MAP

[franklin2]

Yea i figured the code thing out, just trying to get to idle at a normal speed. It want to idle around 1000+, after warm up. Trying to clean the MAP sensor. Its the original. Its strange there's a part number on a sticker that reads E6EF-9F479-A1A and under the sticker is an embossed part number E7EF9F479A1A, no dashes. Dirty

I have tried making them idle faster, it doesn't like it. The computer is programmed to idle the engine at a certain speed (around 750 or so depending on the model) and if you try to fudge it, it drives terrible. It throws the TPS voltage off, and the cold idle speed when you start it in the morning is so high you can't hardly drive it. They have it programmed a certain way, it's hard to get around it. I even tried to disconnect the IAC and use a hand throttle control for warm up fast idle. It drove terrible. What they call "tip in" was really jerky, it was a mess.

 

[RonD]

Will need a sensor with baro port, then.

Well first he needs to diagnose Code 34

Cold engine test can cause 34, same as 21, like franklin2 said

And then see what EGR Valve he has
1987 could have EVP sensor wire on EGR Valve, so no EGR pressure sensor

 

[dirtymike]

Ill run it down the highway for a couple good stretches then do the test again after i get some cleaner for the map and see if that does it. check the temp sensor first to see if it is working right. Dirty

 

[PetroleumJunkie412]

Good plan of attack

 

[dirtymike]

Map sensor cleaned and engine warm reads 160 hz applied vacuum steadily and it swept to 100 smoothly. ECT cold measured 77.2 ohms, Hot it was 10.4ohms. Dirty

 

[dirtymike]

operating temp i get a code 34 KOEO and a code 3 KOER

 

[RonD]

ECT resistance is going down as it should but what scale OHMs were you using

Resistance shown here: http://www.fuelinjectedford.com/page28.html
1k scale

77 would mean cold temp was under 32deg(freezing)
10 would mean engine is only at 120deg warmed up


Look at your EGR valve and see if it has TWO vacuum hoses attached or ONE vacuum hose and ONE wire

 

[dirtymike]

The chilton manual says 200,000 scale. That's the 200K scale on my meter, correct. It has two vacuum hoses attached to the EGR, one in front and one in back. the back one goes to the egr sensor wich has three wires going to it. replaced both a year ago when i did the top end. Dirty

 

[dirtymike]

The ETC is off amazon its a standard motor products TX6T. Seems the ohm values are out of scale for ambient temp here. It was 76 degree's when i too the reading, so the reading should have been around 30.0 ohms. After a hour of running it was 10.4 ohms. Scale says it should be around 3.0 ohms. I have a 192 thermostat in. Dirty

 

[RonD]

Do you have the old one, to test cold, ambient temp?

"New" just means NEVER TESTED now-a-days, lol

 

[dirtymike]

No, sure wish i would have kept the old one. Could have ohmed it out with cold and hot to get values. Yeah its a gamble nowadays when you get aftermarket parts. Dirty

 

[dirtymike]

Cleaning the MAP vacuum port with cleaner seemed to smooth idle out but the idle is around 900+. Code 34 went away but cant figure out the code 3, there is none. Dirty

 

[RonD]

There is no code 3, just 2 digit codes and no "0's"

After engine is warmed up and idling
Unplug IAC Valve, it will close and RPMs should drop to 500 or so, engine may even stall either is GOOD, it means no vacuum leak(but also means the computer was setting the high idle??, which could be because of low temp, 120deg, on ECT)

If idle stays high then there may be a vacuum leak OR someone has messed with the anti-diesel screw on the throttle linkage, looks like an "idle screw", its not, can't use an idle screw with fuel injection, everyone knows this, lol

With IAC Valve still unplugged, and high idle, turn the anti-diesel screw Counter Clockwise(unscrew), 1/2 a turn, if RPMs start to drop then keep turning until engine is barely running, anti-diesel screw is now reset, done, plug IAC Valve back in and idle should go up to 650 or so

If turning the anti-diesel screw did NOT lower RPMs then turn it back that 1/2 turn, its not the problem

Could be vacuum leak causing the higher idle

 

[dirtymike]

If i unplug the IAC it dies. I have to screw the anti-diesel screw in to get to idle at all. Got good vacuum but the tube going from the EGR to the exhaust seems to be loose on the exhaust side. Guess up in the air she goes. Dirty

 

[RonD]

Could be the ECT temp thats causing the higher idle, cold engine should idle above 1,000, then as ECT shows warm up idle will drop down, computer is closing IAC Valve a bit, when temp gets above 170deg, warm engine idle should be set, 650 manual, 750 automatic

But if ECT is staying at 120-130deg then 900rpm idle would be about right, for coldish engine temp

Not that its related but does dash temp gauge show just below 1/2 after 10minutes or so, full warm up?