Hello all, I need some more help. I've been struggling with some popping exhaust and trouble codes on my '87 Ranger with the 2.3, 5-speed.

I had an old thread about the problem, have done some repairs and changed things a little. The old thread is https://www.ford-trucks.com/forums/s...d.php?t=415756 if anyone is interested in looking at it.

Basically the problem started several months ago with a bad ignition control module. I fixed that and my truck ran fine for a while, then started exhibiting problems again. First it started choking up at high speeds, probably when it entered closed loop. Then it started running poorly, like on two or three cylinders all the time. This was first accompanied by some occasional black exhaust, which has since changed to popping exhaust. I found several bad components, including the EGR valve which was stuck partially open.

I finally got the valve replaced and started the truck up. It died a few times at first, then popped a bit and died. After a few tries my truck actually idled perfectly for about 20 minutes. After I cut it off and restarted it the popping has come back intermittently. I also have the following trouble codes during the KOER test: 32, 13, 73 and 25. I ran the test twice and received the same results with the exception of a code 72 that appeared in the first test but not in the second one.

The code 32 seems to indicate EGR solenoid problems, as the valve and its position sensor are new and functional. The 13 indicates trouble lowering rpm at idle I think. The 73 indicates insufficient throttle position change during goose test. This seems to mean that I messed up the test, but I opened the throttle up when I was supposed to and the engine responded. The TPS is new and works fine when tested. The 25 is confusing, my book says it indicates that 'knock' was not sensed during the goose test. Anyone know what this means?

Sorry for the long-winded post, just looking for some help and insights.

 

I know you have been fighting this for a while but I don't recall if you have run the pinpoint tests for all of these codes?

The 25 is a knock sensor code, the KS listen for spark knock (ping).

 

The knock thing confuses me because as far as I know this truck doesn't have a knock sensor? Am I incorrect? I have tried to test for the 13 and 73 and haven't found any problems. The 25 and 32 are new since the EGR repair. The old 41 and 34 codes I was having before the EGR replacement are now gone.

Another thing that is strange is while the KEOR test is being performed there are changes in engine performance, revs up, down and such. It got real low at one point, which I thought was the EGR portion of the self-test. But I still get RPM and EGR related codes. And the occasional rough idle and popping sounds.

 

Since the repairs, have you pulled the battery cables to reset the computer to get rid of the old learned logic, that was gathered with the faulty components????

Then do a relearn cycle, from a cold start, to full warm up, so the computer can relearn & readjust to the new items in your repairs????

 

Yes I left the battery disconnected for a good while after the last round of repairs. I let the truck warm up for a good while, over half an hour. What was nice was that it actually idled and revved really nice during that half hour warm up period. But then it started again with the intermittant popping and bogging.

I notice that some of the codes changed since the replacement of the stuck EGR valve. Could any of these codes cause these kind of symptoms? With what the truck is doing I'm thinking it's gotta be either an ignition problem or a valve problem. Would that be a correct assumption? The only two ignition parts that are still original are the distributor and the computer. The head is only about five years old with 32k miles on it, but a problem could still be there. Would a messed up valve show up as an intermittant problem or would it just be constant?

 

Ok good feedback on resetting the computer.

Well if you had something like a burned valve, you'd likely have a constant miss/spit from the exhaust pipe.

Howsomever, if you had a intermittent sticking valve, the problem could come & go!!!!

If you've had the valve cover off & found some pretty heavy deposits in there, say especially varnish deposits, they can collect on the valve stem & cause it to hang in the guide & be slow to open or close, or if really bad to stick open.

If you think this might be so, you could try a cleaner like "Seafoam Engine Tune".

Say, some in the oil & gas, as the directions call out, run it some, not too hard, & see if you notice any difference in the intermittent exhaust popping.

If you notice improvement, suspect valve stem deposits & run the tank of SeaFoam out, then change the oil & filter.

It seems the computer still isn't happy with the feedback it's getting from the throttle, as several of these codes have to do with sensing what the throttle is, or has been doing, or not being able to control engine idle speed.

So I'd look to that area yet again, for a bad electrical connection or faulty sensor or maybe a damaged electrical connector, pin, socket, or wire, & do the pinpoint tests Ken suggested.

If reference voltages aren't present, or the wrong value, or aren't making it back to the computer consistantly, the computer can get confused with whats going on.

Make sure the feedback port inside the manafold & below where the EGR bolts on, is decarboned well. If it's plugged up, the new dpfe won't control the new EGR valve properly.

 

My 1988 Ford manual indicates a 25 is a valid code for a 2.3. Are you sure a wire didn't get pulled/damaged when you were doing other repairs.

The 13 sounds like a damaged IAC or a vacuum leak, it indicates high RPMs that it can't control. What happens if you pull the electical connector off the IAC, the RPMs should drop, if they don't someone messed with the stop screw.

Sounds like you have the 32 under control.

For the 73 you really have to floor it and hold it for a second, I know it's had to do this.

By the way it's normal for the engine speed to change in the KOER tests.

 

As far as a knock sensor goes, I can't find a reference to it anywhere in my repair manuals. Could anyone (Ken maybe) give me an idea where it would be if one is on my engine? And what does 'knock not detected' mean exactly anyhow as related to the 25 service code?

As far as the IAC goes it is pretty new and engine idle does decrease when I pull the connector from it. I haven't found any wiring problems but it couldn't hurt to look again. I know from watching the engine run that the system has some control over idle, it's always had a bit of a habit of the RPMs dropping at idle followed by a ramp up that makes it idle real smooth. Unfortunately I don't have an RPM gauge so I don't know the exact numbers it operates at.

I had the valve cover off a couple years ago and things looked pretty pristine in there, but with only about 25k on the engine at the time I would expect that. Could a valve have been damaged by the ignition control module going out? The thing that bugs me about that possibility is that the truck ran fine for a good bit and then slowly started going downhill.

 

I found something about a knock sensors location on the Autozone website. It says:

UNDER HOOD, DRIVER SIDE, LOWER ENGINE AREA, MOUNTED ON SIDE OF INTAKE MANIFOLD ASSEMBLY

Do they mean the lower intake? Surely this isn't referring to the IAT sensor mounted into the upper intake? Also, could someone tell me what exactly this sensor does? A picture of it's location, or at least a slightly better description would also be very helpful. Thanks to everyone so far for helping me out, I really appreciate it.









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The knock sensor detects if your engine is knocking basically, and informs the computer so it can attempt to correct the situation.

Your intake manifold should be on the top of the engine, since you have the I-4 it may be on the driver's side as Autozone said, my V-6 has it on top, it should run from the intake to all the cylinders basically, hard to explain sorry. It is probably a bright aluminum colour if that helps any. Look for the part that connects intake to engine. The sensor should be sticking out of it somewhere.

 

I would guess that the ECU advances the timing during the KOER test to the point the engine pings and it's not seeing the ping. I can't help with the location, I'm not familar with the 2.3.

Have you run the pinpont tests for the IAC?

A burned valve would show up in a compression test, have you checked the compression?

Sorry if you answered these questions in another thread.

 

I finally was able to get another compression test done and I think I know my problem know. The readings were: 100(1), 150(2), 130(3), 150(4). Putting a little oil in the first cylinder hole didn't change the reading. So I'm thinking that I have a problem with the exhaust valve in the first cylinder. Would that be a safe assumption based on the evidence?

Since it's looking like I'm gonna have to tear off the head I'm looking for some advice on gaskets and perhaps on a good place to purchase a rebuilt head. I'm seeing good prices on Corteco brand gaskets, the head gasket is half of Fel-Pro's price. I've always used Fel-Pro in the past, but thought I'd seek some opinions/advice here.

Also, is it necessary to drain the coolant from the radiator, or can I just drain the block? Does anyone know where exactly the block drain is located on my 2.3?

 

If you are going to tear into that engine, and it hasn't been rebuilt, it might be time if you have the money for it to just rebuild the whole thing. Just a suggestion...

 

That's the part of this that really irritates me, this is a rebuilt engine with about 30k on it. So the block should still be pretty fresh.

 

Any kind of warranty on the rebuild? Or did you do it? The block shouldn't have any problems to speak with at that age.