1537 / 1538 Codes & IMRC

[rtoddharris]

Some info about codes 1537 / 1538 from my experience with 98 Windstar 3.8 liter.

If you have a 98 Windstar, you are likely to have this problem show up on your codes at some point when you get a check engine light. I have 145K miles, this the second time for me. You may have your Windstar stall at idle or when turning at slow speeds or with little throttle.

The problem for me has been that one of the IMRC actuators has developed a leak and then neither work as they should.

They are located on the passenger side of the intake manifold, look on the engine side of the alternator and there is one in front of the other. The one in front is the right one and the one in the rear is the left one. They are just a few inches apart, bolted to the intake manifold. They have an electrical connection (on the side) and a vacuum connection (on the top).

The way they are supposed to work:

1. When the engine is off, there is no vacuum to these actuators, and the butterfly valve inside the manifold that they are linked to is closed. A spring in the IMRC actuator holds the butterfly valve linkage closed.

2. At engine idle and less than 2900 RPM, there is vacuum to these actuators that overcomes the spring in the actuators with diaphragm and this opens the butterfly valves inside the manifold and this allows more air to pass into the intake.

3. At engine speeds above 2900 RPM an PCM activated switch turns vacuum off to the spring in the actuators closes the butterfly valves. This is supposed to increase performance during heavy engine load or acceleration.
I wonder....?

The problem is that one you get a leak in one of the IMRC actuators (diaphragm seal likely) s it is usually big enough that when vacuum is applied, neither IMRC gets vacuum so neither butterfly valve is open at idle. These things devleop leaks because (in my opinion after having taking a failed one apart) that they are so close to the heat of the engine that the seal of the diaphragm and housing breaks with age.

The first time I got a leak in one of these, I replaced it, it is easiest done with the alternator removed. The Motorcraft part numbers if you want to do replace this are:

CK2258 (right or front located one)
CK2259 (left or rear located one)

They are ~$180 each if you shop online, at a dealer ~$270 each.

The second time I got a leak in one of these, I decided not to replace it, since I doubted how much performance increase I got above 2900 RPM, and my problem was stalling at idle and slow turns.. What I did was remove the old one, which for me was the right one or the front located one, and plugged the vacuum line. This allowed the one remaining good one to work as it is supposed to. I then took a small spring and used it to hold open butterfly valve by connnecting it to the linkage to the butterfly valve and one of the bolts that formerly held the IMRC actuator.

As I suspected, there was little loss of performance above 2900 RPM, and the it quit stalling at idle. It took a little bit of driving for the PCM to retune with the butterfly valves open like they should be as low RPMs.

When the next one fails, I am going to do the same thing, remove it, plug the vacuum line and use a spring to hold open the butterfly valve.

I am cheap, but I really do not think that you get that much improved performance (above 2900 rpm) and do not they are worth replacing. When you take one of these apart, they are simple as dirt and Ford did a lousy job with the durability of these things and the price is outrageous for the part.

If you try this, I would like to know, and if you have any questions, let me know.



Todd

[jalo215]

I have the same problem with my van. Do you remember the web site you found them for that price?

[rtoddharris]

Hi Jalo,

www.rockauto.com It is in the fuel/air section and it is called a choke pull off. I left off K in the part numbers in my previous post. Here are part numbers from motorcraft site. You can look up CK2258 or CK2259 on google an you will get some sites that sell that part, like rockauto.

Select Part Number Part Description Qty Per Vehicle Buyers
Guide CK2258 Choke Pulloff (Carbureted)
RIGHT HAND - F65E-9S514CD 1</SPAN> CK2259 Choke Pulloff (Carbureted)
LEFT HAND - F65E-9S514DD 1</SPAN>

[Freakzilla69]

I'm having a problem with them... I could swear I've read that the engine running state for the valves is closed below 2,900. It's supposed to open at higher RPM to increase air flow.

I just cleaned out the intake manifold plenums and replaced all my air intake gaskets (upper and lower) allong with the IAC and throttle gaskets. I also replaced my ERG vacuum hoses (the big ones).

Next I'm going to replace the small ones, specifically the ones to the IMRCs.

When I block the front IMRC hose with my finger I can feel a vacuum, but it feels weak, and the other IMRC does nothing. When I feel for vacuum on the rear one, there is no vacuum at all.

My question is, the spring that holds the IMRCs open when running under 2,900 rpm is pretty strong, how strong is the vacuum in those hoses supposed to be?

I'm guessing the culprit may be the "Y" connector that splits the hose to go to each IMRC.

[rtoddharris]

hi freakzilla,

When you had your intake manifold off, you would have been able to see the butterfly valves that the IMRC actuators operate. The butterfly valves are spring loaded closed. This is what I remeber. In any case, with vacuum on at idle, the actuators work in the opposite direction to the internal spring on the butterfly valves to the intake.

If I were you, I would check both of your IMRC actuators, it sounds to me like one or both of them are leaking. There are at least a couple of ways to check:

1. With the car off, look at the position of the actuators, start the car, both actuators should move and this will open the butterfly valves inside the intake.

2. If they do not move, or you want to check without starting your engine, remove the vacuum line to the actuator and see if the actuator will hold vacuum. You can hook up a hose and see. It should hold vacuum, if it does not, it is not working. If one of them is leaking, it is likely that vacuum is not reaching either actuator, though one of them could be good, it still would not operate since it does not see enough vacuum to operate.

The spring I used was ~1/4 diameter and ~1.5 inches long, not very strong, but strong enough to overcome the internal spring that holds the butterfly valves closed.

If you do use a spring to hold these open, the car's computer will take a few miles (10-20) to adjust if you have been running with the IMRC actuators in fail.

I have been running with one of them held open for about 3 K miles, no more stalling, no more idle problems, no more codes. I did hook up the electrical connections to the IMRC actuator that was no longer connected to the internal butterfly valve linkage in case the car's computer was looking for feedback of some type.

[Freakzilla69]

I must be confused, but it doesn't make sense to me that they would close at high rpm... but whatever. I'm trying to get rid of the 171, 174 and 1538 codes so I can pass emmissions. I think I missunderstood what "lean" means for those 171, 174 codes. I thought it meant there wasn't enough gas in the mix but not enough air kind of makes sense the way you describe it.

I'm going to troubleshoot where exactly the leak is tonight (since the kids will be off trick-or-treating, and not "helping"). I know at least one hose doesn't have any vacuum and the other is weak, so I pray it's not the controllers. If it is I'll have to go to the pull-a-part yard.

I've never replaced vacuum hoses so I have a question about that:

Do I just pull the old hose off the fittings, that is, the 90 degree fitting that connects to the controllers, the connections at the "Y" connector and the fitting on the back of the manifold and cut the new hose to length and push it on to the old connectors?

I looked at Autozone and didn't see any replacement connectors. They had all kinds of plastic "T" and "F" connectors though.

[rtoddharris]

The vacuum hoses just "pull" off the acutators and other parts. Be careful not to break the plastic hoses and fittings, you can repair or replace if you do though. You may have to use a screwdriver to help ease/pry the hose off the fitting...

To test the actuators, just pull of the existing vacuum hose and put a new hose you can pull vacuum on, I just suck on it like a straw, though that probably is not the recommended method. You will be able to tell if it is leaking.

If you find them leaking, you can use a small spring to hold them open opposite of the position they are in when the car is off. I think this opens them, though I am not 100% sure. Here is a picture (from someone else's post) of part of the intake and you can see these valves are closed and I think that is the way they are. I have read both open and closed in this forum.

Sorry the kids will not be there to "help" you, though you may have to answer the door all greasy to give out candy...


Good luck.

[Freakzilla69]

Guess what... it's the front IMRC.

I put a bolt in it's vacuum line.

I used some 16 AWG aluminium wire threaded through the runner eye (I shredded the little white grommet, which I happen to have a brand new pair of from the dealership for when I get a new controller, it crumbled like a cracker) and around the bracket that holds the IMRC on, to hold the runner closed. I cleared the codes with my scanner.

My commute is about 110 m round trip, hopefully the SES light will stay off and my 171, 174, 1538 and 1506 codes will not come back and I can slide through emmission testing sideways until I can go to pull-a-part and find one that works...

I'll update tomorrow.

OH! I tested them by doing the human vaccum test first, but I wasn't sure so I plugged the hose for the one I thought was bad, started the engine and the other one (back) worked.

To verify, with the engine off, I rotated the runners and plugged the controller... the good one stayed closed(/open, I'm sure running idle is closed), the bad one did not.

[rtoddharris]

I hope things worked well for you, I would be interested in knowing if you passed the test.

[Loogie]

I have Tested if the IMRC's Leak and they are Fine, There is no Vacuum at the IMRC's though. What would be the Next thing I need to Check?

[Freakzilla69]

Originally Posted by rtoddharris

I hope things worked well for you, I would be interested in knowing if you passed the test.

All my codes came back but it runs noticably better. So I haven't gone to retest it.

I suspect the IMRC I thought was good has a slow leak, it doesn't open all the way. I'm going to try wirring it shut/open(?) as well.

I disconnected the IMRC mechanically from the runner and left them plugged into the sensors, maybe they are still reporting the 1538 and 1506 codes? Should I just disconnect them electrically?

I know this is for a different topic but...I think I have a vacuum leak going to the A/C somewhere because it only blows through defrost and only blows hot in the back. I've replaced both switches (front mode switch and front aux fan switch) within the past year so I hope that isn't bad again. Could this be causing my 171 and 174 codes?

[rtoddharris]

Originally Posted by Freakzilla69

All my codes came back but it runs noticably better. So I haven't gone to retest it.

I suspect the IMRC I thought was good has a slow leak, it doesn't open all the way. I'm going to try wirring it shut/open(?) as well.

I disconnected the IMRC mechanically from the runner and left them plugged into the sensors, maybe they are still reporting the 1538 and 1506 codes? Should I just disconnect them electrically?

I know this is for a different topic but...I think I have a vacuum leak going to the A/C somewhere because it only blows through defrost and only blows hot in the back. I've replaced both switches (front mode switch and front aux fan switch) within the past year so I hope that isn't bad again. Could this be causing my 171 and 174 codes?

You could still be getting the 1538 code if the one remaining one has a slow leak and if it doesn't open/close? all the way. I left mine connnected electrically and I do not get the 1537/1538 anymore so that is my experience.

It is funny, I had to replace a vacuum actuated switch a couple of years ago because the back blew heat when the A/C was on in the front. The switch was behind the heating/air controls on the front panel, a little black box with vacuum connections. In my case, this part was not leaking, it just didn't work correctly anymore. I replaced this and the A/C then began working int he back. A vacuum leak can cause the 171 / 174 codes. I dont know about the 1506 code. Here is what I got from another website about these codes.

Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.
Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.
Symptoms

You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.
Causes

A code P0171 may mean that one or more of the following has happened:

• The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled
• There could be a vacuum leak downstream of the MAF sensor.

Possible Solutions

Possible solutions include:

• In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
• Inspect all vacuum and PCV hoses, replace if necessary
• Check for a dirty fuel filter and proper fuel pressure

[rtoddharris]

Originally Posted by Loogie

I have Tested if the IMRC's Leak and they are Fine, There is no Vacuum at the IMRC's though. What would be the Next thing I need to Check?

There is a PCM activated switch on the rear side (near the firewall) of the engine. This switch could be bad, you can check to see if you have vacuum to it. You have to get back behind the engine, which for me meant taking apart the front cowling (the black plastic piece that the windshield wipers come out from). The switch should allow vacuum to go to the IMRC actuators at idle.

[Freakzilla69]

I wired both IMRCs closed and plugged both vacuum hoses. I cleared the codes by disconnecting the battery. After my 55 mile drive to work today I had no codes so I think they're gone.

Hooray!

[Freakzilla69]

Update... the temporary fix has gotten rid of the IMRC codes, now I have to figure out the 171/174 problem.