Big Blue's Transformation

[Gary Lewis]

And, here's the latest suspect: Dashpot Preposition. As you'll see in the writeup, it says "the basic concept may be envisioned as a sort of parallel throttle", so this is in addition to the air that the ECU thinks is needed to let the engine idle.

In the screenshot below my #'s are on the left and Bill's are on the right. I'm thinking this may well be the culprit, and I think I'll set all of those numbers to 0 and see what happens.

Today I changed Dashpot Preposition to 0 @ all RPMs and one more culprit has been exonerated.

In truth, the air mass value going through the MAF sensor went down from 1.4+ to 1.2+, so maybe if I set the Lower Limit to Enter Dashpot RPM Control back to 1.4 we'd go into RPM control. But even if that worked it would be masking the problem as the factory setting for this tune is .4 and Bill's is at .12.

And the Idle Speed Control duty cycle is running at about 35%, so something is calling for more air which is causing the duty cycle to go up and, therefore, the air mass to be too high.

The quest is still on...

 

[85lebaront2]

Today I changed Dashpot Preposition to 0 @ all RPMs and one more culprit has been exonerated.

In truth, the air mass value going through the MAF sensor went down from 1.4+ to 1.2+, so maybe if I set the Lower Limit to Enter Dashpot RPM Control back to 1.4 we'd go into RPM control. But even if that worked it would be masking the problem as the factory setting for this tune is .4 and Bill's is at .12.

And the Idle Speed Control duty cycle is running at about 35%, so something is calling for more air which is causing the duty cycle to go up and, therefore, the air mass to be too high.

The quest is still on...

Gary, could it be due to the cam you are running? Remember Darth still has a well worn, rather low compression 460 with a stock 1986 cam.

[Gary Lewis]

Gary, could it be due to the cam you are running? Remember Darth still has a well worn, rather low compression 460 with a stock 1986 cam.

I don't think so Bill as it idles pretty well. About 17" of vacuum.

The flag to go into computer control of the idle RPM isn't getting set, so the computer isn't bringing the idle down to the "desired" RPM of 648 that I've set. And it has plenty of room to do so as the ISC is running at about 35% for that 800 RPM idle, so it would be easy to drop the duty cycle and bring the R's down.

I'm doing a lot of reading trying to figure out what the issue is. And I keep going around in circles. Decipha's writeup on adjusting the idle doesn't talk about that flag, which surprises me. But it does talk about a number of functions that I'm slowly mapping my way through.

Anyway, I'm hoping to understand what sets the flag and then discover what I need to do to get the computer controlling the idle. And since I now have the mass airflow at idle down to 1.2ish I might set the lower limit to 1.4 again and see if that will do it. Somehow when I set it to 1.4 before the airflow had gone to between 1.4 and 1.5 so it never set.

[Gary Lewis]

I don't think so Bill as it idles pretty well. About 17" of vacuum.

The flag to go into computer control of the idle RPM isn't getting set, so the computer isn't bringing the idle down to the "desired" RPM of 648 that I've set. And it has plenty of room to do so as the ISC is running at about 35% for that 800 RPM idle, so it would be easy to drop the duty cycle and bring the R's down.

I'm doing a lot of reading trying to figure out what the issue is. And I keep going around in circles. Decipha's writeup on adjusting the idle doesn't talk about that flag, which surprises me. But it does talk about a number of functions that I'm slowly mapping my way through.

Anyway, I'm hoping to understand what sets the flag and then discover what I need to do to get the computer controlling the idle. And since I now have the mass airflow at idle down to 1.2ish I might set the lower limit to 1.4 again and see if that will do it. Somehow when I set it to 1.4 before the airflow had gone to between 1.4 and 1.5 so it never set.

Mid-day report. I did two things this morn:

1. I set Lower Limit To Enter Dashpot RPM Control to 1.4 lbs/min.

2. I asked a question regarding this on Decipha's forum.

Then I took it for a drive and did some data logging. And when it was warm and at idle the ISCFLG was still at 0, meaning it was in dashpot prepositioning, not RPM Control. And the idle was still too high.

But by then Decipha had responded with "if your stuck in dashpot then your either not setting the closed throttle flag or you did something to prevent dashpot from decaying out." Sure enough, the parameter of APT was at 0 at idle, and APT is "Throttle Status" with a -1 signaling closed throttle, 0 meaning part throttle, and 1 = WOT. And APT did got to 1 when I ran it up through the gears, so I know it is connected.

I'm not going into "closed throttle" mode! Now to figure out why that is...

[85lebaront2]

Mid-day report. I did two things this morn:

1. I set Lower Limit To Enter Dashpot RPM Control to 1.4 lbs/min.

2. I asked a question regarding this on Decipha's forum.

Then I took it for a drive and did some data logging. And when it was warm and at idle the ISCFLG was still at 0, meaning it was in dashpot prepositioning, not RPM Control. And the idle was still too high.

But by then Decipha had responded with "if your stuck in dashpot then your either not setting the closed throttle flag or you did something to prevent dashpot from decaying out." Sure enough, the parameter of APT was at 0 at idle, and APT is "Throttle Status" with a -1 signaling closed throttle, 0 meaning part throttle, and 1 = WOT. And APT did got to 1 when I ran it up through the gears, so I know it is connected.

I'm not going into "closed throttle" mode! Now to figure out why that is...

Gary, the EEC-V and the EEC-IV 1987 up treat whatever the TPS voltage is a startup as closed throttle. The early EEC-IV (1985-86 302) actually needed the idle screw to be used to bring the TPS voltage in spec, too high on those would actuate the EGR solenoids and lead to some very strange surging.

Are you using the aftermarket throttle body or the factory one? In either case, I would check what the closed throttle TPS voltage is, and if it is adjustable either by reducing the throttle opening or if possible moving the TPS pot in the direction of open throttle.

We had a 1990 Lincoln Town Car with the last year (for Lincoln) 302 SEFI engine. Idle setting on it was an issue and there was a TSB that called out a spacer under the IAC with two small needle valve screws to allow air bypass so idle and TPS could be brought into tolerance.

[Gary Lewis]

Gary, the EEC-V and the EEC-IV 1987 up treat whatever the TPS voltage is a startup as closed throttle. The early EEC-IV (1985-86 302) actually needed the idle screw to be used to bring the TPS voltage in spec, too high on those would actuate the EGR solenoids and lead to some very strange surging.

Are you using the aftermarket throttle body or the factory one? In either case, I would check what the closed throttle TPS voltage is, and if it is adjustable either by reducing the throttle opening or if possible moving the TPS pot in the direction of open throttle.

We had a 1990 Lincoln Town Car with the last year (for Lincoln) 302 SEFI engine. Idle setting on it was an issue and there was a TSB that called out a spacer under the IAC with two small needle valve screws to allow air bypass so idle and TPS could be brought into tolerance.

I'm using the BBK throttle body.

But these EEC-V's don't exactly use the startup TPS voltage as closed throttle. There's a function that BE calls RATCH that captures that startup voltage and then TP_REL is calculated by subtracting RATCH from TP. And the ECU then uses TP_REL.

I've gone through Decipha's instructions on checking to see that the TPS is working and it is. It is within the min and max voltages that are allowed, and it is varying. But APT never goes to -1 indicating closed throttle.

However, I had the thought that maybe it has never gone into closed throttle so went back in the logs. Sure enough, a month ago it was working! On May 6 at 10:21 I logged a run that had it working fine and the idle speed was close to "desired". But on May 7 the first log never went to closed throttle, and I'm pretty sure that no log has since, although I've just spot-checked several logs.

So now I'm trying to figure out what changed. Unfortunately I didn't save a tune file each time I made a change, so there are a lot of changes in there that I'll have to work my way through.

But the good news is that I have found a speeding bullet. Now I need to find the smoking gun. (Is that a mixed metaphor? )

[85lebaront2]

I'm using the BBK throttle body.

But these EEC-V's don't exactly use the startup TPS voltage as closed throttle. There's a function that BE calls RATCH that captures that startup voltage and then TP_REL is calculated by subtracting RATCH from TP. And the ECU then uses TP_REL.

I've gone through Decipha's instructions on checking to see that the TPS is working and it is. It is within the min and max voltages that are allowed, and it is varying. But APT never goes to -1 indicating closed throttle.

However, I had the thought that maybe it has never gone into closed throttle so went back in the logs. Sure enough, a month ago it was working! On May 6 at 10:21 I logged a run that had it working fine and the idle speed was close to "desired". But on May 7 the first log never went to closed throttle, and I'm pretty sure that no log has since, although I've just spot-checked several logs.

So now I'm trying to figure out what changed. Unfortunately I didn't save a tune file each time I made a change, so there are a lot of changes in there that I'll have to work my way through.

But the good news is that I have found a speeding bullet. Now I need to find the smoking gun. (Is that a mixed metaphor? )

I guess it beats a smoking bullet and a speeding gun.

[Gary Lewis]

I guess it beats a smoking bullet and a speeding gun.

Well, it depends on your definition of "bullet". In RED Bruce Willis throws a bunch of rounds, which some call bullets, in a frying pan and turned on the burner. And they smoked a bit until they went off. So in that sense a smoking bullet isn't good.

As for the differences between tunes where closed throttle works and tunes where it doesn't, I don't have a good answer. And that is because I didn't keep good enough records.

I have a tune file called "05042022 Misfire Dashpot for MPH and Idle Changes" and I have several log files with that name plus a time stamp, and they all have a working APT, meaning it goes to -1 for Closed Throttle. But it looks like there were changes made to the original tune file without saving it under another name. And then there's the tune file called "05072022 Manifold to 3 and Idle Change plus 96", and none of the log files with that name and a time stamp have a working APT.

So, I think what I need to do is to write the 05042022 file into the ECU, fire it up, and see if the APT goes to -1. If so then I can write the 05072022 file in, fire it up, and see if it doesn't work. If so, then the problem is either Intake Manifold Size in Liters, which I set to 3, or Idle Air Adder for ECT, which has two of the temps set to +96 RPM.

But, if the 05042022 file doesn't "work" then I'll have to back up file by file until I find one that does work and then find the differences.

Does that make sense?

However,

[85lebaront2]

Well, it depends on your definition of "bullet". In RED Bruce Willis throws a bunch of rounds, which some call bullets, in a frying pan and turned on the burner. And they smoked a bit until they went off. So in that sense a smoking bullet isn't good.

As for the differences between tunes where closed throttle works and tunes where it doesn't, I don't have a good answer. And that is because I didn't keep good enough records.

I have a tune file called "05042022 Misfire Dashpot for MPH and Idle Changes" and I have several log files with that name plus a time stamp, and they all have a working APT, meaning it goes to -1 for Closed Throttle. But it looks like there were changes made to the original tune file without saving it under another name. And then there's the tune file called "05072022 Manifold to 3 and Idle Change plus 96", and none of the log files with that name and a time stamp have a working APT.

So, I think what I need to do is to write the 05042022 file into the ECU, fire it up, and see if the APT goes to -1. If so then I can write the 05072022 file in, fire it up, and see if it doesn't work. If so, then the problem is either Intake Manifold Size in Liters, which I set to 3, or Idle Air Adder for ECT, which has two of the temps set to +96 RPM.

But, if the 05042022 file doesn't "work" then I'll have to back up file by file until I find one that does work and then find the differences.

Does that make sense?

However,

Yes, it makes perfect sense. I had a bit of trial and error with Darth and there is still the need once the new engine is installed to finalize my VMV settings. I could have just left the EVAP system as an open system, but wanted it working since ethanol gas and extremely damp air mix too well and can really do a number on tanks and pumps.

[Gary Lewis]

Yes, it makes perfect sense. I had a bit of trial and error with Darth and there is still the need once the new engine is installed to finalize my VMV settings. I could have just left the EVAP system as an open system, but wanted it working since ethanol gas and extremely damp air mix too well and can really do a number on tanks and pumps.

Thanks, Bill. I'll give it a try tomorrow and let you know.

As for the vent, I do smell gas at times from Big Blue. But I don't don't want the complexity, although I can see that where you live the humidity mixes all too well with the ethanol.