Replaced Heater core 2weeks ago

[Kevindjac]

         So I replaced the Heater core a few weeks ago, and got everything back together the the auto function doesn't seem to work like it did before I took it apart.

         Engine has been idling erraticly, although that maybe from bad gas I got not sure.Also mpg previously was better than 13 on present avg. now after replacing core can't get over 9.0

         I also went thru diagnostics and under climate control it says climate sensor fault never seen that error before. If anyone can shed some light on these issues for me I would very much appreciate it. TIA

[Ronnie]

Gas mileage is way to low, both before and after replacing the heater core. Should be at least 19-20 even around town. What code did you get for the climate sensor fault? Knowing the code number would help diagnose the problem. Could you have pulled one of the vacuum lines loose when replacing the core?

[Kevindjac]

Not sure Ronnie on the vacuum lines will have to check out perhaps this weekend, when it warms up, could you point me in the right direction of the vacuum lines you are referring to? There was no code for the climate sensor fault I was in the sub groups On the middle bottom button on the touch screen in the Diagnostics and everything showed ok but yet under climate control it said sensor fault. Yes mpg is too low although since I've had the car it's always read around 13.0 under present avg. Noq on instantaneous it is higher around 17-20 sometimes higher at least before the replacement haven't looked at instantaneous since I replaced core since present avg was so low.

Edited January 5, 2022 by Kevindjac
Add info

[Ronnie]

Are you using these instructions for checking codes?  How To Access ECM, BCM & CRT Codes  If not you should do that and see what codes you get. The vacuum lines I was referring to go to the HVAC controller located under the dash on the passenger side. Check the vacuum lines for a proper connection at the controller and the ones under the hood that supply vacuum to the controller.

 

[jon L]

Hey, Ronnie, I only get 10-12 mph. Do I have a problem?

 

[Ronnie]

13 minutes ago, jon L said:

Hey, Ronnie, I only get 10-12 mph. Do I have a problem?

 

Going from red light to red light with your right foot on the floor is probably causing your gas mileage problem. 🙂 

[Kevindjac]

A few other things Ronnie I forgot too mention is at about 45-50 mph the who car shakes and if I go faster than that it goes away, Also the heat only comes out at the floor, when bi level is selected the air thru the vents is cold. Sorry for all the questions, I didn't imagine all this happening for just at replacing the core, however I really appreciate your knowledge more than you know!.

Edited January 5, 2022 by Kevindjac
Spelling

[Nailhed66]

Seems like a vacuum issue especially in regard to the blend doors. My ‘88 averages 21mpg city/24 highway and even that is a bit lower than I was expecting after hearing that the next gen series 2 3800’s can get 30 mpg. 

[Ronnie]

3 hours ago, Kevindjac said:

at about 45-50 mph the who car shakes and if I go faster than that it goes away,

That sounds like it might be an ignition system problem. Especially if it does it when the engine is under load at low RPMs. Maybe bad spark plugs and/or wires or a bad ignition control module. 

[Kevindjac]

Dammit just replaced all that not even 2 years ago. Well I'll try to sort out the others issues first then move on too that, thanks again I'm planning on working on it Saturday when it warms up I'll keep ya posted.

[DAVES89]

I would start with the simple things like the idle air control and the housing it fits in. Then the Mass Air Flow sensor. After that I would do the Ignition Module and coils. If you did the plugs and wires that would be last on my list.

[Kevindjac]

Dave I replaced the coil pack at the same time as the plugs, but yeah I'll check the MAF and IAC, it's just weird cause all this happened after replacing the heater core. Working on it now so looks like all the vacuum lines are hooked up under dash on passenger side. I'll keep you all posted.

[Kevindjac]

@Ronnie below is picture of what I was talking to you about, I went into status then clicked on Diagnostics, then even the climate control said ok I pressed the button and this popped up. 

Secondo checked codes only had E047 and E048,  one is a misfire so I'm guessing the plugs are bad already connections are all tight.

The other issue with the air not coming through the vents all the vacuum lines look like they're tight and there's none that are cracked or broke that have leaks. the metal rod on top of where the heater core is that hooks to the two levers on top of that moves the flapper for the where the heater core is both them levers are solid they neither one moves so I'm not sure if it's just stuck or the motor is just that turns those if there is one is bad or what. any advice  you or anyone else that can shed light on these issues would be greatly appreciated cuz right now I can't drive the car as it is I'm just frustrated.

[DAVES89]

5 hours ago, Kevindjac said:

Dave I replaced the coil pack at the same time as the plugs, but yeah I'll check the MAF and IAC, it's just weird cause all this happened after replacing the heater core. Working on it now so looks like all the vacuum lines are hooked up under dash on passenger side. I'll keep you all posted.

Coil pack/Ignition Module more likely to fail then a plug deciding to start misfiring.

[2seater]

Ignition module is more likely to fail than the coil pack on a Magnavox. Was the ICM replaced as well as the coils? Did you check for vacuum at the black line connected to the center of the bunch of vacuum tubing on the bottom of the HVAC Programmer, (engine running)? It is the main feed to the controller and the other end is at the tee shown in Ronnie's photograph.

To test the air diverter door for the HVAC system, you must change the temperature on the climate control, up and down, and observe the rod from the controller through the glove box opening. It does not move rapidly but it should move visibly when the temperature is adjusted. If it doesn't, that may be part of the communication issue.

[Kevindjac]

Thanks @2seater you will check those out and can you tell me where the ignition control module is I've been searching but can't find a picture of it. I will let you know, thanks again.

[Kevindjac]

So I unhooked the vacuum line under the hood that goes to the HVAC controller on passenger side dash with the motor running and the one unde dash both with no noticeable effect on how the motor was running.

[Ronnie]

You have two problems. Poor running engine and heater controls not working properly. I recommend working on one at a time. Trying to do both at the same time just makes this topic confusing. Which problem do you want to fix first?

[2seater]

On 1/9/2022 at 11:46 AM, Kevindjac said:

Thanks @2seater you will check those out and can you tell me where the ignition control module is I've been searching but can't find a picture of it. I will let you know, thanks again.

ICM is below the coil pack. The best guide for this is to go to the top of this page under How To Guides, choose Ignition System in the Electrical system menu, and then choose Ignition System Troubleshooting. The video explains better than I can. 

[2seater]

23 hours ago, Kevindjac said:

So I unhooked the vacuum line under the hood that goes to the HVAC controller on passenger side dash with the motor running and the one unde dash both with no noticeable effect on how the motor was running.

I suggested checking for vacuum at the connection on the bottom of the HVAC controller with the engine running and everything else connected. This is to verify the line is not pinched or melted and vacuum is actually getting to the controller. It was not intended as a tool for helping the idle issues.