ReneH Posted March 19, 2023 Share Posted March 19, 2023 Hi, now that seems all to be fine, the hissing noise coming from the throttle body is back...I have had found a vacuum leak before directly in my MAP line and solved it. Now my question is if someone have had heard such a sound before. My suspects are another vacuum leak or something with the throttle body. I have given the body for cleaning to a company that also has cleaned my engine, cause of the real big amount of deposits inside. They also have done the bore for the stroker kit. It's off-topic, but so it looks a half year ago: Link to comment Share on other sites More sharing options...
mat in tn Posted March 19, 2023 Share Posted March 19, 2023 not sure that I'm understanding the question but that is one "nasty" engine! I would suggest the old trick of using a length of hose as a stethoscope and track down exactly where the whistle is originating from. it is very possible for a stroker to pull hard enough on the throttle plates to find a "whistle point." Link to comment Share on other sites More sharing options...
ReneH Posted March 19, 2023 Author Share Posted March 19, 2023 not sure that I'm understanding the question but that is one "nasty" engine! I would suggest the old trick of using a length of hose as a stethoscope and track down exactly where the whistle is originating from. it is very possible for a stroker to pull hard enough on the throttle plates to find a "whistle point." It sounds that it comes directly out of the throttle body. I can get rid of it when opening the throttles to the maximum the idel screw let me do. Maybe it's caused due the cleaning of the throttle body? Also the engine runs not good in idle. Rpm going up and down. At the last starts it dies sometimes in idle... Maybe I need to drill the throttle plates, cause of the stroker? As I've said, I have the 302 throttle body... So that's why I suggested another vacuum leak...I have already sprayed every connection and also all parts of the mainfold which I can access. No real change of rpm...so there seems no leak. Maybe at the cabin or at the C6. Btw: what does the vacuum vent do at the gearbox? Currently I also can set so gear. Maybe too less oil (about 9 liters inside since filter and oil-pan change)... Link to comment Share on other sites More sharing options...
mat in tn Posted March 19, 2023 Share Posted March 19, 2023 It sounds that it comes directly out of the throttle body. I can get rid of it when opening the throttles to the maximum the idel screw let me do. Maybe it's caused due the cleaning of the throttle body? Also the engine runs not good in idle. Rpm going up and down. At the last starts it dies sometimes in idle... Maybe I need to drill the throttle plates, cause of the stroker? As I've said, I have the 302 throttle body... So that's why I suggested another vacuum leak...I have already sprayed every connection and also all parts of the mainfold which I can access. No real change of rpm...so there seems no leak. Maybe at the cabin or at the C6. Btw: what does the vacuum vent do at the gearbox? Currently I also can set so gear. Maybe too less oil (about 9 liters inside since filter and oil-pan change)... if you are concerned about a possible vacuum leak in an accessory circuit then that is real easy to test. just locate the circuit and cap the port at the intake. it will eliminate that circuit and tell you which has a leak if it is that. the brake booster is also a possibility. however, I don't see an accessory vacuum leak causing the throttle body to whistle. and if it runs/starts better with more air then the afr is off. now that it is running it is behaving as if you have an incompatible camshaft for the ecu. im sure that this was tripple checked and discussed much earlier in the troubleshooting process Link to comment Share on other sites More sharing options...
ReneH Posted March 20, 2023 Author Share Posted March 20, 2023 if you are concerned about a possible vacuum leak in an accessory circuit then that is real easy to test. just locate the circuit and cap the port at the intake. it will eliminate that circuit and tell you which has a leak if it is that. the brake booster is also a possibility. however, I don't see an accessory vacuum leak causing the throttle body to whistle. and if it runs/starts better with more air then the afr is off. now that it is running it is behaving as if you have an incompatible camshaft for the ecu. im sure that this was tripple checked and discussed much earlier in the troubleshooting process Hi! ok, I will deactivate all vacuum circuits one by another and check this. But what if the mainfold gasket is the problem? As I've said, I have sprayed everything I could reach. To reach the backside of the mainfold between the firewall isn't very easy. But I'm wondering about the camshaft...I have a 351W stock camshaft and also a 351W stock ECU...should't they work together better than a 351W cam with a 302 ECU? What do you mean with afr? Link to comment Share on other sites More sharing options...
ReneH Posted March 20, 2023 Author Share Posted March 20, 2023 Hi! ok, I will deactivate all vacuum circuits one by another and check this. But what if the mainfold gasket is the problem? As I've said, I have sprayed everything I could reach. To reach the backside of the mainfold between the firewall isn't very easy. But I'm wondering about the camshaft...I have a 351W stock camshaft and also a 351W stock ECU...should't they work together better than a 351W cam with a 302 ECU? What do you mean with afr? Hi, Regarding the throttle setting/idle screw I have found this: I will try this after testing all vacuum circuits for leaks. But I have to admit, that I have not understood to 100 percent, what's to do...especially these plugs...I think I don't have them... Link to comment Share on other sites More sharing options...
ReneH Posted March 20, 2023 Author Share Posted March 20, 2023 if you are concerned about a possible vacuum leak in an accessory circuit then that is real easy to test. just locate the circuit and cap the port at the intake. it will eliminate that circuit and tell you which has a leak if it is that. the brake booster is also a possibility. however, I don't see an accessory vacuum leak causing the throttle body to whistle. and if it runs/starts better with more air then the afr is off. now that it is running it is behaving as if you have an incompatible camshaft for the ecu. im sure that this was tripple checked and discussed much earlier in the troubleshooting process 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. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 20, 2023 Share Posted March 20, 2023 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. Interesting! I've never seen that part, but I probably have TSB 91-25 and can post it tomorrow if it'll help. Link to comment Share on other sites More sharing options...
mat in tn Posted March 21, 2023 Share Posted March 21, 2023 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. imagine that. somebody makes an idle air bleed to compensate for the iac. a tunable vacuum leak! again, you do not have a 351w. you have a heavily modified 5.0. the intakes on the 5.8 are much smaller than the 5.0 and the camshaft is larger than the truck 5.0 camshaft. this has everything to do with velocity inside the individual intake runners. the 5.8/351 was built and installed in heavy vehicles expecting a slower throttle response under a load yet the ability to keep up engine vacuum while doing so. all accesories need vacuum. the 5.0 on the other hand has larger rectangular ports and a larger volume in the intake which relates to the vacuum available for throttle response. consider the mustang. they took the 351w cam and installed it in the 5.0 and tuned it accordingly for a 3200 lb car expecting it to be "wound tight." I would not be surprised if the 5.0 ecu would not run this engine better. the camshaft you listed says stock replacement but not for a 5.0. only for a 5.8. it is greatly increased over the broncos original camshaft. if you were building a carbureted system or even a sniper then you would not be in this situation. Link to comment Share on other sites More sharing options...
ReneH Posted March 21, 2023 Author Share Posted March 21, 2023 imagine that. somebody makes an idle air bleed to compensate for the iac. a tunable vacuum leak! again, you do not have a 351w. you have a heavily modified 5.0. the intakes on the 5.8 are much smaller than the 5.0 and the camshaft is larger than the truck 5.0 camshaft. this has everything to do with velocity inside the individual intake runners. the 5.8/351 was built and installed in heavy vehicles expecting a slower throttle response under a load yet the ability to keep up engine vacuum while doing so. all accesories need vacuum. the 5.0 on the other hand has larger rectangular ports and a larger volume in the intake which relates to the vacuum available for throttle response. consider the mustang. they took the 351w cam and installed it in the 5.0 and tuned it accordingly for a 3200 lb car expecting it to be "wound tight." I would not be surprised if the 5.0 ecu would not run this engine better. the camshaft you listed says stock replacement but not for a 5.0. only for a 5.8. it is greatly increased over the broncos original camshaft. if you were building a carbureted system or even a sniper then you would not be in this situation. Hi! Thanks for the information. I understand what you mean. I had the opinion that the throttle body of the 351W and the 302 are the same. Also the IAC and the TPS. I know about my situation and it wasn't planed in this way...I opened the intake mainfold, cause two outlets were wet from oil...you have seen upon, what I have seen. The whole block looks like this. Two connection rods were bent, the cylinders had piston tipper. Alle crankshaft and camshaft bearings were worn out... So i tried to get stock parts, but without success..neither they aren't available nor very expensive...so it comes to the stroker kit. I have completely reworked the whole engine and nearly changed all parts at it. The most parts selected with the help of people from the FSB board...as they were with the latin at the end, they told me about this forum and that there are specialists regarding the EFI engines...so, thats my story... But back again: After checking the accessories vacuum and found no leak, I will unmount the throttle body and rework the sharp edges...I have already read in the past about problems after cleaning the throttle body. As I've bought the car all edges were covered with deposits...all fine smoth edges, like a coating. Now everything is nice and clean but also sharp...especially the bore of the IAC bypass. What does the book mean with this orifice inside the blades and about to plug them or not "plug select from go/no go using gauge pegs" Does this mean, that there are throttle plates with pluggable holes inside that can be removed or plugged to adjust the idle airflow? Link to comment Share on other sites More sharing options...
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