Tired of chasing my tail on this..

[blowby]

I've made several posts regarding this ongoing problem with my '94 3.2ATX with 190k.

Originally the problem presented itself after a 3 month storage, as a misfire(assumed) at cruise (surging) that would come and go at will, but ususally over 50mph but not under accel.

Codes were rich and lean readings from both O2's.

Fuel pressure was a little low so Replaced Fuel pump and filter. (OEM)
Cleaned the dirty MAF and problem went away for a day.

Since then the problem has continued (2 months) and changed a bit.
The car always starts fine. However now during almost every cold start the engine will rev. to 1,500-1,700rpm and then fall like you turned the key off.
Sometimes causing the engine to stall other times it will barely recover.
Either way, if you restart it or if it recovers, the idle will remain constant and smooth at 650+/-.

Occasionally I will get CEL flashes just after start up.
Only codes I am getting now are Lean Front and rear from O2's.
I can hear what sounds like a slight miss during idle if I put my ear to the tailpipe.

Recently replaced items (over the last year)

Bosch O2's
OEM fuel pump and filter
Plugs/wires (Motorcraft AGP++ plugs)
New upper gaskets and plug well seals (cleaned Intake and checked for vacume leaks)
Cleaned IAB
New TPS
New ECT
New EGR vavle
Replaced the MAF with another used unit
Replaced coil pack with used unit

The car runs fine until the CEL comes on usually during cruise after the temp comes up to range.
My milege isn't horrible, 20 avg. 25hwy.@75-80mph

The trans. seems to shift fine. however the OD selector wont work unless the car is in neutral...it does work, you just can't lock out OD unless you put it in neutral.
That seem like an unrelated problem that maybe someone can address as well.?

I was thinking maybe a clogged injector? going to clean them next.

Any Ideas?

TIA

Bryan

 

[sdpatt]

Sounds like unmetered air is getting into the intake manifold to cause the O2 rich/lean codes. Since you mentioned that it didn't occur "until the CEL comes on usually during cruise after the temp comes up to range," it could be related to the EGR system. Double check the hoses and gaskets on the EGR system. Make sure the metal riser tube is still connected at the ****** at the exhaust pipe. Have it rewelded if necessary.

Also, if your idle really is at 650 rpm there is something amiss with the idle speed control. Check the sticky on setting the idle speed program here to ensure that the EEC is programmed correctly (if not already done).

You mentioned CEL flashes just after startup. The EGR system and O2 sensors are not brought into service until the engine comes up to normal operating temperature. If the flashes are due to the O2 sensors out of range then a problem could be the engine temperature sensor that provides the signal to the EEC. The engine may think it is warmed up when it is not.

 

[blowby]

I'll double check the idle speed.
I did do an idle reset a couple days ago when I was checking the ground wires in and around the engine compartment.

When you mention the engine temp sensor are you referring to the coolant temp sensor or is there another sensor I am unaware of?

I'll check the EGR hook up in the next couple of hous and let you know.

thanks,

Bryan

 

[sdpatt]

Yes, the ECT or engine coolant temperature sensor. This is the larger, more expensive, two-wire sensor below and to the aft of the throttle body. The temperature sender for the instrument panel gauge is the $3 one-wire sender below the thermostat.

 

[blowby]

Ok, I rechecked the idle..it's more like 750-800. My bad.

I checked the EGR hook-up and all is well with that.
I sure was hoping...

I replaced the ECT sensor last summer (the 2 wire one).

Bryan

 

[SolidState]

DPFE....I am am going to bet that it is either plugged nostrils, or a bad DPFE sensor.

 

[blowby]

Good thought.
Ideas on how to check DPFE to see if faulty?
I can pull hoses off to check nostrils.
Also, I believe it is pretty hard to get the hoses on in the wrong position, but does it matter which goes where?

The DPFE is located on the intake correct.?
What is attached to that mounted on the firewall? An actuator?

Bryan

 

[SolidState]

vaccum canister...

Is the car throwing any odd EGR related codes?

first thing to do is to pull off the throttle body and try to clean the nostrils at the 'V' in the plenum.

 

[blowby]

The entire intake just recently went through a thorough cleaning including the nostrils and the EGR passages.
I am only getting 172/136 codes now.
The CEL comes on 99% of the time under constant speed.
The EGR system could be the culprit, being that is when it is supposed to be operating.
If the EGR is open and the system doesn't recognize it it would lean it out and give me the 172/136 codes which would in turn cause the engine to try to richen the mix which would cause the rich codes I was getting on both banks before as well.
Also I can often get the CEL to go off after a bit of acceleration.
Then it comes back on after a mile or two.
And that could also explain why my mileage is down as well.
Do you suspect that migh also be why I don't get the CEL to come on over 80mph? (EGR valve not trying to open)
Now.... where to start?
Just replace the DPFE or can I clean it?
What about the vac. canister. Can it go bad as well?
Maybe I should just replace the EGR and DPFE.
Or can I just put a block-off plate on and eliminate the EGR.
No emissions testing here....

Bryan

 

[SolidState]

If you block off the EGR, you will get a constant CEL due to a no-flow situation on the EGR. You gas milage might suffer, emissions will increase, and you might find that combustion chamber temps increase, potentially creating pinging with lower grade fuel. I experienced all of the above whenI had to temporarily cap my EGR due to the EGR tube snapping at the ******.

The DPFE isn't really a complicated device, and it is riveted shut. I have heard of people opening and cleaning them, but when I attempted to clean my old one, it was destroyed internally. And, it was REALLY coked up with carbon.

Personally, I'd stay away from the Wells DPFE. I have heard they don't last long, and that leaves only the Motorcraft part from you local dealership. $$$. Very expensive.

I haven't heard of the vacuum canister ausing problems, however if it isn't functional, I could see it causing the EGR to either stay open or closed.

The next time I have a DPFE problem, I will no be replacing it, but rather I am going to purchase a TwEECer and delete the EGR all together.

 

[blowby]

I cleaned the nostrils on the DPFE.
They weren't that bad, considering the miles on it.
Anyway, that didn't help at all.
I am not getting any EGR codes.

Here is what I am getting:

KOEO: 111

MEM: 176, 177, 172, 543
(reset mem codes last week)

KOER: 172, 543

The 543 code is strange to me. (fuel pump monitor circuit shows no power)
Being that the car starts fine.

Any clues?

Bryan

 

[SolidState]

the 543 is caused by the other codes. Sounds funny, but it is true. On my orignal O2s (at about 140k) I had a 543 and 172, 173, 176, 177. Once I replaced the HEGOs, the 543 went away.

I see that you have replaced your HEGOs recently, so I am leaning towards there being a possible intake leak. Be sure to check all vaccum hoses.

oddly enough, I have had recent codes 172 and 176 due to a failing fuel pump, but that only occured at WOT.

 

[blowby]

I had another mechanic look at it with me the other day to see if I was missing something.
We sprayed it down with ether and no noticeable increase in RPM.
Checked intake vacume and it was great.
The thing that is getting me is that the car HAS to be WARM to get the codes.
The temp guage has to be well into the normal operating range on the guage before the CEL comes on. (I need to drive it for 5 miles or so)
The CEL then will stay on until it idles for 20-30 seconds or so or sometimes if I give it a hard accel. it will go off for a bit until the speed levels back out and I am steady with the pedal again.
I am Not getting any codes but the 172 and 543 now.
The gas mileage is down (consumption is up).
For the most part the car seems to run fine, however if I cruise with it at a steady speed for 15 miles or more it will start to buck a bit, assumably a missfire, when it acts like this the speedo jumps around 1-2mph (more of a wiggle really) but the tach stays steady.
If you give it gas the "bucking" stops but the CEL may stay on.

I am now wondering if it is just that O'2 that has failed.

Bryan

 

[SolidState]

doubtful, but possible.

have you checked the exhaust for any restrictions?

 

[blowby]

No,
But the flow out both tailpipes seems fine.

Bryan

 

[1slickRED89]

what part of Michigan are you in? if you want you can swing down to my garage, I have a break out box (BOB) and a tweecer (to spot check and log engine parameters.) I bet we could get to the bottom of it.

 

[blowby]

I'm just south of Grand Rapids.

 

[Griffin1001]

Let the rest of us know what you found, I am having similiar problems on my 94.

Thanks,

 

[blowby]

I have not had time to get this to someone with a BOB or Tweecer.
But I have noticed that when it starts it is REALLY rich.

Not sure if anyone has any clues to this puzzle....

I will hopefully have time to get this checked out again soon.

ITMT..if anyone has any other suggestions please comment.

thx.

Bryan

 

[Off Road SHO]

How do you know it's rich?

Tom