Serious miss/skip?

[tlava]

I installed a new water pump, belts, radiator, spark plugs and did a valve adjust; put all back together, and now have a serious engine stutter/miss--There was a slight miss previously, but much worse now.

The plugs are from Toyota and supposed to be pre-gapped==the gap was about .025

the old plugs were gapped at about .042, if that makes any sense...

could I have messed something up on the valve adjust?

[Derek up North]

The FSM, if I'm not mistaken, calls for a gap of 0.031".

[zero]

A plug gap set too wide could make the engine skip and short to ground somewhere (before the plugs) if you've got bad wires, cap, etc. Try starting the engine in the dark and see if there are any visible sparks. Or, close the gaps a little. Worth a try. Setting the plugs .042" instead of .031" takes an extra 3000-5000 volts to fire.

Valves too tight will really make it run lousy - but I guess you already thought of that.

[tlava]

the previous plugs were gapped wide. The new ones I put in came pre-gapped at .025--but would a tight gap account for a rough idle/miss?

I just did the valve adjust, so that's what I'm wondering--I followed the diagram: I believe it indicated to adjust exhaust 1 & 3 and intake 1 & 2 with piston #1 at TDC, then rotate 360 and do intake 3, 4 and exhaust 2 and 4 (set the exhaust to .011 cold)

I didn't change the intake valves since they seemed OK

if I got the exhaust a bit too tight, could that account for the skips/misses?

I'm thinking I could check them hot, then let the engine cool and see what the diff is, then try to adjust cold again.

[WME]

To small of a plug gap will make an engine idle bad.
As long as there is clearance on a valve things are ok. Even if the exhaust was at 009 you would be ok. But you would have to readjust real soon.
Try correct plug gap before messing with the valves.

[Maineah]

If you think you have a valve tight do a compression test and if you find a low cylinder recheck the clearance. If it stumbles just off idle moving disconnect the vacuum line to the EGR and try it.

[waiter]

Check, make sure vacuum hose are re-connected properly, and to the correct locations.

clogged PCV valve, sticky idle air valve, etc

John Mc

88 Dolphin 4 Auto

[tlava]

OK-- what do you think: I re-gapped plugs to approx.032, readjusted valves on a "warm" engine--loosened all just a bit to get a fairly easy slide with what I felt to be a little drag on the gauge

idle is OK but still a skip/miss every few secs--so it runs more or less the way it did before I changed everything. I hear a very slight ticking if I listen close to v. cover, but doesn't seem like enough to readjust?

also noticed that the whole time the engine was idling, there was some white smoke in the exhaust--and it idled for a long while, maybe 45 min. We've had cool wet weather, and I haven't run car for a while, so maybe just normal moisture? It also took a while for the hot air to kick in with the heater full on and fan on high, but eventually it did get hot and some "burping" (bubbles) out the neck of the radiator before it settled down.

could the miss/skip still be valve related? or I'm wondering if the white smoke could indicate a beginning head gasket issue--could that cause a skip? I tried turning the big screw on the EFI housing, but it didn't help...

Also, I bought a new 3-core radiator, and now the old orig Toy cap doesn't fit--the neck on the new radiator is quite a bit smaller. How do I get the right cap for this, with the correct pressure, etc? Does the cap pressure have to be compatible only with the radiator, or is is a function of both the engine and the radiator? Also, since I wasn't able to replace the cap after burping the radiator, will I have to repeat the process again once I get a cap?

another radiator Q: I also installed a supplemental elec fan (as pusher), but I damaged a few of the thin copper fins between the cores while installing, pushing the plastic mounting rods through--seems inevitable--will this cause any problems?

[zero]

idle is OK but still a skip/miss every few secs--so it runs more or less the way it did before I changed everything.

could the miss/skip still be valve related?

A valve related skip will be consistent and not "off and on."

[Bob C]

It can take a while to get the heater core flooded with coolant. Until this happens, you will not get any heat. That is the air coming out of the core that caused your late burps.

[tlava]

Hi All--

THanks for verification--but what does this sound like to you:

cold start--idles fine

when engine STARTS to warm--needle just on or near the "C"--very rough

engine gets warmer--operating temp

the miss/skip seems to mostly clear up

always a bit of white smoke, but when I rev the engine--very noticeable....

I'm wondering if the radiator flush stuff I put in didn't all come out and could have somehow damaged the head gasket?

It was odd that no matter how long I flushed the radiator with water, while engine running and heater full on, the water would run clear, then, when I shut of the engine and let the radiator drain down, toward the end, red coolant would wash out again; I tried this a few times--the water would be running clear; I would shut down and let the radiator drain, and the last few pints quarts (or pints, not sure) would always come out red...or at least pinkish, getting more red in the last bit...

so thinking back I'm wondering if the system didn't completely drain and residual flush could have causes a problem...

I will try to post some videos of engine running--

[tlava]

Hi Folks

Some vids of the engine idling. The one labeled "2.3 is the engine when cold.

"4.3," after it has begun to warm, you can hear an irregular miss/skip (have to listed closely).

"6.3" shows smoke out the tail pipe under normal idle--this smoke is constant, no matter how long the engine idles, though I haven't had the RV on the road yet to know if it clears up;

"11.3" shows smoke revving the engine.

"9.3" is I think the sound of the engine after it warms to operation temp

[waiter]

Hard to tell, sounds a little loud (ticking), but I didn't see any roughness in the engine shaking or the sound.

Not sure about white smoke, I don't think I could see any in the exhaust.

Is the engine consuming coolant i.e. you fill the radiator, and it goes somewhere and you need to fill the radiator again.

Jo0hn Mc

88 Dolphin 4 Auto

[zero]

Have you tried putting a timing light on it to see if the timing mark bounces around instead of sitting still?

In regard to the white smoke - you might want to test the coolant in your radiator for carbon monoxide. That's the best sure way to tell if that white smoke is from buring coolant.

Here's one person's explanation of how to check for CO in coolant that is well written. Note there are also paper test strips that can be dipped in your coolant to check for CO.

http://repairpal.com/how-to-test-for-head-gasket-failure

How to Test for Head Gasket Failure

Catastrophic cylinder head gasket failure can be easy to determine. A large stream of white smoke billowing from the exhaust and an overheating engine are sure signs. However, more subtle cylinder head gasket failure signs may be more difficult to diagnose. The engine may experience mysterious coolant loss, or only lose coolant when the engine is driven under heavy load. You may even experience a rough running engine when you first start the vehicle.

An initial inspection of cooling system components and a comprehensive test drive may be necessary to confirm the customer's complaint of coolant loss or overheating. Check for the presence of white steam/smoke coming from the exhaust. Steam coming out of the exhaust may smell slightly sweet as the steam gently dissipates into the surrounding air. (It is normal to see drops of water from the exhaust of a modern car as it is warming up.) Another sign that the head gasket may be leaking is the presence of oil in the cooling system. Check for oil residue in the coolant reservoir.

It is important to confirm actual engine running temperature and accuracy of the temperature gauge. This can be verified by using a non-contact infrared heat detection gun. It is a non-intrusive method used by most repair shops to verify temperature gauge accuracy and actual engine running temperature.

Pressurizing the cooling system (to eliminate coolant leaks as being the source of coolant loss), checking for proper operation of the cooling fan, and checking radiator efficiency are important before jumping to the conclusion that the head gasket is defective.

The most effective and accurate diagnostic test to determine if the cylinder head gasket is sealing combustion gasses is to check for the presence of combustion gasses in the engine coolant. This must be done with the engine warm and the radiator cap removed. This can be a bit tricky so be careful when warming the engine with the radiator cap removed or removing the cap when the engine is warm. With the radiator cap off and the engine warm, place a funnel where the radiator cap would normally be. Start the engine and let it run. Watch the coolant as it circulates. It is normal to see the presence of some bubbles in the cooling system, but the presence of lots of bubbles in the cooling system may be a sign of cylinder head gasket failure. Be very careful when running the engine with the radiator cap removed. Hot coolant may be expelled from the radiator unexpectedly.

With the engine running, a tool (pictured) is used to draw fumes from the cooling system through a chemical that checks for the presence of carbon monoxide (CO) in the cooling system. Carbon monoxide will only be present if the head gasket has failed or the cylinder head itself is cracked. The chemical starts off blue in color, but turns green or yellow in the presence of carbon monoxide. This test is known as a “block check."

Another method is to use the gas analyzer that the shop uses to check vehicle emissions. When this machine is used, the presence of hydrocarbon (HC) gasses escaping from the coolant will be measured and if the HC reading is over 50 PPM, then the headgasket is leaking. Always make sure the reading is noted on the repair order whenever this method is used.