Author Topic: Strange hunting issue  (Read 881 times)

Offline ttpower

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Strange hunting issue
« on: June 02, 2007, 08:10:53 PM »
Hi people. Finally got it started today but its causing a little issue.

a) Its hunting, revs up to about 2800rpm and drops to about 1300rpm constantly.

b) showed boost as 131mmhg at highest point.

c) Temperature went up to 82`c and the fans didnt kick in, i think this may be the relays as i jumped them to turn the fans on!!

Its got a power fc fitted to it, i heard about a learning issue with them, but the hunting seems a bit strange, could it be the throttle position sensor or bacv or even the power fc??

Any help please :god :god

Offline scooby_si

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Strange hunting issue
« Reply #1 on: June 02, 2007, 10:38:35 PM »
if the power FC hasn\'t been mapped it\'d or gone thru the start up proceedure be a good place to start?
Si

Offline shaunwil

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Strange hunting issue
« Reply #2 on: June 03, 2007, 11:01:00 AM »
Fans don\'t kick in till about 95deg. Check that the boost sensor hasn\'t come loose or that you have a leak in a vac line.

Shaun
1994 White FD with A-spec GT3574R - 358bhp at the hubs at 0.9bar :3gears-lh
2003 Mondeo 2lt 130ps Diesel Estate Daily :driving

Offline ttpower

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Strange hunting issue
« Reply #3 on: June 03, 2007, 12:40:25 PM »
hmm, in that case i\'ll let it idle until it reaches 95deg and see if they kick in, cheers for that. Checked all the vac hoses and they seems fine. will give it another check over, where is the boost sensor located?

evo_ray

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Strange hunting issue
« Reply #4 on: June 03, 2007, 12:44:57 PM »
I fitted my Apexi PFC two weeks ago and went through the standard \'learning\' procedure after which the car would hunt whenever stationary. The more I drove it, the less it hunts. I haven\'t yet had it mapped so that is on the long list of things to do but the car hunts a lot less now and runs a lot better. I thinkk the Apexi has a lot of learning to do.

Offline shaunwil

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Strange hunting issue
« Reply #5 on: June 03, 2007, 12:50:50 PM »
An easier way to check that they are running is to switch the ac on too, at least you know they are seeing power.

It its getting much hotter take it out for a spin to let some air get through the rad.

Shaun
1994 White FD with A-spec GT3574R - 358bhp at the hubs at 0.9bar :3gears-lh
2003 Mondeo 2lt 130ps Diesel Estate Daily :driving

Offline shaunwil

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Strange hunting issue
« Reply #6 on: June 03, 2007, 12:52:33 PM »
Thinking about it, check that the TPS sensor is in spec on closed and open throtle. I had fun with it when i fit my pfc and it was learning idle way too high. Do a search for the figures. May even be in the thread i started a long time ago !

Shaun
1994 White FD with A-spec GT3574R - 358bhp at the hubs at 0.9bar :3gears-lh
2003 Mondeo 2lt 130ps Diesel Estate Daily :driving

Offline ttpower

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Strange hunting issue
« Reply #7 on: June 03, 2007, 04:45:33 PM »
yeah i noticed when its idle checking the sensors on the pfc think its vta1 and 2 or something similar read some values of about 1.4 or something, wheres the thread mate, had a look but cant locate!!

Offline shaunwil

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1994 White FD with A-spec GT3574R - 358bhp at the hubs at 0.9bar :3gears-lh
2003 Mondeo 2lt 130ps Diesel Estate Daily :driving

Offline ttpower

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Strange hunting issue
« Reply #9 on: June 04, 2007, 02:50:38 PM »
thanks mate.

moosey

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Strange hunting issue
« Reply #10 on: June 04, 2007, 08:10:48 PM »
I had this same problem just after my run-in.
Took it back to Hayward Rotary and initially the guys thought it was a vaccum
leak, but after much consternation this was found not to be the case.
Ian eventually took off the intake manifold and cleaned the intake around the
butterfly with brake fluid?!?!? Problem solved. There was tiny deposits of grit
allowing air past the throttle and fooling the engine into believing it was being
rev\'d. Might want to investigate that.
Incidently, some guy trashed his 911 on the M4 that day and I spent 2 hours
in inching traffic listening to that hunting. Nearly went mad.

Offline ttpower

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Strange hunting issue
« Reply #11 on: June 04, 2007, 10:15:35 PM »
lol, cheers for that mate will give it a good clean. shame about the 911 though lol.

moosey

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Strange hunting issue
« Reply #12 on: June 04, 2007, 11:18:50 PM »
Yeah. Collision with a 7.5tonner. Roof gone and everything. Hope he got out.