So I've been having a problem with a miss on cyl. #3 for a while now and after some diagnosis, it looks like I have a sticking valve(s). It has a miss almost everyday for about 10-30 seconds after a cold start up (CEL has lit up about 5 times in the last year w/ a P0303 code) and lately I've been getting motorhome fuel mileage (about 170 miles average on the last 3 full tanks 15-16 gallons) and random power loss.

Over the last year I've changed the plugs, wires, coil boots, cleaned throttle body, IAC, MAF, tested TPS, new coolant temp sensor, and new front O2 sensor. I switched coil packs and the miss stayed with cyl. #3. I had a compression test done today and all is good. They also tested for exhaust gases in cooling system and found none and the cooling system held good pressure. Oil and coolant both look good. So, it doesn't look like it's a head gasket problem. I'm taking it back in tomorrow to have a leak-down test performed. Also all these tests were done thoughout the day while letting the engine cool down between each test. The tech said he thinks a valve(s) is/are out of adjustment and sticking, but cannot totally guarantee that it is the problem. It's going to be about 6 hours of labor plus a few gaskets and shims. The estimate was for $650.

-First question is, does this price sound right, and do you guys think that a sticking valve(s) sounds like the right diagnosis for the miss and my horrible MPGs?
-Should I do a full valve job rather than just have them do the adjustment?
-Or should I just not take any chances and rebuilt the whole engine (I found a local place with an "A" BBB rating that will do it for $1395 + tax and guarantee it for 3 yrs/36K: http://houseofengines.net/ ). Anyone know of them?

Thanks for any advice you can give me.

 

Well it's in the shop right now getting the leak down test and whatever other diagnostics they might do, anyone have any advice before they give me theirs?

 

The strange part is, good compression. I would have bet something was up with one of the systems you have ruled out! Sticking valve? Mmmm... don't see how. Unless your valve spring is weak or broken.

That failing... injector? You can pull them and get Witchunter to do a full rebuild/test for a LOT less than $650.

 

I thought the same thing so I left my truck there all night last night so it would be nice and cold (it will do the miss thing for sure if it's the 1st startup after sitting all night). I told them to re-run the compression test when it's most likely to have the miss during the test.

I was thinking if the HG is leaking, it may heat up and seal itself after 10-30 seconds. I'm really leaning toward full rebuild at this point. With 196K on the odo, I would hate to spend $650 now just for an adjustment only to have the HG blow, burn my valves, or throw a rod in 3 months.

I'm going to ask the tech to test my injectors while he's at it too.

 

Have you checked your exhaust gasket. It might be a small leak and once the metal expands enough it will seal it up. That could also lead to your sticking valves.

 

I haven't but I will, thanks.

 

So after some more testing and ruling out the head gaskets, exhaust leaks, and everything else that's simple, we hooked it up to a transducer and found that the valves were not opening/closing all the way. The wave on the computer screen was way off of normal when it was missing and after goosing it a few times, the wave would level out and start to look more normal and the miss would go away.

We both decided that it may be a dirty fuel injector (or injectors) in addition to the valves and if one of the injectors is clogged, the ECU will overcompensate with the other injectors resulting in a rich mixture and bad mpgs.

So, we decided to do an extensive carbon cleaning for the valves, fuel injectors, piston heads, etc.. with a machine that bypasses the fuel tank and runs different chemicals at different intervals for about 2 hours or so. This seemed like the best option before dropping a ton of $$ doing a valve job or a complete rebuild.

I got it back from the shop today (they kept it overnight to see how it started up in the morning) and I'll say, the cleaning definitely made a big difference! The shop said it started right up in the morning and purred with no missing at all (which every morning for the last several months it has missed for at least a few seconds). The engine also sounds a lot smoother and quieter at idle. When I drove it back to work, it had more power than usual too. The best part is he only charged me $167 after telling me yesterday it was going to be $200 + the chemicals (I think he felt bad for me because I've been dealing with this for so long). I guess I'll have to give it a tank of gas or 2 to know if my mpgs have improved, but so far so good!! Maybe I won't need to rebuild it now after all. Right now it's running as strong as the day I bought it 9 years ago!

 

Right on Brian--good to hear

 

any updates on the mpg's brian

 

Well, I've ran 3 tanks through it now and I got 16 mpgs on the 1st, 16.5 on, the 2nd, and 18! on the last one!! So it was definitely a huge improvement over my 10-12 mpgs before the induction cleaning. I figure I'm actually get about 1 mpg higher than those #s because I'm running 33s and 4.88 gears and my speedo is about 7% off of what the GPS says at 70 mph.

And the miss is gone! It's been starting up and idling perfect ever since.

 

nice that sounds like a deff good way to spend those 2 bills

 

what kind of oil have u been running?

 

Dino Pennzoil 5W30 from about '01-'04, Mobil 1 5W30 synth from '05-'08, and Amsoil 10W30 synth since '08.

 

I know this is an old post but it just helped me so I wanted to reply. My 98 4runner w/grey supercharger threw a "bank 1 too lean" code and then a "cyl 3 misfire" in the following 2 days. My remote start stopped working, it would crank but not fire. It would start with the key then idle really rough during the first 20-30 seconds of warm up. This all started happening as it got colder here in heber. After reading this and a few other posts; I decided it must be injectors or "sticky valves." possibly water in the lines.
I figured I'd end up sending in my injectors to have them cleaned, or do what brian2sun did. So i tried some poor-man remedies first:
I replaced the fuel filter, cleaned the MAF and the k&n air filter and put a bottle of sea foam in the gas tank. the plugs are 6 months old so I cancelled that out. The truck did not really seem any better. rough idle, bad mileage(12).
I then bought the pressurized sea foam bottle and ran it right into the throttle body, almost the whole bottle. lots of smoke but nothing startling. SO the next morning I tried the remote start and it fired right up with a smooth idle!
So for me it seems like the poor-man fuel-system deep-clean worked. I just wanted anyone out there still coming across these threads to have another bit of advice.
thanks to everyone on these threads and best of luck to you frustrated unluckies!