Rough idle after new injectors

Dmod81 · 03-26-07, 07:14 PM

I installed new injectors to fix a hard start when hot condition, which did get fixed. Now it idles really rough. It will hunt for a idle speed for about 20 seconds then settle at the idle speed that it was at before I replaced the injectors, but roughly. Also the new injectors are extremely loud. Any ideas?

Thanks

91 manual

Achilles · 03-27-07, 10:21 AM

What size injectors did you install? Is your motor stock? Did you drive the car to warm operating temps afterwards to reset the ecm.

I usually disconnect the battery before I make any modifications so that on restart the computer can relearn the changes and adjust accordingly. I don't know if that needs to be done with the latest ecm's that are available today, but someone told me that once so thats just what I have always done.

Dmod81 · 03-28-07, 04:54 PM

I believe they are the same as stock, 22lb. I got the ford/bosch yellowtops. Engine is stock, and I did reset the ecm drive it to operating temp.

Achilles · 03-28-07, 07:01 PM

Hmmm...Bosch yellow tops = 22#? I had a set of pink tops that were 22#. Maybe they changed their colors.

If they are 22#, you shouldn't have any problems unless one or more of them are leaking.

vetteboy86 · 03-28-07, 07:18 PM

Possible vacuum leak causing the IAC to search for a correct idle on start up? But that wouldn't make any sense as to why the idle finally does correct itself.

Dmod81 · 03-28-07, 07:26 PM

I looked closer at the fiveo motorsport website. It seems the yellow ones might be 19lb injectors that he is selling as a direct replacement for stock. The set he sells for the chevy tpi are yellow, but say 22lb, while all other yellow ones on the page say 19lb. I think I may have been ripped off.

Achilles · 03-29-07, 09:30 AM

Sounds like it.

vee93 · 03-31-07, 04:30 PM

Maaaaybe not ripped off--maybe the vendor made a bad assumption so a mistake was made!!! I'd contact them with your info about the injectors and have them check.

Achilles · 04-01-07, 07:38 AM

I would ask them for the pink tops. If you actually do have 19#, you may have a lean condition causing you problems.

fatboyreyn · 04-09-07, 05:48 PM

Quote:

Originally Posted by Dmod81

I installed new injectors to fix a hard start when hot condition, which did get fixed. Now it idles really rough. It will hunt for a idle speed for about 20 seconds then settle at the idle speed that it was at before I replaced the injectors, but roughly. Also the new injectors are extremely loud. Any ideas?

Thanks

91 manual

How was the replacement job. How long. Any problems? Thinking about changing mine.

Dmod81 · 04-10-07, 01:13 AM

This was the second time (now third after I put pink tops in) that I have taken the top end apart. The first time was for intake gaskets. So I have it pretty much down to about 4 hrs total. When I get down to the runners, I only take off the passenger side and that saves some time. Job isn't really too bad, except the gas everywhere... Make sure you have something to cap off the fuel lines ready before you start.

jam019 · 05-29-07, 08:10 PM

Hope you didnt buy them for Fiveomotorsport, if so good luck..

Achilles · 05-29-07, 10:15 PM

Quote:

Originally Posted by jam019

Hope you didnt buy them for Fiveomotorsport, if so good luck..

I bought mine from FiveO & had no problems. I'd buy from them again.

jam019 · 05-30-07, 05:17 PM

You might have to.

Black Bart · 05-31-07, 06:47 AM

FORD injectors are rated at 39lbs fuel pressure and GM injectors are rated at 42lbs. so when you put a ford injector in a GM with 42 0r more lbs of fuel pressure the engine will run rich.
People buy the ford injectors because they sell for less and they don't understand that they need to calibrate the ECM for these to run properly.
This is a small difference and unless you have an air/fuel ratio gauge or pay close attention to your mileage you won't know that they are not providing the correct A/F ratio.
I don't think that is the problem with your idle but you need to know that these are NOT the correct injectors for your engine.