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Idle rough, Rev hang and other issues 

 

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 Post subject: Idle rough, Rev hang and other issues
Posted: Thu Jan 14, 2010 4:20 pm 
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Hi guys,

The V8 is having an interesting re birth, i'll start by saying, the engine has the explorer manifolds, 24lb injectors 70mm maf and 65mm tb, to run all this i'm using an EB GT ECU.

Now, yesterday after finishing the manual conversion, i timed it, and set base timing and TPS voltage, when idling the TPS is reading 1.02v is this too high? The idle is semi lumpy and the rev needle fluctuates slightly, car shakes a bit too.

I have the IAT sensor mounted in the intake pipe, as it's an AU intake pipe and it came with the sensor so i just wired it into the harness where the original sensor would have been wired. does it matter how it is wired? I was told it's a variable resistor so doesn't matter which wire goes to what.

When idling the car sits at about 800rpm, if i give it a wee boot, it will hang there and slowly fall back down to where it was previously idling. What causes this?

I also have the feeling i may need a new coolant temp sensor, as even when the engine is hot ,the temp gauge is saying it's just above cold.

Also, i noted in my build thread that gears are hard to select while idling, when i'm driving it's fine, and when the car is off it's fine, but for example if i'm at the supermarket about to reverse out of the park, its hard to select reverse or first gear, it has a brand new clutch, could the clutch be slightly too thick and still gripping the pressure plate when i have the pedal down? I have adjusted the pedal right out, has helped it a wee bit.

Pictures below show the revs at idle, and also the temp sensor when hot.

 

 

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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Thu Jan 14, 2010 4:26 pm 
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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Thu Jan 14, 2010 4:29 pm 
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{USERNAME} wrote:
http://www.fordmods.com/ford-v8-f2/adjusting-base-idle-and-setting-t-p-s-voltage-t56990.html


I've read that, but it says 0.98v key on engine off, i set it at 0.96 with ignition on, but engine off, i then started the car and it was at 1.02, so should i drop the tps down even further to get 0.98 engine running?

 

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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Fri Jan 15, 2010 7:21 am 
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Need to adjust your clutch too.

Your revs hang because I suspect that your ECU is for an auto. Autos have more dashpot meaning idle hang.

Your MAF is probably stuffing your idle up as it has poor low airflow resolution and the EB GT ECU cannot translate properly plus that ECU drives 19lb injectors stock with the larger MAF. You're using 24lb injectors and the ECU again cannot see what the hell is happening with the larger injectors and is trying to compensate.

You need to get a tune done.

 

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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Fri Jan 15, 2010 7:38 am 
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{USERNAME} wrote:
Need to adjust your clutch too.

Your revs hang because I suspect that your ECU is for an auto. Autos have more dashpot meaning idle hang.

Your MAF is probably stuffing your idle up as it has poor low airflow resolution and the EB GT ECU cannot translate properly plus that ECU drives 19lb injectors stock with the larger MAF. You're using 24lb injectors and the ECU again cannot see what the hell is happening with the larger injectors and is trying to compensate.

You need to get a tune done.


The GT ECU is a manual one, and i was told it's tuned for 24lb injectors from factory, hence the reason i chucked in the 24 pounders, as if i kept the 19lb, it would run lean.

For some reason the TPS doesn't want to play fair either, i have dropped it down to 0.94v key on, but when i start the car, it is reading 1.02/1.03v.....

 

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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Fri Jan 15, 2010 7:40 am 
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{USERNAME} wrote:
Need to adjust your clutch too.



I have it right out to get some leverage on it, if i adjust it to sit along side the brake pedal like it should i lose the leverage i had and is even harder to get gears idling

 

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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Fri Jan 15, 2010 11:59 am 
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With the engine running, I believe it has to be 0.9v.

 

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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Fri Jan 15, 2010 4:54 pm 
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It needs to be less than 1v while idling other wise it thinks its in part throttle mode.
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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Fri Jan 15, 2010 6:02 pm 
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{USERNAME} wrote:
It needs to be less than 1v while idling other wise it thinks its in part throttle mode.



I know i'm sounding dumb here, but do you/can you change it while idling? As from what i gathered in that tech doco, you adjust it while key is on and engine is off, i did that, right down to 0.94v, but still get 1.02 idle. Will it be ok if i start the car and adjust it while running?

 

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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Fri Jan 15, 2010 6:57 pm 
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Yes you can adjust while running but it almost sounds like you have some tension on the throttle cable when the engine is running?
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 Post subject: Re: Idle rough, Rev hang and other issues
Posted: Fri Jan 15, 2010 7:07 pm 
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{USERNAME} wrote:
Yes you can adjust while running but it almost sounds like you have some tension on the throttle cable when the engine is running?


I sprayed some brake cleaner on the throttle linkage ball joint thingy, got rid of all the crap. Sit's at 0.98v at idle now. Throttle pedal is a wee bit sticky too, quite "gritty" to press down and bring back up. What causes this?

When it was in getting a WOF today, i had the guy plug in the scanner and he checked for any error codes, came up with none which i assume is a good thing, would the scan pick up a dodgy coolant sensor?

 

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