I have a 97 Sebring Coupe I'm working on.
Problems the car has..
1. Came to me with codes P0300 and P0303 Random misfire (300) and cyl 3(303) MIL on. Cleared the codes and MIL has remained out.
2. When its cold(sitting overnight)
It will not idle -it will run if foot is kept on accelorator and kept above 1000 rpm
When operating temp is reached it will idle & run fine no problems.
3. Will not pass emissions test (plug& play) because it will not pass readiness tests.
Here's what I've done Full Tune up, all O2's changed, IAC changed, Egr changed (then blocked it off completely) Diagnostics run with my handheld scanner not a DRB & no pending or stored codes.
Took it to Dodge dealer & they changed & programmed the computer
NO HELP with any of the issues. I've driven it for the last 3 days & my scanner still says that readiness tests are not complete.
All sensors I can read with my scanner show normal values
Anyone have any insight or recall any past troubleshooting tips?
TIA

 

while driving home last night I had my scanner plugged in to monitor sensors and computer. Half way home it finally registered readiness tests complete.
The only way I knew to check my scanner at that time was... You guessed it the MIL came on
Fault codes registered P0300 and P0303. Random and # 3 cyl misfire.
Any thoughts on troubleshooting before I load the final shotgun shell(Distributor)?

 

Has this just started? Have you checked the gas for any water contamination? May try the least expensive way out for the moment and run some dry gas called "Heet" through the next tank of gas to absorb out any water in the tank or lines!

http://www.goldeagle.com/brands/heet/default.aspx

 

Since the problem seems to be coming from that #3 cylinder, you might want to replace the spark plug wires. I assume you have already changed the plugs. Why was it that you blocked off the EGR? That's not a good idea. The EGR system keeps the engine combustion temperature where it needs to be.
Have you run a compression check?

 

Problem is not recent, This has been going on for about a year and a half This is just the first time it's had to go through emissions with this owner.
I live in Az and we have very few problems with water in the gas, and a few ounces of Isopropyl alcohol has been added to the tank, Thats the same stuff that dry gas is. Alcohol mixes with the water and diperses it into the fuel allowing it to be consumed with the gas in the tank.

When I stated that a FULL tune up has been done I do mean Plugs and wires cap and rotor. Problem was occuring before tune up and continues afterward.
I did mention that after the car was warm there is no problems with how it idles or runs if it actually has a cylinder down or missing you would be able to discern a skip or miss.
My thoughts are that it logs the misfire while it's warming up and running like crap, then once the readiness tests pass it will then show those faults.

 

Have you checked for any cracks in a intake port or manifold intake runner or collapsed gasket on that or any other intake ports?

 

Intake leak checks have been performed with Carb cleaner-no defects-

 

Have you done a cylinder compression test and a leak down?

When was the fuel filter changed last? And if its new, whats the fuel rail psi?

Have you taken out the injectors and cleaned them and do you know what the injectors flow rate and pattern is and is it far off from mfg spec's?

Has the car been ran with a top tier gasoline (name brand, Shell, Exxon etc..) or just any old stuff from the Mom and Pop station down the road?

And have you tried a top end cleaner in the fuel (SeaFoam, BG44K, Marvel Magical Mystery Oil etc...) something for cleaning valves and combustion chambers and tops of pistons, you may have carbon deposits effecting things? Just a guess on that one! Just the same maybe a good idea....

 

Pulled injectors out today. Will be taking them to the cleaners tomorrow.
FWIW Chrysler Tech told me that when they did the computer change
the Throttle body looked pretty dirty and should be cleaned....
What a crock of Shi7 I pulled off the TB today along with upper manifold again and
TB was clean as can be. It didn't look like it had been on the car for 1000 miles. Upper manifold has a dry sooty carbon coating inside, as you would find from a EGR valve.
BTW found old repair receipts in the glove box and EGR, IAC, Distributor, had all been replaced last year. car still had the problems when it left that shop.

 

With all that off right now is a good time to also look at what the plugs are telling you too!