Help me kick my off idle miss/hesitation

[Jordan]

That doesn't sound like a smooth idle to me. Mine is noticeably smoother and doesn't lope. I'm not saying it to brag, but rather just to alert you that you have problems at idle too. I've driven an M42 that sounded like that (a friend's). He said he hit the rev limiter at 7k though, so maybe it's chipped and that's part of the issue.

No I'm not an idiot, but thanks for alerting me that you think I am.

Idle has gotten a lot worse along with the rest of the symptoms since I made the original post. The idle is generally steady in holding around 850rpm or so if you leave it alone. It still misses and varies at idle as well, particularly as of late.

[strad]

That doesn't sound like a smooth idle to me. Mine is noticeably smoother and doesn't lope. I'm not saying it to brag, but rather just to alert you that you have problems at idle too. I've driven an M42 that sounded like that (a friend's). He said he hit the rev limiter at 7k though, so maybe it's chipped and that's part of the issue.

[Jordan]

I created a video for you guys since maybe my description is lacking. Virtual test drive FTW!!

Note that I have purposely driven in a manner that makes it do it as bad as possible so its very clear in the video.

http://oldmary.lqhome.com/~jordansarette/Runsbad.wmv (3.5MB)

[mattdk318i]

well, Ive owned 4 M42 engines. And i had only one that gave me issues. And it ended up being bad compression on 1 cylinder. And a random ground cable that broke inside the insulation. So when i hit the gas it stretched and died lol.
I would have mentioned the other issues i had. But you already eliminated those.

K.I.S.S

[Jordan]

I know the lifters are all fine. Its actually pretty quiet. Even worn so bad it sounds like a tank they won't produce the problems I'm having.

[golde30]

how does the engine sound in the morning? is it loud and kinda sounds like a diesal engine? then after a couple min of driving is all normal? my m42 has started to do this as the weather gets colder.

i spoke to a mechanic, and he swears its just worn hydraulic lifters, and he sees it on every m42 e30+e36.. i dont beleive him, but am going to trouble shoot it for that and see what happens.

[browntown]

harbor freight sells them cheap. They're pretty reliable for occasional use.

[Jordan]

Well I just came back from hopping around all the local auto parts places. They all rent a vacuum pump (the same MightyVac one) and they want $40 deposit. It costs 39.95 to buy it outright. One place didn't have it "in" to rent back out, and the other apparently lost it/it hasn't been returned/come back later maybe we can find it.

No one had just a plain vacuum gauge.

[Jordan]

Interesting, thanks. I'm gonna see if any other places in town will rent those out.

[fretburnr]

I'll have to look up for the m42, but for example (iirc) the m20 should see 15-22 in Hg and steady at idle. Those numbers are usually around the same for most every car I've ever looked at.

with the vac pump, apply some similar amount of vacuum directly to the fpr and watch to see if it holds or leaks back to atmospheric. You may not have to remove the fpr to test, but I did for mine.

I also just found this: general chiltons info. Not engine-specific, but should get you headed in the right direction:

2. Chilton general car care manual.

* gauge reading steady 17-22 in Hg indicates normal engine in good condition.
* gauge reading low (15-20 in Hg) but steady indicates late ignition or valve timing, low compression, stuck throttle valve, leaking carburetor or manifold gasket.
* gauge reading steady but dropping regularly indicates burnt valve or improper valve clearance.
* gauge reading dropping gradually at idle indicates choked muffler or obstruction in exhaust.
* gauge reading slowly dropping to zero as engine speeds up indicates choked muffler.
* gauge reading fluctuating between 15 and 20 in Hg at idle indicates stuck valve or ignition miss.
* gauge reading drifting indicates improper carburetor adjustment or minor intake leak at carburetor or manifold.
* gauge reading fluctuating as engine speed increases indicates weak valve springs, worn valve stem guides.
* gauge reading vibrating excessively at idle but steady as engine speeds up indicates worn valve guides.
* gauge reading vibrating excessively at all speeds indicates leaky cylinder head gasket.

[Jordan]

It's an option either way, anyone know what the specs I'd need to watch for are?

[fretburnr]

damn. i think it was like $12 here, but it's been a few years.

[Jordan]

Yeah, $40 deposit each to rent anything over at my local Autozone.

[fretburnr]

you should be able to rent a vac pump and gauge from autozone etc. for a small refundable fee

[Jordan]

I did check the cam timing. The exhaust cam was off a little bit. I set the engine to TDC and synced the cams properly. It made what seemed like a huge improvement initially, but it really only changed idle quality. The rest of the symptoms didn't change.

I don't have a vacuum pump or gauge available to use. I have sprayed brake cleaner in every little spot I can think of seeing of injector orings or intake gaskets are leaking. Best I can tell they are not. I know I have no vacuum hose leaks as every last hose was removed, checked, and either replaced with new or reinstalled if in good shape.