Has the base idle been set? if so how was it set? was The Tps adjusted properly and lab scoped for glitches?
Another Respected Tech Tosses In The Towel!
- Thread starter demarpaint
- Start date
- Status
OVERKILL
$100 Site Donor 2021
Originally Posted By: firefighter
Has the base idle been set? if so how was it set? was The Tps adjusted properly and lab scoped for glitches?
EEC-IV uses a range of acceptable base voltage for the TPS that it then goes from as a reference point for closed throttle. It resets every time you start it. As long as your base voltage is in range (0.6-1.0V IIRC) it is fine.
I think he has already replaced the TPS anyhow, but I understand where you are going with this. I had the TPS go out on my Mustang and it would randomly idle at like 3,000RPM. Scared the poop out of me! LOL!
Has the base idle been set? if so how was it set? was The Tps adjusted properly and lab scoped for glitches?
EEC-IV uses a range of acceptable base voltage for the TPS that it then goes from as a reference point for closed throttle. It resets every time you start it. As long as your base voltage is in range (0.6-1.0V IIRC) it is fine.
I think he has already replaced the TPS anyhow, but I understand where you are going with this. I had the TPS go out on my Mustang and it would randomly idle at like 3,000RPM. Scared the poop out of me! LOL!
Ok, you said that "timing is spot-on". I assume you mean base timing. But is the timing advancing properly at idle? I've heard of modules failing in such a way that the engine still runs kinda ok at base timing, but the ECM isn't able to apply any advance.
A quick check would be to check the base timing (I forget how you do it on these old fords... maybe it requires a pin jumper or something), then check and see if the timing has advanced at idle. I don't know how much it'll be, and good luck finding a spec. But I'd expect to see a bare minimum of 10-15 degrees of advance at idle (in addition to base timing). Possibly more.
A quick check would be to check the base timing (I forget how you do it on these old fords... maybe it requires a pin jumper or something), then check and see if the timing has advanced at idle. I don't know how much it'll be, and good luck finding a spec. But I'd expect to see a bare minimum of 10-15 degrees of advance at idle (in addition to base timing). Possibly more.
The TPS in this van was replaced. It is fixed position, there is no adjustment, voltage readings are within range.
Curb idle was set when the IAC spacer plate was installed according to the shop manual procedure. When one of the techs installed the spacer plate under the IAC the curb idle was so far off you could cruise down the highway at 50 without touching the gas. I reset it myself because I was a little bit pizt off. That was something he should have figured out backing out of the bay. The problem is when you put the spacer plate in you have to reset the curb idle, and allow it to re-learn the idle strategy. I looked up the process for setting up the curb idle and it is properly set now.
Curb idle was set when the IAC spacer plate was installed according to the shop manual procedure. When one of the techs installed the spacer plate under the IAC the curb idle was so far off you could cruise down the highway at 50 without touching the gas. I reset it myself because I was a little bit pizt off. That was something he should have figured out backing out of the bay. The problem is when you put the spacer plate in you have to reset the curb idle, and allow it to re-learn the idle strategy. I looked up the process for setting up the curb idle and it is properly set now.
Originally Posted By: onion
Ok, you said that "timing is spot-on". I assume you mean base timing. But is the timing advancing properly at idle? I've heard of modules failing in such a way that the engine still runs kinda ok at base timing, but the ECM isn't able to apply any advance.
A quick check would be to check the base timing (I forget how you do it on these old fords... maybe it requires a pin jumper or something), then check and see if the timing has advanced at idle. I don't know how much it'll be, and good luck finding a spec. But I'd expect to see a bare minimum of 10-15 degrees of advance at idle (in addition to base timing). Possibly more.
Base timing is set with the spout connector disconnected. Three of us checked it, and confirmed it is set properly 10* comes to mind. If you forget to disconnect the spout connector IIRC you won't even see the timing mark.
It is hard to convey in typed words expressions. I don't want to come across as a know it all, obviously I don't or this thing would be fixed. Most of what has been brought up here has been covered. But I haven't blocked off the FP regulator yet, and I'm not certain if the tech ruled out the injectors with a cyl balance test. I haven't been able to speak with him yet. The guys that had their hands in it are saying the injectors are good. I need to know how they determined this.
Keep the ideas and suggestions coming. I'm from the school of thought that anything can be fixed. At least I hope so!
Ok, you said that "timing is spot-on". I assume you mean base timing. But is the timing advancing properly at idle? I've heard of modules failing in such a way that the engine still runs kinda ok at base timing, but the ECM isn't able to apply any advance.
A quick check would be to check the base timing (I forget how you do it on these old fords... maybe it requires a pin jumper or something), then check and see if the timing has advanced at idle. I don't know how much it'll be, and good luck finding a spec. But I'd expect to see a bare minimum of 10-15 degrees of advance at idle (in addition to base timing). Possibly more.
Base timing is set with the spout connector disconnected. Three of us checked it, and confirmed it is set properly 10* comes to mind. If you forget to disconnect the spout connector IIRC you won't even see the timing mark.
It is hard to convey in typed words expressions. I don't want to come across as a know it all, obviously I don't or this thing would be fixed. Most of what has been brought up here has been covered. But I haven't blocked off the FP regulator yet, and I'm not certain if the tech ruled out the injectors with a cyl balance test. I haven't been able to speak with him yet. The guys that had their hands in it are saying the injectors are good. I need to know how they determined this.
Keep the ideas and suggestions coming. I'm from the school of thought that anything can be fixed. At least I hope so!
Last edited:
Originally Posted By: demarpaint
The TPS in this van was replaced. It is fixed position, there is no adjustment, voltage readings are within range.
Curb idle was set when the IAC spacer plate was installed according to the shop manual procedure. When one of the techs installed the spacer plate under the IAC the curb idle was so far off you could cruise down the highway at 50 without touching the gas. I reset it myself because I was a little bit pizt off. That was something he should have figured out backing out of the bay. The problem is when you put the spacer plate in you have to reset the curb idle, and allow it to re-learn the idle strategy. I looked up the process for setting up the curb idle and it is properly set now.
What do you mean readings are in range?? what are the actual readings. Why would putting a spacer cause the idle to change(I am not famalier with this spacer update/TSB)?? Since the tps is fixed position suppose some one bent the tang for the adjustment screw for throttle stop. now tps is out of range. If you put on a new tps but the old one was in range, did you scope the new one to see it's reading. It seems we are swapping alot of parts on a guess, and the only thing I see in common is this idle screw being messed with. Just trying to help hope I don't sound to harsh, I work at a driveabiity shop and we get alot of work from other shops that fuel pressure was in specs, or the sensors are all in range whats is wrong with it, and we test and it is more times than not something that was "in range". I just need to know numbers.
The TPS in this van was replaced. It is fixed position, there is no adjustment, voltage readings are within range.
Curb idle was set when the IAC spacer plate was installed according to the shop manual procedure. When one of the techs installed the spacer plate under the IAC the curb idle was so far off you could cruise down the highway at 50 without touching the gas. I reset it myself because I was a little bit pizt off. That was something he should have figured out backing out of the bay. The problem is when you put the spacer plate in you have to reset the curb idle, and allow it to re-learn the idle strategy. I looked up the process for setting up the curb idle and it is properly set now.
What do you mean readings are in range?? what are the actual readings. Why would putting a spacer cause the idle to change(I am not famalier with this spacer update/TSB)?? Since the tps is fixed position suppose some one bent the tang for the adjustment screw for throttle stop. now tps is out of range. If you put on a new tps but the old one was in range, did you scope the new one to see it's reading. It seems we are swapping alot of parts on a guess, and the only thing I see in common is this idle screw being messed with. Just trying to help hope I don't sound to harsh, I work at a driveabiity shop and we get alot of work from other shops that fuel pressure was in specs, or the sensors are all in range whats is wrong with it, and we test and it is more times than not something that was "in range". I just need to know numbers.
Ford had a TSB years ago about installing a spacer plate under the IAC. To correct surging and idle problems. I bought it and installed it, then removed it because there were conflicting opinions about it. Fast forward to last year, a tech said it was a good idea to install, I had the part and told him to try it. They called it an Idle Air Adjust Spacer, it was used to correct sludge contamination concerns of the throttle body bore and plate. Mine was surprisingly clean!
Once installed you adjusted the throttle plate stop screw. When the tech did this he screwed up the curb idle speed. I went through the process to be certain that was correct, after speeding down the street at 50 mph. That's the downside of having a mechanic leave the keys in the visor and you picking the van up after closing on a Friday night.
Once you do this you have to run a KOEO test to verify that no TPS codes exist, and nothing is binding. I also took voltage of the TPS to make sure they were correct or in spec. Hopefully that explains it more clearly. Maybe my terminology is not textbook, sorry.
Once this plate is installed you do not turn the throttle plate stop screw to set idle. It is set by turning one or two allen screws in the spacer plate. There is a procedure outlined for doing this. Again I found this out after the tech screwed up the installation and didn't set the idle correctly.
As far as numbers I don't have them, written down. I gave up on guessing and sent it to two different shops hoping someone could put this to rest. Seems its back in my lap now. I don't want to toss injectors at it until I'm 100% sure. At this point I'm not. When I checked numbers I compared them to voltage readings I was supposed to get for the part I was testing.
Now I'm going off of what these guys are telling me. It is pointless to pay someone to do a job then have to go over it to check their work. I reached out for help because I was stumped. Now I don't feel bad seeing towels tossed in from pros.
BTW you're not harsh, communicating in print is tough!
Once installed you adjusted the throttle plate stop screw. When the tech did this he screwed up the curb idle speed. I went through the process to be certain that was correct, after speeding down the street at 50 mph. That's the downside of having a mechanic leave the keys in the visor and you picking the van up after closing on a Friday night.
Once you do this you have to run a KOEO test to verify that no TPS codes exist, and nothing is binding. I also took voltage of the TPS to make sure they were correct or in spec. Hopefully that explains it more clearly. Maybe my terminology is not textbook, sorry.
Once this plate is installed you do not turn the throttle plate stop screw to set idle. It is set by turning one or two allen screws in the spacer plate. There is a procedure outlined for doing this. Again I found this out after the tech screwed up the installation and didn't set the idle correctly.
As far as numbers I don't have them, written down. I gave up on guessing and sent it to two different shops hoping someone could put this to rest. Seems its back in my lap now. I don't want to toss injectors at it until I'm 100% sure. At this point I'm not. When I checked numbers I compared them to voltage readings I was supposed to get for the part I was testing.
Now I'm going off of what these guys are telling me. It is pointless to pay someone to do a job then have to go over it to check their work. I reached out for help because I was stumped. Now I don't feel bad seeing towels tossed in from pros.
BTW you're not harsh, communicating in print is tough!
Last edited:
Edit to add. IIRC the throttle plate stop screw can cause linkage binding when this plate is installed. I have no clue how, but they make it clear in the directions that binding can occur if this thing is installed wrong.
Another tidbit is this van is a 5 speed stick, there aren't many around. The F series trucks had plenty of them, the M5OD leakers. The idle blip, surge can occur when the engine is under load trying to take off, while letting up the clutch. It will speed the idle up making the take off harsh. It doesn't happen all the time just enough to be annoying. Now it the planets are in alignment and the AC compressor cycles while you are taking off it is a real PITA!!!!!!!!!!!! I wish I could talk instead of type it is easier to convey!
Another tidbit is this van is a 5 speed stick, there aren't many around. The F series trucks had plenty of them, the M5OD leakers. The idle blip, surge can occur when the engine is under load trying to take off, while letting up the clutch. It will speed the idle up making the take off harsh. It doesn't happen all the time just enough to be annoying. Now it the planets are in alignment and the AC compressor cycles while you are taking off it is a real PITA!!!!!!!!!!!! I wish I could talk instead of type it is easier to convey!
Your right communicating in print is tough. With all you have done has the problem ever changed?? Other than the fuel injector cleaning. I don't think injectors are the problem, why would that cause a hot surge that would go away when you tap the throttle?? This iac you swapped out, there is a tsb for this year that replacement iac no longer have a diode in them and you must reverse the wires when you put a new one on don't know if this pertains to you. What is the surge you speak of how much, up to 2000 and back to 500 or what? Tell me more about this stumble then race up as the computer compensates, what does this mean?
Originally Posted By: firefighter
Your right communicating in print is tough. With all you have done has the problem ever changed?? Other than the fuel injector cleaning. I don't think injectors are the problem, why would that cause a hot surge that would go away when you tap the throttle?? This iac you swapped out, there is a tsb for this year that replacement iac no longer have a diode in them and you must reverse the wires when you put a new one on don't know if this pertains to you. What is the surge you speak of how much, up to 2000 and back to 500 or what? Tell me more about this stumble then race up as the computer compensates, what does this mean?
The problem hasn't changed much, the best results were immediately after the FI cleaning.
Interesting point about the IAC and I explained this to the last guy that had the van. The IAC valve replacement valve [FMC part] is NIB but several years old. All the ones I tried including the IAC off my brothers 94 F-150 yeilded the same results. Now if there was an improvement made to IAC valves after 1994 I have not tried one of them!!!!!!!!!! The tech said he doubts the IAC is bad, and I can't get one to try and return. The swap out takes no time at all.
The hot restart surge goes from about 500-1200 rpm or so, up and down, and will continue for 30 seconds or more. The second you tap the gas it stops surging.
The take off stumble is similar, but intermittent. Lets say you're stopped at a light. You go to take off easy on the clutch, the clutch starts to grab, sometimes the computer will detect the drop in rpms, and speed up the idle, now if you are giving it gas to take off, that plus the computer kicking in [compensates] makes for an annoying take off. It doesn't do it all the time though, other times you'll get a little stumble. Almost as if you were new to driving a stick. I've owned and driven them since the mid 70's, every fleet of cars I've had in the last 27 years included a stick shift. My point is I know how to drive stick. LOL
Another thing is if you turn the AC on and are stopped at a light, as soon as the AC engages, and the idle drops slightly it might start surging again. A tap of the gas fixes it. When I say tap, all i'm talking about is enough to move the tach 100 rpms. The AC on surge is also hit or miss.
BTW PM returned....Thanks.
Your right communicating in print is tough. With all you have done has the problem ever changed?? Other than the fuel injector cleaning. I don't think injectors are the problem, why would that cause a hot surge that would go away when you tap the throttle?? This iac you swapped out, there is a tsb for this year that replacement iac no longer have a diode in them and you must reverse the wires when you put a new one on don't know if this pertains to you. What is the surge you speak of how much, up to 2000 and back to 500 or what? Tell me more about this stumble then race up as the computer compensates, what does this mean?
The problem hasn't changed much, the best results were immediately after the FI cleaning.
Interesting point about the IAC and I explained this to the last guy that had the van. The IAC valve replacement valve [FMC part] is NIB but several years old. All the ones I tried including the IAC off my brothers 94 F-150 yeilded the same results. Now if there was an improvement made to IAC valves after 1994 I have not tried one of them!!!!!!!!!! The tech said he doubts the IAC is bad, and I can't get one to try and return. The swap out takes no time at all.
The hot restart surge goes from about 500-1200 rpm or so, up and down, and will continue for 30 seconds or more. The second you tap the gas it stops surging.
The take off stumble is similar, but intermittent. Lets say you're stopped at a light. You go to take off easy on the clutch, the clutch starts to grab, sometimes the computer will detect the drop in rpms, and speed up the idle, now if you are giving it gas to take off, that plus the computer kicking in [compensates] makes for an annoying take off. It doesn't do it all the time though, other times you'll get a little stumble. Almost as if you were new to driving a stick. I've owned and driven them since the mid 70's, every fleet of cars I've had in the last 27 years included a stick shift. My point is I know how to drive stick. LOL
Another thing is if you turn the AC on and are stopped at a light, as soon as the AC engages, and the idle drops slightly it might start surging again. A tap of the gas fixes it. When I say tap, all i'm talking about is enough to move the tach 100 rpms. The AC on surge is also hit or miss.
BTW PM returned....Thanks.
I would be tempted to get another throttle body at the junkyard to swap out. I know you said all the base throttle setting and idle relearn was done. But when you say the base idle screw was adjusted, and that taping the throttle smooths the engine out, I'm very inclined to believe that there is something off on this throttle body that the ECM can't properly compensate for.
Vapor cannister and/or the whole EVAP system may be faulty.
A coolant sensor to the computer [NOT gauge] may be out of spec.
Also, could you get a new computer? Or a test one?
Reflash available at the dealer? Worth a call.
A quick test is to try and squirt flammable carb cleaner in short bursts as the engine is idling. Aim at specific location and note any change.
What if you find it is MMO poisoning?!?!
A coolant sensor to the computer [NOT gauge] may be out of spec.
Also, could you get a new computer? Or a test one?
Reflash available at the dealer? Worth a call.
A quick test is to try and squirt flammable carb cleaner in short bursts as the engine is idling. Aim at specific location and note any change.
What if you find it is MMO poisoning?!?!
I have lots of things to try, but first I have to talk with the last guy that had it and see ask him a few questions.
The computer was a re-man, it did nothing. I'm not sure if a 1988 can be flash programmed?
MMO poisoning, I've stopped using it in this van for a month now. I think its addicted it is showing signs of withdrawal. Honestly over the years I discontinued using it from time to time to R/O it out as the problem. If it were the MMO you guys would know.
The computer was a re-man, it did nothing. I'm not sure if a 1988 can be flash programmed?
MMO poisoning, I've stopped using it in this van for a month now. I think its addicted it is showing signs of withdrawal. Honestly over the years I discontinued using it from time to time to R/O it out as the problem. If it were the MMO you guys would know.
Originally Posted By: demarpaint
Once installed you adjusted the throttle plate stop screw. When the tech did this he screwed up the curb idle speed. I went through the process to be certain that was correct, after speeding down the street at 50 mph.
\
Just to clarify. When you install the spacer plate, you never touch the idle stop screw on the throttle body. The idle air /base idle speed is adjusted with those two little allen head screws in the plate.
Those little kits were not one of FoMoCos better ideas.
Once installed you adjusted the throttle plate stop screw. When the tech did this he screwed up the curb idle speed. I went through the process to be certain that was correct, after speeding down the street at 50 mph.
\
Just to clarify. When you install the spacer plate, you never touch the idle stop screw on the throttle body. The idle air /base idle speed is adjusted with those two little allen head screws in the plate.
Those little kits were not one of FoMoCos better ideas.
Quote:
Does this use the cone shaped air filter with the big clamp that connect two halves? I have seem more than one of these improperly installed (only half on on the bottom) or rotted out,they will leak behind the MAF and throw no codes.
The MMO inverse oiler will not help with the injector internals as its not going into the fuel system but rather the air intake.
This generally throws a "system too lean" code.
Does this use the cone shaped air filter with the big clamp that connect two halves? I have seem more than one of these improperly installed (only half on on the bottom) or rotted out,they will leak behind the MAF and throw no codes.
The MMO inverse oiler will not help with the injector internals as its not going into the fuel system but rather the air intake.
This generally throws a "system too lean" code.
Originally Posted By: punisher
Originally Posted By: demarpaint
Once installed you adjusted the throttle plate stop screw. When the tech did this he screwed up the curb idle speed. I went through the process to be certain that was correct, after speeding down the street at 50 mph.
\
Just to clarify. When you install the spacer plate, you never touch the idle stop screw on the throttle body. The idle air /base idle speed is adjusted with those two little allen head screws in the plate.
Those little kits were not one of FoMoCos better ideas.
Yes that is correct. I had to go through it because he had everything screwed up.
Originally Posted By: demarpaint
Once installed you adjusted the throttle plate stop screw. When the tech did this he screwed up the curb idle speed. I went through the process to be certain that was correct, after speeding down the street at 50 mph.
\
Just to clarify. When you install the spacer plate, you never touch the idle stop screw on the throttle body. The idle air /base idle speed is adjusted with those two little allen head screws in the plate.
Those little kits were not one of FoMoCos better ideas.
Yes that is correct. I had to go through it because he had everything screwed up.
I had a similar problem on an '88 F150 many many years ago. The throttle plates were dirty and apparently closed too far causing a complete seal and causing the IAC to go crazy trying to let in enough air to overcome the sealed throttle butterfly. The cure in this case was to clean the throttle body and adjust the throttle stop to hold the butterfly open a crack - then the IAC could work within it's normal range. The other fix to another almost identical problem later was one of the coolant temperature sensors.
A friend of mine had a similar problem with his F150, I think an '87 or '89. There was some kind of electric fan/air pump that was supposed to run after a hot shutdown to cool the intake area. His stopped working and he had hot start problems. I don't know if the vans had something similar.
In retrospect, it seems like a lot o things caused hot start idle problems.
A friend of mine had a similar problem with his F150, I think an '87 or '89. There was some kind of electric fan/air pump that was supposed to run after a hot shutdown to cool the intake area. His stopped working and he had hot start problems. I don't know if the vans had something similar.
In retrospect, it seems like a lot o things caused hot start idle problems.
Last edited:
After rereading Demarpaint's symptoms and that it perfectly smooths out with a slight increase in throttle, this sounds like it could be the solution. Open the throttle screw setting a little and maybe thn the ISC will be able to control idle. I know Demar went through the setting procedure but the symptoms sound like an ISC control issue.
I'm going to fix this van yet. I had a great talk with Firefighter yesterday, he went out of his way to call me and discuss this issue. The man is extremely educated in auto repair and very helpful. We pretty much ruled out the injectors.
In thinking over what he said and adjustments that were made by the first tech I have a feeling it could be something with the throttle body set screw.
Anyone familiar with these early generation EFI 4.9L I6. Where exactly is the Throttle body set screw located?
The reason I ask is the mechanic that installed the spacer plate on the IAC was messing with something nowhere near the throttle body, and I have a feeling my fix is quite easy! Especially after reading through this thread again!
In thinking over what he said and adjustments that were made by the first tech I have a feeling it could be something with the throttle body set screw.
Anyone familiar with these early generation EFI 4.9L I6. Where exactly is the Throttle body set screw located?
The reason I ask is the mechanic that installed the spacer plate on the IAC was messing with something nowhere near the throttle body, and I have a feeling my fix is quite easy! Especially after reading through this thread again!
- Status
