Poor idle on 4.6 after major tune up

[JFD]

Just finished a big tune up on 04 D2. Head gaskets and all other gaskets, o-rings and seal are new. New water pump, thermostat, plugs, wires. Also did valves lapping, cleaned the exhaust ports really well.

The engine starts really well, can rev up fine, you can feel the torque, but after reaching the normal operation temperature it will have poor idle and sometimes even die.

The only part I haven't put back on is the cruise control module (changing fixing bolts), I don't think the idle is managed by the cruise control but who knows.

I did clean my IACV well with carb cleaner.

What am I missing ?

Cheers

 

[ptschram]

After such intensive work, it is not uncommon for it to be necessary to reset the adaptive values.

Also, on Motronics engines, it is easy to overtighten the throttle cables causing mechanical interference with the idle.

Cruise control has NO control over idle and is not able to be engaged unless the vehicle speed exceeds 35 MPH.

 

[JFD]

After such intensive work, it is not uncommon for it to be necessary to reset the adaptive values.

Also, on Motronics engines, it is easy to overtighten the throttle cables causing mechanical interference with the idle.

Cruise control has NO control over idle and is not able to be engaged unless the vehicle speed exceeds 35 MPH.

Thanks PT

Oh, I forgot, no codes thrown.

I guess I need the computer to reset values

 

[JFD]

At least it's good looking

 

[jymmiejamz]

At least it's good looking

Clean and good are two very different things.

 

[jafir]

My 99 would do that. I won't lie, I tossed lots of parts at it before I figured out that the ECM was getting a noisy speed signal from the SLABS. Even at a stop the road speed, when viewed from a scanner, was 88mph.... so the idle programming didn't think it had much work to do. I washed the ECM as someone on here suggested once, and it started idling as smooth as silk.

 

[JFD]

I washed the ECM

Please explain.

 

[jafir]

Please explain.

I opened it up, and it was green and scaly inside. I took it to the kitchen sink and using warm tap water and dish soap, I scrubbed it with a tooth brush. Then I rinsed it with distilled water and then with alcohol. or was it alcohol and then distilled water? whatever. Anyway, after I let it dry..... (ok, I was in a hurry, so I went to dollar general and bought a $9 hair dryer) I plugged it in, and road speed while stopped was 0, and the idle was normal.

 

[JFD]

I opened it up, and it was green and scaly inside. I took it to the kitchen sink and using warm tap water and dish soap, I scrubbed it with a tooth brush. Then I rinsed it with distilled water and then with alcohol. or was it alcohol and then distilled water? whatever. Anyway, after I let it dry..... (ok, I was in a hurry, so I went to dollar general and bought a $9 hair dryer) I plugged it in, and road speed while stopped was 0, and the idle was normal.

I'll check mine, I guess it's somewhere close to fuse panels ?

 

[ptschram]

I washed the ECM as someone on here suggested once, and it started idling as smooth as silk.

K C Carpenter voice on

That's ridiculous and will destroy the circuit board!

K C Carpenter voice off

 

[JFD]

Just opened mine, it's clean and shiny, the foam pad on the back was falling apart, put a new one and back on.

 

[JFD]

Clean and good are two very different things.

You are right about that.

 

[ptschram]

Alright, let's get back to the basics.

Any vacuum leaks?

Idle air valve attached to correct harness and not to the coil pack?

 

[riceybean]

Alright, let's get back to the basics.

Any vacuum leaks?

Idle air valve attached to correct harness and not to the coil pack?

IAC connected to the wrong plug is what I was thinking.

 

[11b4v]

Just cranked my 01 project truck up tonight after doing the HGs. First, I got misfires on 2 and 4. Discovered I had forgotten to tighten my upper intake bolts and the oil breather / throttle body hose drivers side. I reset my plug wires at the coil and plugs as well. Fixed all that and ended up with intermittent high idle.

Readjusted the throttle cable and its idling smooth as it should.

You might want to try adjusting your cable as well.

 

[kennith]

At least it's good looking

:applause:

I'm not sure how I feel about the color, but that's not the point. Taking pride in a clean job done is a nice thing.

Now, if you can make it a good job well done and clean, you'll be set.

Sorry. Couldn't resist.

Cheers,

Kennith

 

[JFD]

Alright, let's get back to the basics.

Any vacuum leaks?

Idle air valve attached to correct harness and not to the coil pack?

Vacuum hose is brand new, I heard you can check leaks with a small propane tank, I'll try that.
I do feel that the port where the brake vacuum hose connect to the air intake is kind of fluffy, doesn't feel tight at all.

Harness was tagged during work, so I guess I did not mix things up but who knows, I'll check that also, if I remember well, connectors are different colors.

I started it a few more times and if you don't rev it up it will maintain 750 rpm quite good, but if I send it up for a few seconds, then after that idle will become poor and erratic.

Still no codes.

Cheers

 

[JFD]

:applause:

I'm not sure how I feel about the color, but that's not the point. Taking pride in a clean job done is a nice thing.

Now, if you can make it a good job well done and clean, you'll be set.

Sorry. Couldn't resist.

Cheers,

Kennith

I had to choose between about 3 different high temp color paint, I normally use rebuilders grey for most of my stuff but not available right now. I have to import 90% of the thing I use but airlines are difficult with cans and sprays.

Cheers

 

[Roving Beetle]

That's pretty! And most likely the problem.... rover motors are ALWAYS covered in grease oil and mud, thereby sealing the vac leaks. ha ha

 

[JFD]

Seems like the MAF is faulty, I'm only getting 1.10 V on pin Nº 5 at idle speed, I think the normal value is between 1.4 and 1.5 V. I did try to clean it, but I have the same result.
The good thing is genuine MAF prices are much lower than before.