ECM questions

[raggadie]

I am new to the forums and I just had a few questions considering an ECM swap from an 88 to a 86.

I broke the EGR tube when removing the engine, and been having a hard time finding a replacement. I have read plenty times that some have changed the ECM from newer trucks into older ones to compensate for plugging up the ERG valve and tube.

My question is this. I have read many of comments of people saying their truck ran fine after replacing the ECM. Does it mean within emission standards after the swap? Or not running too lean or rich? In short, is it running correctly?
Considering all sensors are reading right.

Also, which EMC would I need for 86 2.9 auto 2x4 from an 88. I think I know I just wanna make sure I am correct.

Thanks,
Ross

 

[RonD]

If you have an '88 then it must meet '88 emissions standards, disabling the EGR system will cause a Fail if they check for a working EGR system, regardless of exhaust pipe emissions.

You would be better off keeping the working ECM and making an EGR tube.

Used ECM may or may not be in good working condition.
An older ECM would have older emissions standards so..........may or may not pass '88 standards.
It may have perfect '86 emissions but would fail '88 standards
You can swap the whole engine and ECM from an '86 into an '88 and when "they" look up the VIN you still have to meet '88 standards.

 

[raggadie]

If you have an '88 then it must meet '88 emissions standards, disabling the EGR system will cause a Fail if they check for a working EGR system, regardless of exhaust pipe emissions.

You would be better off keeping the working ECM and making an EGR tube.

Used ECM may or may not be in good working condition.
An older ECM would have older emissions standards so..........may or may not pass '88 standards.
It may have perfect '86 emissions but would fail '88 standards
You can swap the whole engine and ECM from an '86 into an '88 and when "they" look up the VIN you still have to meet '88 standards.

Ok, so from my understanding based on the year an engine can have different standards of emissions. Thank you for that reply, but it didn't quite give me all I need because passing emissions is not my problem. I will explain my situation more. I was in a hurry today and couldn't get in all the deals.

I just bought an engine from Marshalls, and I have to jump through hoops to keep my warranty void. Now other than the heads (maybe), ECM, and the Egr valve, the engine is not that much different that I know of(if it is, let me know). In order to keep the warranty good, I cannot have pre-ignition, or detonation because of the havoc it can play on an engine.

If I switched the ECM in an 86 to an 88, would it run emissions/air fuel mixture like a 88, if all sensors and the ECM was working correctly? Minus the Egr valve. Even if emissions standard would failed because it might not be the same standard as the 86.

In short, I just want the computer to correct the fuel mixture correctly so I do not run into these problems so it keeps the warranty good. Therefore, if I plugged up the Egr in the 86, and put a 88 ECM in it, would it run just like an 88 engine, if all sensors were working correctly? Would it run the correct fuel mixture to not damage my engine?

Thank you for your time,
Ross Wood

 

[adsm08]

Ok, here is the deal with the 2.9, the emissions systems, et al.

86 and 87 had EGR and a knock sensor. The knock sensor sucked. It caused problems because it would pick up valve train noise and start retarding the timing.

The EGR was good, when it worked. It didn't always work well, and then it caused lots of problems, and as you have seen, parts are becoming scarce.

If you replace your existing 86 computer with an 88+ computer it will run at least as well as it does now, all sensors, air fuel ratio, etc will all be in spec. It may actually run better once the knock sensor is taken out of the loop.

As for emissions, the cats were changed in 88 to compensate for the loss of the EGR system. EGR's primary function (despite what the morons on the internet say) is to lower combustion temps, thereby reducing the amount of NOx produced. NOx (Oxides of Nitrogen) being the actual harmful and toxic tailpipe emission of the modern automobile. The cats are there to finish removing the NOx. Cats take NOx, CO, O2, and HC (residual unburnt fuel) and chemically break them down and rearrange them into H2O and CO2 (which as an environmental agent is harmless, despite what Mr. Gore would have us believe).

If you don't have tail-pipe testing you should be OK as far as emissions. It may end up being slightly high, but no worse than just having a worn cat.

I ran my 87 engine for about a while on an 88 computer with no issues at all. You just need to get one that matches your engine and trans, 4x2 or 4x4 is unimportant.


Also, if you do have some sort of inspection that will look for an intact EGR system may places make allowances for unavailable parts. In PA the rule is that you need to provide a written statement from two parts resalers (generally one junk yard and one parts store) saying that the part you need is no longer available. You take that to your inspection station, and they give you a pass and a form to send in, then you get a letter for future years saying you don't need that part installed.

 

[sjr53]

I ran my 86 BII auto with a plugged up EGR passage in the throttle body for years with no drivability issues. I just would get a 33 code when checking codes. I have also put that 86 ECM into an 88 BII 5spd to test the 88 and the 88 ran fine with the 86 auto ECM.

 

[raggadie]

Ok, here is the deal with the 2.9, the emissions systems, et al.

86 and 87 had EGR and a knock sensor. The knock sensor sucked. It caused problems because it would pick up valve train noise and start retarding the timing.

The EGR was good, when it worked. It didn't always work well, and then it caused lots of problems, and as you have seen, parts are becoming scarce.

If you replace your existing 86 computer with an 88+ computer it will run at least as well as it does now, all sensors, air fuel ratio, etc will all be in spec. It may actually run better once the knock sensor is taken out of the loop.

As for emissions, the cats were changed in 88 to compensate for the loss of the EGR system. EGR's primary function (despite what the morons on the internet say) is to lower combustion temps, thereby reducing the amount of NOx produced. NOx (Oxides of Nitrogen) being the actual harmful and toxic tailpipe emission of the modern automobile. The cats are there to finish removing the NOx. Cats take NOx, CO, O2, and HC (residual unburnt fuel) and chemically break them down and rearrange them into H2O and CO2 (which as an environmental agent is harmless, despite what Mr. Gore would have us believe).

If you don't have tail-pipe testing you should be OK as far as emissions. It may end up being slightly high, but no worse than just having a worn cat.

I ran my 87 engine for about a while on an 88 computer with no issues at all. You just need to get one that matches your engine and trans, 4x2 or 4x4 is unimportant.


Also, if you do have some sort of inspection that will look for an intact EGR system may places make allowances for unavailable parts. In PA the rule is that you need to provide a written statement from two parts resalers (generally one junk yard and one parts store) saying that the part you need is no longer available. You take that to your inspection station, and they give you a pass and a form to send in, then you get a letter for future years saying you don't need that part installed.

Thank you for the information. From your reading, I understand that the combustion chambers temps never get to dramatic extremes without the EGR valve, so Ford just put on a better cat to take out the NOX gasses. Therefore, if I put in the new computer I can close off the EGR valve? Just making sure I am doing it correctly.

Also, you mention a knock sensor, but I was unclear if this was in just the 86 and 87's. Is this in the 88 ECM too? If not, with the 88 ECM, it should not pick up the knock sensor right? Therefore, not mess with the timing.

Next, my first idea was to try and fix the EGR valve, so this was only backup, but do you recommend the swap regardless if I do not have emissions testing. Lastly, if all this is the case, if I ever want to pass emissions with an 88 computer, all I would have to do is replace the cat, right?

Thank you for your time and input,
Ross