Bad computer????

[Fanucman]

My 98, with 2.5L SOHC, has been having power problems for quite some time now. After a compression test and finding very low readings I pulled the engine for rebuild. Found the reason for low readings to be broken comp rings on 2 cylinders. Bored block .030, had crank turned, head shaved, and had valve job done. Put it all back together with new injectors, TPS, IAC motor, crank position sensor and Mass Air Sensor. It runs far better than before. the problem is that it shill has no top end power. Hooked it up to scan tool and at idle it shows the ign timing to be at -3 deg even though a timing light shows +8 - 10 deg at balancer. Checked another 2.5L Ranger with same scan tool and it showed +12 deg ign timing while at idle (did not check this one with timing light). I am old school (don't know much about computer controled engines) but I know that if timing is retarded you get loss of power due to it. I think this is the problem I am having here but don't know how to change the ign timing or why scan tool and timing light would show different values. I am really stuck and need some help please. Is there a way to test the computer itself to see if it is bad? What should I do next?

 

[tbirdsps]

I doubt the computer is bad. Don't forget that the engines without distributors have a crankshaft position sensor so that the computer knows where everything is for timing.

If I were you I'd find out how to adjust the timing on that. My 92 2.3 is essentially the same. No distributor. I'll bet it's a simple correction. Since the engine was overhauled certainly there's an adjustment that can be made very simply.

 

[Fanucman]

I changed the crank position sensor in the rebuild. It mounts in a hole for location with one bolt through an ear on its side to hold it in place so it can't move. It works like a prox switch and picks up on a sprocket behind the balancer. The sprocket is keyed to the crankshaft and thus it can't move either. If there is no movenemt to these two parts I figured the ignition timing has to be controled by the computer as triggered by crank position sensor. Is there a way to adjust the timing manualy? I've always been told that it can't be done.

 

[tbirdsps]

I've never had a problem with timing nor do I know how it's done...sorry.

What I do know is with the DIS system there is no ignition or idle adjustment. So, something is amiss with yours. On my 92 the VECI label instructs to remove the spout then check the base timing that is supposed to be 10* BTDC. Total timing at 3,500 rpm is supposed to be 33-35*.

The only thing is to make sure you have the spout disconnected, which I assume you did, in order to check the base timing at idle with a warm engine. I would assume yours too has a spout. The actual valve timing with the belt would not affect ignition timing at all so the timing belt wouldn't throw off the numbers but if the belt was slightly off wouldn't the crank pulley be off from 0* at TDC which would be the valve timing setting with the belt?

Assuming that everything is correct you should be seeing about what you saw on the known good truck. -3* BTDC would definately affect power, fuel milage and temperature. You are still off on ignition timing if the marks on the balancer is showing +8 - +10 degrees and the scan tool is showing something else. Am I being confused by your information? I'm not used to the + and - information. I usually see terms of BTDC and AFTD. To me a + means BTDC and a - means AFTD which is very retarded for ignition timing.

I would recheck the belt alignment at #1 at TDC and the pully mark at zero degrees. Then remove the spout and recheck to begin with before I'd change a computer.

 

[Fanucman]

Good information. Couple of questions. First, what is the VECI label and where do I find it? There are a couple of labels under the hood about belt routing, spark plug gap and so on but no information like you mentioned. I have a Haynes manual for the specs on it but it only says that there is no adjustment for ignition timing.

Second, what is the spout you mentioned? I may have one but not be calling it by the same name.

Sorry for the confusion on terms. I have never seen ign timing numbers in (-) terms either. I assumed that with the scan tools and computers that (+) & (-) was the new way to describe ign timing. I am assuming the scan tool showing a negative number means ATDC which I would think to be way off.

The balancer is keyed to the crank so I don't believe that the crank pully can be off. I have rechecked the timing marks several times and all 3 (crank, oil pump, and cam) are lined up. BTW - oil pump is where cam position sensor is located (go figure that one out). I have not changed cam position sensor which is what fires the injectors as I understand it. The only other thing I know to do is check #1 piston travel to verify that TDC mark on pully is the very top of the stroke. Once I understand what the spout is I will reverify the base timing and the advance if I can figure out what total is supposed to be.

The scan tool saying one thing and balancer mark something else is what made me wonder if the ECM is bad. A distributor and carburetor would be great right about now!!!

 

[tbirdsps]

Good information. Couple of questions. First, what is the VECI label and where do I find it? There are a couple of labels under the hood about belt routing, spark plug gap and so on but no information like you mentioned. I have a Haynes manual for the specs on it but it only says that there is no adjustment for ignition timing.

VECI is the label where you see the spark plug gap, idle speed and vacuum line routing. Sorry I thought you may have known that. You should see a symbol that kinda looks like a small square with two legs on it. On the label it has instructions as to how to check ignition timing. Step 2 is to remove the spout. On my 2.3 liter 92 it's just forward of the intake manifold on the drivers side. It's gray and is plugged in to a black connector. Two pink wires lead to it. That must be removed to check the timing. I can only guess that the 2.5 liter is similar in layout. It's just a plastic plug that basically turns on the advance. When you remove it it's the same as disconnecting a vacuum hose from the vacuum advance on a older one with a distributor.

Hope this helps.

VECI stands for Vehicle Emissions Compliance Information....I think.

 

[Fanucman]

Thanks for the info. My VECI label is the one that says idle speed and ignition timing are not adjustable. Mine does not have the spout, only a MAF and IAT sensor in the intake pipe. I have a friend who works at a salvage yard and he hooked me up with a new ECM to try. I had high hopes but no luck, it still had the same problem even with the new ECM. I discovered today that it is not only a power problem, it will not rev to full throttle even under no load. I have no clue as to what is causing this.

 

[tbirdsps]

Thanks for the info. My VECI label is the one that says idle speed and ignition timing are not adjustable. Mine does not have the spout, only a MAF and IAT sensor in the intake pipe. I have a friend who works at a salvage yard and he hooked me up with a new ECM to try. I had high hopes but no luck, it still had the same problem even with the new ECM. I discovered today that it is not only a power problem, it will not rev to full throttle even under no load. I have no clue as to what is causing this.

The only thing I can add is good luck. I too have little experience with the computer controlled everything. I'm sure it's simple and you'll stumble on to the fix. Please let us all know the solution.

Steve

 

[modelageek]

Have you changed the fuel filter and check the fuel pressure?

 

[tbirdsps]

Fanucman,

Trust me you do have a SPOUT.

The SPOUT (spark out) signal back from the PCM. The SPOUT signal contains optimal spark timing and dwell time data.

If the SPOUT is non-functional i.e. missing or disconnected the PCM/ECM whatever you wish to call the computer will fire the spark plugs using the PIP signal only. This is a limp mode where the truck runs but will be running poorly. From what I can find the 1998 DIS system is essentially the same as that on the 2.3 liter version.

I'm not saying the SPOUT is bad or missing. I'm saying it's a possibility. The SPOUT is located very near the TFI ignition module. It's gray in color and is a plug in the end of the SPOUT wiring harness. It's about the size of the end of an index finger. In order to check the base timing it must be removed.

Certainly there are other things that could be wrong and one person mentioned fuel filter etc. It is also esential that the fuel pressure be correct and the fuel filter could cause the fuel pressure to be low which will inhibit power as well.

 

[modelageek]

I could not locate my spout connector either. The 2.5 does not have and ICM. I thought we had a EDIS I will have to go to the tech lib and refreash my memory

 

[Fanucman]

modelageek, fuel pump and filter are new. Fuel pressure was about 64 psi after new pump and filter were installed.

tbirdsps, please help me understand where the SPOUT is. I was under the impression from your first description of where it is located that it was in the intake hose between the air filter and throttle body. The only sensors located there are the mass air flow and air charge sensors. The air charge sensor has 2 wires and is inserted in the intake hose, its about the size you described. As I understand it, this sensor communicates the intake air temp to the computer. You said "It's gray in color and is a plug in the end of the SPOUT wiring harness." Does that mean the wiring harness that has the ignition coil plugs? What does it plug into? I did a search on AutoZone.com for it and no results were returned. Not trying to be stupid, just don't know where to find it.

 

[Fanucman]

Ok, been doing some research and I think I may have found some useful information.

tbirdsps, my 98 doesn't have a SPOUT. The SPOUT connects the DIS module to the ICM and mine does not have either of these. However, you are right in saying the the 92 and 98 ignition systems are pretty much the same.

modelageek, our 2.5's are somewhat of a hybrid EDIS since they do not have EDIS modules. I am addiing a link that has some great information on how both the DIS and EDIS work.

http://rockledge.home.comcast.net/~rockledge/RangerPictureGallery/DIS_EDIS.htm

In searching for the SPOUT I did make another discovery. There is single wire terminal by the coil packs not plugged into anything. Based on the information I can find on the internet, a capacitor is supposed to be plugged in to it. Even the Haynes manual does not mention it, although it shows pics of it. This truck was bought for my son and he drove it until a few months ago. He had complained that the truck had lost power but I assumed that he just wanted to put one of my street rod V8's in it. I know that when we bought it that it had much more power than when he got done with it. I now think that at some point he or one of his friends removed it. I am now wondering if the capacitor is what provides the voltage kickback spike when the coil fires. If so, and there is no kickback spike (like what SPOUT does on 92 model tbirdsps) then the computer may not advance the timing correctly. I am going to try to find one and install it tomorrow, but AutoZpne.com doesn't seem to know it even exists. Does this path seem logical to anyone?

 

[red85]

How much did you have the head shaved? When you do this you end up retarding the timing due to the fact that you moved the cam gear closer to the crank. You can get adjustable cam gears for a 2.3/2.5 easily. You can also move the crank sensor to get it to the same position as it was before you had it planed. The cam gear is your best bet to get it right again.

Phil

 

[Fanucman]

Phil, good call on the cam gear closer to the crank statement. I only had it dusted enough to clean up, about .005" to .010" and that shouldn't make enough difference to matter.

I feel so stupid I can't even describe it! I rechecked the fuel pressure as modelageek's suggestion. Got 65 psi with engine not running and 61 with the engine at idle. This time I didn't stop here, I went to WOT and the engine fell on it's face just as the fuel pressure dropped to 25 psi. I hooked up a tach and repeated the test watching the pressure and RPM. I slowly raised the RPM and the pressure started to fall. By the time I was at 3800 the pressure had dropped to about 40 and that's when the engine took a dive. The more I opened the throttle the lower the pressure until it bottomed out at about 25 psi. The pump and filter are only a few weeks old so I suspect there to be a fuel line restriction somewhere. I can't beleive I have not thought to check fuel pressure at anything above idle. Not sure what the deal is with the timing is but I think the fuel pressure is the root of this problem. I believe that the first step is to get enough fuel to the cylinders for the timing to have a chance at it.