EGR Valve: If you kept the valve tipped up while cleaning the plunger, you might be okay. But if you got the least little bit of carb cleaner on the diaphragm, you can kiss that one good by. Also, blowing out the EGR valve will blow the diaphragm.

IAC: The IAC has quite a few rubber like bushings, grommets, seals inside. Carb cleaner will compromise that sensor by melting rubbers and plastics.

TPS: These have thin plastic ribbon wire just on the other side of the terminal. You can melt those as well.

Use something safe , like DeepCreep for the IAC. That lubs and cleans. DeepCreep is made by Seafoam and it good stuff.

If you screwed the TPS up, you'll get a CEL , -almost always. If you blew the diaphragm in the EGR valve, you should get a fault DTC for that as well. The IAC , you probably won't.

Bluegrass covered the misfire. Only thing I can add; - when accelerating normally and at about 45 mph right after the shift into OD, does it misfire ? If so , you have a low grade misfire and that's where a coil likes to act up in the drivecycle.

 

Thanks jbrew. It never occurred to me about all the seals.Lesson Learned on this one. I'm going start replacing all 3 Monday starting with the IAC. Hope to have all 3 done by Friday

 

update... it's been 2 weeks now since I screwed this up. Replaced IAC and EGR last weekend. Finally threw a code of 303 #3 misfire. Swapped out cop and re-checked plug which looked ok. Still runs like crap and C.E.L. came on again last night. Gotta get the code tomorrow for this time. I hate having my truck run like crap and this is driving me nuts. This was suppose to be a routine tune-up. Without my own code reader I have to count on someone else before I can proceed. I'm really considering a Gryphon or such just because of this.

 

A scanner is allot cheaper. Harbor freight had the cheapest , for $39 I believe. Mine was $69 @ Sears.

 

There is a Harbor Freight about 10 miles from me... I will check there first. Thanks JBrew

 

Got new codes this morning from AutoZone. They are 303 (still) and now 316. Gonna try changing out the plug this time and have yet to find any bad vacuum lines but still looking.

Where exactly is the crank sensor located? My Haynes manual is not very specific (edit... n/m.. I think I found it from underneath the a/c compressor)

jbrew, I looked at the Readers at Harbor Freight online. Reviews were a little iffy but the Zone has one for 60.00 I'm going to pick up and try this weekend

 

Well I think I finally got it.... . Ultimately it must have been a bad new plug causing the miss. Didn't do anything with the CHK except unplug it and plug back in. Runs like it should now.

Thanks jbrew and Bluegrass

 

Wait, what did you do? I don't understand

 

Code 303 cyl #3 misfire I swapped out the coil.. again... and changed the new plug back to a previously installed one.

Code 316 CHK sensor I didn't do anything but unplug it and plug it back in.

She runs fine... so far.. drove it for about 30 miles and seemed ok

 

Walmart online has a nice little Equus scanner for about 49 bucks. The $30 one at amazon.com looks pretty tacky.

 

do you have a link for that? I coming up empty so far

 

Light load misfire caused by a bad coil:
Under light load such as in OD and light throttle, the PCM program goes into the EGR mode.
When this happens, the ignition timing is advanced, the fuel is cut back and EGR opened.
If a coil developes lowered output from shorted turns (not a full failure), the very lean mixture from the fuel cutback and small amount of exhaust piped back into the intake through the EGR, missfires only as long as these set of conditions are present.
The program sees the fault, you feel the miss, but doesnot set a fault code or CEL lamp because it's of a temporary nature.
Finding the offending coil is the difficult part because there is no easy way to tell unless you look deep into the program with a good scanner and know what you are to look for.
The reason for the missfire under these conditions is the air to fuel ratio is in the order to 20 to 1 ratio instead of the normal 14 to 1 for gasoline.
These high ratios require much higher coil output voltage to fire.
You can now see why a coil with lowered output will missfire that cylinder under those set of conditions.
To add more info, the advanced timing is needed because the very lean mixture must be 'lighted' much eairler in the cycle due to the slowdown of the flame front speed in the cylinder. All this is being measured for time interval by the crank sensor as well.
The fuel is cut back for at least two reasons. To improve fuel mileage, to allow the EGR action to lower NOX emmissions. The results of these actions is to improve fuel mileage, reduce NOX emmissions and to make the total operation transparent to the driver as far as how the truck drives.
When you have just one issue that upset the whole operation, you then feel the result as a random type of miss, usually under light throttle conditions.
The PCM program is set up to generally run the motor as lean as it can get away with, without missfire to offer better fuel mileage but power does suffer a bit by doing this.
This is why tuners that alter the program, can offer some improvement in power.
Good luck.

 

I understand what you are saying Bluegrass, but certainly 4 different coils could not all be bad. The only thing I had not changed after the initial new COPs/Plugs were installed was the spark plug itself. When I took it out this morning it was wet and definitely not firing. Changed out the plug and now it seems to be ok.

The misfire I had was under all conditions. I could not drive it at 5mph let alone 50 without forcing it to downshift and run harder which I felt was not good for my engine. The next few days will tell

 

http://www.walmart.com/ip/Innova-303...i_sku=13029622

 

Good you got all the issues solved.
You found out these system look at a lot of things.
If you cause more issues than originally were present, it can be maddening to some owners until you go round and round and get even more confused.
Each work operation has to be done carefull and not lose sight of the possibilty of causing additional isses that complicate matters in the pursuit of 'happiness'.
Good luck.