ECU question

[SFCRangerDoc]

Ok so you all may remember me as the guy with the Explorer starting issues here:
http://www.explorerforum.com/forums/showthread.php?t=432962

I ordered a replacement ECU off ebay and matched the part numbers exactly...

EAR and F37F-12A650-SA

The new computer allows the truck to start on the first crank which is good...however the thing now runs like ****. It barely stays alive and idles around 500 or less when in D at a light and maybe a smidge higher in park. Shift points are terrible too. It seems to run alright if you keep the RPMS up but as soon as you come to a stop it just acts like its dying again.


Is there a way to re-program these old ECUs? Or should I attempt a return from the seller (30 day policy minus shipping) and try another ECU? Am i missing something when comparing part numbers? From what I understand the info i listed above is the important part.

Or do i suck it up and get a remanufacture to the tune of nearly 200 bucks.

 

[Explorin'VA]

Mine acted the same way for a while. Figured it was an Ecu issue but after trying a few different ones it turned out to be a short in the spout system. I removed the spout connector which made the stalling go away. Now it just idles high and it accelerates slower than before, so it still needs to be fixed but at least it's not stalling out. What do your trouble codes say?

 

[SFCRangerDoc]

Mine acted the same way for a while. Figured it was an Ecu issue but after trying a few different ones it turned out to be a short in the spout system. I removed the spout connector which made the stalling go away. Now it just idles high and it accelerates slower than before, so it still needs to be fixed but at least it's not stalling out. What do your trouble codes say?

Spout system? Forgive me but that's not a term I have heard before.

As for the codes, im not getting a CEL and honestly I haven't done the wire short out to get the flash codes yet. I'll do that today and post it up. The seller on ebay has agreed to a full refund of the ECU minus shipping so at least im not out 80something bucks.

 

[SFCRangerDoc]

I did the jumper KOEO test and got 111's across the board. Nothing stored in memory either. Just I think I may have gotten a bad ecu. :/ Note that once I swap the factory ECU in the hard starting problems return but once I am actually able to get the car started it runs beautifully. I know its a computer problem I just don't know if its worth trying to get a reman or keep trying used pulls.

 

[Rhett]

I'd give that new ECU some time to relearn. At least 60 miles of driving.

If it's still not behaving after that, I'd verify that the throttle plate was in the proper position at zero, partial, and wide open throttle. Maybe you did that already in the other thread. I can't remember.

 

[malohnes]

Spout system? Forgive me but that's not a term I have heard before.

As for the codes, im not getting a CEL and honestly I haven't done the wire short out to get the flash codes yet. I'll do that today and post it up. The seller on ebay has agreed to a full refund of the ECU minus shipping so at least im not out 80something bucks.

Spout connector = its the shorting block that thats near the blower motor that changes the timing by 10 degrees I think for bad gas or whatever.

I'd pull the ECU out and pop the cover and look for any leaking caps, corrosion or other obvious signs of trace lifting. Mine had corrosion on the traces where the main harness attaches. It cleaned up easily with and pencil eraser and emery cloth.

 

[SFCRangerDoc]

I'd give that new ECU some time to relearn. At least 60 miles of driving.

If it's still not behaving after that, I'd verify that the throttle plate was in the proper position at zero, partial, and wide open throttle. Maybe you did that already in the other thread. I can't remember.

The ECU had been driven for a solid week of surface street and highway driving and is still acting like it. Easily 100miles or more. With the OLD ecu it wont start properly but will run beautifully when it does get started. The new ECU just idles so low the car barely keeps running. I may just return it and try another one. I can't open this one up because it has a security sticker on it and if i break it I can't return it.

 

[SFCRangerDoc]

Spout connector = its the shorting block that thats near the blower motor that changes the timing by 10 degrees I think for bad gas or whatever.

I'd pull the ECU out and pop the cover and look for any leaking caps, corrosion or other obvious signs of trace lifting. Mine had corrosion on the traces where the main harness attaches. It cleaned up easily with and pencil eraser and emery cloth.

I pulled the spout jumper and the car does seem to idle a bit higher now and not act like its dying. Maybe the ECU i have just has terrible timing advance or something. Mrs Doc will drive the car this week and report back.

 

[2stroke]

Well you can easily test that with a timing light. My guess is the computer is fine, and you have other issues.

 

[SFCRangerDoc]

Well you can easily test that with a timing light. My guess is the computer is fine, and you have other issues.

I guess I don't understand how it couldn't be the computer. With the factory original computer it runs and idles just fine when I can get it running... its just nearly impossible to start. The replacement pull computer will start the car just fine but runs and idles terrible. Does not the computer control advance in timing and things like that to some degree.? If the replacement computer had timing that was off or incorrectly set pulling the spout jumper may get it closer to the setting it needs?

 

[natenkiki2004]

I guess I don't understand how it couldn't be the computer. With the factory original computer it runs and idles just fine when I can get it running... its just nearly impossible to start. The replacement pull computer will start the car just fine but runs and idles terrible. Does not the computer control advance in timing and things like that to some degree.? If the replacement computer had timing that was off or incorrectly set pulling the spout jumper may get it closer to the setting it needs?

Here's the thing... These engines are all built the same, from 1991 to 2001 in the Explorers. They're all 60 degree OHV v6 engines. Granted, some of the newer heads are improved but the point is, they're all the same. Ford wouldn't arbitrarily make major timing differences between computers and years. They make small tweaks as the years go on. The timing from a 2001 computer would run a 1991 engine. In fact, Ford implements a buffer zone to cover minor manufacturing differences between engines and their components. So, any given computer off the shelf can run with any given engine pulled off the shelf. You simply won't pick up a computer that has better timing than another computer.

The majority of differences are when the computer learns after driving. It knows what the engine likes, what makes the engine perform the best. Once the computer is unplugged or the battery is removed, it forgets all of that and starts from scratch with the default tables in order to be compatible with whatever engine it's going to be hooked up with.

Pulling the SPOUT connector is more of a diagnostic feature, not a "fix". Too many people rely on it because it happens to prevent their engines from pinging. It's not a proper fix and it withholds power and fuel economy. Pulling the SPOUT connector won't make it run better in normal circumstances, only when something abnormal is going on.

 

[Rhett]

The new ECU just idles so low the car barely keeps running. I may just return it and try another one. I can't open this one up because it has a security sticker on it and if i break it I can't return it.

I'd check the throttle plate like I mentioned earlier. You may well have to tweak its positioning, and your idle may be perfect. I'd do that at least, before I returned it. There is a throttle set screw on the side of the TB.

 

[2stroke]

I should add on to what I said earlier. The ECU is the controller of all of the engine. That said, its not black magic. It takes data from sensors, and through a series of logic controls the ICM and Fuel injectors. The ICM is what actually does the timing for the coil. I'll post a diagram of the 4.0 engine's electronics. You can go through and test everything from compression to fuel pressure, and for sure timing. I have a feeling you should be looking into a new ICM. If you do some research there are some tests you can do to test the ICM, but from what I gather, the only absolute way is to swap with a good ICM. Start with a timing light, and if the timing is in spec, you can totally rule out the ECU and ICM.



This is from a 91 explorer, so there are some minor differences from newer models. I think in 93 fuel injectors were switched to sequential from batch. Strangely this diagram still has an EGR, which was not offered in 91 (maybe on rangers?)

BTW, I'm pretty sure the "shorting bar" between ECU 38 and ICM 10 is the spout connector.

Also, the only electrically controlled shift on the tranny is 3-4 plus torque converter lock up. 1-2 and 2-3 is mechanical.

 

[SFCRangerDoc]

I should add on to what I said earlier. The ECU is the controller of all of the engine. That said, its not black magic. It takes data from sensors, and through a series of logic controls the ICM and Fuel injectors. The ICM is what actually does the timing for the coil. I'll post a diagram of the 4.0 engine's electronics. You can go through and test everything from compression to fuel pressure, and for sure timing. I have a feeling you should be looking into a new ICM. If you do some research there are some tests you can do to test the ICM, but from what I gather, the only absolute way is to swap with a good ICM. Start with a timing light, and if the timing is in spec, you can totally rule out the ECU and ICM.



This is from a 91 explorer, so there are some minor differences from newer models. I think in 93 fuel injectors were switched to sequential from batch. Strangely this diagram still has an EGR, which was not offered in 91 (maybe on rangers?)

BTW, I'm pretty sure the "shorting bar" between ECU 38 and ICM 10 is the spout connector.

Also, the only electrically controlled shift on the tranny is 3-4 plus torque converter lock up. 1-2 and 2-3 is mechanical.

I have done tests with the ICM previously. I swapped in a known working one from my sisters 93 explorer 4door and tested with her ECU as well as the factory sport one against both ICM's. It didn't matter with ICM was in the car with the factory ECU...just would not start. Her ecu started the car just fine with both ICM's so I honestly don't think its the ICM at this point. I will try to get my hands on a timing light so I can see exactly what its doing.

I will also try to make some adjustments to the throttle plate screw to bump up the idle a bit. That might help, honestly. I have 3 more weeks before I have to return the ECU and the guy has agreed to take it back so I'm good there.

Also, i do notice one thing (which i think may be related to the low RPM) but wanted to run by you guys too. The Battery gague fluctuates heavily with this new ecu. will go from the needle just barely touching the N of NORMAL at idle to between the R and M when the RPM's are up. If you bog down the motor with Defrost or wipers or headlights when at idle it will go lower but pop back up as you bring the idle up. Voltmeter shows 14.5V when idling normally but will dip down to 13.2-13.3 ish at times. Battery with the engine off shows 12something volts so that seems in spec.

 

[2stroke]

So what you are saying is when it idles down around 500 rpm the voltage gauge moves? That seems normal to me, but not if it continues at 600+ rpm. Thats good you have a chance to return the ECU if you choose to. There is a simple procedure to adjust the throttle plate, its not "set from the factory" like most old school guys will tell you. The first thing to know is you can make your TPS adjustable by reaming out the holes. I do this to all my vehicles. You need a volt meter for this, and I think the throttle plate screw is a 5.5 mm, but dont quote me. I like to give the throttle body a good cleaning before anything. Then warm up the engine fully, and unplug the IAC. Note the RPM it idles at. IF it wont idle at all, turn the throttle plate stop screw in. The goal is to get it to idle about 500 rpm with the IAC unplugged. The throttle plate is now set. Since that changed, the reading on the TPS has aswell. I think Ford says anything .8-1 volt is ok, but the proper TPS reading is .96-.98 or so. If you ream out the holes, you can actually turn the TPS to adjust the reading with the throttle plate closed. Tighten the screws, verify the TPS reads .96-.98 V (as well as a smooth increase as you open the throttle), and you are done. This, along with zip ties to take up the throttle cable slack almost eliminate felt lag in throttle response.

 

[SFCRangerDoc]

So what you are saying is when it idles down around 500 rpm the voltage gauge moves? That seems normal to me, but not if it continues at 600+ rpm. Thats good you have a chance to return the ECU if you choose to. There is a simple procedure to adjust the throttle plate, its not "set from the factory" like most old school guys will tell you. The first thing to know is you can make your TPS adjustable by reaming out the holes. I do this to all my vehicles. You need a volt meter for this, and I think the throttle plate screw is a 5.5 mm, but dont quote me. I like to give the throttle body a good cleaning before anything. Then warm up the engine fully, and unplug the IAC. Note the RPM it idles at. IF it wont idle at all, turn the throttle plate stop screw in. The goal is to get it to idle about 500 rpm with the IAC unplugged. The throttle plate is now set. Since that changed, the reading on the TPS has aswell. I think Ford says anything .8-1 volt is ok, but the proper TPS reading is .96-.98 or so. If you ream out the holes, you can actually turn the TPS to adjust the reading with the throttle plate closed. Tighten the screws, verify the TPS reads .96-.98 V (as well as a smooth increase as you open the throttle), and you are done. This, along with zip ties to take up the throttle cable slack almost eliminate felt lag in throttle response.

This sounds interesting! I think I'll give it a shot. I was futzing around with the car last night and with the engine warm if i unplug the IAC should i get SOME sort of engine idle change? It didnt seem to do anythign when I pulled the plug.

 

[SFCRangerDoc]

Also, Mrs Doc just reported back to me that the car is running a lot better right now. I currently have the SPOUT connector unplugged and oddly enough, the vacuum line to the fuel pressure regulator unhooked but not plugged. I would think this would make the car run worse but i did notice the engine idled higher with the vacuum line undone...does this make any sense at all? like, the engine likes having the extra bit of air coming in? maybe i do need to adjust the throttle plate...

 

[2stroke]

Yes, idle should drop 100-150 rpm, and often they even die. No change means the IAC is doing nothing.

Kind of thinking out loud here, but California being as weird a state as it is for emissions, especially for a 93 (transition year) explorer, maybe matching part numbers isn't enough for the computer. Assuming this is a California vehicle, maybe you would be better off with a 94 computer. I've never programmed ford OBD-1 (I once watched someone flash a chip for OBD-I throttle body injection chevy), so I don't really know the logic of these computers. If you have a computer that is looking for a signal for a crank senors, or egr valve, or whatever it may be, maybe it just goes to default settings. That's my thinking anyway, being as a 92 being bare bones 3 sensors and it runs fun, compared to 94 that needs 5+. 93 could be a tricky year.

 

[2stroke]

Scratch my thinking. Something is definitely up if it idles higher with the spout disconnected and the FPR vacuum line off. That retards ignition and increases fuel pressure. The amount of air sucked in that line is minor.

 

[SFCRangerDoc]

Yes, idle should drop 100-150 rpm, and often they even die. No change means the IAC is doing nothing.

Kind of thinking out loud here, but California being as weird a state as it is for emissions, especially for a 93 (transition year) explorer, maybe matching part numbers isn't enough for the computer. Assuming this is a California vehicle, maybe you would be better off with a 94 computer. I've never programmed ford OBD-1 (I once watched someone flash a chip for OBD-I throttle body injection chevy), so I don't really know the logic of these computers. If you have a computer that is looking for a signal for a crank senors, or egr valve, or whatever it may be, maybe it just goes to default settings. That's my thinking anyway, being as a 92 being bare bones 3 sensors and it runs fun, compared to 94 that needs 5+. 93 could be a tricky year.

Supposedly this computer came off a CA explorer and my wifes is a CA model as well. Maybe I'll get myself a new IAC for grins and giggles. I don't think at this point its the alternator or the battery. "could" be a coil pack so maybe I'll get one of those too. I didnt swap that out when i replaced plugs and wires.

The car always does seem to run better once warmed up (shocker, i know). I've replaced all sorts of sensors before changing the ECU see below:

Replaced fuel regulator
Fuel pressure sits between 32-38PSI
Checked IAC and TPS. Replaced TPS and verified voltage is in spec for the IAC. (have not replaced IAC though)
Replaced Coolant temp sensor and air charge temp sensor
Verified Relays are running the fuel pump and ECU properly.
Verified coil pack is firing all 6
Replaced spark plugs and wires
Replaced fuel filter
Cleaned MAF sensor but have not replaced it