Coke Car running lean...
09-20-2015, 05:46 PM
#121
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I've fixed cars that had the FPR in the front damper position.
None of those cars would run, at all
None of those cars would run, at all
09-20-2015, 07:24 PM
#122
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I've fixed cars that had the FPR in the front damper position.
None of those cars would run, at all. The fuel hits the backside of the FPR "seat" and is dead headed....because there is no pressure on the other side to "lift" the seat.
Of course, every time this occurred the FPR was new. Perhaps an old worn out FPR would allow a small amount of fuel to bypass?
I've seen fuel filters that were allowed to "dry out" be very restrictive. And, of course, tank strainers can get so restricted that they won't pass enough fuel. The problem with either of these items is that things tend to get worse, when the car is run. I'd think that the performance of the car would have deteriorated as the day went on, at the track.
Fuel pumps that are restricted from either end tend to be really noisy as they struggle to pass fuel. Does the pump sound like it is straining to pump?
None of those cars would run, at all. The fuel hits the backside of the FPR "seat" and is dead headed....because there is no pressure on the other side to "lift" the seat.
Of course, every time this occurred the FPR was new. Perhaps an old worn out FPR would allow a small amount of fuel to bypass?
I've seen fuel filters that were allowed to "dry out" be very restrictive. And, of course, tank strainers can get so restricted that they won't pass enough fuel. The problem with either of these items is that things tend to get worse, when the car is run. I'd think that the performance of the car would have deteriorated as the day went on, at the track.
Fuel pumps that are restricted from either end tend to be really noisy as they struggle to pass fuel. Does the pump sound like it is straining to pump?
I'll take a closer look at the dampers. Since there was an Adj FPR on there, ther may be some other shenanigans going on.
09-20-2015, 07:40 PM
#123
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The pump sounds normal - and I know what a cavitating pump sounds like. When I replaced it, as soon as I disconnected the inlet hose, about 5 gallons of fuel came spewing out of the tank. There was no noticeable restriction there, so the only think I can think of is the filter at this point. I'll replace it, and see if there is any difference.
I'll take a closer look at the dampers. Since there was an Adj FPR on there, ther may be some other shenanigans going on.
I'll take a closer look at the dampers. Since there was an Adj FPR on there, ther may be some other shenanigans going on.
Because of that, I'm mentally dismissing the strainer and the filter.
If you used a regulator with the rubber hose fitting, you could have gotten either a '85/'86 regulator or an "early" '87 regulator.....they are exactly the same in appearance. I do not stock the early '87 regulator, because I do not use them, but I went and looked at my inventory and a '85/'86 regulator is a Bosch #0 280 160 215. You should not be using that one, with Ken's chips.
For an 1985/1986 vehicle, the front damper should be a 0 280 161 008. The rear damper should be a 0 280 161 021.
Last edited by GregBBRD; 09-20-2015 at 08:00 PM.
09-21-2015, 09:15 AM
#124
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To me, it seems like if you were having a fuel volume problem, the car would be lean with the stock chips, too. The fact that it is overly rich with the stock chips and the fuel pressure regulator you are using indicates , to me, that there is plenty of available fuel.
Because of that, I'm mentally dismissing the strainer and the filter.
If you used a regulator with the rubber hose fitting, you could have gotten either a '85/'86 regulator or an "early" '87 regulator.....they are exactly the same in appearance. I do not stock the early '87 regulator, because I do not use them, but I went and looked at my inventory and a '85/'86 regulator is a Bosch #0 280 160 215. You should not be using that one, with Ken's chips.
For an 1985/1986 vehicle, the front damper should be a 0 280 161 008. The rear damper should be a 0 280 161 021.
Because of that, I'm mentally dismissing the strainer and the filter.
If you used a regulator with the rubber hose fitting, you could have gotten either a '85/'86 regulator or an "early" '87 regulator.....they are exactly the same in appearance. I do not stock the early '87 regulator, because I do not use them, but I went and looked at my inventory and a '85/'86 regulator is a Bosch #0 280 160 215. You should not be using that one, with Ken's chips.
For an 1985/1986 vehicle, the front damper should be a 0 280 161 008. The rear damper should be a 0 280 161 021.
That's great information.
I know the new FPR is Bosch 0280160262. That's the one spec'd for the 87.
I'll check the dampers later tonight when I get home and report back.
09-21-2015, 04:00 PM
#125
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Obviously there's enough volume to support fuel pressure in the 40's but not 55.
Of course the stock chips would be rich at idle at 40-ish psi, but not as rich as they'd be at 55.
Depending on the weather, high 11's and low 12's are what the stock chips at stock 36 psi often deliver at higher rpms.
Of course the stock chips would be rich at idle at 40-ish psi, but not as rich as they'd be at 55.
Depending on the weather, high 11's and low 12's are what the stock chips at stock 36 psi often deliver at higher rpms.
09-21-2015, 04:41 PM
#126
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Obviously there's enough volume to support fuel pressure in the 40's but not 55.
Of course the stock chips would be rich at idle at 40-ish psi, but not as rich as they'd be at 55.
Depending on the weather, high 11's and low 12's are what the stock chips at stock 36 psi often deliver at higher rpms.
Of course the stock chips would be rich at idle at 40-ish psi, but not as rich as they'd be at 55.
Depending on the weather, high 11's and low 12's are what the stock chips at stock 36 psi often deliver at higher rpms.
I never figured out what made the car I had the issues with so lean, because it was a work in progress and I just moved on, so I never had a fuel pressure gauge on the fuel rail, monitoring fuel pressure while I ran it.
I'm really intrigued to see what the problem is with this car!
As you know, I've used several sets of your chips on other '85/'86 vehicles to "solve" running issues and have been very impressed with how well your chips work at cruise and in the midrange.....without any obvious issues at full throttle.
I'd love to have an explanation of why I had such a severe "lean" condition on that one car....perhaps AO's issue could be the same as the one I had?
09-21-2015, 05:00 PM
#127
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I'll be diving into things later this evening to validate damper part numbers. New filter will be here tomorrow.
Unfortunately, the timing belt light came on yesterday during a quick spin. Everything, looks and sounds fine from a cursory (external) inspection. I'll need to dive into it a bit further to see if anything is amiss, which may delay things slightly. Then I have to travel for work, so we'll see how far I actually get this week.
Unfortunately, the timing belt light came on yesterday during a quick spin. Everything, looks and sounds fine from a cursory (external) inspection. I'll need to dive into it a bit further to see if anything is amiss, which may delay things slightly. Then I have to travel for work, so we'll see how far I actually get this week.
09-21-2015, 06:34 PM
#128
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Obviously there's enough volume to support fuel pressure in the 40's but not 55.
Of course the stock chips would be rich at idle at 40-ish psi, but not as rich as they'd be at 55.
Depending on the weather, high 11's and low 12's are what the stock chips at stock 36 psi often deliver at higher rpms.
Of course the stock chips would be rich at idle at 40-ish psi, but not as rich as they'd be at 55.
Depending on the weather, high 11's and low 12's are what the stock chips at stock 36 psi often deliver at higher rpms.
why does it depend on the weather? is the system totally open loop? no MAF feedback at all? the stock chip and regulators, I found to make about 45psi and was about 13.5 at WOT with a stock engine.
09-21-2015, 06:46 PM
#129
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Unless it's stuck or clogged.
(Or if the front damper was replaced with a FPR, by accident!)
55 psi. 3.8 bar. Jeez. There are so many numbers thrown around in this thread...
Fuel pressure should go up to 55 or more for a while after shutdown with no vacuum and warm fuel. (Spec is 55 ±3 psi, -3 cold, +3 hot.)
(Or if the front damper was replaced with a FPR, by accident!)
55 psi. 3.8 bar. Jeez. There are so many numbers thrown around in this thread...
Fuel pressure should go up to 55 or more for a while after shutdown with no vacuum and warm fuel. (Spec is 55 ±3 psi, -3 cold, +3 hot.)
It is stock, except the chip. I'm a firm believer in Ken's stuff, just unclear why the 87 FPR which is designed to run at 45psi is not working for me. It's brand new. Perhaps it's a bad/wonky FPR?
I;m just glad I took time to check and figure out what was going on.
Thanks! It was a good suggestion.
In a pinch, it works. The biggest issue was the neighbors complaining about the noise. Woops! That car is LOUD!
As I mentioned, it's a brand new Bosch FPR. Not some aftermarket POS. I'd be willing to try a KNOWN good FPR to see if it that is the issue or not. But the important thing, is that the car is now driveable.
I never drove the car on the track with the 14-15:1 issue. I did, however drive it when it was 16-17:1 which just made no power.
Hopefully the motor didn't suffer. Certainly seems okay, but time will tell.
It is weird how the FP rises after shutoff.
I;m just glad I took time to check and figure out what was going on.
Thanks! It was a good suggestion.
In a pinch, it works. The biggest issue was the neighbors complaining about the noise. Woops! That car is LOUD!
As I mentioned, it's a brand new Bosch FPR. Not some aftermarket POS. I'd be willing to try a KNOWN good FPR to see if it that is the issue or not. But the important thing, is that the car is now driveable.
I never drove the car on the track with the 14-15:1 issue. I did, however drive it when it was 16-17:1 which just made no power.
Hopefully the motor didn't suffer. Certainly seems okay, but time will tell.
It is weird how the FP rises after shutoff.
I've fixed cars that had the FPR in the front damper position.
None of those cars would run, at all. The fuel hits the backside of the FPR "seat" and is dead headed....because there is no pressure on the other side to "lift" the seat.
Of course, every time this occurred the FPR was new. Perhaps an old worn out FPR would allow a small amount of fuel to bypass?
I've seen fuel filters that were allowed to "dry out" be very restrictive. And, of course, tank strainers can get so restricted that they won't pass enough fuel. The problem with either of these items is that things tend to get worse, when the car is run. I'd think that the performance of the car would have deteriorated as the day went on, at the track.
Fuel pumps that are restricted from either end tend to be really noisy as they struggle to pass fuel. Does the pump sound like it is straining to pump?
None of those cars would run, at all. The fuel hits the backside of the FPR "seat" and is dead headed....because there is no pressure on the other side to "lift" the seat.
Of course, every time this occurred the FPR was new. Perhaps an old worn out FPR would allow a small amount of fuel to bypass?
I've seen fuel filters that were allowed to "dry out" be very restrictive. And, of course, tank strainers can get so restricted that they won't pass enough fuel. The problem with either of these items is that things tend to get worse, when the car is run. I'd think that the performance of the car would have deteriorated as the day went on, at the track.
Fuel pumps that are restricted from either end tend to be really noisy as they struggle to pass fuel. Does the pump sound like it is straining to pump?
09-21-2015, 06:48 PM
#130
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maybe someone put on the S4 injectors? they are only 19lbs vs the 85-86s being 24lbs.
I have a working spare S4 FR if you really think that is the problem and want to swap/borrow.
Mk
I have a working spare S4 FR if you really think that is the problem and want to swap/borrow.
Mk
09-21-2015, 08:53 PM
#131
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The LH has no air pressure or temperature compensation maps so stock WOT AFRs will be too rich in summer and tending to lean in the winter.
MAFs are do a decent job reading airmass but after many years of non-stop chip tuning I can tell you they are not perfect.
Air pressure makes a big difference in fueling at WOT. Low pressure = lean, high = rich.
The MAF outputs different voltages depending on whether it is hot = lean or cold = rich.
(I don't know if it is because it reads the relative temperature of the sensor wire to the air flowing through it, or if it is the relative temperature of the MAF electronics, or both, or something else. Basically, it sucks to be a tuner guy.
)
As well, there is no gear or speedometer input so AFRs are variable according to the gear ratio.
(Fueling tables are based on RPM vs. MAF. Change one of the variables and you are in the wrong part of the map.)
MAFs are do a decent job reading airmass but after many years of non-stop chip tuning I can tell you they are not perfect.
Air pressure makes a big difference in fueling at WOT. Low pressure = lean, high = rich.
The MAF outputs different voltages depending on whether it is hot = lean or cold = rich.
(I don't know if it is because it reads the relative temperature of the sensor wire to the air flowing through it, or if it is the relative temperature of the MAF electronics, or both, or something else. Basically, it sucks to be a tuner guy.
)As well, there is no gear or speedometer input so AFRs are variable according to the gear ratio.
(Fueling tables are based on RPM vs. MAF. Change one of the variables and you are in the wrong part of the map.)
09-21-2015, 09:05 PM
#132
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OK... I hate to disappoint, but:
FPR is a Bosch # 0 280 160 262 ('87 S4 FPR)
Front Damper is Bosch # 0 280 161 008
Rear Damper is Bosch # 0 280 161 021
So that's not it. Next hypothesis, please.
I initially suspected that too and even posted a picture to confirm. Ken confirmed they were 24#, and the evidence confirms it's not an injector issue. It has to be a pressure/flow issue.
The fuel rail gauge clearly shows that the pressure is less that the spec'd 45-50psi. and the WBO2 also shows it to be lean. So there are 2 forms of evidence to support that the fuel is not being delivered - one at the input, and one at the output. If the evidence was only at the end, then I would still suspect the injectors, but it has to be upstream of the FPR, or the FPR itself.
I'm quite certain if I were making the fuel pressure that I should be, it would not be running lean with Ken's chips.
The dampers are the correct part numbers and the FPR is brand new. I suppose it could be a bad FPR. Interestingly, when I swapped the new pump in, I pressurized things to check for leaks and to see if I got better pressure. Static pressure (car off, pump running) was ~55psi. Does that sound right?
So it's got to be either a filter issue or some other restriction in the line. The new filter did not show up today, so maybe tomorrow.
FPR is a Bosch # 0 280 160 262 ('87 S4 FPR)
Front Damper is Bosch # 0 280 161 008
Rear Damper is Bosch # 0 280 161 021
So that's not it. Next hypothesis, please.
The fuel rail gauge clearly shows that the pressure is less that the spec'd 45-50psi. and the WBO2 also shows it to be lean. So there are 2 forms of evidence to support that the fuel is not being delivered - one at the input, and one at the output. If the evidence was only at the end, then I would still suspect the injectors, but it has to be upstream of the FPR, or the FPR itself.
I'm quite certain if I were making the fuel pressure that I should be, it would not be running lean with Ken's chips.
The dampers are the correct part numbers and the FPR is brand new. I suppose it could be a bad FPR. Interestingly, when I swapped the new pump in, I pressurized things to check for leaks and to see if I got better pressure. Static pressure (car off, pump running) was ~55psi. Does that sound right?
So it's got to be either a filter issue or some other restriction in the line. The new filter did not show up today, so maybe tomorrow.
09-21-2015, 09:10 PM
#133
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The fuel rail gauge clearly shows that the pressure is less that the spec'd 45-50psi. and the WBO2 also shows it to be lean.
The dampers are the correct part numbers and the FPR is brand new. I suppose it could be a bad FPR. Interestingly, when I swapped the new pump in, I pressurized things to check for leaks and to see if I got better pressure. Static pressure (car off, pump running) was ~55psi. Does that sound right?
The dampers are the correct part numbers and the FPR is brand new. I suppose it could be a bad FPR. Interestingly, when I swapped the new pump in, I pressurized things to check for leaks and to see if I got better pressure. Static pressure (car off, pump running) was ~55psi. Does that sound right?
Front damper could still be fubared? Got-a-spare?
55 is correct, warm-not-super-hot engine, engine off, relay jumpered.
09-21-2015, 09:23 PM
#134
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Left field, but...how about a blocked or restricted vent (carbon cannister) hose?
Wasn't the car smooshed on the front right corner?
On a race car the vent system should look like below or even better just a 'U' at the firewall to connect the to and from lines. Chuck/cap everything else.
(The vent line dumps/breathes behind the center of the rear aluminum bumper.)
Wasn't the car smooshed on the front right corner?
On a race car the vent system should look like below or even better just a 'U' at the firewall to connect the to and from lines. Chuck/cap everything else.
(The vent line dumps/breathes behind the center of the rear aluminum bumper.)
Last edited by PorKen; 09-21-2015 at 09:41 PM.
