Hard to diagnose

[Ebony LSE]

I purchased a 2004 LSE V-8 with 65,000 miles on it back in September. It had an engine misfire when I got it and I took it to Ford to have COPS replaced. They did 2 of them and I ended up replacing the other 6 on my own dime not wanting to bring it back to them 3 more times. All 8 COPS and spark plugs were replaced within 100 miles driving. The car then developed an issue with stalling. It stalled in traffic on the highway and I had to restart with a truck bearing down on my bumper. That was solved with my mechanic cleaning the throttle body especially the throttle plate. He checked for air leaks in the intake and found none at the time. No stalling since then.

The car has been running well for the last couple of months, but I only got 10 mpg on one 8 gallon fill and the car is slightly hard to start and runs rough for a couple of minutes when I drove it 30 miles on the highway then parked it for 20 minutes. Rough idle cleared up almost right away.

My typical drive in this car is short distance under cold start conditions, so mileage is mostly about 15 mpg, but sometimes is much lower (10). The prior owner also drove mostly short distances. This is a California car and cold start is about 50 to 60 degrees outside temperature -- no snow or ice.

So drivability is mostly good now. Acceleration at mid throttle or wide open throttle is always good, but I would like to have everything perfect if possible. Any advice on what to look for would be appreciated. I really like this car and want to keep it in top condition.

 

[G-RELL]

not sure what the life of a fuel filter is... but you can start there

 

[LS4me]

Gas brand? Using 91 octane?

 

[Ebony LSE]

Thanks G-Rell and LS4me. I did the maintenance items when I bought the car in September, including fuel filter and engine air filter. I use Chevron 91-octane and Shell or 76 when that is not available. Bad gas is pretty rare with these brands, although some say all California Winter gas is pretty bad. Also, I have never had a check engine light since I've owned the car, and ODBIII scanner turns up nothing.

 

[wade0731]

Check your CAT, this could cause stalling and bad MPG I believe. Have it tested at a shop to see if it is clogged.

 

[Ebony LSE]

Check your CAT, this could cause stalling and bad MPG I believe. Have it tested at a shop to see if it is clogged.

Can a catalytic converter be clogged without drivability issues all the time? The engine revs fine and idle is stable other than the warm restart issue I mention in the first post. Engine power also seems good.

 

[joegr]

Can a catalytic converter be clogged without drivability issues all the time? The engine revs fine and idle is stable other than the warm restart issue I mention in the first post. Engine power also seems good.

Never say never, but probably not.

I wonder if maybe you have a fuel injector that is not closing all the way?
It also seems like maybe you aren't often getting the engine hot enough to burn off the bad stuff in the crankcase.

 

[Ebony LSE]

I wonder if maybe you have a fuel injector that is not closing all the way?

Joe -- This makes some sense. The warm start up issues seems to me to be similar to what we used to have on carbuerated cars with a flooded engine or when the choke was pulled out when trying to restart a hot engine. How would you go about testing fuel injectors to see if they are not closing all the way?

 

[joegr]

One way would be to pull the rail and all the injectors out just after shutdown and see if any are dripping from their nozzle. Be warned that if you do, you should replace all the o-rings.

 

[Telco]

Before you go through the hassle of pulling injectors, try running some Lucas fuel injector cleaner through the car. If it's varnish buildup or debris holding the injector open, chances are this will clear it. Alternatively, you can use Marvel Mystery Oil in the gasoline. I've used both effectively. If either of these products fail to clear the problem, you can always pull the injectors after.

 

[Ebony LSE]

Before you go through the hassle of pulling injectors, try running some Lucas fuel injector cleaner

Hey Telco, I never noticed much difference after running gas treatments but I started reading some of the reviews for Lucas upper cylinder lubricant and it has a lot of fans. I will give it a try and let you know if this clears the problem.

 

[jjcool00]

When I had a clogged cat I noticed severe hesitation issues.

 

[Ebony LSE]

I plan to put some 3M gas treatment through the tank next week to see if I can clean out the injectors and will report back with results. I have to figure out who to take the car to in the SF Bay Area to get the fuel injection diagnosed as I am not confident I have the skill and tools to do it myself. I wanted to check with some of you experts out there and see if anyone has had an issue with heat soak of an injector with winter gas causing vapor to build up in the injector when the warmed up car is parked for a while. My car is a 2004 V8 with no modifications and 65,000 miles.

I saw this on a Jeep CJ forum with the symptoms "Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a prior 10 to 20 minute heat soak." This is exactly the symptom my LS is exhibiting. Here is the Jeep forum post:
http://www.jeepforum.com/forum/f11/rough-start-when-warm-heat-soak-1152025/

 

[Ebony LSE]

Well I used a bottle of 3M gas treatment and the car does seem to idle smoother than it did before. It could just be my imagination. I have run a couple of tanks of Chevron 91-octane through the tank and I have not experienced the heat soak problem again, but my theory is still that my issue was due to California Winter gas. I am pretty sure the last tank I got is not the Winter blend, so I will have to wait another year to see if the problem reoccurs.