I need a new/rebuilt ECM--where to look? | Page 2 | Ford Explorer Forums

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I need a new/rebuilt ECM--where to look?

Andy, have you checked the fuel pressure with the engine running on gasoline? I just finished changing my fuel pump after having codes P0171 and P0174 for several months. Just recently I discovered that my fuel pressure was low. I had 55psi at idle, dropping below 50psi with winging the throttle.

The 99+ fuel pressure should be 56-65psi, mine has been just on the edge, so I have had random times when a code would appear. If you have a 99 truck, you need a 99+ PCM, if that is the problem. There are no mid year PCM's, don't go looking for a 99 PCM made in 98, forget that waste of time.

The bottom line is that you should baseline your engine. You need to get it running properly on gasoline, before diagnosing things which are different with LPG. The symptoms you are getting with LPG will likely cloud the troubleshooting, experts can help get the gas system running correctly very fast. Get the truck running with gasoline first, find and fix the problem, then switch back to LPG. Check the fuel pressure, good luck.
 



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My truck was built in August 1998 but not registered and sold until May 1999. Would I be better off with a 98 or 99 PCM? I do not beleive the fuel pump is the problem as this is not used for LPG and the problems are the same on petrol and LPG. If the pump was the problem then the truck should run fine on LPG when the pump is bypassed.
 






I didn't think of the fuel pump being out of the system with LPG.

Check your door jamb, or the decal on the radiator support. Your registration, those tags, and all paperwork should all properly identify the truck as a 1998 or a 1999 model. Buy parts based on that model year, regardless of the manufacture date. You must use the matching PCM, the 99 is much different than the 96-98 PCM. In the USA that is a 1999 model for sure.

Still you have a problem which would be far far easier to diagnose if it is running on gasoline. There are thousands of competent mechanics who can figure out what it is, when it is running on gasoline. There are countless member here who can. My point is that there are an insignificant number of competent LPG experts here, or where you are looking.

You may have more than one problem. I suggest that you run the truck on gasoline, get it to run properly as a stock engine. Then switch back to the LPG and see if anything is better. I'm sorry that I don't know the magic answer that you need. Good luck,
 






This can also be something as simple as a vac leak in the brake booster,bad vac lines,leak in the inlet tubing between the maf meter and throttle body,throttle body gaskets,etc. Before swapping a computer I would definately determine the source of the problem. I don't believe you have a computer problem.

How would I check these leaks myself? I don't want to throw any more money at a garage but I have not really had to work on a car before. I have heard of spraying something around pipes to check for leaks but would this work for the brake booster or vac lines?
 






Hello again Andy, still no luck? Most of that checking amounts to basic cleanliness and double checking items. That is most often when you will find other problems. It is somewhat common to find a clamp screw loose on one of the inlet hoses, start with those. You can pull one or more of those hoses off and check, or clean the MAF sensor or throttle body.

I don't know how dirty your engine is, but it is much easier to work on a clean engine, and that is a ten minute job, if there are no odd exposed electrical devices. So if you have any added devices with unprotected electronics, don't clean the engine without experience doing that. Basically that is as simple as spraying it all down with engine degreaser, and after soaking for 5-10 minutes, rinsing it all off, including the hood and fenders.

You should be able to dig around everything under the hood looking for anything loose, appearing odd, finding an excessive amount of residue from oil, etc. If it is so filthy that you are afraid to touch anything(cold), then the mechanic will treat it the same way. They will not look hard for issues.

General good maintenance will find most problems before they become bigger.

FYI, the 2nd gen. Explorers(your SOHC PCM) does not relearn or alter its own programming like the dealer has told you. Those PCM's didn't begin until the 2002 4dr. Explorer models. Thus ignore what they tell you about reprogramming because of the PCM changing over time, that is BS. Disconnecting the battery will take your PCM back to its base settings, it will not adjust dramatically like the 2002+ models. The difference will not be what others have told you. That is only helpful(slightly) when you make a significant change, like a high flowing air cleaner, MAF, throttle body etc. Good luck,
 






After a bit more research and speaking to a different LPG specialist, who provides tech support for others in the area, it appears that the PCM will try to run the truck on LPG as well as petrol. This means it is always a possibilty to get the O2 sensors finding a problem but it shouldn't idle funny.Therefore I am completely ignoring the fact that it also runs on LPG.

It appears that there is something wrong on petrol which is being duplicated on LPG. I have already tried a used PCM which made absolutely n o difference. I have experimented a little and find that if I rev the truck, in neutral, to a point where the throttle opens that it revs fine. Then as soon as I allow the revs to drop and the throttle to close, completely as I have just been told Explorers do, it begins to jerk and buck again. This leads me to believe it is only something that is used at idle, that isn't then used when the throttle opens. All the idle problems began shortly after a backfire, with smoke coming out the airbox, so I will check the throttle plate and air pipe. Any other suggestions?

Thanks for the advice everyone
 






Check the IAC(Idle Air Control} solenoid on the top of the intake. Clean it out, and listen to any whistling noises coming from it. It should be clean and quiet.

Beyond normal tune-up items, I'd have a PCM programmer look at the air/fuel ratios. It likely needs some professional PCM tuning, requiring a flasher and wide band O2 sensor to check the programming. Good luck,
 






I tried cleaning the IAC valve, I also tried running the engine with the IAC valve electrical connector disconnected but everything was the same. I heard that if you disconnect a faulty IAC valve then the idle should improve? The CEL and O2 sensor readings will likely be solved by some kind of tune to take account of the LPG but I think that the idle problem is something else as it has had 2 completetly different PCMs in and with both it produced the same poor idle. I am going to check the air pipe for damage/obstructions and throttle plate to see if it is bent from the backfire but then I am pretty much out of ideas.
 






I agree about the condition being unrelated to the PCM, generally when a PCM is faulty you have much much bigger driveability issues.

Quoting the statement of yours, "...if you disconnect a faulty IAC valve then the idle should improve?" That is not quite accurate, it may improve, not should improve. It is equally likely that the IAC is bad, and disconnecting it results in basically the same conditions. I bought a new IAC valve a while ago to change for my normal high maintenance. Performance and efficiency can be degraded when they still function, but not perfectly.

Testing of the MAF, TPS sensor, and A/F ratios would be my highest priority. Many things could affect the idle, even simple vacuum leaks cause big troubles. Before doing those more involved or expensive checks, double check every vacuum line and component of the intake system.

The TPS you can easily check with a volt meter. It must have a range of 0-5 volts, something around one volt at idle, and a smooth curve. It does not have to be at any magic figure, .5 volts is fine for idle, and so would 1.5 volts. As long as the range is in the ballpark, the PCM can handle it. Another words, do not adjust the TPS of any 95+ vehicle, ever.

The LPG complicates things still, check on those things and consult with a tuner. Hunt James(jah81592) here above, he is very good with tuning these PCM's. Hopefully just looking at the A/F ratios now will point to the trouble.

You might start a new thread also to separate this from the original poster. Regards,
 






Thanks, I have had a new TPS and Maff sensor so I'll try a new IAC valve as they're pretty cheap and see what happens.
 






What type of petrol are you using? Which brand?
 






Supermarket own brand 95RON as it is the cheapest in the UK at, wait for it, $9.60 a gallon!
 






Ouch, per gallon, I'm hunting for fuel economy for our $3/gal gas.
 






Need a ECM also!!!! 93 Explorer XLT

I need one also.

93 Explorer XLT 4x4 4 door auto
Won't start, engine turns over but no sputter at all.
I have fire to plugs.
Shoot gas in intake and it sputters.
Installed my PCM Power Relay in another Explorer, it ran.
Replaced Fuel Pump Relay, Fuel Pump, Fuel Filter, no go.
Checked Inertia Fuel Shutoff Switch, ok.
Had it towed to a recommended, been in business a long time, generator, alternator & electrical shop. They say it's the ECM (computer). I'm to find replacement.
F37F-12A650-ZB
I was told by a junk yard that an AKB and FA are interchangeable with ZB. Do you know if this is true?

What should I look out for if getting a used one?
What should I look out for after getting a used one?
Will I need to take it to a Ford dealer for a "tune up"?
 






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