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3vze rough idle


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Anyone know a good honest shop in Coeur d'alene Id. Spokane Wa. area. Motor runs rough at idle even more rough in drive at a stop, but runs great when rolling. I installed plugs, wires, cap, rotor, new air intake boot because it was cracked at the throttle body. Did the paper test on exhaust. Have checked all vacuum hoses visually. Don't have the tools or energy to test all the other things it could be. Anyone in my area that has had a good experience having a shop work on their motor home around here would be much appreciated.

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Same here: rough (not terrible) idle at stop in Drive, and it’s done this for a few years, despite tune-up and lots of Lucas Upper Cylinder lubricant/cleaner. Good, smooth-running engine on the highway though.

 

I'd love to hear more details as you all troubleshoot. (My next step will likely be compression test on each cyl.)

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My check engine light is not on. When I check for codes it just blinks continuously which means no codes. So not sure where to go from there. I don't want to just start throwing parts at it. It did need a tune up it had been close to 40 k since last tune up. Without a code I guess my next step is to check compression.

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when was the last time the throttle plate and housing was cleaned

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When was the last time the valve adjustment was done. This engine is known to be VERY sensitive about valve clearance. 

As miles add up the valve clearance DECREASES and if ignored you will start burning exhaust valves.

Your planned compression check is a very good starting point.  

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I have all maintenance records from PO. She had it from 74 k to 104 when I bought it, it know has 112 k. She put over 10 k into it but I see no valve adjustment in paper work. There was a timing belt done at 86 k.  I'm having a hard time finding a shop that can do a valve adjustment. They just work on new stuff. I did hold a paper towel to the exhaust and it did not suck it in. I heard that was a good test for burnt exhaust valve. Thank's for the input.

 

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The 100k mark tends to be the life of the 3vze motor for those that do not have the valve clearance adjusted. Becomes a far more costly repair. Keep up with the valves and the motor will be reliable as Toyota is known for. 

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I'm hoping the valves were done by the 1st owner, but the owner I bought it from had no paper work from that owner. I just got back from a 110 mile trip and got 11.5 mpg in 35 to 45 mph winds over and back over 5.5% grade Forth of July Pass. It pulled the pass at 50 to 55 mph and ran like a top all the way to Wallace Id and back home. It just idles rough at stop lights and not so rough in park or reverse. I'm hoping someone on this forum lives in my area and can recommend an honest shop that they have had their Toyota worked on. If not I guess I will have to try to adjust the valves myself. I really don't think a valve is burnt yet but I don't know how to diagnose that other than the paper towel up to the exhaust pipe and it just blows the paper towel out. Any advise or input I can get is much appreciated.

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a compression test will show up any burnt valves. compression will be lower than the other cylinders.    if the valve clearance is reduced, compression wont be affected. thats why checking is important. if your valves are tight you will have burnt ones eventually

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Thank you extech. What your saying is confusing me. So low compression  Means burnt valves? But reduced valve clearance won't affect compression? I thought reduced valve clearance is what caused burnt valves.

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yes . as the clearance diminishes, the valve open sooner  and sooner eventually they open soon enough that combustion starts blowing past the valve. 

  this is where the burning happens.  you really won't know the clearance is getting smaller unless you check

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So I'm not sure how the compression wont be affected if the valve clearance is reduced. At least that is what I think you were telling me. Why do I still get good mpg and have plenty of power if I have a burnt valve? The motor runs great except at idle.

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Mine is a similar issue, I’m going to replace the injectors just as maintenance, I’ve been leaning towards a manifold issue, I’ll look into it more when I have the intake off. 

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16 hours ago, Scott iv said:

The 100k mark tends to be the life of the 3vze motor for those that do not have the valve clearance adjusted. Becomes a far more costly repair. Keep up with the valves and the motor will be reliable as Toyota is known for. 

Respectfully disagree. I’ve had tons of these engines in Toyota’s over the years and currently have 6-94 and older model pickups. I have probably adjusted the valves on 2 in the last 25 years. Especially when I was younger and off-roading  we put these engines through Hell and back with not much maintenance. 

Edited by MaineJed
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I have pretty much identical symptoms with Willys: good runner around town and highway, getting about 12mpg, and rough idle only happens with foot on brake at stop light. Also, no check engine light or codes when I check ‘em. My valve adjustment was done in 2017 at 86K, and I just passed 100K (woohoo!) on a trip to MI last week. 
 

I do have a fairly loud, constant tick as well that is NOT going away, but seemed to be an injector when I last troubleshooted. 

Edited by Ctgriffi
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There's a pretty clever home fuel injector cleaning technique on YouTube I used, and it works. During COVID my usual shop was booked for months and I had a Gen III Supra finished except injectors.  You use a can of brake cleaner for pressure, a rubber tire valve as a connector, and just feed it 12V to cycle.  Went from a rough idle (sat 19 years), to smooth as glass. You can clean from each end in turn.  Buy seals and you are ready for reinstall!

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first. rough idle with foot on brake.  clamp off hose to brake booster. if problem goes away you need a new booster.

   next. never apply 12v to an injector. pulsers can be had to activate them . they never get powered for the length of time you just touch the wires.  milli seconds is all. very easy to burn out an injector

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Mine runs rough in park with out foot on brake, just not as rough as it does in drive. Will be doing a compression test soon I think. What should the compression be at?

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good compression would be over 100 psi, and less than 10% difference between highest and lowest

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Factory compression specs

Warm engine, all sparkplugs removed. WOT, 5-10 compression strokes

normal 171 psi

minimum 142 psi

max difference between high and low cylinder 10% (14psi)

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Did compression test today. Not looking good.

 

#1=120

#3=40

#5=120

#2=105

#4=115

#6=115

Did #3 again with oil and no change in compression. Since #3 has some compression would adjusting the valves on #3 bring compression back up? About how much would it cost to have a shop pull the heads and have them rebuilt?

 

 

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Adjusting the valves at this point is a crapshoot, it depends on how long this has been going on. Fairly short time, adjustment might do, longer time and the valve seat is burned and the head has to come off.

If you have time and talent, just do the one side. Watch utube for videos on how to do this, it is a major pia. You have to take things apart and measure the clearance, then remove cam to remove the shims. Measure the shims, do the math and order new shims of the right thickness. Reinstall the cam and measure everything AGAIN and hope your math skills were good.

Never mind the cost, just try and finding a shop that will work on that engine and has access to the shims.

The 22re is SO MUCH simpler with adjusting screws.  Some folks wonder if the extra power is worth it.

 

P.S. I put a zillion miles on a VW Rabbit with the same valve adjustment setup. When I sold it I gave the new owner a half of a Crown Royal bag full of used shims. You could reuse shims with different valves. The shims were so hard they never wore.

I used a tool set like this to compress the valve and pop out the shims.

https://www.ebay.com/itm/196374460186?itmmeta=01J09NRHWXS67EAE44X11GBXT5&hash=item2db8d4771a:g:f5wAAOSwvUtlKBgL&itmprp=enc%3AAQAJAAAA0Dw3P%2F9qudluWAOEjMDRulO1vvmWX2n1ZEjvNDeCmRmr6c2fSHx1weeUy6MHl2bAnd1VuyzFqzk4YkywtzksGgQiDicGhdfmsrgVjed0%2BkRep6A%2FuZxMPsKrgHWyIOaNOTzFKeCQRUTIjZckU8h8SQsVFqnGpzJQ5mbtt3dvXMIn7W%2F3aQ8QDthjLYP6T3vw6vRwqNK0XTsBJDC70fqL7JTYLgZDj%2B9soSJ39%2BR%2BkjkH%2BZHfBiWofLPtD28Y3XuMtbIqQko7gw75kADr20mSifg%3D|tkp%3ABk9SR8ie4rWCZA

 

 

 

Edited by WME
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not much chance of it being ok if it ran with it like that for any length of time, the valve is burnt

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In the motorcycle world there is a tool to hold the shim bucket down when turning the crank so you are able to then use a magnet/tool to get the shim out without having to remove the cam. I have a Yamaha xj bike and have had to swap out shims using a bucket holding tool. My particular bike has a bucket holder you can secure to the head. However, I've seen other hand held bucket holding tools for other bikes. Worth researching as not having to complete a lot of disassembly is a major time saver. You can learn online about cam lobe position on the shims for getting the correct measurement on both sides. Shop time will be costly. 

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The motor idled fine last summer.  After a long winter our first trip this spring to Bigfork Montana was when I noticed the rough idle. I've put 755 miles on it since the rough idle. Is that enough miles to burn the valve? I've watched a couple youtube videos on the valve adjustment and one guy used a Honda motorcycle tool to compress the bucket. I'm pretty handy with tools and vehicle maintenance but old and have no shop, but I have lots of shade on the property. The Yotashop over in western Washington has shims ranging from 2.20 to 3.40 for $18 apiece and the adjusting tools for $45. I was a carpenter for 35 yrs so math is no problem but the old back is not what it used to be. I will do the adjustment if you guy's think I haven't put too many miles on it. I can't thank all of you enough for all your input!

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do you have an air compressor? you can use a leakdown tester to see if the valve seals after removing the shim

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OOPS got my 6 cylinder engines mixed up. Using the tool set will let you change the shim with the cam installed.

Removing the valve cover and doing valve checks, is not heavy lifting, removing the heads IS heavy lifting

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Do I have to put the valve cover and plenum and everything else back together after I pull the shim to do the leak down test? Do I pull intake and exhaust shim?

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