Truck still idling rough when cold and hesitates when i first take off, i decided to buy an OBD1 scanner, 19 bucks on amazon I got the innova ford code reader, its pulling up code 552- thermactor air diverter solenoid circuit failure and code 10 cylinder #1 has a problem. I no it has fresh plugs egr valve, wires, cap, and a couple other things, Could it be as simple as a Diverter Valve? did some googling and people say check vac hosing and what not. Any have an idea or has gotten this code before, the truck is so solid i just want to nail this last issue and have it running great.
Thanks

 

 

What year is your truck? It would either give out three digit codes or two digit codes, but not both.

The diverter valve is on the back of the heads - see this article for how the smog pump system works and how to replace all of your vacuum lines:

http://www.fullsizebronco.com/forum/...es-rubber.html

 

 

Code 111 means system pass

Code 10 is just a separator code the scanner puts out.

Code 552 says the TAB reading is off - so it is probably the vac line, electrical connection, etc. Or it could be the vacuum reserve canister (passenger fenderwell, looks like a coffee can) or lines to it that are failing.

 

Thanks I think i found it, super hard to get to and yes I was wondering what that can thing was ill start checking hoses. I'll probably end up ordering a new DV looks like there arond $50 and change out all the hoses and most likely give it to my mechanic to install..to be continued......

 

EEC-IV code readers are notoriously UNreliable - I recommend you try to return it for refund ASAP. All you need is a jumper wire (paperclip). It will never lie to you.


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There are no "0"s in our trucks' DTCs; the single flash simply separates the KOEO (or KOER) codes from the CM codes. Click the first link in that caption for more info.

The diverter valve has no circuit to fail. And it's very UNlikely that the solenoid controlling the valve has failed. Assuming that definition is correct (and I don't think it is), the fault would either be in the wiring between the EEC & TAD solenoid, or inside the EEC (which is very common on pre-'94 EECs). A vacuum leak could not generate a circuit fault (again assuming the definition was correct).

That 2G alternator is dangerous - they're known to set trucks on fire, so if it ever fails, replace it with a 3G. It's cheap & easy.

All your truck's details should be in your signature (similar to BLDTruth's) so we can find them when we need to answer your questions. Read this caption:


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It's a little scary that Booba was writing tech articles 7 years ago (and I don't remember him asking to use my pics) - that wasn't long after he got into these trucks. This caption might be clearer:


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