Forrun4fun

Hi guys,

I have spent the last week searching these forums and reading dozens of threads in an attempt to diagnose my problem here, so let me say before I am flamed, I have done the research and cannot locate an exact scenario of a problem just like mine. That's why I am posting a new thread.

First of all, this problem developed suddenly, one day while driving down the interstate. My 1989 pickup (22RE, no A/C installed) went from running fine to a major power loss and massive pinging. Cruising along at 2900-3100 RPM up a mild grade, and then BAM, there is the problem, without ever having shown any symptoms prior.

At the time the problem appeared, there was no CEL - only the power loss and ping. My general knowledge tells me that pinging is a result of a lean mixture or high combustion temps. My research on this forum was pointing to an EGR problem. I did not have time to address is immediately, so I just backed off the throttle every time I heard the ping (which is so loud it cannot be missed, sounds like someone shaking a can of spray paint in your ear). This gave me some time to pinpoint the exact conditions under which the problem occurs. It has gotten progressively worse as the days go by without repair. At first it was only in 5th gear going uphill. Then it started appearing in 4th gear, and now I can produce the problem in 3rd gear with heavy throttle.

Only once did it stumble enough to produce a CEL, but it immediately recovered and the light disappeared after only a second or two (I do not have the equipment to pull any code, if there even is one).

As mentioned above, I suspected an EGR problem. Yesterday afforded me some time to investigate, so i dove into the EGR system. The first thing I did was pull the vac line from the top of the EGR valve and attach a length of hose to it. With the engine idling I can apply vacuum directly to the EGR and the engine will stumble and die, which indicates that the valve is not stuck and opens freely when vacuum is applied. This frustrated me as I was sure this was the problem. For my own peace of mind, I pulled the EGR valve anyway. I was surprised at how open the tubing was - only a thin powder of carbon on the tubing walls. The only blockage I noted was in the small stainless steel tube that exits the EGR valve about half way up the neck and attaches to the bottom of the vacuum modulator. This was completely plugged, as was the rubber tube that goes to the modulator. I was able to clear the hose, but the tube proved too difficult. I sprayed tons of carb cleaner and routed it out with a small piece of wire as best I could, but could never get the wire in deep enough to satisfy me that the passage was completely clear into the main tube.

This is where your help will be appreciated. Not having a master of understanding of exactly how the EGR system works (other than the theory of why its there and what it does), I have no idea if a blockage of this particular passage would produce a problem of my severity. I know I could just replace the EGR valve with a new one, but that is $100 I'd rather keep, especially if a blockage in that passage would not lead to my particular problem.

I know that vacuum applied to the top of the EGR successfully opens the valve, but I have no idea how to determine if the appropriate vacuum is being applied under the right conditions. According to the FSM, the system uses a huge amount of self-feedback from multiple components to regulate the opening of the valve and amount of exhaust gas.

I could just replace all the components in the system (EGR, modulator, VSV, BVSV) but for some reason, these parts are still hundreds of dollars for a 24 year old engine - go figure. Plus, without a definitive diagnosis, that could be money spent in vain.

To help with any diagnosis, I can provide the following facts :

The truck idles fine - no misses or stumbling
The plugs, wires, cap, and rotor are all new (less than a month old)
The injectors were just cleaned at the dealership using their $75 procedure
The timing chain was done about 50K miles ago at the dealer and the timing has not been touched since (distributor is tight)
Truck has 229K miles
Fuel filer is new
I can find no other symptoms of vacuum leaks (like poor idle, etc)

Problems like this are not easily addressed at the dealer (as they will start replacing components at their leisure, at retail prices, and $85/hr labor). This seems like something I should be able to rectify - if I can just find it.

I am nagged by my inability to clear that last passage on the EGR valve, but again, without knowing what it does exactly, I cannot be confident that its the problem, especially when the rest of the unit's operation seems fine.

I will mention as a side note that the engine does not have the factory camshaft. Several years ago, I replaced it with a Northwest Off-Road cam that was of their mildest variety, and the truck has run flawlessly since (and the chain was done after that so the timing was verified by the dealer).

As always, any/all input is greatly appreciated.

Fordless

I would pull the valve cover and shine a flashlight down on the drivers side to see if your guide on that side came apart. My truck was doing the same thing...It would rattle at a certain rpm in every gear. Most of my drivers side guide was in the oil pan. If you had the chain done at the dealer I assume they used the factory timing kit and it would've come with plastic guides and 50K is enough that it's worth checking.

BamaYota1

You only need a paper clip to check codes.

Forrun4fun

Thanks for the replies. I am relatively positive that the timing chain is not to blame. I have done the chain twice on this engine, and the last time (although the work was done at the dealer) I used an after market kit with heavier guides. I have had two of these engines in the past and am very familiar with the timing chain noise that results from a broken guide and/or worn tensioner, but this is most definitely detonation/ping.

I would enjoy finding out if there are any stored codes, and I have seen the process of reading them explained here, but I can't seem to recall it. I'm sure I can find it - unless you'd care to lay it out for me...LOL.

Out of curiosity, what code(s) would indicate that I am on the right track by suspecting the EGR system?

Forrun4fun

Ok, I found the article on code reading and followed the instructions.

The flashes are as follows :

3
short pause
1
long pause
4
short pause
2
long pause
5
short pause
1

Then the same process repeats.

Can anyone translate these into actual codes for me?

smithyboy69

Im pretty sure thats 3 codes, code 31, 42 and 51 which i believe relate to your TPS

4runrjunkie

you may have already figured this part out ... but it means you have codes 31, 42, and 51 stored. A simple search online should help you out in figuring out what these codes represent.

derockus

iTrader: (1)

31 - MANIFOLD AND/OR AIRFLOW METER SENSOR SIGNAL CIRCUIT

--AIRFLOW METER/CIRCUIT

--MANIFOLD PRESSURE SENSOR/CIRCUIT

--ECU

42 - VEHICLE SPEED SENSOR SIGNAL CIRCUIT--NO SPD. SIGNAL FOR SEVERAL SECONDS

WHILE VEHICLE IS OPERATED UNDER HEAVY LOAD (TPS/MAP/AIR FLOW INPUTS)

--SPEED SENSOR/CIRCUIT

--ECU

51 - SWITCH SIGNALS

IDL (tps) CONTACTS OFF, NEUTRAL START SWITCH OFF, A/C SWITCH "ON" SIGNAL TO ECU

WITH DIAGNOSTIC CHECK CONNECTOR SHORTED

--A/C SWITCH/CIRCUIT

--A/C AMPLIFIER

--TPS/CIRCUIT

--NEUTRAL START SWITCH/CIRCUIT

--ECU

From: http://www.4crawler.com/4x4/CheapTri...l#TroubleCodes

Co_94_PU

iTrader: (-1)

http://personal.utulsa.edu/~nathan-b...26diagnosi.pdf

It should be apparent but incase it's not, codes are 31 42 and 51. That is a lot to go wrong all at once I'd suspect grounding issues. Check the ground straps in the drivers kickpanel.

You need to check timing when you change ignition components.

Vacuum line is cheap and available by the foot at the local parts store. Also you tend to need something a little stronger than carb cleaner to break up baked on carbon. You know it's clean when you apply vacuum to the EGR and the engine idle drops, and all the lines are free of obstructions.

Pretty sure there is a chart that explains this.
http://personal.utulsa.edu/~nathan-b...18egrsyste.pdf

Forrun4fun

I have never pulled the codes from this engine in its wonderful 24 year life, so they may not all have gone wrong at once....lol.

I can recheck the timing, but again, the distributor has not been moved. Additionally, the only reason I changed the ignition components was in an attempt to rectify this problem.

The idle does drop when i apply vacuum manually, so I know the diaphram/plunger are working properly. My concern is whether the system is applying the necessary vacuum to the valve when conditions dictate it should have it. For example - if this passage I cannot clear is obstructing some sort of feedback loop to the modulator, then the EGR might work right, its just not getting the vacuum signal to open.
Thanks,


Ryan

BamaYota1

Write the codes down, and pull the efi fuse for a few minutes to let the ecu reset. Then run it for a while and reset.

Forrun4fun

Before I reset the ECU by pulling the fuse, allow me to ask this. Are the codes that I currently have (31,42,51) stored in order of malfunction? By that I mean, does the ECU flash them in order that they were recorded, or does it flash them simply in numerical order from lowest to highest?

This may help me determine which one is the most recent and thereby zero in on the most likely solution.

Co_94_PU

iTrader: (-1)

Stored maybe(not that you can read them directly, generaly speaking), but not retrieved.

They always come out from low to high #

BamaYota1

Nope, purely lowest to highest.

Forrun4fun

This is odd, I pulled the EFI fuse from the block and left it out for an hour while I did other things. I replaced the fuse and the codes are still there. How is this possible?

BamaYota1

That is odd. Try taking negative off battery.

j2the-e

Egr has nothing to do with your problem. Move on to something else. Like diagnosing the codes you have. I'd start with the code 31. You may have a bad air flow meter or broken wire in the vs or vc circuits. Can definitely cause your symptoms. Check with an ohmmeter from the air flow meter to to the ecu.
The 42 is possibly a bad speedo or speedo circuit. The speedo cable operates the speedo. The speedo then sends a signal to the ecu. So even if the speedo shows the correct speed, it could be failing. Shoudn't cause your symptoms though. It may affect cruise control operation though.
And the 51 could be a faulty or mis-adjusted tps. The tps has a circuit that tells the ecu that you are at idle. It's a common failure. Again, shouldn't cause your symptoms. Mainly controls idle quality I think.

j2the-e

An easy way to check the tps idl circuit is with your jumper and a timing light. If its working properly, the timing will change when you install the jumper at te1 and e1, same wires you jump to check codes. If its not working, timing will not change with the jumper wire installed

Co_94_PU

iTrader: (-1)

Please don't tell people not to fix things they know aren't working correctly

EGR sub system
The vacuum modulator is an important part of the EGR sub system.

You didn't mention what model year you have?

Only the last one of these will cause predetonation and result in knocking, code 51. But that would require the Test mode to be active and You would notice if the malfunction light was flashing at you I'm pretty sure. And actually I doubt even that would happen then, the computer is smart enough to know that someone has moved the accelerator it leaves the fixed timing mode if IDL isn't connected to ground.

Once you have the modulator working and the codes cleared take it for a test drive, and follow the directions on EG1-120 for code 71 (FSM Link), and promptly check the codes again to make sure none of them have reappeared.

If none of them come back you should be all set, if they do then you can diagnose which ever ones do. No sense wasting time trouble shooting things that aren't broke, since you don't know how long those have been there.

j2the-e

I didn't say that.
He said its an 89 22re truck
Wrong
He already said the codes will not clear.