Looped engine running after rebuild

[operator]

I just finished a complete rebuild of my 22RE engine. New pistons (.050 over), crank balanced, new LCE camshaft, LCE header. Cleaned everything real good and got it all back together. All new Vacuum hoses. The exhaust right now ends right after the header because I have to get a shop to connect it to the rest. It started fine, adjusted timing and runs smooth. Except when I give it gas and hold the throttle steady to give I guess 2K RPM, it loopes, like as if I was pumping the gas, which I am not. Anything higher than that it runs fine. Her is my initial guess at it: Since the O2 sensor sits only 1 inch before the end of the exhaust it might not get the most accurate reading and cause that? Also the back pressure might not be steady due to the incomplete exhaust. Anybody already run into this before or have any pointers?

Thanks

[whomadewho]

Had the same problem with mine - 92- 22re with racing pistons mild cam ect. Spent hours trying to figure it out. What I discovered - The problem is in the air induction system. The air fuel mixture has to be changed,due to the change in pistons / cam ect. You can change the setting in the -Air Flow Meter or go on line to - LC Engineering and look at Part # 1065021

[operator]

OK. So that means my computer is not able to figure out how to deal with the new more air in and out deal. The gauge from LC that you posted the link to, what does it do or show me? If I want to go without that, how do I adjust the computer?

Thanks

[whomadewho]

That is correct the computer is set up for a stock engine and is not set up for the changes you made to the engine. The map sensor seemed to work because your not changing altitiude. Here is how I came to the conclusion. There is a sensor located below the thermostat, the end is green in color. This sensor acts like a choke,and sends a message to the computer and the air flow meter ect. which controls the the air flow and fuel mixture. What I did,I tested the air flow meter which tested ok,so I checked out all the wire connections,no problems. Thinking the sensor was bad,I bought a new one -NOT CHEAP, The result the same engine lope. After weeks of checking,I discoverd the air fuel mixture needed to be changed. There are two ways of doing this. You can take the back off the air flow meter and set the pointer either to the right or the left depending if your running rich or lean? Or you can either make or buy the set up where you can control the mixture by turning a knob in the cab to control the mixture.What this does,its hooked to the sensor below the thermostat,and the computer and it fools the computer into thinking the engine is either hot or cold depending which way you need to go. As far as the gauge - NOT A CLUE what it does?? What I did was to install a aftermarket vacuum gauge and I set the air fuel mixture between 18-20 inches at idle. There is no way to adjust the computer to change the air fuel mixture. I even changed the computer,thinking that was the problem,with the engine lope.I hope you can learn by my mistakes,and not waste a lot of time and money changing parts. The next time I visit the doctor, Iam going to get some sleeping pills,so I dont lie in bed at night thinking about how to solve vehicle problems.

[operator]

OK, thanks for all the info. I have seen the geen sensor, figured it had something to do with temperature. My engine ran all fine before the rebuild so I guess all sensor are working. I will get the exhaust done, see if that changes anything, I guess it won't but I will try anyways, gotta get it done. What about not worry about it and leave it looping? It only does it without load at higher RPM's... I may just drive it for a while and see.

To hook up a Vac gauge and use it to adjust the mix: The Vac gauge goes in the normal Vac system and then I adjust the green sensor until I get the desired Vac reading in idle? I am totally out to lunch in this one I guess, can you explain a little more?

Thanks for the help!!

[whomadewho]

Usually when the engine lopes the vacuum is not in the normal range.You are not adjusting the green sensor,you are adjusting the air fuel mixture by turning a knob in the cab of the vehicle,This device is wired to the GREEN SENSOR. The wire from the sensor goes to the computer. Thats where you wire the device in the cab - to the computer. - WHERE THE VAC,GAUAGE COMES INTO PLAY. - You start the engine and with the engine at IDLE SPEED. You set the air fuel mixture, by turning the knob either to the left - lean - right -rich Until the vac. reaches 18-22-inches. Running the engine with the air fuel mixture either to RICH or LEAN is not good. The engine is going to get the best fuel mileage with the vac between 18 - 21 inches. Another BIG MISTAKE I made.I use my pickup as a daily driver,no off road use The wheels are 10 inches wide.with oversize tires. In 5th gear at 65 mph,the engine is running at 1750rpms, The vac.is between - 10-14 inches. Before I installed the tires I was getting between 22-24 miles per gallon. With the oversize tires the best I have gotten is 18 miles per gallon. The lope in my engine was around 1500-2000 rpms,thats why I installed the device.

[operator]

Thanks for the detailed explanation. The site was down so I couldn't respond and since a lot more problems have emerged. But first things first. I finished the exhaust and hooked it all up, looped idle problem gone, runs fine.
But it had low oil press. Dummy light came on in idle when warm. Changed sensor. Same thing. But went out when giving it gas so I figured it is OK, just gotta get it broken in. After 3 miles the engine seized. After cool down down it turned over again. Found out a plug was left out after cleaning the oil canals by the shop. Took front cover over, placed plug in, oil pressure problem gone. However now the engine has a loud knock to it at around 2K RPM without any load on it, i.e. reving it up or shifting up/down. It runs and idles fine, just very loud knocking/diesel like sound at a certain RPM. Any ideas? Tear it apart again?

[whomadewho]

Sorry to hear about the bad luck. Its GETS even worse if your married, especially if she has kept a close tab on the amount of money you spent.and what she could have bought ect. Before you tear the engine down, you might want to consider hooking up a positive oil pressure gauge and see what you have for oil pressure at idle and at a higher RPM. This will help you determine if the main and rod bearings are ok. If you decide to go with a after market oil gauge,make sure you purchase an adaptor kit,because the threads in the engine block are METRIC. With the engine running at idle,remove the oil cap to see if the top half of the engine is getting oil. IF the oil pressure is good, remove the rocker arm cover and inspect the rockers and the cam lobes for wear. With the engine cold,with a feeler gauge, check for an excessive gap between the rockers,this may help you determine if a rocker or a cam lobe is bad. Can you hear where the knock is comming from? You may also want to drain the oil to see if you have metal fillings in the oil.

[operator]

I already checked the topside after it happened and it is good. Changed oil, nothing too bad there, cut filter open, nothing there. But since I already took the engine out of the Truck again I dropped the oil pan. And tata, severe metal shavings. Way too big to fit through the metal screen of the oil pickup. However since it ran after the seizure again and the topside looked good it must be either rod or main bearings. I haven't gotten to that yet, I will tear into that tomorrow. I just hope my crankshaft survived....