The truck idles low and high when i disconnected the egr sensor the truck did not idle much different. does this mean the egr and valve are no good. also go signal for tps and hego. is the tps the one on the side of the throttle body 89 5.8l

 

Punctuation is a wonderfull thing.. it would really help us understand your post.

The sensor atop the EGR valve is a position sensor and has no direct affect on EGR operation, it just tells the computer if the valve moves or not when it commands the EVR to apply vacuum to the valve. To test the valve you have to apply engine vacuum directly to the EGR valve nipple, it should open and make the engine stumble. The valve should also open a small amount when the engine is reved if the EVR and vacuum line are intact and functioning correctly. This movement will be visible through the openings in the side of the valve.

TPS is on the bottom of the TB, IAC is the cylinder on the side of it.

 

Thanks. Ok I got 5 Volts going to the sensor so the sensor should have no issues. If I test the TPS and the IAC and they come up good, what would be my next reasonable place to check next.

 

The TPS is a potentiometer, which means the voltage varies with the angle change of the throttle body. Voltage range is ~.9 V closed and 5 V WOT on the return circuit, the voltage in is 5 volts vs ground. If you measure the rtn circuit versus ground then you will see the right range, if you measure vs the input you should start at about 4 volts going to almost 0 volts. If you have the same voltage no matter the angle you are measuring the wrong circuit.

What are the symptoms of the ailing vehicle you are trying to correct? Have you pulled the computer codes yet?

The EGR typically operates during cruising speed of the vehicle not at idle, Just like Conanski stated is the proper test of the EGR.

 

yes the computer codes stated that there was a complete system failure for the EGR and under voltage, HEGO switch, and the TPS sensor were the codes that came up. The truck seems to idle low then high, when I hit the gas it is almost like it stays at the rpm for a bit then drops down, then drops down again. I dont know if this has anything to do with it but their are a couple of tubes on the drivers side with two seperate small canaster looking things and when I shut the truck down I hear what sounds like air escaping.

 

You may want to check the condition of the vacuum lines. If they are the factory color coded plastic ones, they have probably failed after years of exposure to the environment under the hood.

 

Yes they are all factory colured. is there an easy way to test them I pulled allot of them off and I could feel suction. I also put water on them and could not see anything. Would those likely be it would it be worth replacing or checking the other stuff first. Or just replace the vacume lines. Would they cause the engine to act that way evan if it is such a small hole

 

If you have a high idle condition, yes you should consider replacing them. I replaced all of them on my truck for 30 bucks with bulk rubber vacuum hose from the auto-parts store, but that was before gas shot up to 4 bucks a gallon here in the US.

But the hunting for idle would best be address with the distributor first. You didn't answer if it was one side of the cap not firing, just every other wire or ...

 

I think it is fireing on all pistons just the idle seems to be a bit crazy. But it could be that as well. I guess I could pull each wire and see if their is a spark. If that is the case I am planning on replacing the rotor cap and plug wires. In the mean time I Guess I can check the timeing.

 

My 95 mustang idled high,and I put on a new idle air control valve.Problem solved,not saying that is your problem,but it's worth a shot.

 

Never trust ANY of the vacuum lines/circuits. Use a hand held vacuum pump/gauge to test each circuit individually. I replaced all the vacuum lines and two reservoirs on my recently acquired '92 F350 after finding each one would NOT hold a vacuum. Before I started I had no error codes, but the idle varied between 800-1200 RPM. After fixing all the leaks it runs a steady 600-700 RPM in drive and 700-900 in Park/Neutral depending on the ambient/engine temp.

You can use the same vacuum pump to test your EGR valve and EVP sensor operation BEFORE throwing money on new parts. The IAC is another well known cause of idle quality issues. Take it off and clean it. This topic has been covered here and many other website forums. Most of us buy these old trucks because we don't have the money or need to buy a new/newer truck. Use common sense, use the Search function and read.

Everyone has a different comprehension level of all things related to automotive repair. We are all here to learn and help out.

 

are you speaking of the idle being erratic as in it varies up and down rhythmically, or does it stay high at times...and then stays low at other times. If it is cycling rhythmically, what is the range between high and low rpm's.. Once we had a bitch of an explorer that had a hunting idle and it turned ot to be a noisey signal wire for the tps. Backprobing at the tps it checked fine, but backprobing at the ecm showed a varied reading at idle. Ran a new wire and it was fixed. The ecm uses the key on engine off reading of tps at first start up to know when throttle is at rest or idle. When our signal was varying, the computer had no idea what to do and causing an erratic and high/low idle condition. Im talking 600-1200 rpm's, back and forth.

 

Never trust ANY of the vacuum lines/circuits. Use a hand held vacuum pump/gauge to test each circuit individually. I replaced all the vacuum lines and two reservoirs on my recently acquired '92 F350 after finding each one would NOT hold a vacuum. Before I started I had no error codes, but the idle varied between 800-1200 RPM. After fixing all the leaks it runs a steady 600-700 RPM in drive and 700-900 in Park/Neutral depending on the ambient/engine temp.

You can use the same vacuum pump to test your EGR valve and EVP sensor operation BEFORE throwing money on new parts. The IAC is another well known cause of idle quality issues. Take it off and clean it. This topic has been covered here and many other website forums. Most of us buy these old trucks because we don't have the money or need to buy a new/newer truck. Use common sense, use the Search function and read.

Everyone has a different comprehension level of all things related to automotive repair. We are all here to learn and help out.

 

Yeah it seems like it is hunting just at idle though then it seems to get better.

 

need to figure this thing out. Do the vacume lines need to be the same diameter as the original is it best just to go to ford and get them.