Hissing whistling noise

[85lebaront2]

I have checked the vacuum lines...no change if I clamp them.

But I have read a lot...as you see in my post before. I also find much people that use this part to adjust the idle

eBay

It seems to be a common problem with the throttle body...also sharp edges can cause the whistling...so I think I have some at the bore of the body to the IAC...

My unsteady idle can also be a problem of ignition timing...maybe 12 degrees are better as using a Stroker.

I also have measured the voltage between IAC and VPWR. 0.5 volts while idling at about 1000rpm. I don't come down much more, cause the engine will die otherwise...so many it's really not enough air coming in.

Maybe I should try to bore the 2mm holes inside the plates, like Bill told me to do.

I will unmount the body, make the bore and also clean the sharp edges as next.

I had that exact kit on my 1990 Lincoln Town Car with the last of the 302 speed density sequential injection systems. Same issue, inability to get the idle speed high enough without getting the TPS voltage too high.

The hissing sound from the throttle body is due to the air going through a narrow opening at high speed. If you take a small hose and hold it near your ear, the same sound is in a carburetor, you have to get the hose into it far enough to hear. I synchronized many a set of multiple carburetors (SU, Weber, Zenith-Stromberg, Rochester HV, Carter YH) that way.

As for the engine not wanting to run correctly below 1000 rpm. it could be a TPS voltage issue, or, if the cam has too much overlap/duration, the vacuum may be pulsing too much which will cause problems.

[ReneH]

I had that exact kit on my 1990 Lincoln Town Car with the last of the 302 speed density sequential injection systems. Same issue, inability to get the idle speed high enough without getting the TPS voltage too high.

The hissing sound from the throttle body is due to the air going through a narrow opening at high speed. If you take a small hose and hold it near your ear, the same sound is in a carburetor, you have to get the hose into it far enough to hear. I synchronized many a set of multiple carburetors (SU, Weber, Zenith-Stromberg, Rochester HV, Carter YH) that way.

As for the engine not wanting to run correctly below 1000 rpm. it could be a TPS voltage issue, or, if the cam has too much overlap/duration, the vacuum may be pulsing too much which will cause problems.

Hi Bill,

ok, that sounds good, as you seem to know the problem. So what was your solution for your 1990 Lincoln Town Car? Was it thisone you have done the 2mm bore into the throttle plates?

What do you think about the IAC spacer-kit? May that solve the problem?

OK, so my next step to unmount and smooth the sharp edges will not be bad at all...

About the cam: Is that possible? Like posted in another threat, it's a 351W stock cam. Has this cam so different overlap/duration across

From the original 302 cam? As far as I have read while buying the stroker kit from summit, they prefer much more aggressive cams for the kit. As I don't want to build a racing car, I've decided for the stock of the 351W, to have better times for the valves regarding to my bigger displacement.

Is there any way to remove the cam from the suspects?

Have I told you, that I use an adjustable timing chain?

Currently set to factory 0 degrees.

[85lebaront2]

Hi Bill,

ok, that sounds good, as you seem to know the problem. So what was your solution for your 1990 Lincoln Town Car? Was it thisone you have done the 2mm bore into the throttle plates?

What do you think about the IAC spacer-kit? May that solve the problem?

OK, so my next step to unmount and smooth the sharp edges will not be bad at all...

About the cam: Is that possible? Like posted in another threat, it's a 351W stock cam. Has this cam so different overlap/duration across

From the original 302 cam? As far as I have read while buying the stroker kit from summit, they prefer much more aggressive cams for the kit. As I don't want to build a racing car, I've decided for the stock of the 351W, to have better times for the valves regarding to my bigger displacement.

Is there any way to remove the cam from the suspects?

Have I told you, that I use an adjustable timing chain?

Currently set to factory 0 degrees.

Rene' the 1990 Town Car I used the kit on, it mounts between the IAC and the throttle body. The one I drilled the holes in was my son's 1986 F150, essentially the same setup as your Bronco, just had two fuel tanks. His issue was the throttle opened far enough for a good idle would put the TPS voltage high enough to cause the EGR solenoids to "chatter" and as they did the idle would surge as the system tried to find it's best balance. Part of the issue was his TPS, he had bought an aftermarket one and it read high at closed throttle. Once he purchased a Motorcraft one the problems went away.

We drilled a pair of 1/16" holes in the throttle plates if I remember correctly.

Do you have the specifications on your cam? These speed density EFI systems are extremely sensitive to cam duration, overlap and lobe separation.

[ReneH]

Rene' the 1990 Town Car I used the kit on, it mounts between the IAC and the throttle body. The one I drilled the holes in was my son's 1986 F150, essentially the same setup as your Bronco, just had two fuel tanks. His issue was the throttle opened far enough for a good idle would put the TPS voltage high enough to cause the EGR solenoids to "chatter" and as they did the idle would surge as the system tried to find it's best balance. Part of the issue was his TPS, he had bought an aftermarket one and it read high at closed throttle. Once he purchased a Motorcraft one the problems went away.

We drilled a pair of 1/16" holes in the throttle plates if I remember correctly.

Do you have the specifications on your cam? These speed density EFI systems are extremely sensitive to cam duration, overlap and lobe separation.

Hi Bill,

Ok, now I understand. So the plate is maybe an option to control the idle. But as far as I understand this distance plate, drill holes into the blades will have a nearly similar effect.

My TPS seems in range...only about the upper value I'm not 100 percent sure. About 4.38V...is this too low?

I have bought this cam:

Summit

The values are:

Intake Duration at 050 inch Lift: 210

Exhaust Duration at 050 inch Lift: 214

Duration at 050 inch Lift: 210 int./214 exh.

Advertised Intake Duration: 254

Advertised Exhaust Duration: 258

Advertised Duration: 254 int./258 exh.

Intake Valve Lift with Factory Rocker Arm Ratio: 0.478 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.485 in.

Valve Lift with Factory Rocker Arm Ratio: 0.478 int./0.485 exh.

Lobe Separation (degrees): 114

So also about the 10 degree BTDC I'm not sure...maybe my setup should be better with 12 degree?

[85lebaront2]

Hi Bill,

Ok, now I understand. So the plate is maybe an option to control the idle. But as far as I understand this distance plate, drill holes into the blades will have a nearly similar effect.

My TPS seems in range...only about the upper value I'm not 100 percent sure. About 4.38V...is this too low?

I have bought this cam:

Summit

The values are:

Intake Duration at 050 inch Lift: 210

Exhaust Duration at 050 inch Lift: 214

Duration at 050 inch Lift: 210 int./214 exh.

Advertised Intake Duration: 254

Advertised Exhaust Duration: 258

Advertised Duration: 254 int./258 exh.

Intake Valve Lift with Factory Rocker Arm Ratio: 0.478 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.485 in.

Valve Lift with Factory Rocker Arm Ratio: 0.478 int./0.485 exh.

Lobe Separation (degrees): 114

So also about the 10 degree BTDC I'm not sure...maybe my setup should be better with 12 degree?

Rene' here is what I dug up quickly on Speed Density Ford systems: https://www.corral.net/threads/speed-density-camshaft.788163/

I know when we were building my new engine, the builder prefers Sig Erson cams so we placed a call to Sig Erson and his very first question was "how much tune ability do you have in that MAF system?" The cam he sent is here:

[ReneH]

Rene' here is what I dug up quickly on Speed Density Ford systems: https://www.corral.net/threads/speed-density-camshaft.788163/

I know when we were building my new engine, the builder prefers Sig Erson cams so we placed a call to Sig Erson and his very first question was "how much tune ability do you have in that MAF system?" The cam he sent is here:

Hi Bill,

Ok. Thanks for this. Reading this article shows in my opinion, that my cam values seems to be in range.

And I'm still thinking it's a matter of air combined with maybe a too small base timing regarding the idle.

So, assuming this and I hope you are with me to this theory, I have still the two options:

1. Drill holes into the blades.

2. Buy a adjustable IAC spacer.

With one if this modifications I play it save, that my TPS idle value will not get too high.

I'm also be able to remove my current TPS and set my old TPS to 1V, without mounting it to the throttle body, to simulate closed throttle, independent to the throttle position. So I should be able to check, if there gets too less air inside while idling...

But regarding the TPS, there is still my question left, if my maximum TPS value is too low with 4.38V.

[mat in tn]

Hi Bill,

Ok. Thanks for this. Reading this article shows in my opinion, that my cam values seems to be in range.

And I'm still thinking it's a matter of air combined with maybe a too small base timing regarding the idle.

So, assuming this and I hope you are with me to this theory, I have still the two options:

1. Drill holes into the blades.

2. Buy a adjustable IAC spacer.

With one if this modifications I play it save, that my TPS idle value will not get too high.

I'm also be able to remove my current TPS and set my old TPS to 1V, without mounting it to the throttle body, to simulate closed throttle, independent to the throttle position. So I should be able to check, if there gets too less air inside while idling...

But regarding the TPS, there is still my question left, if my maximum TPS value is too low with 4.38V.

your peak voltage return of 4.38 will have no effect on the issues that you are experiencing. at best it will show up at wide open throttle under a heavy load.

[ReneH]

your peak voltage return of 4.38 will have no effect on the issues that you are experiencing. at best it will show up at wide open throttle under a heavy load.

Hi, you are right. Nothing that's regarding my current issue. But if I know by now that 4.38V isn't enough for registering the ECU a wide open throttle, it will be the next problem.

I only try to work one time at one part...if possible...so I want to avoid to work on the TPS again, if I can be relatively sure by now, that my maximum voltage isn't enough...

So, that's the aim of asking for this right now.

[ReneH]

Hi, you are right. Nothing that's regarding my current issue. But if I know by now that 4.38V isn't enough for registering the ECU a wide open throttle, it will be the next problem.

I only try to work one time at one part...if possible...so I want to avoid to work on the TPS again, if I can be relatively sure by now, that my maximum voltage isn't enough...

So, that's the aim of asking for this right now.

So, I reply myself...I have found this in my new Bible...

So it seems my TPS upper voltage is absolutely in range. I also seem to have enough space in the closed value.

So I will proceed as planned and unmount the throttle body and clean the edges at first.

[ReneH]

So, I reply myself...I have found this in my new Bible...

So it seems my TPS upper voltage is absolutely in range. I also seem to have enough space in the closed value.

So I will proceed as planned and unmount the throttle body and clean the edges at first.

So I see...the time shift leads me to talk to myself...

I have cleaned the throttle body out of sharp edges:

I also have bent the counterplate of the idle screw back to parallel to the body;

So I will set my basic throttle opening again to about some steps below 1V, if I'll still reach about 4.5v at fully open throttle.

And I have figured out that the 90th IAC has a 3mm greater bore of the inlet and outlet compared to the 1989th version.

I will first mount the 80th version without silicone to check if there is a difference. Both are also internally different. I my opinion the 89th version seems to close better and also completely. The 90th version seems to be stuck open a bit, also when no voltage applied.