Gary Lewis Posted November 21, 2023 Share Posted November 21, 2023 Maybe i don't understand these early fuel injection systems, but shouldn't the idle air control valve be able to get the rpms up above 1k? The difference between intake air temp and coolant temperature should be what the computer uses to set injector pulse width. Is this year using a coolant heated throttle body? Yes, the IAC should be able to get the RPM above 1K. But we don't know what the ECU wants the idle RPM to be immediately after startup, which is somewhat based on ACT and ECT. Big Blue goes to something like 1400 for a few seconds after starting when everything is "cold". So something's not right, for either starting or idling "cold". And yes, this year probably had a coolant-heated throttle body initially. But it may not now, although I doubt that would make much difference in startup or cold idling. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted November 21, 2023 Share Posted November 21, 2023 Yes, the IAC should be able to get the RPM above 1K. But we don't know what the ECU wants the idle RPM to be immediately after startup, which is somewhat based on ACT and ECT....... This year probably had a coolant-heated throttle body initially. But it may not now, although I doubt that would make much difference in startup or cold idling. I didn't mean to suggest that the heated throttle body would make any difference with a cold start. Like I said, im not as familiar with these early systems as I should be, and just wanted to be sure I knew what I was talking about. Surely the ECU should command enough 'idle speed' that the engine runs. Regardless the lookup table, it doesn't want the engine to stumble and die. Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 21, 2023 Share Posted November 21, 2023 Yes, the IAC should be able to get the RPM above 1K. But we don't know what the ECU wants the idle RPM to be immediately after startup, which is somewhat based on ACT and ECT....... This year probably had a coolant-heated throttle body initially. But it may not now, although I doubt that would make much difference in startup or cold idling. I didn't mean to suggest that the heated throttle body would make any difference with a cold start. Like I said, im not as familiar with these early systems as I should be, and just wanted to be sure I knew what I was talking about. Surely the ECU should command enough 'idle speed' that the engine runs. Regardless the lookup table, it doesn't want the engine to stumble and die. I'm not familiar with them either. I know they don't have the full capabilities of what the EEC-V systems have, but I don't know how much less they have. I think where we are is that with the given inputs we are either outside the "startup" lookup table or the answers in the lookup table aren't adequate to get this engine to run. But by opening the throttle just a touch the answers get it to start. However, even then the answers aren't adequate to get it to run at a reasonable RPM until it warms up. It may be time to read up on the EEC-IV. I found this which might help: EEC IV Inner Workings. I'm reading Link to comment Share on other sites More sharing options...
ReneH Posted November 21, 2023 Author Share Posted November 21, 2023 The starting problem seems to be associated with the throttle position. At cold temps it takes a rich mix to start the engine, but if the TPS is telling the ECU that the throttle is closed more than it really is then maybe the ECU won't give it enough fuel to start? Hopefully the adjustment this weekend will fix that. If not then maybe it is time to replace the ACT? I have the TPS as suspect every time... I set the TPS between 0.9 and 1.0 volts when the throttles are closed (laying at the stop screw). Currently I have about 4.5 volts at full throttle. Maybe I have understand something wrong about setting the TPS... Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 21, 2023 Share Posted November 21, 2023 I have the TPS as suspect every time... I set the TPS between 0.9 and 1.0 volts when the throttles are closed (laying at the stop screw). Currently I have about 4.5 volts at full throttle. Maybe I have understand something wrong about setting the TPS... Yes, I suspect the TPS as well. But I don't know that much about adjustable ones, so will tag Bill, who does. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted November 21, 2023 Share Posted November 21, 2023 I'm not familiar with them either. I know they don't have the full capabilities of what the EEC-V systems have, but I don't know how much less they have. I think where we are is that with the given inputs we are either outside the "startup" lookup table or the answers in the lookup table aren't adequate to get this engine to run. But by opening the throttle just a touch the answers get it to start. However, even then the answers aren't adequate to get it to run at a reasonable RPM until it warms up. It may be time to read up on the EEC-IV. I found this which might help: EEC IV Inner Workings. I'm reading Thanks for that, Gary Link to comment Share on other sites More sharing options...
ReneH Posted November 21, 2023 Author Share Posted November 21, 2023 I'm not familiar with them either. I know they don't have the full capabilities of what the EEC-V systems have, but I don't know how much less they have. I think where we are is that with the given inputs we are either outside the "startup" lookup table or the answers in the lookup table aren't adequate to get this engine to run. But by opening the throttle just a touch the answers get it to start. However, even then the answers aren't adequate to get it to run at a reasonable RPM until it warms up. It may be time to read up on the EEC-IV. I found this which might help: EEC IV Inner Workings. I'm reading I also haven't an adjustable TPS...I only have widen the holes of the sensor to be able to rotate it slightly and adjust das basic value. Link to comment Share on other sites More sharing options...
85lebaront2 Posted November 21, 2023 Share Posted November 21, 2023 Yes, I suspect the TPS as well. But I don't know that much about adjustable ones, so will tag Bill, who does. Ok, Rene' I believe you said you are using a later computer, so it should not be as sensitive to closed throttle voltage. The newer computers measure the TPS voltage on startup and use that as the closed throttle value. The 4.5V max you are reading gives two questions (1) how far open is the throttle at startup (2) is the throttle opening fully (plates should be parallel to the bore at wide open throttle). The chart I have for TPS values shows 4.538V at full throttle as normal. 5.0V is only reached in "overtravel" or when the full throttle stop is bent, or damaged. Base idle rpm is set with the IAC closed and I can't remember if it defaults to closed when unplugged. I believe it does as it needs to be at minimum air flow in order to set base idle. If your TPS values match the chart (+/- 3%) then everything is correct. If you can't get a good base idle rpm without a lot of throttle opening, see if the new throttle body has bypass holes in the throttle plates, these allow more air flow without having to open the throttle. If there are holes, they will probably be in US measurements, fractional inches. Find the nearest size metric drill you have and go up one increment (.01 or .1 depending on what is available to you) IMPORTANT, remove the throttle body while drilling and blow it off afterwards. Link to comment Share on other sites More sharing options...
ReneH Posted November 22, 2023 Author Share Posted November 22, 2023 Ok, Rene' I believe you said you are using a later computer, so it should not be as sensitive to closed throttle voltage. The newer computers measure the TPS voltage on startup and use that as the closed throttle value. The 4.5V max you are reading gives two questions (1) how far open is the throttle at startup (2) is the throttle opening fully (plates should be parallel to the bore at wide open throttle). The chart I have for TPS values shows 4.538V at full throttle as normal. 5.0V is only reached in "overtravel" or when the full throttle stop is bent, or damaged. Base idle rpm is set with the IAC closed and I can't remember if it defaults to closed when unplugged. I believe it does as it needs to be at minimum air flow in order to set base idle. If your TPS values match the chart (+/- 3%) then everything is correct. If you can't get a good base idle rpm without a lot of throttle opening, see if the new throttle body has bypass holes in the throttle plates, these allow more air flow without having to open the throttle. If there are holes, they will probably be in US measurements, fractional inches. Find the nearest size metric drill you have and go up one increment (.01 or .1 depending on what is available to you) IMPORTANT, remove the throttle body while drilling and blow it off afterwards. Hi Bill, Yes I use the 1989 EEC-IV for the 351W. Thanks, this chart is very helpful! I think, I have to adjust my TPS along with this chart. The plates of my new body have holes, but they're plugged with rivets. But I'll try to set the idle alone the original Ford procedure, first and look about what values I'll get back from the TPS. Link to comment Share on other sites More sharing options...
ReneH Posted November 22, 2023 Author Share Posted November 22, 2023 Ok, Rene' I believe you said you are using a later computer, so it should not be as sensitive to closed throttle voltage. The newer computers measure the TPS voltage on startup and use that as the closed throttle value. The 4.5V max you are reading gives two questions (1) how far open is the throttle at startup (2) is the throttle opening fully (plates should be parallel to the bore at wide open throttle). The chart I have for TPS values shows 4.538V at full throttle as normal. 5.0V is only reached in "overtravel" or when the full throttle stop is bent, or damaged. Base idle rpm is set with the IAC closed and I can't remember if it defaults to closed when unplugged. I believe it does as it needs to be at minimum air flow in order to set base idle. If your TPS values match the chart (+/- 3%) then everything is correct. If you can't get a good base idle rpm without a lot of throttle opening, see if the new throttle body has bypass holes in the throttle plates, these allow more air flow without having to open the throttle. If there are holes, they will probably be in US measurements, fractional inches. Find the nearest size metric drill you have and go up one increment (.01 or .1 depending on what is available to you) IMPORTANT, remove the throttle body while drilling and blow it off afterwards. So, I have done Ford's procedure this evening. The TPS voltage is about 0.89 to 0.92 when the throttle hits the stop screw now. It's about 4.42 to 4.55 on full throttle when key on and engine off. I'll see, how it behave tomorrow. We should get about 0 degrees Celsius. What is about the canister that filters the gasoline haze? If I clamp the vacuum hose that is connected to it, the engine is about to starve...is this canister a possible part, that can cause a vacuum failure? Link to comment Share on other sites More sharing options...
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