I've been reading threads related to my problem lately with interest, but after this morning I need help. My '95 Aerostar with 152k miles started acting up last week--getting heavy stumble on accel from stop, cold or warm. Seemed like changed pedal positions would sometimes help, but stumble would frequently return after next stop. Could reach only 30 mph or so, then the problem would vanish and it would be normal for a few minutes.

So, replaced fuel filter (it had been a while) and pulled codes. Got a 114-ACT sensor out of self-test, and 118-ECT sensor circuit open. Replaced the ECT sensor, since the ACT was out of stock. After that I got a 114 and a 111. So far, so good, but it didn't solve the problem.

This morning, the van stumbled again until warm, then would "idle" at about 2500 rpm (just a guess) at lights. Blipping the throttle did no good, so I proceeded to work trying to minimize stops. Same behavior after work, so I did both KOEO and KOER this evening. Results below:

KOEO
121 TP sensor is out of self-test
111 Pass

KOER
114 ACT sensor is out of self-test
121 TP sensor is out of self-test
411 Cannot control RPM during KOER low RPM check
538 Insufficient RPM change during KOER dynamic response test
412 Cannot control RPM during KOER high RPM check
then 121, 411, and 538 again.

Again, the vehicle engine speed was very elevated during the test. What do I make of this, and what should I try next? I have my suspicions, but many have warned here about just replacing parts *****-nilly. So who'll step up to the challenge? Thanks in advance for your help.

 

Welcome truckbuilder to Aero forum,

from your codes, looks like your '95 is an OBDI ECU system with diag port on firewall...Ford changed mid year 95 to OBDII with diag port at bottom of dash plastic in front of steering column

the 121 TP sensor code is the first to correct, check and make sure electrical plug is connected-on top front of throttle body at least on 96 4L...check for damage to connectors and wiring then clean connectors with electrical spray or throttle body spray and retest...check for any binding between throttle and sensor movement....still 121 then time for new TP
you could go thru all the hoops of measuring TP resistance at wide open and closed position but they do wear out

same with next culprit ACT, check and clean electrical connectors, located on black air tube between air cleaner, MAF and throttle body
rerun OBD tests

disconnect batt. neg. lead for 10 minutes to clear ECU K.eep A.live M.emory after each sensor replacement so that ECU will relearn from default new op. parameters, OBDI takes 10 minutes or so of driving to relearn

how long since MAF serviced, either replaced or cleaned?
Also same question for IAC?
how many miles on O2 sensors?, slow delayed action contaminated old O2 sensor on it's last legs will not always show on OBDI code tests but will show in performance and fuel mileage

run cyl. balance test to get idea of condition of plugs and wires

has vehicle been ran thru deep water to cause corrosion to sensors and connectors, strange that several would fail at same time?
how long has CEL/MIL been on?

 

Thanks, 96_4wdr, for your welcome and trying to help me out.

My Aerostar was built in Aug. 1995 and has the OBDI port on the firewall.
I'll try the fixes you suggested for the 121 code. Strangely, drove it to work today and had no idle speed problem and no CEL. It did stumble as usual before warm-up. On the ACT, the local parts store said they had 3 different ACT's for this vehicle in the book and would need the old one to compare. Any way I can know what I have without disabling the van, since they have to order a new one?

To answer your questions, MAF and IAC never serviced to my knowledge,unless they would have been touched when my head gaskets were repaired 3 years ago. Don't have those records handy but I doubt it.

O2 sensor is original. Performance isn't bad, don't track fuel econ closely since its my in-town daily driver and rarely have it out of town. I tried to get cylinder balance test to initiate, but it didn't and was getting late so I'll need to try again. Good suggestion.

No deep water ever, certainly not in last 4-5 years. CEL has been on intermittently for several months, a few seconds at a time, during accels. Usually accompanied by noticeable pinging, but backing off the throttle would invariably make it go away. (Lest you think me negligent, I tried once to get it checked and the local dealer said they didn't have a scanner for something that old anymore. I should have come here and done what I'm doing now but its apparent they didn't want to mess with it and I got too comfortable with the CEL since it didn't stay on. My bad.) Strangely, or perhaps not so strangely, it doesn't ping on accels anymore.

Any of this help to point out a trouble spot? I have had friends mention the O2 sensor as well, for the reason you stated. I'm trying to run this down myself, out of aversion to having a shop do $100/hour diagnosis and parts repl. labor on a 10 year old van.

 

should be a Ford part # on your ACT, read it off and order using it

going to have to get the codes solved to get the engine running half way smooth enough to run the cyl balance test...

try cleaning MAF, throttle body throat and plate gap, and the IAC with throttle body cleaner....nothing stronger or will cause damage...search Aero forum for tips, instructions...Ford says IAC cannot be cleaned, some on forum have success

time for a new O2 sensor, every 80k to 100k miles per Ford and O2 manuf's

all this can easily be done by DIY'er.... lotso fun, satisfaction and saved $$$$ in wallet

 

Well, did a few things tonight. First ran another KOEO and KOER test sequence. Unlike last night, got the following: KOEO-111 and 118, KOER-538 only. 118 was for the ECT I replaced earlier, and the other KOER codes had disappeared. Hmmmm. Repeated attempts to start cylinder balance test failed.

Anyway, I also popped off the inlet air duct and cleaned the throttle throat and plate thoroughly. Pretty cruddy in there, and it seemed for a second as if the throttle plate stuck when I was trying to move it manually. (I won't be that lucky though.) Nice and shiny now though, and the plate moved smoothly. Also checked the TPS voltage at around 5V, couldn't do the sweep test on it tonight. TPS connector seemed OK.

Other things--noticed 2 small cracks in the accordian section of the clean air duct. Hopefully this is not a problem. And my radiator fan hub is partially cracked through. Another part to replace.

And I noticed a loose, apparently never-used harness end, just under the TPS, which looked just like the ECT sensor connector. It went into the main harness the TPS and ECT are plugged into, but appeared to have no purpose. It's female connector ports were pretty dirty, so it didn't look like it came off something, but what would it be intended for? Another vehicle or engine?

 

That's for the temperature gage if you have a digital dashboard. If not, just ignore it. We all have that.

 

150k miles on Aero, you're doing great, another 150k left in her yet of good crusin

if throttle plate is cruddy, expect the same thing in the IAC and MAF

spray some TB cleaner on 2 small cracks in clean air tube, engine speeds up and smooths out=holes...time for new tube...heat and time take their toll

extra unused sensor plug was for optional digital display temp gauge

there is also a wiggle test for OBDI that really helps isolate failing connectors and wiring...both KOEO and KOER...listed on pg 6-4 of Haynes......i'm spoiled by OBDII computer scanner

the 4L OHV Ford is notorious for carbon build up in heads combustion chamber, top of pistons and ring pack...a Seafoam 1 hr hot soak and hard run clean the ring packs and a qt of water slowly injected in thru TB or plenum at 2k rpm on a hot engine make the heads/pistons sparkle and is completely safe...change oil after...will be black if not done for some time...

agree on cracked fan hub, don't want a propeller going thru the radiator, ruins an otherwise good day
saw an inboard prop come apart on a Herc 130 on takeoff one time...ruined the fatigues on several guys before it finished chopping up aluminum
moral=never lean over an engine while revving it and never set near the red line inside a Herc 130

 

Yeah, that was my weekend project, cleaning the IAC, checking connections, now cleaning the combustion chamber and other carboned up parts, re-run KOEO and KOER. Got a can of the Seafoam already in the garage. Don't think I'll touch the TPS yet until I see if a few other things help.

Probably I'll get an oxygen sensor since they seem to have a finite life and I'm way over it. Are these hard to replace, ie break loose?

Left ignition on last night, so I had to jump start and warm up in garage this morning. Much less stumble on way to work, but we'll see tonight when I start it and drive off while cold.

 

Definitely do the O2 sensor. 60K miles was how long the original one in my van lasted. As for breaking them loose, there is nothing a big pipe wrench cannot handle

He he, I feel better already. So I'm not the only one who forgets things. Misplace my eyeglasses hundreds of times a day

 

Did the engine stay on the Herky Bird?

Ken

 

Welcome!


Still having probs with the Aero?

 

Hey, before pulling those codes, did you let the engine fully warm up? If not, some of those codes could be invalid, though the TP related codes definately need fixing.

 

Yes, I'm still having the problem, although I was able to drive my daughter's car today. I usually check the codes after driving to or from work, which is about 15-20 minutes. Long enough to fully warm up I think. But the stumbling problem usually occurs within 3 minutes of cold, or warm, startup, then goes away.

Tuesday night I got 111 and 116 from the KOEO and 538 from the KOER. The 116 points me back to the ECT I replaced--is it possible the new sensor is bad too? Not the first time for electrical parts, but... I'm also starting to suspect the harness for the ECT. And the 538 seems to be pretty consistent, does that indicate a fault in any specific part?

I've been busy all week but I hope to do the O2 sensor this weekend, unless I get shocks for my E150...there's always something.

 

538 - System did not receive "goose" test

You did not give the gas peddal enough of a push at the begining of the KOER, or you are having issues with the TPS.

I would disconect the battery for 20 minutes and see if the 116 code comes back again. If it does, than the new sensor is bad, or you replaced the wrong sensor (You might have replaced the temp gauge sensor.)

 

OK, I finally had time to do a few things. Replaced the O2 sensor Sunday, poured a bottle of Seafoam in the tank, changed the oil, and replaced a rotting flex pipe section between the converter and muffler. (The last two probably don't help my condition, but at least it sounds quieter.)

Anyway, the O2 process required pulling the battery cable, and after reconnect I did a KOEO and got 111 and 118 codes. Next morning I still had the cold stumble condition, and got a few short CEL's when warmed up, so after getting home that evening I ran the KOER--116 and 538 codes. Darn, that suggests 93nighthawk is right and the new ECT sensor, or wiring, is bad too. Is there any way to test the harness, and would that being damaged also give a 116? And I thought I floored the pedal, so how long do you have to hold it down to get rid of the 538?

Over the last two days, the cold stumble has diminished considerably, but it may be the higher ambient temps at startup (40-50 degrees F, not 20-30 like before). Would anyone expect the Seafoam in the tank to have such a dramatic effect? Or the O2 sensor?

If you think I need to be more aggressive during the KOER to initiate the goose test, that'll be the next thing I try, plus replacing the TPS. Any other suggestions?