That actually sounds about right.

 

check the cop's !! before throwing more parts at it

 

If you have high milage and old O2's replace them, it will do wonders even if that isn't the only problem.

 

Just finished getting a Flowmaster Super44 muffler put on the truck and man was the stock muffler heavy not to mention not even a speck of light shone through it. I have no Cat convertor just a huge resonater and boy does it sound sweet. Noticed a difference but, I'll know more tonight when I'm not at work.

New serp belt put on cause my other one was ready to blow up.

 

No change after muffler except for better low range power. O2 sensors are next. How to you check cop's when the only time the truck is acting up is under load and still never had a CEL. Are the COP's grounded through the manifold? Could this be EGR or TPS related? I'm grasping, any aadvise is greatly appreciated, thanks.

 

A misfring coil will not cause a CEL unless there is a complete failure of the coil. You can always buy a coil and start swapping it around to see if the problem goes away.

 

I have noticed that since I got the muffler changed that the engine will not idle properly, fluctuating and somtimes dying. Could this be because the engine computer needs to re-map or reprogram for the performance muffler that was just installed? After doing the MAF, cam sensor and muffler I did pull the positive cable off to erase the computers memory. does that trick even work on the newer OBD2 systems?

 

It may be the muffler is not allowng the proper backpressure (to much/not enought?). Which muffler you have on there now? Do you still have the stock one you can put back on as a test?
Pulling the battery cable will earse the "adaptive" learning that is stored in the PCM. It should then go back to factory values and relearn from there.

 

Flowmaster Super44 muffler. The stock muffler heavy not to mention not even a speck of light shone through it. I have no Cat convertor just a huge resonater and boy does it sound sweet. Just gotta get rid of the dreaded flutter...

 

A muffler will have absolutely no effect like what is described here.
This is a fueling/spark related issue,or possibly a poor condition engine with very low compression.
JL

 

My truck performs better with the headers exhaust and muffler. I've never had any ill effects when switching out a muffler, going to headers or even swapping out cats. The problem is elsewhere.

 

I guess we got off topic a bit with the muffler.

The origional problem is harsh pinging or valve float. I'm leaning more towards pinging due to a fuel condition.

What i have done sofar is:

1) Replaced the MAF sensor with a new one 40kms ago
2) Plugs (motorcraft) about 5000kms ago
3) COP boots about 5000kms ago
4) New air filter (K&N OEM replacement style) about 3000kms ago
5) New feul pump and fuel filter about 4000kms ago
6) New cam position sensor 40kms ago
7) New muffler (Flowmaster super44) 40km ago
8) Seafoam treatment through brake booster line 5000kms ago
9) Inspected crank endplay - Good no movement 1km ago
10) Tested fuel pressure - Good within range 40km ago
11) Replaced serpentine belt (New Dayco) 40km ago

Next on the list is to replace the crank sensor and both O2 sensors and buy a COP and start rotating it till I have all 10 tested.

My bank account is looking a little thin right now but, good thing I'm a mechanic or labour would kill me. This is really frustrating me because I should know how to fix my own truck, right.

 

I just threw my Hand held cheapo scanner on the beast and got a glimmer of hope. No codes but, I got a I/M moniter condition for a EGR valve. Never showed up before but, I will have one tommorrow to put in. Let you know

 

Just hooked up my cheapo scanner and it came up with a pending EGR condition. No codes but it showed a possible problem with the EGR system so I have one on order. The closest leed I've had yet. Should have it replaced by tommorrow and I'll keep you posted

 

Dang, I keep forgetting that the '99 has an EGR... that could very well be the pinging problem.

Before just going out and buying one though, hook a hand vacuum pump up to the EGR and pull vacuum on it - if the engine stumbles at the exact same time, that means the EGR is functioning. Then go back from there and see if it's really getting a vacuum signal from the engine. Hitting the throttle slightly while at idle SHOULD make the system apply vacuum to the EGR. Should... when at normal operating temp.