timing

[litlred]

ok so a 4.0 from a 91 exploder is 10 btdc, how do you adjust it?

 

[adsm08]

you don't. Distributorless ignition systems like those found on all years of the 4.0 are not adjustable. The computer takes care of it.

If you have a timing issue I'd look at your cam sensor, but the same feature that makes it non-adjustable also makes it really really hard to accurately check with a timing light, so unless you are getting no-start or 20 some degrees, I wouldn't worry about it too much.

 

[litlred]

my chilton said it wasn't adjustable, I'm having a real hard time starting it, once it does crank it run great. It weird to me. I checked it with a light and it looks right.

 

[Shran]

Well if it runs great once it is started then that would seem to me that the timing is not at fault.

Does it just crank forever and not catch, or what?

 

[litlred]

Exactly, turns and turns and when your about ready to give up it finally starts. It was starting fine when I pulled it from the explorer, ive tried two different computers, it has new plugs and wires....

 

[Shran]

I guess I would start by making sure you have adequate fuel pressure and spark.

 

[litlred]

the 2.9 from a 90 bronco ii and a 4.0 from a 91 explorer carry the same fuel pressure right? as far as spark goes, whats the best way to check spark?

 

[TheOne]

take a spark plug out with the wire still attached and touch the electrode to something metal on ur rig and see if it arks

worked when i couldt figure out why my old b2 would always just randomly die..turned out the coil got to hot and would quit... ie no spark

 

[adsm08]

Yeah, you don't have a timing issue. Try cycling the key a few times before cranking it, see if that helps any.

 

[litlred]

Ill try those things tommorrow, if that doesn't work, anymore ideas?

 

[litlred]

Thanks for the help

 

[litlred]

Okay spark is good, tried cycling the key a several times, no luck. Still takes a while to crank, I found a wire connection that I didn't hook up on the drivers side. When I look in the wiring diagram it says it goes to the canister purge solenoid. Its gray/yellow strip wire, and a solid red wire. Where is the purge solenoid? And would it cause hard start? If you follow the engine harness its the connector farthest from the computer, thanks for any help.

 

[kimcrwbr1]

there are two lines off the vapor cannister one to the fuel tank and the other is to the purge solenoid off of the TB

 

[kimcrwbr1]

Not sure on the 91 but if you look in EEC-IV troubleshooting when you turn the key to start it changes the timing for a quick start it either advances or retards it I would try checking for voltage to the start pin on the TFI it can either be the ignition a wire or connector

 

[litlred]

So the purge is on the throttle body? What does tfi stand for? Thanks