Persistent Engine Missing

[Aeroguy]

About a month ago my Aerostar began missing/hesitating while accelerating every now and then while cold... ran almost perfect when warm (usually). The plugs and wires were only a couple of months old. I didn't have time to deal with it myself, so I brought it to a shop that found a tear in one of the spark plug boots. They put electrical tape on it as a quick fix and the missing/hesitation was gone, but it idled rough and had a loud tapping after starting it when it was cold.

I continued to drive it with the taped plug boot until I had a chance to fix it and every morning it made a loud tapping noise after starting that would gradually go away as the engine warmed (I'm pretty sure it's an exhaust leak). Also, it began having trouble starting cold (first thing in the morning)... first requiring the engine to turn over a couple of extra times, then later requiring a LONG time to finally catch. The engine sounded strained, like the battery had a weak charge (turning over slowly), but I haven't had any other battery problem symptoms, and I even hooked a battery charger up it it one morning (set on 'engine start'), but it made no difference at all. Late last week, the missing/hesitation seemed to return a little bit. One day, the engine began running very rough and the check engine light came one (Random Cylinder Misfire), but cleared up minutes later and didn't return.

I finally got around to replacing all the spark plug wires last weekend (found another tear in a different wire, WTF?) and the idle is perfect now, it doesn't require nearly as much time to start (but it still sounds like it's straining to start when cold), and the tapping is unchanged. Missing/hesitation was gone.

This morning, I notice the missing/hesitation was back a little bit... casual accelerating above 30mph. It was very noticeable getting on the highway both on my way to and from work, where then engine would seem to stumble a bit at full throttle.

The Air flow sensor, throttle position sensor, and fuel filter were replaced in the last year.

Plugs were replaced by the shop two weeks ago, and I replaced the wires three days ago.

I don't have the time or money to begin replacing every part under the hood, and I don't want to bring it to another shop to be billed $500, only to drive away with a piece of electrical tape and a loud tapping noise. My next guess would have been the coil pack, but looking around the forum, many seem to think the coil pack is rarely a problem area. Any help at all would be greatly appreciated.

 

[BrooklynBay]

Check the engine coolant temperature sensor, and the ignition timing. The spark control module or the camshaft/crankshaft position sensor might be at fault.

 

[Aeroman59]

The strained starting condition could be a sign of your starter motor getting weak. I had that problem about a year ago ( at 275,000 kms). Mine also was cranking at significantly lower speed, & finally would sometimes not crank at all, then a few seconds later it would crank normally, finally I could only get it to crank with a tap on the starter housing with a broom handle (well known trick with worn carbon brushes).
After replacement engine turns over rapidly & without problem, it also fires up quicker in 1 second the motor catches instead of 2-3 secs.

The misfire could be several things, but normally ends up being plug or wire related. What type of plugs or wires? best to stick with Motorcraft or Autolites, this engine uses EDIS ignition with waste spark system. High reverse voltage on one bank of cylinders requires double platinum plugs otherwise premature centre electrode wear will occur. This would happen in say 25,000 kms instead of 100.000 kms.
Also if you had the plugs changed by a garage they will often conveniantly forget the passenger rear plug, it's really difficult to get at but only requires 1 plug to give misfire symptoms. Check it out!

Last misfire problem I had was caused by a loose plug ,which occured just a few weeks after I'd changed them. The engine would misfire once warmed up but only under light throttle. To cut a long story short I got the misfire code & found the plug #2 was not quite tight enough. I re-torqed the plug & the misfire was gone ! THAT simple. I hope yours is something like that.

Another possibility with a misfire is your EGR valve is sticking. You should have no EGR at idle but this is when a sticking condition, where the valve is opened slightly, will affect the engine idle. If open at higher speeds, when it should be closed; power output will be reduced & gas consumption will be increased. It could also be your dpfe sensor, which can get corroded & give incorrect flow data to the EEC. Both of these problems should give you a code after a while.

Let us know what you find,
Good luck,
ATB Aeroman.

 

[Aeroguy]

Thanks for the responses.

This got bad real quick... this morning's ride to work proved that the missing/hesitation was 100% back, if not worse. Misses occationally during acceleration, but it seemed to occur more when I had my foot on the gas only enough to keep the van at a specific speed. It even missed a couple of times at idle, which wasn't happening before. On the way home was a slightly different story... it only missed a few times while maintaining speed. Acceleration and idle seemed fine... until I was almost home, when the engine suddenely started idling very rough and stumbled very badly when I tried to accelerate. It lasted only about 30 seconds. A test drive this evening showed the same... missing while maintaining speed. Idle was 100% perfect.

I replaced the ECT sensor... no change. I also bought a crankshaft Position Sensor, but didn't get a chance to install it. Tomorrow I'll stop by Ford for a few more parts.

I tried replacing the starter, but the damn axle was in the way (AWD). Ford's manual failed to mention this. It almost fits by sliding out over the crossmember, but no luck.

The wires and plugs are Motorcraft (installed myself). When I replaced the wires the second time, the plugs were all tight. I double checked everything tonight, but it all seemed fine.

I'll install the CPS tomorrow and will probably get a coil pack from Ford if things don't get better.

Thanks for the help.

 

[Aeroman59]

Thanks for the responses.

This got bad real quick... this morning's ride to work proved that the missing/hesitation was 100% back, if not worse. Misses occationally during acceleration, but it seemed to occur more when I had my foot on the gas only enough to keep the van at a specific speed. It even missed a couple of times at idle, which wasn't happening before. On the way home was a slightly different story... it only missed a few times while maintaining speed. Acceleration and idle seemed fine... until I was almost home, when the engine suddenely started idling very rough and stumbled very badly when I tried to accelerate. It lasted only about 30 seconds. A test drive this evening showed the same... missing while maintaining speed. Idle was 100% perfect.

I replaced the ECT sensor... no change. I also bought a crankshaft Position Sensor, but didn't get a chance to install it. Tomorrow I'll stop by Ford for a few more parts.

I tried replacing the starter, but the damn axle was in the way (AWD). Ford's manual failed to mention this. It almost fits by sliding out over the crossmember, but no luck.

The wires and plugs are Motorcraft (installed myself). When I replaced the wires the second time, the plugs were all tight. I double checked everything tonight, but it all seemed fine.

I'll install the CPS tomorrow and will probably get a coil pack from Ford if things don't get better.

Thanks for the help.

Sounds like you have the worst type of problem........... an intermittent like that can be very hard to catch. to me sounds like it could be fuel system related, have you checked fuel pressure? Like I mentioned previously sticky EGR valve can cause this type of problem. Might pay to replace it with a junk yard item, also DPFE sensor will give these driveability problems. Infact lots of things could cause it..... but being it is not constant something which can fail intermittently is what needs to be looked for. I've not yet heard of a coil pack failing on an aero, they are very reliable. Injectors can get sticky though. A scan tool would help out with this but you would need an experienced tech to pick out where the fault is. All sensors & the fuel system can be monitored with a good scan tool. Yours should be OBD2 so eventually you should get a code. Check all vacuum lines & connections, PCV, fuel cannister purge solenoid & tubes.
I had the cam sensor on mine fail & it did not cause any driveabilty issues but I've heard other owners who have had stalling problems at idle with the code PO340.
Yet another possibility is the crank position sensor, this can cause the engine to momentarily cut out, but you should get a code for this problem.
Is your CEL on?

With regards to the starter motor accessibilty, try jacking the vehicle body up to increase clearance between the engine & drive shaft.

Good luck , Aeroman

 

[BrooklynBay]

Did you ever perform a compression test or test the exhaust for a clogged catalytic converter?

 

[Aeroguy]

Sounds like you have the worst type of problem........... an intermittent like that can be very hard to catch. to me sounds like it could be fuel system related, have you checked fuel pressure? Like I mentioned previously sticky EGR valve can cause this type of problem. Might pay to replace it with a junk yard item, also DPFE sensor will give these driveability problems. Infact lots of things could cause it..... but being it is not constant something which can fail intermittently is what needs to be looked for. I've not yet heard of a coil pack failing on an aero, they are very reliable. Injectors can get sticky though. A scan tool would help out with this but you would need an experienced tech to pick out where the fault is. All sensors & the fuel system can be monitored with a good scan tool. Yours should be OBD2 so eventually you should get a code. Check all vacuum lines & connections, PCV, fuel cannister purge solenoid & tubes.
I had the cam sensor on mine fail & it did not cause any driveabilty issues but I've heard other owners who have had stalling problems at idle with the code PO340.
Yet another possibility is the crank position sensor, this can cause the engine to momentarily cut out, but you should get a code for this problem.
Is your CEL on?

With regards to the starter motor accessibilty, try jacking the vehicle body up to increase clearance between the engine & drive shaft.

Good luck , Aeroman

No, I didn't have the fuel system checked. I always use good gas, change my fuel filter regularly, and use fuel system cleaner from time to time. I would be shocked to find out it was the fuel system, but I'll see about have the system cleaned professionally.

I think I'll pick up an egr valve tomorrow instead of the coil pack.

When I brought it in to the shop, a full diagnostic was performed... nothing came up. They said is passed with no problems whatsoever. The CEL was on after my first incident with the bad idle... came up 'Random Cylinder Misfire'. Nothing else.

Did you ever perform a compression test or test the exhaust for a clogged catalytic converter?

No compression check, but it feels just as strong as my last Aerostar which had excellent compression. Even the shop I brought it to said it feels very strong and doesn't see any problem with the engine itself. As for the cat, I'll have to look into that.

Thanks!

 

[Aeroman59]

No compression check, but it feels just as strong as my last Aerostar which had excellent compression. Even the shop I brought it to said it feels very strong and doesn't see any problem with the engine itself. As for the cat, I'll have to look into that.

Thanks!

Probably not the cat converter. Make sure all your vehicle ground connections & battery terminal connections are good. A bad ground can cause all kinds of gremlins to surface!
Also make sure you have no air or vacuum leaks on the intakes.

 

[Aeroguy]

Yesterday, my Aerostar was even worse... seems to be getting worse each day. Instead of periodic hesitation, it was occurring very regularly... at all times (idling, cruising, accelerating). Ford didn't have the EGR valve in stock, nor did any local part stores. I ended up going home and ordering a code scanner.

Today, I didn't drive the van to work, but I test drove it afterwards and once again, it was even worse then the day before. Now, it hesitates and shakes 100% of the time, at all times. I hooked the scanner up and got code P1000... Monitor Testing Not Complete. Searching the Internet for a detailed description, the PCM hasn't completed a full drive cycle since the power was last disconnected... that was Wednesday, however I drove it for nearly an hour since then, totaling 25 miles. The 'answer' to this code is to simply drive more, but in its current state, that doesn't seem like a possibility.

 

[Aeroguy]

Probably not the cat converter. Make sure all your vehicle ground connections & battery terminal connections are good. A bad ground can cause all kinds of gremlins to surface!
Also make sure you have no air or vacuum leaks on the intakes.

The cat seems fine. Power and grounds are good... checked them when all these problems started. No vacuum leaks that I could see (or hear).

 

[Aeroman59]

Yesterday, my Aerostar was even worse... seems to be getting worse each day. Instead of periodic hesitation, it was occurring very regularly... at all times (idling, cruising, accelerating). Ford didn't have the EGR valve in stock, nor did any local part stores. I ended up going home and ordering a code scanner.

Today, I didn't drive the van to work, but I test drove it afterwards and once again, it was even worse then the day before. Now, it hesitates and shakes 100% of the time, at all times. I hooked the scanner up and got code P1000... Monitor Testing Not Complete. Searching the Internet for a detailed description, the PCM hasn't completed a full drive cycle since the power was last disconnected... that was Wednesday, however I drove it for nearly an hour since then, totaling 25 miles. The 'answer' to this code is to simply drive more, but in its current state, that doesn't seem like a possibility.

You should soon get a code.,,, sounds like a multiple misfire problem. A crank sensor (CKP) could cause that problem if the magnet comes loose. To complete a drive cycle. all sensors for those particular tests must be good otherwise the cycle will not complete.
Did none of the tests complete? Continuous & Non-continuous?
That would be unusual.

 

[Aeroguy]

I swapped out the crankshaft position sensor today... no change. So I took it for a drive. Misfires during idle, but once you begin driving, the entire van shakes constantly... ranging from a moderate shake to violent. Full throttle, I can feel the engine shake like mad, but the power seems to be all there. The only time it didn't shake and misfire was when I was coasting with my foot off the gas. I can also add one more symptom... backfiring during acceleration. Light backfiring, but sounding like popcorn.

All this and NO PROBLEM CODES!!! How can the engine run so bad and nothing be happening? The only code I get is the P1000, after driving it another 20 mphs. How long does this take?

Comparing the data I got from the scanner to the reference values I got from the Ford PCED manual, here are a few:

Idle:
____________Scanner______Manual
Abslt TPS(%): 19.2_________(listed in voltage)
Engine Spd:___620-710rpm__790-820rpm
Calc Load(%): 26-27________23-25
Ign Adv(deg):_20-21________15-22
Coolant (ºF):_185-194______160-200

There were no readings for the O2 sensors nor the speed sensor. One strange thing I noticed was that the reference values say the ignition advance should go from 15-22º in idle to 25-29º at 30mph, however at one point the readings I got showed my van went from about 21º and actually decreased to 10-15º while accelerating to 30mph, before going up to 26º.

My wife, who was following me at the time, said she noticed the exhaust smelled pretty strong, but there was no smoke. It didn't smell of gas, coolant, or sulfur, just a plain exhaust smell only much stronger.

 

[BrooklynBay]

Did you check the spark control module as suggested in post # 2? The smell from the exhaust is probably unburned fuel from cylinders that are not firing consistently.

 

[Aeroguy]

Did you check the spark control module as suggested in post # 2? The smell from the exhaust is probably unburned fuel from cylinders that are not firing consistently.

I thought you were refering to the coil pack. Where is the spark control module? I wasn't aware that the Aerostar had one.

Once again, thanks for all the help!

 

[BrooklynBay]

Do you have the 3.0L or the 4.0L?

 

[Aeroman59]

Can your scantool read I/M monitors ? In a drive cycle the ECU goes through a set of tests to establish that all the engine component monitors are working normally, such as fuel system, EGR, Evap, o2 sensors etc. If one of these has failed then the p1000 code comes up as a warning. So you should be able to find out which monitor is not completing. You say that the o2 sensor is not reading? & no cel thats strange! The van shaking is definately the engine? what happens if you coast the vehicle in neutral?

BTW a strong smell usually comes from a rich exhaust as noted above, but you should also get a code for rich or not switching o2 sensor -stuck rich, I guess there is some reason why no codes but why I'm not able to tell you. Can you check your fuel rail pressure? A failed fuel pressure regulator can cause a constant rich condition if the adaptive system is not able to compensate you will be running very rich, Whats your gas mileage like?

 

[Aeroguy]

Do you have the 3.0L or the 4.0L?

1997 4.0L, AWD.

Can your scantool read I/M monitors ? In a drive cycle the ECU goes through a set of tests to establish that all the engine component monitors are working normally, such as fuel system, EGR, Evap, o2 sensors etc. If one of these has failed then the p1000 code comes up as a warning. So you should be able to find out which monitor is not completing. You say that the o2 sensor is not reading? & no cel thats strange!

Yes, it reads I/M monitors, however I can't remember what it displayed. I'll check on that in the morning. O2 sensors are only about 6 months old.

The whole 'no CEL' problem is very strange indeed. With all my other vehicles, the CEL always let me know beforehand of any problems and would light up on the slightest incident (specifically with the air/fuel mixture being too lean or rich). Here, the van is almost rattling the engine out and it acts like nothing's wrong.

The van shaking is definately the engine? what happens if you coast the vehicle in neutral?

Yes, it's definitely the engine. Haven't tried the neutral thing though... not yet.

BTW a strong smell usually comes from a rich exhaust as noted above, but you should also get a code for rich or not switching o2 sensor -stuck rich, I guess there is some reason why no codes but why I'm not able to tell you. Can you check your fuel rail pressure? A failed fuel pressure regulator can cause a constant rich condition if the adaptive system is not able to compensate you will be running very rich, Whats your gas mileage like?

Up until just before the problem returned, gas mileage was no different then it always had been, and exactly the same as my last Aerostar. No telling now that I've been driving it so erratically now.

Now that I'm thinking of it, the 'fuel used' stat on the trip computer has been off lately... usually when I fill up, it's within .1 or .2 gallons of what I end up putting in the tank. Over the last couple of months it seems to be coming up short by about a gallon. Maybe a leaky fuel injector?

I'll pick up a fuel pressure tester tomorrow if I don't find anything new with the scanner.

 

[BrooklynBay]

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1105209&parttype=7172

1997 FORD AEROSTAR 4.0L 245cid V6 MFI: Ignition Control Module Price Total $173.79.
AIRTEX Part # 6H1107
Distributor-Less

The price is kind of high to take a gamble, so you might want to look around for a used one.

 

[BrooklynBay]

http://www.autozone.com/autozone/ca...cal+&+Lighting&parentId=cat10012&questions=[]

OEM Number: 906B- 12K072- BA; 91BB- 12K072- BA; F0TZ- 12K072- B; F1TZ- 12K072- B; F1TZ- 12K072- BA; F4ZZ- 12K072- B; ZZL0- 18- V80; ZZM2- 18- V80.

 

[Aeroguy]

My van doesn't have an ICM. The ignition system is described in the factory manual as follows:

Ignition Components, Electronic
The electronic ignition (EI) for the 4.0L engine consists of the following components:

Crankshaft position sensor (CKP sensor) (6C315) and 36 minus 1 tooth trigger wheel.
Ignition coil (12029).
Powertrain control module (PCM) (12A650).
Related wiring.

From the Chilton manual:
1996-1997
The 1996-97 models do not have an individual ignition module. The Powertrain Control Module (PCM) regulates the spark timing without the need of a separate module.