Rough Idle almost no vacuum

[whistlin']

Daughter's 87 LeBaron 2.5 tbi. Bought the car with a head gasket issue but have that fixed. Problem I'm having is a rough idle and very low vacuum. Double checked cam timing and I'm sure it's right where it's supposed to be.
New plugs, rotor and cap. Pretty sure there's no vacuum leaks.
I'm scratching my head on this one and not getting anywhere. I haven't run a compression test yet but get the same rpm drop from each cylinder as the plug wire is removed. I really don't think it's one cylinder causing the problem.
I know what happens when a slider cam is placed on a roller setup. Has anyone ever ran a roller cam on sliders? Am I over thinking this?...LOL.
Any help would be appreciated.

[tryingbe]

Test the compression
Check cam timing
Check spark timing

Roller camshaft is fine as long as you use roller rockers as well.

[RoadWarrior222]

Block the PCV nipple on the VB and see if vacuum picks up and idle smooths, if so suspect stuck open PCV valve or damaged hose. Check any EGR lines and fittings for cracks and leaks also, and check valve for operation.

[cordes]

I would triple check the timing after doing a compression test.

[whistlin']

Test the compression
Check cam timing
Check spark timing

Roller camshaft is fine as long as you use roller rockers as well.

I'm pretty sure the cam timing was dead on, spark timing is right on 12. Just haven't run compression test yet.
The roller cam question was more "If someone else put a roller cam in with sliders what would happen?"

Block the PCV nipple on the VB and see if vacuum picks up and idle smooths, if so suspect stuck open PCV valve or damaged hose. Check any EGR lines and fittings for cracks and leaks also, and check valve for operation.

That's one I haven't tried yet.
This car runs great going down the road, fuel mileage isn't the greatest but with these below zero temps it's expected.

[JDAWG]

but if you use a square tooth cam in place of where there was a round tooth isnt the timing off?

[Murphy]

4* cant remember which way tho

[whistlin']

Yes the timing would be off. I'm just wondering about the cam profile. I accidentally stuck a slider cam on a roller setup before and I don't think the valves were completely closing. I'm wondering if in a reversed scenario whether the valves would be opening far enough.

[whistlin']

Well the cam and ignition timing were perfect and the pcv valve was good. The compression test pointed out my problem 150-90-95-145. I put a squirt of oil in the 90psi hole and boosted to 180. Looks like I've got some stuck or broken rings because the cylinder walls looked fine when doing the head gasket.
I guess I'll let her drive it until I find a good common block to stick in, not going to mess with the tall block.

[RoadWarrior222]

You could try a rislone, marvel mystery oil, ATF or water treatment, if the rings are stuck or carbed up, it's possible to cure it. ATF or water, you just drizzle into the intake at about 2500 RPM when the engine has warmed up. The other stuff, follow instructions. You should be able to hear a ticking sound if they're actually broken... use a shadetree mechanics stethoscope, 18 inches of broomhandle.

[whistlin']

I ran some water through last night with no results but I could try it some more.
I have an actual stethoscope. I'll listen to it and see what I come up with.
I don't know the history on the car. As clean as it is I wouldn't be surprised if the rings are stuck just from putting around town.

[whistlin']

Well I ran about half a gallon of water down the throttle body while keeping it running. I don't think there's any carbon left, cat was cherry red...lol. I still have the miss at idle. Listened with the stethoscope and didn't hear anything unusual, just the usual top end noise.
Car runs good going down the highway which is what it's driven most the time so I'll just leave it like that until I come accross a better motor.
Thanks for the replies!

[cordes]

Glad to hear that it is running a little better at least. I hope it last a long while for you too.

[2.5L_Turbo_Sundance]

have you checked the map sensor? and the vac lines on the throttle body?


not sure if it would mess with the compression or not....



i know i had the map vac line disconnected from the throttle body and i had to either keep on the gas or when it was hot, it idled rough at like 1350 RPM or more..... and you could SMELL it. so i would check into that.



Alex