Seemed to me awhile back one of the other culprits to look for with this is the o-ring being worn out on the idle set screw; if it's worn/rotten, the idle won't stay set. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Hi Ted

I talked to Tod for quite a while today and he seems to think it's more of a tuning problem. He suggested the obvious-timing, vacuum leaks and then compression to eliminate something funky internally and lastly, if all else did not reveal a tuning problem, a dyno run or two.

I've had most every bike I've owned on the dyno for years but I've never thought about putting the truck on one. That just might be what I need since we can't seem to figure out why the truck runs the way it does.

Tod suggested, as you did, that the timing might be off by a tooth. Now, I didn't personally put the motor together but I doubt the guy that did built it made that mistake. However... mistakes do happen. I really don't want to tear it all apart to check that unless it's a last resort.

So, I'll dive in with the compression test and see if I can find a vacuum leak again. I'll have to do some homework to see who might have a dynomometer around here and knows how to use it.

When the idle is stuck down really low, sometimes I notice a faint smell of gasoline. Tod suggested smelling the oil to see if it smells like gas and I haven't done that yet.

Any other ideas are welcomed. I'll report my findings... wish me luck!

PS I can be at the shop in about 15 hours or so. Maybe I should point the truck north with a 12 pack and let the master figure this one out. <img src="/forums/images/graemlins/lol.gif" alt="" />

>>>*I would discount the timing chain being off a tooth, the report of nice offroad response suggests that you are running her a tad harder rpm's and probably in lower gears when out in the outback.

A lot of driveability issues relate to loading, for example the fellow that likes to glance down at the sweet young thing in the next lane might have a set of 38's, of course then he is way down on RPM and no matter what we do we can't fix that with a cam and head.

Looking for rich/lean or variations at different throttle settings can be a clue, I bet Tod picked up instantly on the "16-17 MPG" and he knows that is down from normal about 10-15%. Of course different drivers have different size right feet so who knows there.

The part that doesn't set quite right is the nice report of offroad, but poor torque on the highway? That has just a couple of possibles, either you run different tire/wheels offroad????

Or you drive differently on the highway...Lot's of folks do drive differently on the highway, something about "rules" and little signs.

The report suggests a mild need for a gearing change, but you could have issues like ignition timing responding slower as RPM comes up, things like that.

A dyno test will indicate rich/lean or timing concerns, at the minimum tell you where the engine wants to run, then the trick is to use that rpm band. That could be as simple as dropping a tire size or so..

These little engines really do manage to handle way more than the tiny size suggests, but throw too many straws on the old Camel's back, and we all know the result..

*BTW: Anybody shows up around here with beer, we are probably going to end up out on the jetty trying to catch a lingcod...*LOL**...Or down on a secret (really!) mud flat I know about digging up Horsenecks....*EB

I'm running it pretty mellow off road-it just doesn't need much RPM to get around. I have to run it a little harder on the asphalt when there is any kind of grade/hill. I don't like to spin it up too much-it just makes me nervous. 4k gets my attention and by 4500 I can't stand it anymore so I try not to wind it up too much.

I'm running 33" tires and have regeared to 4.88. I've had that set up for years with no trouble. I just have one set of wheels/tires so there is no swapping around.

I really do drive mellow on the road. If I want to have fun, I throw a leg over the Honda and can get all the weirdness out of my system. In the truck, I'm usually at the speed limit-maybe 5 over if I'm really feeling rushed. I don't race from stop light to stop light or do anything weird.

I'll be able to check a few things later this week and I've got an appointment on a dyno for the 13th. At least we'll have a baseline to work from at that point.

I'm glad to hear that you don't think the timing is off a tooth. I did NOT want to have to deal with open motor surgery again.

Thanks so much for your help EB!

What kind of beer do you drink? <img src="/forums/images/graemlins/cheers.gif" alt="" />

What kind of beer do you drink? <img src="/forums/images/graemlins/cheers.gif" alt="" />
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>>>*It was called Budweiser, the last one I had was.....*Hang on, I had to go ask the wife....

>>>*1988, she says, seems I won a case of Beer in a bowling tournament. Plus I don't drink whiskey anymore, either, too busy.

Now fishing??? I am either doing that, going to do that, or coming back from doing it.. <img src="/forums/images/graemlins/lol.gif" alt="" />..*EB

Hey EB

I think it's time to grab the fly rod and go fishing myself.

I can't believe I'm actually looking for a problem and disappointed that there isn't one that can be found-so far. What better way to spend Friday night than leave the GF on the couch snoozing while I tinker with the truck?

Compression is... a bit low? Toyota says 172 in the manual. Maybe the Street RV head has something to do with my numbers. At least they are all within range.

#1 150
#2 150
#3 145
#4 155

I might have 3 and 4 reversed. I left my notes in the truck.

What was a bit odd is that the plugs look pretty worn for having less than 10k on them. The insulator even started to melt a bit on at least one of them. They are Denso something or others... Again, my notes are in the truck.

I sprayed WD40 anywhere that I thought air might be leaking by and came up with a big fat zero. I even did it when it was idling really poorly just for fun but the idle never picked up.

Come Wednesday morning, I've got an hour scheduled on the dyno. Maybe something interesting will come of it. There is a problem waiting to be found somewhere!

>>>*Those number are a shade soft, that affects power but shouldn't cause a surge or idle change.

Compression ratio increases are a gross gain of about 7% for each single point, note I said gross.

Camshaft lobe timing affects crank speed pressure numbers, we see 150-175 when all is solid with the StreetRV head.

More than that tends to ping a bit much.

I will be very interested in the results of the dyno run. if the operator is good they nearly always find a few ponies in there..

*I got used to the 355's I used to tune, then send down to the dyno and have them find 5-10 ponies I missed, it finally hit me that every engine is ever so slightly different....*EB

I was a little disappointed at the compression numbers. I'm not sure what to expect next and have no idea why the numbers are low.

Speaking of pinging... I'm getting a fair amount of pinging.

You're right on that one, it even worse with toyota's newer EFI. When you buy a tuner from URD, they give you a base map, but it always needs alot of work, just because every MAF sensor is different (and how the engine is, re: timing/detonation)... so its a pain!

>>>*One thing to remember is that 150# of crank speed pressure actually is a lot. The only reason we can even run that much at all is the fact that the head is aluminium which bleeds off heat, plus control systems that allow it by tightly controlling the flame front (when all is right.)

*Noting a fair amount of pinging suggests that something isn't quite right, that is why the dyno run and a computer analysis can be a benefit. We see systems that have just that typically "tipon to the throttle" crackle or "ping" with crank numbers of 180# and up.

Properly quenched (piston to head clearence) the engine will create less ping at higher compression than it will at lower compression, also. Interesting stuff, I remember when the 9 to one rule came along for the 5.0L Chevies, lord we had hot engines until we figured out the cam changes and what to do with the combustion chambers. Those designs had crank compression numbers of around 120# and put down 550 H/P. I remember the 355" we had in the number 43 car, she had 105# crank pressure and that one made right at 700 H/P. Static compression ratio was 13.8 to one, still only 105#, big duration camshaft of course..

The late 22RE combustion chamber is very efficient, the problem with very efficient is the engine then becomes extremely sensitive to ignition timing and valve timing. I keep saying just right is just right and everything else is just wrong.

In the old days we increased the compression ratio through the roof, then advanced the timing until she rattled. At that point we jacked up the octane of the fuel and went racing. The pistons all had huge domes and they ran so close to the head at temp that the chambers left marks in the tops of them.

Now it is flat top pistons, tight chambers, close quench and we also have to be concerned about what comes out the tailpipe.

Nearly always when we hear a report of soft crank compression and pinging, with mileage a bit lower than it should be, I start suspecting that the piston is down the bore a bit too much at TDC. If that part is right, next we look to see how much total advance she has at each step.

One part of our world fights the other, can't have emissions so she needs to run at stoichiometric, at that point power fades since power means fuel, bumping the fuel curve to around 14.5 to one increases the power but now the tank goes dry too fast, advancing the valve timing brings the power peak in early, but then she pings so the system backs off the timing..Then we realize that heat means power but heat means NOX, so we bolt on an EGR valve to dilute the fuel/air mix to cool the heat.....*LOL**...

*Everything is a balance...and a compromise......*EB