL_TKE · Posted: Fri Jun 27, 2008 2:04 pm Post subject:

I was just about to say you should check your IAC and TPS. I used to have an off idle stumble and it turned out to be my TPS. Since then I've set it where it's supposed to be and no more stumble.

Twilightoptics · Posted: Fri Jun 27, 2008 4:56 pm Post subject:

"the" fouled cylinder?

If it's just one I'd be looking at something with that port/cylinder. Be it ignition, leak, etc.

dlp · Posted: Fri Jun 27, 2008 5:09 pm Post subject:

Is it oil fouled or fuel fouled? That is the question. If fuel fouled, pull the plug and look at it closely. I have seen weird stuff happen becuase of a cracked spark plug, especially if it is on the drivers side, were the 02 sensor is.

iansane · Posted: Wed Jul 16, 2008 10:40 am Post subject:

The fouled plug was from a shotty MSD wire. I went to replace the wires with Taylors and the boot slid right off the terminal. Nice. At the same time I noticed a huge exhaust leak. That I thought was caused by some of the poping through the exhaust it had been doing. No. The rear header bolt on the driver side had backed out and disappeared. I replaced it along with new gaskets and silenced it. It seemed to have fixed the problem. I reset the ecm and was content. A day later the stumble was back. Albeit significantly reduced, it's still there. It occurs during part throttle cruising (bucking) and at idle you can tell there is a miss.

Fairly agitating...

blue89 · Posted: Wed Jul 16, 2008 11:23 am Post subject:

Have you checked your spark? Might be caused by a weak spark in combination to a leaky injector.

iansane · Posted: Wed Jul 16, 2008 12:59 pm Post subject:

I know it''s getting spark. I had a brand new MSD coil that I never got around to putting on and finally mounted it up. I guess next thing to check is injectors? What's a good way to do that? Pull the rail off the manifold with the injectors still attached and let it sit primed?

blue89 · Posted: Wed Jul 16, 2008 1:13 pm Post subject:

I wouldn't assume a new part is functioning. Pull a boot off and let it jump to the chassis or get a real spark checker. You may also want to check your compression too. I believe a dead hole will foul plugs and act like that. Maybe someone else will comment.

If you have a fuel gauge hook it up and watch the pressure. You can check spray pattern by powering the injectors while on the rail but I'd check pressure and leakdown first.

iansane · Posted: Wed Jul 16, 2008 1:53 pm Post subject:

Well it's acting the same with this coil as it did with the old coil so I just assumed it was okay. (ya know what happens then!) I had thought about compression but hadn't gotten around to it. I guess I should.

I've got a FP guage set up at the end up the rail on a permanent mount so I'll double check that but it seemed to be within the range it had been before all my issues.

aaron_sK · Posted: Wed Jul 16, 2008 2:10 pm Post subject:

Ian have you check the ignition module and pickup coil? I had a real similer problem in the IROC which turned out to be dropped spark. New dizzy fixed that right up.

iansane · Posted: Wed Jul 16, 2008 9:12 pm Post subject:

I figured since the module and pickup were original to the car I'd slap new ones in; and of course it's cheaper to get the whole dizzy than the individual pieces.

After I put the dizzy in I went to roll the motor over to find TDC and the crank bolt just spun freely. F**k. If it's not one thing it's another.

Schultzy89GTA · Posted: Wed Jul 16, 2008 9:17 pm Post subject:

Dang man. I feel for ya.

-Schultzy

blue89 · Posted: Thu Jul 17, 2008 7:20 am Post subject:

Did the bolt break or strip out? Thats a terrible sinking feeling...

305 302eater · Posted: Thu Jul 17, 2008 6:48 pm Post subject:

WOW. That sucks Ian.

iansane · Posted: Thu Jul 17, 2008 7:04 pm Post subject:

iansane · Posted: Thu Jul 17, 2008 7:06 pm Post subject:

chevymad · Posted: Thu Jul 17, 2008 7:48 pm Post subject:

I think i'd try a helicoil myself. But you know, i think the bolts stripped in my truck and I just left it that way lol. The early sb's didnt even have a tapped hole in the crank.

iansane · Posted: Thu Jul 17, 2008 8:13 pm Post subject:

Really?

Do I even need that bolt?

Shocked