EFI first start up problem

garyp · Jul 4, 2012

Motor started up, timing off, moved rotor one notch, timing at 12btc, installed spout, motor timed and sounded perfect for 5 minutes, and then all of a sudden the rpm went to 2000 with a loud sucking noise at the throtle body filter. I have not pulled codes since the first KOEO. Any advice would be helpful.
Thanks, Gary

Viperwolf1 · Jul 4, 2012

Sounds like a vacuum leak. Follow the sucky noise.

MarsChariot · Jul 4, 2012

Might need to re-torque the intake. Happened to me. I also had my EVR vacuum hoses switched (50-50 chance of getting them right the first time). But your s sounds more like it could be a big leak. Maybe a vacuum line is totally opened somewhere.

garyp · Jul 4, 2012

Tried again and idled perfect for 5 minutes and shut off like you turned the key off. Did this twice, and then went to the high idle again. I checked the voltage at the IAB and was good, and now getting a KOER code 12 which is the IAB motor I think.

NYLES · Jul 5, 2012

isnt 2000 rpm part of the KOER test? I REMEMBER MINE going to 2K for about 3 mins while running a koer test...but it never died and returned to normal idle.

KyleQ · Jul 5, 2012

Idle Air Control - you either have it in backwards or its bad. I had issues with my EFI swap where the motor would rev high and stay there for a second or two and settle down.

I replaced the IAC and it ran better - didn't make all the damn sucking noise and high RPM crap.

garyp · Jul 5, 2012

Replaced the IAC today and still runs 2 to 3 k rpm. It is installed backwards for the BC throttle cable per their instructions. I checked the voltage at the TPS and green was .02v, orange/w was 5.02v, black was .02v. I think the 5.02 is ok but not the others. Any tips please.

MarsChariot · Jul 5, 2012

With the throttle closed TPS voltage should be around 0.6-0.8 volts. It should be closer to 4 to 5 volts at wide open throttle. Something sounds screwy. Maybe a bad TPS.

G's Baja Bronco · Jul 5, 2012

spray carb cleaner around the intake and make sure you have no vacuum leaks, the TPS voltage sounds low!

DFP1129 · Jul 5, 2012

GaryP---Dad---

correct me if im wrong, but The TPS we used was from the explorer motor, we spliced in the sensor to the mustang harness via the diagrams we obtained.. So IF we bought a mustang TPS would it fit properly in the same place OR should the explorer one work correctly taking into account we wired correctly..?

You like how I say "we"?

David P.

ransil · Jul 6, 2012

adjust the throttle stop screw in a little bit , you might have the throttle plate fully closed

My IAC did not work when installed per BC instructions, I had to install it per factory..

garyp · Jul 6, 2012

I'll try switching the IAC back, and adjust the screw on the tb. I read somewhere that a mustang tps will fit so I might pick one up and see. Thanks

KyleQ · Jul 6, 2012

You are NOT supposed to be messing with the throttle stop, that is carefully calibrated and I had nothing but issues with that IAC when it was backwards - swing it back around.

garyp · Jul 6, 2012

KyleQ said:
You are NOT supposed to be messing with the throttle stop, that is carefully calibrated and I had nothing but issues with that IAC when it was backwards - swing it back around.

Will do tonight and let you know.

ilovemaui · Jul 6, 2012

you can pick up a TPS at autozone for about $30. I'd start with the right part.

ilovemaui · Jul 6, 2012

ransil said:
adjust the throttle stop screw in a little bit , you might have the throttle plate fully closed

My IAC did not work when installed per BC instructions, I had to install it per factory..

I was able to rotate mine without issue.

ransil · Jul 6, 2012

KyleQ said:
You are NOT supposed to be messing with the throttle stop, that is carefully calibrated and I had nothing but issues with that IAC when it was backwards - swing it back around.

Get it running then dial in the stop screw to the perfect" calibrated" idle just make sure its open so the thing can start

Sent from my Galaxy Nexus using Tapatalk 2

DFP1129 · Jul 6, 2012

I bought 2 TPS units today.. for some reason they had two part#'s listed in the system at Advanced auto parts..

so in true fashion i bought both

..

ill take back the one that i dont need.

both are for an 89 5.0 mustang

DAVIDP

garyp · Jul 6, 2012

Reversed the IAC and that did the trick, but after a few minutes it started to try to die so I unplugged the MAF and it idled ok. Ran KOEO and 81,82,84,85. Ran KOER and 98,66, but I had the MAF unplugged. TPS voltage is .94v closed, 4.64v open. I think I'm almost there or somewhere.

Viperwolf1 · Jul 6, 2012

What are you using for a MAF? Might try cleaning it.

EFI first start up problem

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