how do you test the IACV?

[Rich]

hi all wondering if any techies know how to test if the idle control valve is functioning correctly,I have it off the car.

 

 

thanks Rich:)

[Robert]

im sure the only way to test it is when its on the car, while its off give it a good clean with brake cleaner.

[JohnA]

whatever you do, avoid WD40 --- if it goes through the intake tract you risk damage to the oxygen sensor.

 

I'd prefer carb cleaner rated safe for catalysts.

[TLicense]

hi all wondering if any techies know how to test if the idle control valve is functioning correctly,I have it off the car.

 

 

thanks Rich:)

 

Disconnect ISC valve connector

Measure resistance between terminals:-

 

Termainal Resistance

5 (B1) - 4 (S1) 10 - 30 ohms

5 (B1) - 6 (S3) 10 - 30 ohms

2 (B2) - 1 (S2) 10 - 30 ohms

2 (B1) - 3 (S4) 10 - 30 ohms

 

Here's a text diagram of the plug of the valve. The two ! indicate the tabs on the plug to help you orient it.

 

--------!--------!-------

| 3(s4) 2 (B2) 1 (S2)|

| 6 (S3) 5 (B1) 4 (S1)|

-------------------------

 

If you get anything other than that then it needs repairing/cleaning/replacing.

 

If their all OK then:-

 

Remove ISC valve

 

Connect the battery positive lead to terminals 5 (B1) and 2 (B2), and the negative to terminals 4 (s1) - 1(s2) - 6(s3) - 3(s4) in that orer. the valve should close (ie the plunger should move to blocking the hole that you can see it in)

 

Then connect the batter positive led to terminals 5 (B1) and 2(B2) and the negative lead to terminals 3(s4) - 6(s3) - 1(s2) - 4(a1) in that order, the valve should open (move in the opposite direction to the above)

 

Again if it doesn't then it needs repairing/cleaning/replacing.

 

There's also a test you can do using an oscilloscope, but you've probably not got one, and my skills at drawing waveforms in text aren't up to the job.

 

Why do you think there's something up with it? Y'know it should make a whirry clicky noise as standard right?

[Rich]

Disconnect ISC valve connector

Measure resistance between terminals:-

 

Termainal Resistance

5 (B1) - 4 (S1) 10 - 30 ohms

5 (B1) - 6 (S3) 10 - 30 ohms

2 (B2) - 1 (S2) 10 - 30 ohms

2 (B1) - 3 (S4) 10 - 30 ohms

 

Here's a text diagram of the plug of the valve. The two ! indicate the tabs on the plug to help you orient it.

 

--------!--------!-------

| 3(s4) 2 (B2) 1 (S2)|

| 6 (S3) 5 (B1) 4 (S1)|

-------------------------

 

If you get anything other than that then it needs repairing/cleaning/replacing.

 

If their all OK then:-

 

Remove ISC valve

 

Connect the battery positive lead to terminals 5 (B1) and 2 (B2), and the negative to terminals 4 (s1) - 1(s2) - 6(s3) - 3(s4) in that orer. the valve should close (ie the plunger should move to blocking the hole that you can see it in)

 

Then connect the batter positive led to terminals 5 (B1) and 2(B2) and the negative lead to terminals 3(s4) - 6(s3) - 1(s2) - 4(a1) in that order, the valve should open (move in the opposite direction to the above)

 

Again if it doesn't then it needs repairing/cleaning/replacing.

 

There's also a test you can do using an oscilloscope, but you've probably not got one, and my skills at drawing waveforms in text aren't up to the job.

 

Why do you think there's something up with it? Y'know it should make a whirry clicky noise as standard right?

 

my car is struggling to maintain a smooth idle on the AEM,did a comp. test and all the cylinders were fine ,all almost identical to 2 psi of each other,so I thought it might be a problem with the idle control valve or a leak somewhere on the inlet manifold as it has been removed and put back on recently when installing the fuel system,other than that it might be the map.

[TLicense]

What idle learned values are you getting? What AFR's do you get at idle, and also what timing? (It should be 14.7 AFR and 10degs)

Other "gotcha's" are the timing not being sync'd with the car (ie you need to make sure that when the ECU is telling the car it's firing at 10 degs, it is firing at 10deg's)

You also want your high idle to be maybe 100 - 150 rpm's higher than your target rpm, and the high idle wait time to be about 0.5 secs. My high idle speed is 10mph.

[Rich]

What idle learned values are you getting? What AFR's do you get at idle, and also what timing? (It should be 14.7 AFR and 10degs)

Other "gotcha's" are the timing not being sync'd with the car (ie you need to make sure that when the ECU is telling the car it's firing at 10 degs, it is firing at 10deg's)

You also want your high idle to be maybe 100 - 150 rpm's higher than your target rpm, and the high idle wait time to be about 0.5 secs. My high idle speed is 10mph.

 

the car is now being tuned,the poor idle is still there and the car drives very jerkilly under 3000 rpm,when it comes on boost it is fine,the mapper has tried changing the aeromotive fpr for another one,this has not solved the problem,the compression on the engine is fine accross all cylinders.

 

no matter how the fueling is adjusted at low rpm ,there is no cure to the problem,could it be an issue with the fuel pump ECU,one of the warlbros etc?

when the extra fuel pump was fitted the existing fuel filter on the old line was not changed,could it be that?

 

if anybody has any ideas that would be great?

 

thanks

 

Rich:)

[Soonto_HAS_soop]

Could be bad lambda sensor, coolant temp sensor or even throttle position sensot in theory. They are all testable in some form or another.

[Rich]

Could be bad lambda sensor, coolant temp sensor or even throttle position sensot in theory. They are all testable in some form or another.

 

wouldnt these 3 things just affect the idle though?

the car drives poorly accross the whole rev range from 1000rpm through to3000rpm.

it is very jerky when you back off the throttle under 3k revs and idle is up and down hunting.

[TLicense]

Well there's 1 way to check if it's a fuel presure problem. Fit a fuel pressure sensor and log it. I'm pretty confident it won't be an issue though, and will most likely be down to the mapping.

 

Who's doing the mapping for you? Bijal at Future Motorsports is AEM trained, so perhaps he could take a look at it.

 

If you post up your calibration file, I'm sure somone can take a look for anything obvious.Or if you prefere, if you internally log ignition timing, AFR,air temp, coolant temp, throttle, rpm and idle learned value I could take a look at it and make sure the values are as they should be.

For your reference at idle the AFR should be as close as you can get to 14.7:1. The ignition timing should be 10 degrees.