94 2.3L w/ 17# injectors - Intermittent Rough Idle

[alwaysFlOoReD]

This may be a dumb question, but what does the brake cleaner do? Get sucked in an combusted? Is that how you hear a difference?

Yes, it gets combusted. If the idle surges up in rpm then you've found a vacuum leak. Brakeleen is a mixture of mainly toluene and [IIRC] acetone and a few other chemicals. If that or propane gets sucked in then the idle changes, usually faster. Spray at all intake gasket surfaces, throttle body, and the tubing from the maf back to the throttle body, and any other place that could let air in where it's not wanted.

 

[Mark_88]

Here is the reference I used: http://www.ford-trucks.com/forums/115928-egr-vacuum-regulator-evr.html

I see the valve is powered from the PCM. I hope the outputs are current limited to avoid ruining the PCM when a short like this occurs.

Wow...I read through that entire post...didn't realize there was a potential leak on that valve...might have been what was causing my 96 to stumble slightly...but I didn't have to follow that up after I sold it...

Good work...keep us posted on the results of changing that valve if you do...

 

[wizkid00104]

Thanks. I am hoping that will solve the problem along with reseting the computer again.

If not, than hopefully I am one step closer. I just find it so interesting that the vacuum side of that valve would not hold vacuum and that it is a planned leak point. The only reason I can think of that is if it held vacuum and the valve actuated, it may not have to force to unseat the plug from the vacuum.

I have some more lines to test as well. Hopefully I will get to all of this tonight.

 

[wizkid00104]

And here is the booster test if anyone needs it (from SSBC):

http://ssbrakes.com/attachment/85301-Vacuum Brake Booster Testing and Diagnosis.pdf

Vacuum Brake Booster Testing and Diagnosis​

This procedure will require the use of a hand operated vacuum pump with a vacuum gauge.
If you do not own one it can often be rented or borrowed from most “big box” parts stores. (Note:
18”HG is the minimum engine vacuum at idle in gear to effectively operate a vacuum booster

1) Remove vacuum hose from check valve on booster. Place hose from vacuum pump onto
check valve and draw booster to 20” of vacuum.

2) Let booster sit with vacuum applied for 5 minutes. If vacuum does not stay steady at 20” it is
faulty and needs to be replaced. If vacuum does hold steady at 20” proceed to step 3.

3) With 20” of vacuum in booster depress brake pedal once and release it. The booster should
transfer some but not the entire vacuum in reserve. Depending on how hard the pedal is
depressed it is normal to see 5-10” of vacuum depleted from reserve. The most important
thing is to ensure the booster does transfer vacuum but does NOT transfer the entire vacuum
in its reserve. If vacuum remains at 20” OR goes to zero the booster is bad and will need to be
replaced. If vacuum transfer is within the above parameter proceed to step 4.

4) Once again draw booster down to 20” of vacuum. Go inside car and depress brake pedal and
hold down for 30 seconds. You should see the gauge drop slightly and then hold steady.
Vacuum should stay steady as long as you are holding the pedal down. If vacuum drops while
pedal is being held down the booster is faulty and will need to be replaced.

 

[wizkid00104]

$30 well spent a Harbor Freight. It comes will all the adatpers for testing.


The hopeful culprit....

 

[wizkid00104]

Learned a little more.....

New solenoid has 32.5 ohms resistance.



Here is a comparison from old to new so you can hear the difference.



I got this back in. Now that it is working you can actually hear air getting sucked through little filter at idle.

I still had really shitty vacuum pressure.... so I removed my EGR valve. I expected to find that it was not functioning, but it was.... so I used the vacuum pump to actuate it and the pull vacuum EGR tube. It held vacuum no problem. So I pulled vacuum on the portion that bolts to the manifold. No vacuum here... I blew air through it and could here it coming out the back side of the diaphragm. A seal is worn out there. So I picked up the new one and installed it. The idle is now holding smooth and steady at 17-18 inHg after a computer reset.



So it ran good, it drove good, and after getting it up to temp I let it idle. For 45 seconds it was fine, then it did this.



I found this excerpt about the IACV. I replaced it 2 years ago because the factory one went bad. I am wondering if I need to clean my current one out.

This tip is from Lonnie F:

I did find another problem that others may have had. My truck had a rough idle and like I said would bog. It would bog at take off, cruising at a low rpm, and if I was turning a corner. What I found was that the idle air control valve was gunked up and not working like it should. I didn't notice it really w/ the 14 lb injectors but the 19 lb injectors need a little more air at idle and even though I adjusted the idle screw the computer was fighting it's self. Anyways I removed the valve and completely cleaned the inside where the plunger is with throttle body cleaner. Then I sprayed the spring and plunger with wd-40. Once I put it back on and reconnected the battery it only took a couple of seconds to find it's idle and learn it. I've drove a full day yesterday in it putting over 100 miles on it. And it runs perfectly without bogging or any hesitation. Maybe others were like me and started having a sticking IACV but didn't realize it until the larger injectors were in place. By the way I love how this truck accelerates now. It's so much more fun and easier to drive.

This will be my next attempt. Then I'll remove the JET trip and try that. Anyone else have suggestions? I have verified all legs of the vacuum system with the exception of the vapor canister.

 

[alwaysFlOoReD]

Great job so far! You're doing much better at diagnostics than me. Keep the updates coming.

 

[Mark_88]

Yes, great work...

I would like to see it redone as a tech article submission and given a different name...like how to find and fix Idle stumble in the 2.3...or something similar.

It sounds like part of the problem I was having with mine and wouldn't have known where to start because I read everything I could find and only got as far as fixing a serious arcing in the wires...

 

[wizkid00104]

I appreciate the compliments gents. I'd be happy to do it as a tech article, but I feel as though I need to completely solve it first lol.

I will say before the stumble after 45 seconds, it is the smoothest idle I've had in a LONG time. The engine is happy and runs really well. It's just that final stumble that needs solving.


Sent from my iPhone

 

[wizkid00104]

I drove it about 75 miles today. It is adjusting to the new injectors well. I still have something going on at idle. I sprayed some brake cleaner today and picked up something near the PCV valve. I am going to pull the manifold tomorrow to inspect further.

This morning I cleaned the IACV, MAF, throttle body, and intake tubing. I also popped the core out of my air muffler and put the housing back in instead of using the cast iron drain pipe I have had in there for the past 8 years...



IACV Before:


IACV After:


Throttle Body Before:






Throttle Body After:




Harbor Freight sells tube brushes that really come in handy for cleaning the holes in the throttle body.



I used Valvoline Carb and Choke Cleaner for the IACV and MAF as well as CRC Mass Air Flow Sensor Cleaner.

 

[wizkid00104]

Still working on the idle. I turned up the stop screw by 1 full turn. It now idles around 900, but has yet to sputter and cough. Drove it to work today. I am now past the 100 mile mark with the new injectors. Getting off the turnpike on my way to work, the check engine light came on when I downshifted. I am very curious to see what the code is since the truck seems to be running really well. I am getting an odd feeling that it is going to be EGR related.... like the little flow sensor that hasn't been replaced yet.

 

[Mark_88]

I was under the impression that these engines did not have an idle stop screw...mine had a warning printed on the side saying not to turn that screw and others advised me that it would damage the engine (or throttle body) in most cases.

As long as you know how much you turned it you can always set it back to original position.

If the truck is running better otherwise I think your cleanup did more to help than anything...did you disconnect the battery at any time during that process? That would reset the computer and allow the sensors that may be affecting this do a learning cycle and maybe correct it with the cleaner flow...

 

[wizkid00104]

I saw one place that said to try adjusting it a bit. There is also a sticker that tells you not to clean the throttle body because of a special coating. Well that coating was covered in petroleum gook, so that was ignored as well.

I did not reset the computer after the cleaning because I wanted to see how it reacted. I am sure there will be another reset in the future. I want to get the CEL code and I may have found a vacuum leak with brake cleaner at the PCV. Just need some more time to research.


Sent from my iPhone

 

[wizkid00104]

Another update....

So the check engine light code was 332.

332 (R,M) EGR did not open/respond during test or if memory code, did not open intermittantly

For Reference:
http://www.thorssell.net/hbook/eectest.html
http://www.thorssell.net/hbook/3digit.html

I thought this was odd, but it didn't bother me. So I also wanted to inspect the leak I thought was the PCV. Sprayed brake cleaner and heard the RPM pick up. I popped the vac lines off of the EVR solenoid just to make sure the fumes were not being ingested through the vent on that valve when I discovered that one of the fittings was gone. It broke clean off. I have a feeling this is why I got the check engine light.



So I decided to pull the manifold back off and also check the new EGR for the vacuum leak on the manifold side as well.

For the manifold, this is what I found (look at the top left corner):





I am now even more certain that this is my vacuum leak. My dumb ass forgot to pull the old piece of gasket off the upper intake manifold.

So............

I went back to Advance and they ordered me a new valve (at no charge) and a new manifold gasket that will be there this afternoon. I should be able to get it reassembled tonight, reset the computer again, and see how she runs.

As for the new EGR valve, it did no hold vacuum on the manfold side. So what I thought was a problem with the old valve may not be. I am going to reinstall the old one and see how she runs. That will save me $55 if I don't need it.

So just so it is in writing... The EGR system has intentional leaks:

1. The EVR solenoid has a leak in it. This is by design. When it is functioning properly, you can hear it sucking air at idle. It should not rattle when you shake it and the coil needs in the neighborhood of 30 ohms resistance to prove it is functioning.

2. When the EGR valve is closed, it draws air through the non-vacuum side of the diaphragm. To test the EGR, you should apply vacuum to the diaphram and hear the valve pop open. You can apply vacuum to the exhaust fitting of the valve and it should hold vacuum. This ensures the valve is not leaking exhaust. Finally, if you apply vacuum to the manifold connection, it should not hold.

I really thought I was onto something with the EGR the other day by blowing air into it. I have both on the bench, I will have to try again and see if there is a difference.

More to follow

 

[fastpakr]

Subscribing. You're describing similar symptoms to my '94, and I've chased EGR/EVR issues on it off and on for several years.