New ECM new problem

[9er9er10]

I have a manual 1992 Ford Ranger 4.0 engine has been running rough for a couple months and I finally took it to the shop and they diagnosed it with a bad ECM. They got to the conclusion because when the engine was running rough, they couldn’t receive any data from the ECM however when it was running fine since it was an intermittent problem they could. So now I put in a new ECM and the original problem is gone, but now I have a check engine light that comes on whenever I go to move the truck and the truck completely bogs down at 3500 RPM in any gear weather in four low or low range. I checked and made sure that the part I ordered was for the manual transmission too and when I CD rack the part number again was the old one they were the exact same. If it helps I have a code 18,74,and 77 coming up with a key on engine running test and a code 22 with a key on engine off test

 

[rusty ol ranger]

It only bogs down in 4wd?

Heres a list of codes....

OBD-I Diagnostic Trouble Code - 2-Digit Ford Codes - The Ranger Station

Differences in test mode noted as: (O) = Key On Engine Off test (R) = Key On Engine Running test (M) = Memory code Code Definition 11 System checks OK 12 Idle Speed Control motor or Air Bypass not … Continued

www.therangerstation.com

Looks like 18 and 22 are the ones to focus on. The other two relate to not hitting the brake during testing and not doing a "goose" test during testing.

18 relates to timing. 22 relates to MAP sensor.

Since on a 4.0 timing is done totally through the ECM (theres no distributor to adjust) id test/replace MAP sensor once you verify that the vaccum hose to it is hooked properly, and the hose isnt leaking, and the wiring/connections are good.

Im not great with 4.0 stuff but im going to bet the MAP also plays a big role in timing (code 18) because the MAP basically uses vaccum to calculate engine load and gives the info to the ECM to do whatever it needs to do to give correct performance.

 

[9er9er10]

Alright I’ll definitely give the map a look. And
Sorry for being confusing it doesn’t only bog down in four-wheel-drive. It bogs down in every gear including four-wheel-drive at around 3500.

 

[jballard81]

I have a manual 1992 Ford Ranger 4.0 engine has been running rough for a couple months and I finally took it to the shop and they diagnosed it with a bad ECM. They got to the conclusion because when the engine was running rough, they couldn’t receive any data from the ECM however when it was running fine since it was an intermittent problem they could. So now I put in a new ECM and the original problem is gone, but now I have a check engine light that comes on whenever I go to move the truck and the truck completely bogs down at 3500 RPM in any gear weather in four low or low range. I checked and made sure that the part I ordered was for the manual transmission too and when I CD rack the part number again was the old one they were the exact same. If it helps I have a code 18,74,and 77 coming up with a key on engine running test and a code 22 with a key on engine off test

did you toss your old ECM?
was the replacement a refurb? i ask b/c unless it's been re-capped, you will likely run into ECM related issues in the future.

i re-capped my 94 ECM and when doing so i found all caps were leaky and had damaged the board a little. however, the traces were still good so i was able to clean it up and still use it. glad i didn't wait any longer!

 

[9er9er10]

what do you mean by re cap it ? And no I still have the old one

 

[9er9er10]

And I don’t think it was a referb

 

[jballard81]

what do you mean by re cap it ? And no I still have the old one

New capacitors. that's what kills our ECM's.
Here's what mine looked like for example.

might be worth opening up your old one to see if it's salvageable.

 

[9er9er10]

All right, I’ll take a look thanks

 

[bobbywalter]

4.0 is maf....

it dont use a map sensor, well....it does use a map sensor....but only as a bap sensor. false air can peg it(the maf) to 3-4k and low fuel volume as well...

could be a nds issue where it is hitting the rev limiter because it thinks it is in park/neutral.


or it could be fuzzy green corrosion hell like shown above...

or all and any combination of all of this fun.

 

[pjtoledo]

below 3500, like from 1000 to 3000 does it have full power? in all gears?
able to maintain speed on a long hill?

 

[9er9er10]

Yup below it has all the power it needs but as soon as it hits 3500 it’s useless

 

[9er9er10]

4.0 is maf....

it dont use a map sensor, well....it does use a map sensor....but only as a bap sensor. false air can peg it(the maf) to 3-4k and low fuel volume as well...

could be a nds issue where it is hitting the rev limiter because it thinks it is in park/neutral.


or it could be fuzzy green corrosion hell like shown above...

or all and any combination of all of this fun.

4.0 is maf....

it dont use a map sensor, well....it does use a map sensor....but only as a bap sensor. false air can peg it(the maf) to 3-4k and low fuel volume as well...

could be a nds issue where it is hitting the rev limiter because it thinks it is in park/neutral.


or it could be fuzzy green corrosion hell like shown above...

or all and any combination of all of this fun.

sorry I’m just starting to learn all this stuff. It has a new maf on it. And I don’t know what a BAP or a NDS sensor is.

 

[bobbywalter]

bap/baro barometric pressure sensor.... so it knows elevation.

neutral drive switch. this can depend on auto or manual as to state recognition.

some processors if it is not returned to ground or pin 46 will limit rpm as a neutral limit to keep from over revving the engine with no load because it thinks its in park or neutral..

some.....not all do this.....some have both a road speed limiter and a free rev limiter....some have niether.

no rhyme or reason on the calibrations i ever figured out.. generally the rev limiter kicks in right about 4800-5000 on a 4.0..i have seen it as low as 4200..or valve float...

generally speaking....anything under 4k is a neutral limiter.

 

[rusty ol ranger]

4.0 is maf....

it dont use a map sensor, well....it does use a map sensor....but only as a bap sensor. false air can peg it(the maf) to 3-4k and low fuel volume as well...

could be a nds issue where it is hitting the rev limiter because it thinks it is in park/neutral.


or it could be fuzzy green corrosion hell like shown above...

or all and any combination of all of this fun.

A 92 4.0 is maf?

I thought they were MAP untill they switched to OBD2.

My bad.

 

[9er9er10]

bap/baro barometric pressure sensor.... so it knows elevation.

neutral drive switch. this can depend on auto or manual as to state recognition.

some processors if it is not returned to ground or pin 46 will limit rpm as a neutral limit to keep from over revving the engine with no load because it thinks its in park or neutral..

some.....not all do this.....some have both a road speed limiter and a free rev limiter....some have niether.

no rhyme or reason on the calibrations i ever figured out.. generally the rev limiter kicks in right about 4800-5000 on a 4.0..i have seen it as low as 4200..or valve float...

generally speaking....anything under 4k is a neutral limiter right?

So as it stands since it’s definitely under 4k I should look into the neutral limiter.