EFI surging idle???

[BroncoinAlaska]

The EFI has developed a surging idle problem. I cleaned the IAB but it had no effect. I also cleaned the the MAF sensor but that made no difference. The only other idea I had was a vacuum leak. What is the best way to search for a vacuum leak on the EFI?

Also searched and found that the position of that IAB could effect the idle. What is the correct position? I also have a BCBroncos throttle cable and plate so it seems as there is only one position that will fit.

 

[DirtDonk]

The BC cable (with the wedges) can actually be aimed in different directions depending on the orientation of the pair of wedges.
They're designed to go one way, to more accurately line up the cable end with the pedal, but I'm thinking that some applications could use some more angle to the driver's side.
The GT40/Explorer upper is right in the way of the cable as it exits the firewall and "aiming" the cable to the left a bit seems like it would help in that regard.

As for testing for vacuum leaks, as long as your paint isn't new, I prefer spray carb cleaner to check each seam, joint or seal. Obviously, with new paint around, that wouldn't necessarily be a good thing to use!
A spray bottle of water than? Maybe even brake-cleaner would be ok, since it rarely stays liquid long enough to hurt paint.
But you didn't hear that from me.

Whatever you use, as you spray it around, your idle will change the second you find a hole. Depending on how the engine is tuned, and what chemical you use, your idle might either go up, go down, smooth out, or get rougher. Bottom line though, is that if your idle changes when you spray a certain spot, that's a leak.

Paul

 

[Broncobowsher]

Question for you,
Did it ever run correctly?
That is did it run right and then develop this problem?
Or is it new EFI and it has never had a smooth idle?

I see a 347 in the signature, what else has been done to the motor?

 

[BroncoinAlaska]

Pulled the 347 out of a Mustang and little was know about the motor. Had to I'd it through the block number and inspection of the bottom end confirmed that it was a 347. The cam is still unknown. I have had the EFI running for a while but have had little time to run it as the Bronco is located in NM and I am not. I get to work on the Bronco a couple times a year. The surging has become more evident the more that it has run. It could have been there from the start but is really noyicable now. And I am still waiting for my WH tach to actually see how much the RPMs surge.

 

[jw0747]

I always post this info because it has helped on more than a few occasions. 5 parts included.

http://www.muscularmustangs.com/iac.php

 

[BroncoinAlaska]

Thanks for the link. There is some useful EFI maitance procedures. Cleaning and flipping the IAB seems to have done the trick. The idle is now steady and dose not die when the bronco is shifted from drive to reverse any more. Now on to the next issue. Probably the weak explorer power steering turning the 35's.