After Valve job - idle high then rough

[tedder]

I performed my first valve adjustment on my 86 last month along with a tune up, and since I buttoned it back together the idle has been off. High idle when cold at ~1600rpm, when hot it drops to ~1100 and feels like it is missing. Then yesterday while poking around with it idling in the garage I pulled on the throttle, revving it up to ~4k+ for 10 seconds and afterwards it wouldn't hold idle at all. Just stumble at 800 rpm for 2-5 seconds then die.

What I changed between running well and now:
- adjust valves
- new spark plugs (Bosch copper)
- oil filter & oil (Castrol high mileage gtx 20w50)

Mods from stock
- Mas air flow sensor
- autothority chip
- cone air filter
- Fabspeed premuff + M&K 1/1 sport muffler

One other data point is that the voltage at the MAF is way high (1.3 at idle vs ~0.9 normally) which would make it go very rich I expect.

From the records I have from the PO, the Oxygen sensor was new about 7 years and 27k miles ago, as was the CHT sensor, ICV and plug wires. Distributor rotor has ~ 2 years an 10k miles on it.

I have checked the ICV and it is operating properly. The Oxygen sensor is still firmly plugged in (and not that old). Removing/replacing the oil filler cap does not seem to make any difference. Exhaust does not smell too gassy but I have a poor nose.

What should I try next? I have a new fuel filter that I'll throw on this morning but I doubt this will make a difference. What else should I try and what else could I have messed up doing the valves?

Thanks

Ted

[tedder]

One thing I forgot to mention, above idle it seems to run fine. Pulls strong and smooth (no misses) from 3k->6.5k on the onramp. When decellerating in gear there is some roughness below 3k, smooth as glass above 3k

[al lkosmal]

I would check the basics 1st. All spark plug wires connected properly (can't tell you how many times I've double and triple checked this...I always write the order on my distributor caps with a sharpie.) Did you change the distributor/timing in any way.....I'd get out the timing light and double check this, as well.

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[tedder]

I have pulled and re-attached all the spark plug wires twice. None seemed obviously wrong in doing so. I also added the new fuel filter and cleaned the (reusable) cone air filter. Since the pull on the throttle yesterday I am not seeing the high idle anymore, just the rough/miss idle at ~1100 rpm with an occasional jump to 2k for .5 sec.
I dont have a timing light. Is it possible that when I put the distributer cap on I didn't get it properly aligned? I made no attempt to change the timing in any way deliberately. The plug wires were lablelled also so I am certain they are on the right cylinders, plus the fact that the engine is smooth above 3k rpm.

[afterburn 549]

The timing got bumped too far ahead.. or you have a vacume leak ( hose un hooked )

[tedder]

so, for the timing, I need to get a stobe correct?

How would I go looking for a vacuum leak though? I have seen that referenced on these boards several times but I am still a beginner shade tree mechanic so I am not quite clear on what/how to look for for this.

Ted

[afterburn 549]

Timing light works best...Static time is ....OK but leaves out the dynamics of it all.
As far as a vacuum leak, I would visually check all vacuum hoses as a loose connection on most of these engines induces false air and the eng tries to rich n it up and it speeds up and rich n s it up and the dog chases its tail.
You can spray carb cleaner at offending connections and the eng will slow dwn should you hit a spot....................

[tedder]

Given that this is an 86, it looks like the timing is not lileky. I can't find anything in the Bently, Haynes or 101 projects manuals about timing for a post-83 other than a comment that it is handled by the chip.

On the vacuum side of things I am trying to figure out where to look. So far, of the stuff on this diagram
the only thing I can find is the ICV. Everything else is a mystery to me. If I can't find the hoses, I can't check their connections or spray carb-cleaner on them (the presumed next step) to see how they change the idle.

[tedder]

Still struggling on this one. I grabbed a couple of cans of carb cleaner and hit every rubber line I could in the engine bay with it. Didn't seem to make any difference anywhere. I am convinced it is way too rich but I have no idea why. I am also at a loss to explain why the previous high-idle when cold/ rough when hot has given way to rough cold or hot after I revv'd it up in the driveway one time. Video of the rough idle coming along tomorrow (should've broght home the laptop tonight...)

[Steve@Rennsport]

Although I hope I'd be wrong, this smacks of the MAF conversions I've seen.

Assuming that your intake system has zero vacuum leaks, the oxysensor is connected & functioning, I'd reinstall the stock AFM/airbox and chip and see how it runs,...

[tedder]

Well, I have the stock chip but have never had it in the car in the 2.5 years I have owned it. Don't have the stock airbox as that didn't come with the car. I guess I am assuming that the 02 sensor is good since it is only ~7 years old but I certainly could have hit it with the ratchet while removing/replacing the valve covers.

Here is what it idles like at the moment. This is on a cold engine. Foot on the gas pedal smooths it out ~2500 rpm

[tedder]

well I am about ready to give in and call the mechanic. Double checked all the hoses and plugs (found a broken connector on the oil pressure sender) and still no idea why it is running so rich. DME relay is good, I am plum out of ideas at this point. Looks like I have to put out some $$, I want to drive now that the weather is warming up.

Could I hae mucked up the valve adjustment severely enough to cause this? If so, shouldn't it run worse at rpm under load?

[vreference]

Do you not have any kind of airfilter on in that video? I hear a massive sucking sound. I don't have anything like that even with just a K&N Conical.

[tedder]

There is a reusable cone air filter (not K&N, PO installed and not sure of the source) hiding up in the shadows. I cleaned it earlier in this process as well so it should be good...

Can't get into my local p-car mechanic until April 16th so I have another week to try to find the source. So far the only connector I found that was off was for the oil pressure sender. The plastic that goes on the plug broke (probably due to me bumping it) so my oil pressure gauge is now pegged at the top. Double checked all the plug wires again and they look right. Still stumped.

[jcunning]

It's possible that your new spark plugs are not liking the very rich engine conditions and you have fouled them up already. What did the old plugs look like? Maybe try throwing those back in and see if it makes any difference.

I'm not sure how your new plugs work in rich conditions. Some plugs are able to cope better than others. Maybe you have the wrong heat range or you might need a platinum plug. A colder plug might be better.

The O2 sensor can also get fouled up from rich conditions, so you may need to take a look at that as well. An easy test for this is to just unplug it. The engine will then go to open loop mode and basically just run a default program. If you are still super rich, then your chip or MAF is most likely at fault.

I remember reading somewhere on this forum about there being a switch or something in the ECU to change the fuel setting. Maybe you could find this and check it out.

Be careful with this kind of condition. Besides getting bad carbon deposits everywhere, you can also burn up your catalytic converter. The extra gas gets the converter so excited it turns red!

[tedder]

I unplugged the 02 last night and it went from bad to worse, so I suspect it is OK. I was wondering if I had fouled the plugs. I think I'll try swapping the old ones back in next to see if it helps. They came out looking fine, greyish-tan on all of them.

Next step after that may be to try the stock chip which is somewhere in the box of parts I got from the PO.

I do have a feeling about the MAF, since it is showing too high a voltage running, but correct with the engine off and key on. I am now convinced that the root of the problem is being too rich as I am getting over my cold and can smell the gas a bit now in the exhaust.

[afterburn 549]

Ok to the root of the problem.. Have you ever Adj. valves B4 ? Is there a mistake in your math??

[tedder]

No, this was my first attempt at valve adjustment. Not sure what you mean about a mistake in my math, but the possibility that I screwed up on the adjustment is high. What makes me uncertain is;
- I tried to err on the side of loose, but no loud ticking when running
- ran fine and strong from 3k->6.5k rpm. If valves were way off I would expect it to be worse under load at speed
- the 'high idle ~1500rpm right after the adjustment was smooth with a cold engine which gave way to rough when warm. Now it is rough whether warm or cold.

Pulled the plugs yesterday night, 5/6 were gassy, the 6th was rich. Replaced with old plugs and no change to the idle.

Taking the son camping this sat night so I am not sure I can do another valve adjustment this weekend. WIll try to put the stock chip back though and see if it helps (I suspect not)

[tedder]

well its not the chip either. Swaped back the stock chip last night. Maybe slightly better (leaner) but nowhere near good. Down to busted MAF or way-out valves to check out...

[tedder]

Well, managed to re-do the valve job again and things are same as ever. Valves were slightly lose (backside method measure) and I adjusted again and rechecked via backside before buttoning it back up.

Still too rich to the point of flooding out at idle. Fine at higher RPM. Going to the mechanic on Wednesday...