Need some help, please...

[hidesertrat]

First off, let me say: Great site!!! Wish I had found this before I started my discovery of the 2.9 engine!

I have an 87 Ranger 4x4 which overheated and cracked the heads. Decided to go ahead and overhaul the engine. If I had read the posts earlier, I may have went with a 4.0 exchange, but to far into the project for that now. At least I did get enough information to replace the heads with 89 heads instead of sticking with the poorly made 87 year heads.

Anyhow, I have read the posts on the 2.9 missing at warm up and under a load, which is what mine is doing. So plan on diconnecting the O2 sensor tonight and see if that makes a difference. After which, depending on the results, I will go from there on that problem.

However, I have a couple of other questions, as silly as they may be:

1. Where the heck is the connector to pull the codes located at? I have looked all over for this thing and haven't been able to see it. Knowing how things usually go, I have found it several times, just haven't "seen" it!

2. Upon reassembly of the engine and putting everything back in its place I broke the input port to the EGR pressure sensor. Tried to glue an other plastic piece onto it so I could connect it back up, but that didn't work (yet). What I would like to know is this: What does this thing do? I know the hose that connects to it has pressure on it, not vac. I am sure it feeds a signal back to the PCM, but what is it for? Is there any way of testing the sensor to ensure it is still working? There are three electrical contacts on the connector. I have tried connecting a ohm meter to them in different configuations and blowing pressure into the input port, looking for a change in the readings, but haven't seen anything. Any ideas on how to check it?

3. I had heard that an after-market temp sensor would give you a poor reading. I may have this problem also, so is there a good sensor to get, or does it matter? My gauge always reads hot, which makes you nervous but even worse I tend to ignore it. I have purchased a infrared temp gun and even when the gauge is reading "HOT" the front of the cover on the t-stat is at about 180 degrees and the area around the sensor is about 192 degrees. Any ideas of other areas to check and what the temp should be would be helpful, as I am just making sure the newly rebuilt engine doesn't over heat and blow up on me. I don't want to have to redo the whole thing any time soon....getting old and slow!

Thanks in advance for any and all advice.

 

[90rangersuper]

1. Where the heck is the connector to pull the codes located at? I have looked all over for this thing and haven't been able to see it. Knowing how things usually go, I have found it several times, just haven't "seen" it!

welcome to TRS

my trucks a 90 so it might be different, the 2 plugs were located on the passenger side right behind the fuse box under the hook, it should say ecm on that, there are 2 plugs in there, look in the tech library for help obtaining the codes through that using a ohm meter, they have listed the codes there as well, haynes manual helps to,

 

[hidesertrat]

Thanks 90rangersuper, I will take another look there, but I thought there was only one connector. Maybe that is why I haven't been able to find it, I don't know what I am looking for!!!! I was looking for a black rectangle type connector that had, if I remember correctly, about six pins on the top row and five on the bottom. Anyhow that is how it was on an 84 Tempo I have.

I haven't been able to get into the "Technical Library". I get the page that shows and area for videos, but nothing is there. Will have to go back and give it another try.

I do have a Haynes and Chiltons manual on this truck, but they haven't been much help in this area.

After thought......The truck doesn't have an "check engine" light. I found this out after tearing the dash apart when it failed smog, because the light didn't come on. Only to find out this particular series didn't have the light installed. Does that mean it may not have a code connector? I would think there still would be a way to pull the codes, it has a computer (PCM).

 

[90rangersuper]

you got it, the 2nd plug in there just has a single connection, try this address to get you to the directions

http://www.therangerstation.com/tech_library/OBD_I.html

should work for you, the haynes manual has the list of codes there
if not just post um here and we can help

 

[MAKG]

1. Where the heck is the connector to pull the codes located at?

On an '87, it is lying on top of the passenger side wheel well. You might have an easier time seeing it if you pull the airbox out. There are TWO of them -- one "doghouse" and one single-connector.

2. Upon reassembly of the engine and putting everything back in its place I broke the input port to the EGR pressure sensor.

Your options are to buy a new one or pick up one from the junkyard. As these aren't nearly so prone to blowing up as the 4.0L DPFE sensors are, I'd chance the junkyard. If it's nonfunctional, you WILL flip an EGR code.

The sensor tells the computer how far to open the valve (in a PWM sense). It isn't just yanked open and left there.

3. I had heard that an after-market temp sensor would give you a poor reading.

All electrical temp sensors -- including stock -- suck. Get a mechanical temperature gauge or you're pissing into the wind. Electrical temperature (and oil pressure) sensors measure the quality of the electrical system more than anything else. And I'll place a bet that your instrument voltage regulator is bad (they almost all are, and incorrect gauge readings suggest as much, especially if more than one gauge is F'ed). Any calibrated mechanical gauge should be fine. If you're going that route, I'll suggest adding oil pressure, system voltage, and perhaps vacuum.

A decent spot to mount these is dead center on the bottom of the dashboard. Make sure you won't hit them with a shifter.

 

[hidesertrat]

Hey that worked, the link took me right to where I needed to go. Need to figure out why I can't get there on my own.....with time.

The connector thing was eating at me, so had to go out to the truck and take another look. Feeling pretty foolish right now, the connectors were right there. I will have to admit, they were tucked under the air box, but I should have seen them earlier!

Well, got some things to check out tonight and even know where to check them now!!! Good-to-go!

Thanks for your help.

 

[hidesertrat]

Thanks MAKG,
Found the connectors, yes they were tucked under the air box.

Not sure how the EGR pressure sensor would regulate the EGR valve as there is no electrical connection on the EGR valve itself and the sensor isn't mounted to the EGR valve. The only connection between the two is the pressure line/hose from the EGR to the sensor. Having said that, I know I have to replace it, just was wondering how the darn thing worked since I didn't see any physical/electrical connection between the two. Also was trying to figure out how the sensor could be tested to see if it electronically was functional. Figured there would be a way to look for a change in the reading while applying pressure to the input port.

Agree with you on the gauges. I will be installing more reliable gauges in the near future.

Thanks again for the input.

 

[MAKG]

There might be no electrical connection to the EGR valve, but there is a physical connection. That's what the exhaust tube does. An open EGR valve affects the backpressure. This is (more or less) directly measuring the effect of the valve, which is exactly what you want from a feedback system.

 

[hidesertrat]

Thanks MAKG, I will have to do some reading on that one (EGR).

Well, disconnected the O2 and didn't make much of a difference, other than the strong smell of gas after driving for a while.....must be running a bit rich!

Plan on checking the wireing and vac lines this weekend. Also have an appointment at Auto Hobby Shop on base to run some diagnosic tests. Hopefully, I will find something. I hate to replace stuff just hopeing it is the right thing.

Is there a possibility (I hope not) that the torque converter could be locking/unlocking? Seems the "miss" happens most when under a load (hill). Since most of my driving is in town, this is hill is taken at about 45 mph / 2K rpm. It was just a thought, but I would think the torque converter is either going to work or not work.

 

[hidesertrat]

Just wanted to say thanks for all the help, thoughts and support.

Here is what I found:

Strong gas smell....not because engine running rich, but because I had a small gas leak from the o-ring on the fuel regulator. Fixed that, smell went away, but still had miss.

Got to run an ignition scan on a diagnostics machine and found that the "new" split-fire plugs were POS. Seems one was shorted, the others were not firing hot enough and for a very very short duration. Went down and got some $1.99 Motorcraft copper plugs and the miss went away.

I still need to replace the EGR sensor, but the engine is running great!

Once again thanks, just wanted you all to know how things turned out. I hate it when you help someone and never find out if they got the thing fixed or not, so now you know.

See ya on the next post.

Semper Fi