Ok, so here's the deal. A couple of days ago the wifes 98 Expy started having part throttle exceleration issues that activated the CEL. Pulled the codes, and found 0133, 0401, 0308. Did Vac check on the EGR, engine stalled. Looked for vac leaks, hoses and fittings appear to be in good condition, with no noticable hissing sounds. PCV hose assembly was replaced about a year ago, along with all COPs and plugs due to multiple misfire codes and finding vac leaks during that episode.

Knowing the 0401 code could cause multiple symptoms I chased that to the DFPE sensor. Reset codes and next came 1100, 0153, and 0308. Again, I replaced all COPs less than a year ago with Accel COPs, and replaced all plugs with Motorcraft plugs. So I am having trouble believing one of those could be faulty. One question coming to mind is this: could the 0153 code cause a lean condition that would cause the part throttle (1/4 - 1/2) miss, and the 0308 misfire? The intermittant MAF sensor could play into this too I think?!?

I also performed a KOEO test using the AutoEnginuity ScanTool and came up with several O2 sensor monitoring warnings, Catalyst bank1 and 2 switch ratio warnings, Evap system warnings. So much information, I am beginning to think I did something wrong.


Any help would be greatly appreciated.

Fyrbrd

 

It happens all the time, so why are you having trouble believing a part can be faulty or fail prematurely? Swap the #8 COP with the one next to it and see if the code moves with the COP.

 

Hi alloro,

Thank you for your response. To be honest, the reason I don't believe it to be the #8 COP is the truck idles smooth, and with less than half throttle it excelerates smoothly. It only acts like its misfiring with more throttle. If I advance the throttle smoothly, it behaves, if I stomp it, it stumbles. Also, getting the 0153 code is making me think a faulty O2 sensor could be creating a lean or rich condition that is triggering the misfire. Yes, changing out the coil to see if the misfire follows is one approach. You know how much of a pita that COP is, so I hope you understand why I am looking for other possibilities.

Thank you,

Fyrbrd

 

This is classic weak spark symptoms. Weak spark can't fire with more throttle because the density inside the cylinder has increased. A bad O2 sensor is more likely to effect all 4 cylinders on the same side of the engine rather than just one cylinder. This is because each O2 sensor helps to control the air/fuel mixture for that side of the engine.

 

Hi Alloro,

That's what I'm afraid of. Let's say for instance it is the #8 cop, could that trigger the 0153 code? Unfortunately, I won't get home from work until around 10pm so I will have to wait till morning to swap the cop. Just don't like doing that job buy work light, too much crap to work around.

 

Well, they are both on the same bank.
Could also be an issue with the #8 injector.

Look at AE's freeze frame data. The DTC that appears there is the first code that was set.

Have AE display the MAF voltage PID while you wiggle the MAF connector and lightly tap on the MAF. If the MAF V PID drops below .25V or spikes above ~4.5V there is an intermitant issue with the MAF sensor.

 

Even though you have replaced some of the PCV vacuum hoses a year ago you should get the elbow off of the back of the intake and check it carefully in the area of the 90* degree bend as that matches your symtoms, IMO. If the elbow is the problem it's available at Autozone for less than $5.00

 

Helo All,


Thank you for your replies, they are all helpful. When the problems presented I did check all the vacuum lines, including the 90 degree elbo at the back of the intake. When I changed the COPs the first time, I kept a couple of the good ones that I took off. Swapped the #8 Accel COP with one of those and for now the part throttle miss seems to have been resolved.


Now my question is this: could the misfire on the #8 cyclinder have caused evap system issues, the MAF sensor issue, and the O2 sensor issue?


I suspect the rich exhaust condition created by the #8 misfire is the casue of the O2 sensor? Is it possible that the recirculation of the rich exhaust gasses casued the PCM to send bad information to the rest of the system?


Thank you all for the help you have provided.

 

No.

No.

Maybe.


I'd write the codes down, clear them, and see what, if any, come back.

 

Hi Pdq,

Thank you, that' s what I am doing. Took it out yesterday evening to see if the cel came on again, it didn't. Figure I'll check for codes this evening even if the cel is not triggered.

Fyrbrd

 

It can't be hard to chase a Gremlin with an Expy. I think they only had about 100hp.

 

Sorry I was wrong, in the last year you could option up to racing stripes and a buck and a half.

 

Their Back!!!

I know it has been almost a year, but the gremlins came back. Friday 11/8/13, the truck decided it no longer needed the #2 plug. It ejected it completely buggering up the threads and destroying the COP. Being cautious, I took it to Ford and let them fix that problem. I know, chicken s**t... Well, got the truck back and it still has a miss at part throttle, but only while under load ie: driving. I can not duplicate the miss sitting still. The miss is not triggering cel. I used my AE scantool to see if there were any non cel triggering codes present, nothing. With AE still connected in live data monitoring I selected engine misfire monitor and took the truck for a drive...during the drive when I made the truck misfire the AE engine misfire monitor would read 1, let off the gas and reapply throttle slowly AE would change back to 0. Still no dtc's present.

My question is, what is AE telling me, cylinder #1 misfire or one cylinder misfiring? Is there something else I can monitor to help narrow this down?

Fyrbrd

 

You want to select "OnBoard Test Results" and then scroll down until you come to TID $53/CID$01. There you will find the % of misfires per 200rpm for each cylinder.

 

Hi pdq,

Thank you for your reply. As I mentioned in caverjoe's thread I was able to find the TID $53 results, however it was displaying 0 occurrences. After letting the wife drive the truck yesterday, the misfire triggered a flashing cel. Freeze frame data showed #4 misfire. Changed the cop, cleared the codes and everything seems fine for now...

Thank you,
Fyrbrd