chrison600

Hi all,

It's been a LOOONG time since I've posted here, but we used to be pretty active in the red color section back when people were ordering their 2006 models. We ordered a red GT convertible with tan interior, black top, etc. It's been a great car. The only thing that's gone wrong is the alternator, which was an easy swap.

My wife recently got another car, so I've been driving the GT as my get around town car. I noticed some time ago that it seemed to be running rich, or at least starting rich, moderate fuel smoke, and has that rich running smell on initial start up. I thought it might just need plugs, so I had them changed at about 100k along with the trans and diff fluids and an oil change. There didn't seem to be much difference.

I'm wondering if there is anything I should be looking at as the culprit given the high mileage. Besides the smell/smoke on cold start, I detect a miss when bogging the engine from dead stop. Worse, there is an increasing top end "rattle" on cold start, like the cams are dry.

Could an issue with the injection system be washing the oil off of the top end?

Any help is appreciated.

Thanks,

Chris

07 Boss

First off, the injectors can't was down the top end. Impossible if you know how an engine works.

Since this is happening during open loop operation and you haven't done anything with the tune i would say it is mechanical in some way. Could be a few things. Injectors may need replacing if they are dumping too much fuel in the cylinders. Could be the MAF just needs cleaning. it is not putting the right amount of fuel in given the reading from the MAF. Could be incomplete combustion for a number of reasons. Bad air fuel mix or poor ignition.

The noise from the upper end can be just worn out parts or can be a oiling issue. These injectors themselves tend to be pretty noisy. Could be the phaser is not working correctly.

You're going to have to do some troubleshooting on your own to eliminate different possibilities. Could be variety of things going wrong.

Rather B.Blown

No CEL or anything like that?


If it sits for long periods of time between drives, enough oil could be draining back down into the pan to have a brief clatter on first start up, but if the oil pump is in good order it shouldn't be a very long period before it quieted down. Is the oil pressure showing to be in the range where its always been? How quickly does the oil hand come up on initial starting when cold and been sitting?


There's no way the fuel could be washing the oil out of the top of the engine, you'd have fuel in the oil pan and it would smell of gasoline on the dipstick. And for that to happen, you'd have to have a big problem that would cause much more serious symptoms in driveablilty than what you've got.



Maybe something in the throttle body? Maybe a sensor that monitors engine temp for cold start up and when to lean out? Maybe an injector leaking or sticking and dumping in fuel when not needed?

chrison600

Thanks everyone. I wasn't sure on the fuel washdown. I think this motor is direct injection, so the fuel can't get to the top end anyway.

I think I'll look at the basics of the intake: filter, MAF.

Is it common for the injectors to wear out at 100k miles?

What about the O2 sensors? At 100k maybe they should be replaced in order to send good info to the ECU?

Chris

07 Boss

On cold start, open loop, the motor is running strictly off tables based on air in and not using the exhaust sensors to adjust A/F. So the tables haven't changed that is why I was thinking MAF not giving you the correct air reading. Or bad injectors. Or bad ignition.

Are you sure it's fuel? The car will smell rich on start up anyways and maybe you're just noticing it because of the smoke. Could you be leaking oil down the valve guides or something like that? That would pool oil and smoke on start up. Oil in the cylinders would cause less fuel to be burned too. Maybe post up a video of the start up with the smoke and the top end noise.

mrkabc

No, this is not a GDI (Gasoline Direct Injected) engine. It's a multiport fuel injected system. Semantics aside, you are correct in that an injector would not be able to get fuel into the top end. Does your oil smell like gasoline?

First order of business IMO is to clean the throttle body with a can of throttle body cleaner. Also clean the MAF with a can of MAF CLEANER ONLY (not the throttle body or carb cleaner!!) Disconnect the battery so that the computer will clear. Wait 15 minutes or so to reconnect the battery, then start and test.

No, injectors shouldn't wear out that soon. They are noisy as hell, but the stock ones should last well into high 100k miles or more. Fuel injectors can be a suspect, but I'd consider a bad injector low on the priority list.


Are you throwing a code for bad O2 sensors? If not, that would be spending good money and effort for little gain.


When you had the plugs changed, did you save the old ones? Any oil/fuel fouled out plugs? Have you had a compression test done for the engine?


Start with the easy things first (cleaning TB and MAF). Also, try to isolate the rattle, does it sound like a fuel injector tick? Or does it sound metallic? Cam phasers are known to wear on our engines, that may be an issue if you are hearing a metallic rattle - however, before you go down that road try to isolate where the noise is originating, i.e., which cylinder bank, and approximately where in the cylinder bank.


Keep us posted as to what you find!

m05fastbackGT

Perhaps I may have misinterpreted part of your post, but if not.. None of the 05-10 Mustang 3v 4.6 engines have direct injection.. Not even the 11-16 4v Coyote motors have direct injection..

Anyway, just saying

chrison600

Sorry everyone, I meant MPI.

I'll clean the throttle body and MAF sensor and report back.

I'm pretty confident this is fuel smoke/smell. I'm familiar with the differences in smell, so a few times I've started the car and run back to smell the fumes and it's definitely fuel. Both the fuel smoke and rattle are new and worsening behaviors, so there's definitely something changed/changing. The rattle stops once there's oil pressure (just a few moments), so I do think it something lubricated by oil that's making the noise.

I'll report back once I clean things a bit.

Chris