High idle/surging when in foreward and reverse gears

[RyanDS650X]

Iac and tps have less than 3 miles on them. Havnt blocked off the egr because the valve isnt stuck, its working normally.

[hobbyturnedobsession]

Just because they're new doesn't mean they aren't malfunctioning.

[RyanDS650X]

Voltage and resistance check out though.

[Rmc]

Found this thread for you, maybe there's something in there you haven't tried?

http://broncozone.com/topic/22532-surging-idle/

[hobbyturnedobsession]

How about the O2 sensor? Could be malfunctioning and keeps wanting to heat the cat up?

[Silverslk]

Computer? Seem weird the speedo jumps...... Short behind the speedo?

[Rmc]

Computer? Seem weird the speedo jumps...... Short behind the speedo?

I totally agree. The speedo dosnt add up unless stray voltage from someplace.

[RyanDS650X]

Computer is next on the list. I dont feel so bad about throwing new parts on an 18 year old vehicle with 170k but damn i sure hope one if these parts fix my problem.

[Silverslk]

Where is the computer located on your truck? My neighbor has a 1988 Mazda 323GT (factory turbo car) and when he bought it, it had all sorts of weird running issues. When we pulled the dash to do the leaking heater core, we opened up the ECU (to check for a chip) and found it with a decent amount of water in it and it would short the injector drivers out and flood the engine from time to time...

[RyanDS650X]

Mines up on the firewall drivers side behind the kick panel.

[AussieRod]

Im thinking wiring short or PSOM with this. I might be wrong here, but I'm sure the VSS signal starts from the VSS on the axle housing, thru the ABS computer, to PSOM, then to ECU. If the speedo is dancing and the truck is not moving, there may be a damaged or pinched VSS wire(s) along the chassis, the ABS ECU has gone tits up or the PSOM is malfunctioning. If the engine ECU gets a bad or faulty VSS signal, it will think the truck is moving and will adjust as required. If disconnecting the VSS at the axle makes it better, I'd say thats a possible source of the problem. EEC5 is much more dependant of sensors working correctly, so I'd get dirty and start tracing the wiring harness, looking for damage, pinched or broken wires and make sure you have continuity between all the ECUs in line to the the engine ECU.

[RyanDS650X]

Great post rod thanks for the heads up and this is where it gets tricky. Not only do I have an ABS delete but I also have a leduc VSS relocator off the transfercase. I didnt do the delete or vss kit and im not sure on the procedure... Im going to try and contact the PO and see if he can shed some light on this.

[Silverslk]

Ryan, when did this start? After a hard run or anything? Hoping something like a jump and hard landing might help isolate where to start looking....

[RyanDS650X]

It never idled smooth always hunted around but got worse when i put a new IAC on it and hasnt gotten any better over time. That was about 8 months ago.

[David Kennedy]

The truck idled well until I put the E303 cam in it. I added the Ford IAC adjuster plate (between the IAC and the throttle body) to attempt to tune it in better. Make sure the two bleeds stews in that plate are still present. I also added the adjustable fuel pressure regulator in hopes of improving it.

I never had the engine increase in idle speed though.

Here are a few thoughts. If it works well when cold (open loop) and starts to behave poorly when in closed loop id check the tube from the MAF to the throttle body for leaks. I'd also make sure the breather from the valve cover is still connected correctly. The ECM needs to account for that PCV flow too.

[RyanDS650X]

Thanks for the reply David. It does seem to act up only once its up too temperature. Ill go over your suggestions and report back.

[AussieRod]

Ryan, have a read about the air adjuster here and see if it sounds like your issues. This part might help. We are going to try it on my brothers 5.0 in his Falcon.
http://www.mass-air.com/Products.htm

[RyanDS650X]

Sweet baby jesus! That thing list allllll of my symptoms and verifies David's findings with the E303. No mention of the bouncing speed though.

[AussieRod]

Sweet baby jesus! That thing list allllll of my symptoms and verifies David's findings with the E303. No mention of the bouncing speed though.

Yeah, the same with my bro's Falcon, it has the E303 in it too. Must be something with that particular cam. I'm thinking the bouncing speedo might be a function of the relocated VSS, because the t/case tone ring is much smaller than the ring gear tone ring. The driveshaft turns at a higher speed than the axle shaft, so vibration in the driveshaft could cause magnetic scatter at the VSS sensor. That MIGHT account for the needle dancing. Fix the engine issue, then tackle the speedo.

[RyanDS650X]

" OK, then yes, the Air Adjuster!! is what you need…the e303 cam swap changed the amount of air flowing past the mass-air sensor and the computer is unable to compensate for it….from our experience, I can guarantee you that ANY 302/351 engine with the e303 cam WILL need an Air Adjuster!! to run properly, due to the airflow change caused by the cam."
This is the response i got from the link you posted from their tech guy.