It did pass, by the way.

 

Ok, thats good, normally they fail your exhaust if they find any leaks.

 

Replaced the IAC and it is still running rough. Same codes? Any thoughts, now I'm stumped. Even one of our maintainers are stumped. Checked it all as I said. Good to excellent milage.

 

So, what codes remain? ECT and MAF? Did you clear the codes before starting it up again?

 

As posted. The codes pulled were. 116 ECT higher or lower than expected-temp was normal,
157 MAF sensor curcuit below normal voltage
536 BOO curcit failure/not actuated during KOER ( did it but came up)
538 Insufficent RPM change during KOER dynamic response test

 

Ok, the 536 and 538 are not true codes per se. After the engine RPM returns to normal dureing the test, apply the brakes, and temporarily floor the throttle. 536 means you did not apply the brake during the test, 538 means you did not apply throttle and cause a change in engine speed sufficient to satisfy the test. As for the code 116, replace the ECT sensor, as it is faulty. Try claening the MAF one more time, but it may be beyond cleaning and require replacement.

 

Did it done it. Check wiring, You name it I've checked it. I've restored 4 cars and am very mechanical. So I'm no new guy. Just I'm stumped. It runs rough but milage is great? Yes I've changed the MAF and ECT.

 

Hi Cdnsoldier:

If you have replaced the ECT and the MAF, and it still gave you those codes, I suggest you check the 5V reference voltage. For the 4.0L, it's pin number 26 on the Engine Computer's connector. Color is Brown with White Stripe.

Looking into the back side of the connector, where all the wires are (not the side with the connector pins), the middle row starts with pin 21 on the leftmost side. Go right 5 pins and that's pin 26.

With the key on, it should read 5V. I remember reading one thread here not too long ago that a short in the Transmission Solenoids or the Transmission Solenoid Connectors caused the Engine Computer to blow the voltage regulators that maintain the 5V that goes to all the sensors.

Anyway, even if those regulators are blown, they can be fixed, so there is no need to pay hundreds of dollars for a new computer.

 

any corrosion on connector plug socket pins into ECU/PCM? specifically the ECT and MAF lines

one cylinder in a V6 not carrying it's full load will cause rough running and lots of shaking

have you ran a OBDI cylinder balance test? results?
may be injector/s, poor spray pattern may cause uneven fuel/air mix at idle, some areas in combustion chamber too rich and some too lean, and poor idle but increased air flow at higher rpms smooths out the mix.

cylinder compression and leakdown tests? results?

 

Balance test OK. I'm going to change the plugs,wires, etc this week. Then take it in to have it checked, if it does not clear up. Maybe resetting the PCM may do it.

 

When the car is running, does the "Check Engine" light go on? If it doesn't, then all you are reading are the old codes that was stored earlier. You would have to clear the PCM by disconnecting the battery for a few minutes.

Also, I should have caught this sooner, but you quoted a gas mileage of 6-8 Km/L. That's only 14-19 mpg, not the 20-25mpg that you thought. Depending on where you drive and how fast you drive, this mileage could be good or bad. I'd say that's about average for a 4.0L. For freeway driving at about 60mph (approx. 100km/h) I get about 23-24mpg for my 4.0L, but around town it gets only about 14mpg.

 

disconnecting the neg bat lead not only clears stored old codes but also resets-clears the unique learned dynamic parameters stored by your sensors for your driving style, fuel and climate in the ECU/PCM. takes 10-20 miles for computer to learn new optimum parameters and store.
newer OBDII systems will replace and update new parameters after every 80 warm up cycles.
you may be driving with the old parameters from the old IAC, dirty MAF and other parts repaired-replaced.

using a code reader to clear codes only clears the codes, leaves the old learned parameters in place

many hi tech upscale shops now run top end rigs on a dyno to relearn parameters into PCM or send the shop kid out to drive the rig for 30 minutes to relearn, then they retest codes.
low end-mid scale shops just tell the customer that rig will improve performance after 20-30 miles of driving.

 

Copper
6-8 K/110 is 20-25m/gal. The lower the number the better. I am avergaing 24m/gal. on my fuel computer thats at 120ks. (70mph). And about 15-18 m/gal city. I have cleared all the codes, and used a vehicle tech, friend's (ReadTech) 1900$ reader, to read, clear and check.
The same codes comeup after reset and we check it all. and same damn codes and rough running. He's a Adv vehicle Tech, he's stumped also. I have phoned Ford and they also have no clue.
I'm going to change the wires and plugs anyway. Then drop it off to Ford, while I'm gone away. They can run some tests the Readtech cannot.
I will post after.
Thanks fellas.

1994 Ford Aerostar Wagon
Sorted by Liters/100 km (city), Click on column headings to resort
Use your gas prices Switch to English units

Canadian

Model city hwy /100 Lts


Ford Aerostar Wagon
6 cyl, 3.0 L, Man(5), (FFS), Regular 13.8 9.8 $1736 8.8 NA


Ford Aerostar Wagon
6 cyl, 3.0 L, Auto(4), (FFS), Regular 13.8 10.2 $1736 8.9 NA


Ford Aerostar Wagon
6 cyl, 4.0 L, Auto(4), (FFS), Regular 14.7 11.8 $1940 10.0 NA

US Milage

Model city hwy M/gal


Ford Aerostar Wagon
6 cyl, 3.0 L, Man(5), (FFS), Regular 17 24 $1736 9.7 NA


Ford Aerostar Wagon
6 cyl, 3.0 L, Auto(4), (FFS), Regular 17 23 $1736 9.8 NA


Ford Aerostar Wagon
6 cyl, 4.0 L, Auto(4), (FFS), Regular 16 20 $1940 11.0 NA

 

Hi CdnSoldier:

Oh, you use (Liters/100km) and I thought it was (km/liter).