Fuel Issue-Running Rough And Stalling While Driving

[marie]

Lets see how well I type now that I’m stoned on throttle body cleaner. The plugs were black as pitch, but powdery not sticky. So, now we know it is/was running rich. The plug wires all looked good except for the one I broke, which of course was the last one. I will get a new set tomorrow. I disassembled the throttle body and removed the IAC. I cleaned all, including as far as I could reach into the intake manifold itself. Everything had varying degrees of soot. All parts are clean and shinny. I did not have time to get to the EGR before nightfall, nor could I reassemble the throttle.

 

It passed the NV smog test just two weeks ago, which would not have happened if it was running rich. And the smog test was after the first episode of the bucking and stalling. I am wondering if the running rich aspect is new and separate from the stalling. What say ye?

[cruiser54]

Make sure the hose/piping from your throttle body to the MAP sensor on the firewall is flawless. No pinches, cracks, melted spots, loose boots etc.

[marie]

Yeah, I looked it over pretty carefully the other day when we were talking about it. I will take it completly off tomorrow and reinspect. I'll clean it and myabe even blow in one end of it while blocking the other end and make sure there are no leaks.

[cruiser54]

Good idea.

Unplug the electrical connector at the MAP and check it out.

 

Did you ever get a meter?

[marie]

yup, I did! So, what makes it run rich? Would the IAC being fouled make it run rich? The stalling is something separate isn't it?

[cruiser54]

Yes. The IAC will affect idle but not cause rich running.

 

Rich running will cause crappy idle though. Richness at idle can be caused by a faulty oxygen sensor.

 

Cold only extremely rich running is caused by, in this order, MAP, CTS, and IAT.

 

Your 88 has the dreaded C101 cnnector. Have you addressed that?

[marie]

Well, I had to look up all those acronyms except the MAP, because I just put a new MAP in. So the MAP is good. Now the C101, is that that bunch of wires and connectors right above the master cylinder, and is it one of those wires or the whole thing? I’m just finding out that the coolant temp sensor on an 88 is all in one with the dash gauge for temp right? That could be an issue because the dash temp gauge didn't work when I got my truck back from the guy who put the new engine in. I am finding out that he screwed a bunch of stuff up, so it's not surprising to find out that that was important. He said it wasn't. I actually bought the temp sensor to put in a month ago. I can plainly see the connector for it. I can't seem to find the hole it's supposed to go in. I have seen several pictures on the internet of where it's supposed to be but I don't see a hole there. It should be near the firewall end of valve cover driver’s side, right? This could be a/the problem. But it hasn’t been there for 2 years now and it ran fine. I figured it was just for the dash gauge alone. Your thoughts? I will have to find the IAT.

[cruiser54]

The sender and sensor for the coolant are NOT a combined unit in an 88. The CTS is located on the driver's side of the engine block. The sender is located at the driver's side rear of the head. I wonder if the guy put a later model engine in there that has no provision in the head.

 

 

The C101 connector on 1987 and 1988 Renix Jeeps was a source of electrical resistance when the vehicles were new. So much so that the factory eliminated this connector in the 1989 and 1990 models. The factory recommended cleaning this connector to insure the proper voltage and ground signals between the ECU and the fuel injection sensors. We can only imagine how this connector has become a larger source of voltage loss and increased resistance over a period of almost 25 years. The C101 connector needs to be cleaned at least once in the lifetime of your vehicle. Chances are it’s never been done before.

 

 

 

Almost every critical signal between the engine sensors, injectors, ECU, and some to the TCU, travel this path through the C101 connector.

 

The C101 connector is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the bolt and pull the halves apart. You will find the connector is packed with a black tar like substance which has hardened over time.

 

Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth.

 

If you have a small pick or dental tool, tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter before bolting both halves back together.

 

　

 

Revised 07-17-2012

IAT is screwed in to the intake manifold just rearward of the throttle body and has two wires on it.

 

C101 is indeed the connector near the master cylinder and it carries a BUNCH of signals between your computer and fuel injection system.

 

Try this, and it esplains a bit more about it.

 

Renix Jeep C101 Connector Refreshing

　

[marie]

ok, I had an epiphany this afternoon. I think I work my job not so that I can put a roof over my head, but so I can buy parts for my Jeep. :yes:

 

cruiser54, you were right the C101 it totally gunked. There is so much tar in there I'm pretty sure I am going to find dinosaur bones! What an ugly mess. I will clean it. I ran out of light tonight and have to work tomorrow till noon, but I will have the rest of the day to do hopefully finish up.

 

As for the CTS and the gauge sending unit for the dash (have I got that right?). I found the hole for the sender, so I thought. I found a small flat plug that took an allen key to get out. It was almost flush and had been painted over. It was located next to the last bolt for the head right next to the valve cover, firewall end, driver’s side. Right were the pics I've seen said it is. The sending unit I got from Napa fits nicely on the cap but does not fit in the hole. I have some pics, I will figure out how to put them in photo bucket so I can post them. I can pass on this for now because it's the CST I'm most worried about, right?

 

So I just found a picture for the location of the CST http://autorepair.about.com/library/images/bl825a-lib.htm (it's not a link, you'll have to cut and paste) it's for a 90 but it looks like what you are talking about. I will have to wait for daylight to look for it.

 

I went to pull the tubing off the MAP to check it and I broke it. I'm 5'5", 120lbs and female, you'd think I would know how to be delicate, but no, I'm a bull in a china shop at times. I am hoping I can buy one at Napa??? Please tell me it's not a junkyard only part? :( I WILL be careful with the C101!

 

I have not looked for the IAT yet, will do tomorrow. I will try to post some pics in a few minutes. Thanks for your help cruiser54, I really appreciate it.

[marie]

That's the sending unit I bought and the plug I took out of the head.

That's the location of the plug I took out

OMG, have you ever seen C101 that bad? T-Rex is in there somewhere, I just know it. And yeah, the other side looks just as bad. I left this pic big so you could really see the gunk!

[Jeep Driver]

The sender should be 1/8" NPT.........if you got an earlier sender it maybe metric........just a guess as to why it won't fit.

 

NAPA sells the vacuum harness and I don't know if the map tube is included however you can make your own.

[cruiser54]

Good job Marie.

The sender shroud thread right in there. They're all standard thread. They go in at a slight angle so be aware of that.

 

C101 is in need of cleaning for sure. They all are at least once in their lifetime!

 

I've tried to find a part number for the TB to MAP hose but haven't had any luck. Just using rubber line isn't recommended either. Tha line needs to run in a downhill fashion from MAP to TB with no low spots. A decent parts store should have the plastic tubing. You can remove the rubber ends off yours and re-use them on the new tubing with just a small dab of adhesive to hold them on. The tubing can be bent using a hair drier.

 

IAT is directly behind the throttle body and has 2 wires to it. Remove it and spray off it's tip with throttle body cleaner. They get gunked up and send faulty signals to the eCU. Got your meter yet?

[Jeep Driver]

[marie]

Most girls dream of a nice little house with a white picket fence. I dream about having a three car garage with a lift, a pit and the walls lined with every tool box and tool imaginable, and a pneumatic tool system taboot. ahhhhhhh, I would feel like a Queen in a castle!

 

I'll see what I can get from Napa on my way home from work. I'm not sure about that sending unit, it seems to be too big in diameter to fit in the whole. It's like the unthreaded part will go in as deep as the thread in the head then it feels like it bottoms out. I will see what I can do to wiggle it around/angle it.

 

I will report this afternoon. Thanks again guys, I really appreciate the help.

[marie]

This evenings report:

 

I wound up working until 4 so I didn't get as much done as I wanted to, i.e. it's not running yet! But I did make good progress. Located the IAT (see pic). Now that I have located it, what do I do to check it?

The IAT is the nut with the white in the center and two wires, right?

 

I believe I found the hole that the CTS is supposed to go in. It too, like the sending unit hole, has a plug that is painted over and need an allen key to unscrew.

the allen key whole you see in the picture on the right, directly behind the motor mount is in a similar place as the diagram. On my engine block there is another sensosr closer to the firewall that has wire connected to it and I was told that that was a knock sensor. Is that correct? My so called knock sensor is about in the place the diagram shows the block drain plug. But, the diagram is for a 90, so it might not be right for my 88.

This is what I believe to be the connector that should be connected to the CTS. It doesn't look like it's been connected for years. As a matter of fact I remember taking something out of my old blcok from that spot that was broken. That must have been my old CTS! BTW, I checked with Napa and the engine I bought was an 88 and not a later 4.0. I was happy to hear that.

 

I also have the C101 mostly cleaned, nasty gunk for sure! I am cleaning the back of the unit a little too, being very careful not to damge the wires.

[mountainman]

I forget to check this for a few days and come to see all this. :eek:

 

Marie.. you ROCK! this is awesome to see you working through it yourself. I'm sure youll get it now, its just a matter of time before its all dialed and working properly.

The CC is great, everyone is so helpful. :yes:

[cruiser54]

Good progress. The one photo is of the IAT. Unplug it, unscrew it and clean off the tip of it with throttle body cleaner. You'll understand when you see it. A little dab of Permatex #2 smeared on the threads before you put it back in.

 

That connector in the one photo looks to be for the knock sensor and actually has part of a busted knock sensor still attached. It originally attached to a threaded hole in the block just above the oil pan. It is not critical to engine operation at this point.

 

The CTS should be threaded into one of those 2 coolant passage holes like in the diagram you posted. Generally, the most forward one.

 

The harness for the O2 sensor, CTS, and knock sensor runs down by the front of the intake manifold BTW.

[marie]

So there are two holes in the driver's side of the block. You saw the one first one in my last post. Here is a pic of the one closer to the firewall which has something installed in it already. Could this be the CTS and it's in the wrong hole? I am aslo posting a picture of the only wiring harness in that area and one of them is connected to what ever is in the second hole.

This is the hole that is closer to the firewall, is that the CTS?

This is the wiring. The top wire goes up somewhere into the upper part of the enginge (sorry I should have traced it). The middle wire goes to what is in the pic above. The lower one goes to what you told me looks like a broken knock sensor. So, please tell me which is which? And BTW, the broken knock sensor wire will not reach to the first plugged hole from the previous post.

 

So may wires, senders and sensors....so little time.....sigh I have to go to job #3 today but i will be back by 1:30-ish. Thanks for the help :)

[Jeep Driver]

That's not an '88 block as NAPA told you.

 

See first pic above.

[cruiser54]

They put the CTS in the rearmost hole. That other harness (three wires) goes to the oxygen sensor in the exhaust manifold.

 

The knock sensor threaded in JUST above the oil pan into the block. Not into any passages or anything. It's just there to "hear" engine pinging.

 

PM me your email address and I'll send you a real good Renix manual with diagrams, descriptions, and diagnostics.

[marie]

@Jeep Driver: How can you tell it's not an 88? I don't doubt you, I just want to learn how to tell the differences.

 

@Cruiser54: So, is the CTS in the wrong hole? I am assuming because it's in fluid, it doesn't need cleaning. I found the O2 sensor too, does it need cleaning?

 

Here's my nice clean C101, the other side is just as clean. Compare it to the gunked one on page two of this post, very time consuming but worth it. I took the covers off too and cleaned the other side and cleared the holes that go all the way through. It should last another 25yrs. Hopefully I'll still be running too!!

 

Here's the IAT. It was pretty black and gunked, but I did clean it. Do you think I need a new one?

 

I am letting everything dry out tonight. Hopefully I will remember how to put it all back together tomorrow...... :eek:

[cruiser54]

Your IAT looks just fine. You could always test it using the manual I sent you if you wanna.

 

CTS can be in either hole.

 

Near the CTS is a 10 digit part number on the block. Get that and I can tell you the year for sure.

[Jeep Driver]

The Chrysler mark near the CTS is like a billboard.....lol

 

 

AMC in 88.

 

 

I have owned a 89 that had a mix of AMC and Chrysler parts. IIRC Chrysler bought out in 89..........90 and up is all Chrysler.

[cruiser54]

They bought them in 1987 and began phasing the two together after that. AMC had contracts with parts suppliers that they were obligated to fulfill.

[marie]

When I put the clean C101 back together should I put some of that electrical connector grease on the prongs? Would that help retard the black gunk from reappearing? What is that gunk anyway, some kind of by product on the plastic casing? I have never seen an electrical part do that before.

 

By the way, I got the the temp sender installed In that hole. It took a little fenageling but you were right, slight angle. I was able to hand turn it a few times so hopefully I didn't cross thread it. What is the name of the skinny tube that goes into the top of the valve cover right next to that? I broke it while putting the sender it :(. Bull in a china shop as I have said before lol!!