Hey guys, for the last couple months or so every time I start the truck up cold it runs super rich, can smell raw fuel in the exhaust, and idles like crap. After she warms up in like a minute or so it smooths out and runs great. If I start it up while its still warm it runs fine, its just when its cold.

The only engine codes I've gotten is a cyl.#1 misfire every few weeks or so then it goes away. I got a cyl.#8 misfire the other day but I cleared it and hasn't been back. When ever I get a misfire code it occurs after a cold start so pretty sure it has to do with the rich problem.

I replaced the map sensor ans ECT recently thinking they may be the culprit but no such luck. Tune up with plugs, wires, cap/rotor done within the last 10K. Also new NTK O2 sensor not too long ago but really not thinking o2 because this occurs when its cold and the o2's not being used.
Fuel pressure test shows 46ish psi, and it does drop off after the fuel pump primes but i know my check valve in the fuel pumps leaks because I gotta prime the pump 2-3 times before it will start.

Only other thing I can think of is a leaky injector and thinking of pulling the rails and turning the key and see if fuel leaks out of any of them.
Any other ideas or suggestions would be greatly appreciated!

 

If it were a leaking injector, just warming up probably wouldn't solve that. Are you blowing black smoke at a startup?

 

Only thing I can think of is maybe you have a injector or two that a little sticky and are slow to close up till they warm up.

 

Thanks for the replies,
HeyYou: no its not blowing black smoke, or any smoke for that matter at start up or any time.
Silconcer: That's possible, would ohming them give me an idea? I did take off the rails and turned the key a few times and none a leaking when its not running anyway.

 

Unplug the electrical connector from the coil. (not the wire to the dist, the one that feeds power TO the coil) Crank the engine a LITTLE bit, injectors should spray, and stop. If they don't, thats a problem.

When is the last time you changed your oil?

 

Last time i changed oil was about 100 miles ago, so not too long ago. the oil didn't smell gassy at all so that's a good sign.
While i was in there today I took the TB off to clean it again and took a sneaky peak down the intake and notices there was oil pooling, not terrible but more to suggest just the PCV. I fixed my plenum about 30k ago with just gasket and shorter bolts. I don't think a leaky plenum is related to my problem but i don't know.
After I saw that I went a little over bored and jumped on ebay and bought a Mopar M1 intake that comes with 8 new injectors....
Once I get that all together I'll see if new injectors solve the problem, wish I would have read your post before I tore down, I'm kind of curious to see if they stop or not.
Just wondering by the way, does the air intake temp. sensor have much to do with the air/fuel mixture at start up?

 

Yep. PCM will use that to alter injector pulse according to temp. If it's REALLY cold out, ya get more gas.

 

Ok thanks, do you think its possible a faulty iat sensor would cause it to dump a bunch of fuel and then lean out as it warmed up, and not throw any codes?

 

Possibly. Get a scanner that you can hang onto for a bit, and see what the PCM thinks air temp is when the engine is cold. (should be VERY close to ambient. and around 130 or so when engine is fully warmed.)

 

So just an update, I replaced the intake along with new fuel injectors and all new sensors up top (iat, tps, map, iac valve, ect). BTW I got a good deal on this stuff otherwise I wouldn't be throwing that kind of money at it if I was paying retail price. Anyway it idles MUCH better and overall runs better, however after start up I still can smell a hint of fuel. I thought I'd check over the EVAP system for leaks and such, long story short I broke off the end of the evap canister where the line coming from the gas tank hooks to...
So two questions,
1. Does it hurt to bypass the first canister (the round one) and hook everything directly to the 2nd one (the rectangular one) temporarily until I get a new one?
2. Do you think that some faulty thing in the evap system would cause a fuel odor on cold start ups at all?
I wish I could get a hold of one of those scanners the display real time data so I could get a better idea if it is a sensor somewhere.