Mustang Injectors, Now it Won't Idle

[ClayW]

I installed Bosch 0280155710 injectors (eBay rebuilds) in my M42 and now I can't get it to idle. It dies if I don't keep the throttle up. I found that I could keep the engine alive by holding the AFM door open a little.

My first thought it that I messed up the intake manifold gaskets and it's getting air, but reading less from the AFM, which would explain the change when I open the AFM. Tomorrow morning I will remove the intake and try to patch things up with RTV (new set of gaskets on the way, even if I don't need them).

Barring that, any other ideas on why it might not be working? Can I test the basic functionality of the injectors when I have the intake off?

Thanks in advance.

[DesktopDave]

I'm thinking you're right...a vac leak.

I whipped up a test rig for my injectors with a 9v wall wart, a momentary switch and an old injector connector.  They click when they're energized (whether clogged or not).

[ClayW]

http://www.youtube.com/watch?v=PIOJAiLU4Vo&feature=youtu.be

Here is a video of the rough idle. I removed the intake and sealed up the gaskets, which improved it to this level.

Is there possibly a step that I missed with the new injectors? Was this plastic part supposed to be removed?



EDIT: One more idea: The gas in the car is 6-7 months old and I can't be sure how well the fuel vapor system is sealed, if at all. Could bad gas cause this behavior?

[d.hitchcock]

I'm no expert on these injectors, but it looks like you're missing the pintle caps on the ends.

[Geoff]

I agree, these injectors usually have those blue caps on the end, or some kind of pintle cap
                                                       Geoff

[ClayW]

These are Bosch 0280155710 injectors. Should I remove the pintle caps from the old injectors and put them on the new?

I bought them from this guy: http://www.fuelinjector.citymaker.com/catalog/item/4494564/4706227.htm

[Geoff]

you should probably get in touch with the vendor and ask him if they should be used on those particular injectors.   I will say I have always seen them on there.
                                                               Geoff

[lqbanotxano]

I have the 700 injectors & they don't have a pinttle cap. They look just like the 710's. Mine have been running fine for about a year. I don't have a washers on mine....they are just installed as the originals. They do fit a bit more loosely in the manifold than the originals though.

[ClayW]

I have the 700 injectors & they don't have a pinttle cap. They look just like the 710's. Mine have been running fine for about a year. I don't have a washers on mine....they are just installed as the originals. They do fit a bit more loosely in the manifold than the originals though.

So you just installed them as is, with no washer or pintle cap?

[mr ilia]

The thin injectors have flat bottom tip. The op's picture shows proper hats. There is nothing is missing.

Also, old gas as well as possible vacuum leak is a likely reason for poor idle.

[ClayW]

I used RTV to seal up the manifold gaskets (proper replacement tomorrow) and it smoothed out a little, but it still won't hold an idle.

I did the stomp test and got the 1215 code, indicating an AFM problem. I'm checking that now. I'll update in a bit.

Further UPDATE: We tested the AFM and it's fine, so we assumed a vacuum leak. I held the AFM to keep the engine lit while spraying carb cleaner around the gasket surfaces. There was a throttle blip when I sprayed around the #3 upper manifold gasket. So, new gaskets are coming tomorrow.

Here is the test video: http://www.youtube.com/watch?v=7ZwuXsBg98w

You can see the blip on the tach here: http://www.youtube.com/watch?v=fesDkjzZutc

[ClayW]

I ordered new gaskets and decided to try another set of injectors. When we removed the manifolds to prepare them for the new gaskets, we found this:



I have no idea how this part of the manifold got hit hard enough to gnarl the mating surface, but it was certainly enough to not allow #3 to seal up, in addition to a torn gasket. So, we carefully filed it down to flat.

Did I mention that I'm road-tripping this weekend to North Carolina?

[ClayW]

We buttoned everything up last night and she started right up, idling smoothly at 800RPM. The Bosch 0280155710 injectors seem to be working like a charm. I'll be interested to see how the fuel mileage works out.

[mr ilia]

I did my injectors a week ago and did about 500km, new injectors already paid for themselfs, my milege increased by about 30%....this is certainly surprising. On 30 liters of premium i did 350km, where before with old injectors i had to get full tank to get the same distance.

Forgot to add, the injectors that i installed are off 1997 lincoln continental 4.6 dohc...i beleieve they are 24lb @ 43.5 psi.