TinMan

Here's the deal,

94 4x4 standard cab, 22re, manual, pickup. I have had it for about 3 months. I got it with a fresh rebuild, complete with cheap after market rockers that ate through a lobe on the cam. But believe it or not, it ran like a raped ape, just was noisy as all get out.

I put on a new stock head with 268 cam, and toyota rockers from EB. And an LCE adjustable cam. Cam was not dialed in, just matched up to another cam so the gears aligned.

Since then I have been battling a miss in the 1800 to 3000 RPM range. It is not bad and most people would just live with it. But it's bugging me to know that it does not run perfect.

Engine idles perfect. And under a load the miss is hardly noticeable.

Things I have done to try and find the cause of the miss.

Retarded and advanced the cam with no difference in the miss.
Replaced all the vacuum lines.
Sprayed carb cleaner around all vacuum lines, throttle body, intake, and air box with no change.
Checked the routing of all vacuum lines.
Checked all the electrical connections.
Checked the AFM.
Checked the TPS.
Blocked off the EGR.
New cap, rotor, and button from Autozone.
I am not getting any CEL codes.
Good compression, 160+/- on all cylinders.
Good results on a leak down test.

This is the tune I have on the engine right now.
AFM richened 4 teeth.
Cam advanced 2*
Base timing set at 5*
EGR restricter plate with 1/8" hole between the plenum and the EGR.
Plugs still show that it is running a little lean. In this tune it should be running fairly rich.

Tonight I started to unplug sensors and see if any of them took the miss away.

When I unplugged the TPS the idle raised and the miss at 1800 - 3000 went away. Tested the TPS again and it tested out good, and seemed to be set right.

I am convinced that unmetered air is getting in, but I just cant figure out where.

Any ideas, I am about to replace all the intake gaskets just to be sure that there is not an issue there.

Remember it idles fine.

Thanks

diablo

I to had a miss at around 2500 rpm,mine was bad plug wires. It seems my header was heating em up and they were out of spec. when I tested em. I since put new plug wires in and re-routed them out of the way, no miss after that

TinMan

Yeah I guess I should have added that I do have header. But the plug wires are good and flexable.

It does seem to do it more once the engine is at running temp. I will switch them out and let you know how they do.

Also when I unplugged the TPS, the miss went away and it immediately started to smoke black smoke, like it was running rich, which it should be. But it tests out fine.

se7enine

iTrader: (2)

Mine is starting to miss now at 2-3k rpm while driving in this cold weather , usually after about 15 min of driving. No check engine light though. Maybe I'll wrap my header with some heat tape and see if it helps. I should replace my fuel filters too.

TinMan

The miss is very gentle, and happens during no load throttle between 1800 and 3000 rpms, nothing before that or after. Idles fine, the time mark is good solid at 5* at idle. Engine is very responsive to idle adjustments. I can easily adjust the idle down until it will almost dies, and upwards to 2000 rpms. I can hold the rpms in the miss. And throttle past it.

As bad as the tires vibrate it is hard for me tell if I can feel it while the truck is moving down the road. If it is happening under a load, i.e. moving down the road, it is not enough to make the truck surge.

Funny thing if I unplug the TPS the miss goes away, and starts running rich. But the TPS tests fine.

I did another leak down test tonight, just to confirm. Cylinders 1,2,4 and four are holding 0% loss of pressure, and only a slight hiss out of the dipstick tube. Which would be normal. Cylinder 3 is holding a 3-5% loss of pressure, and a more pronounced hiss from the dip stick tube. No air leaking anywhere else was noticed. I don't believe a 3% drop on a cylinder is anything to worry about. Tomorrow I will run it back up to operating temp and do another compression test.

plugs looked ok tonight, a little lean, but nothing to worry about.

I don't know, I am at a loss, everything test fine. I feel like it is a vacuum leak but I cant find it.

later

TinMan

Engbldr 268 cam, valve lash is set at .007 intake, and .009 exhaust, which is what EB calls for. I am using adjusting screws for LCE, and they seem a little short. But the valve lash is spot on. I kind of though maybe a valve was sticking, but that would have turned up on the leak down test.

Leak down test is the best way to find out what is going on in your engine.

TinMan

I replaced the AutoZone brand cap, button, and wires with Toyota brand cap, button and NGK wires, along with a set of stock NGK plugs, and now the little 22re is running like a top now. I will most likely unblock the EGR now, and see it goes.